<?php
declare(strict_types=1);

$controlApiLibrary = defined('CONTROL_API_LIBRARY') && CONTROL_API_LIBRARY;

if (!$controlApiLibrary && session_status() !== PHP_SESSION_ACTIVE) {
    session_start();
}

require_once __DIR__ . '/../config/config.php';

if (!$controlApiLibrary && !signed_in()) {
    json_out([
        'ok' => false,
        'error' => 'login_required',
    ], 401);
}

function bytes_human(int|float $bytes): string
{
    $units = ['B', 'KB', 'MB', 'GB', 'TB'];
    $v = (float)$bytes;
    $i = 0;

    while ($v >= 1024 && $i < count($units) - 1) {
        $v /= 1024;
        $i++;
    }

    return ($i === 0 ? (string)(int)$v : number_format($v, 2)) . ' ' . $units[$i];
}

function command_short(string $value, int $limit = 120): string
{
    $value = trim(preg_replace('/\s+/', ' ', $value) ?? '');

    if ($value === '') {
        return 'N/A';
    }

    return mb_strlen($value) > $limit
        ? mb_substr($value, 0, $limit - 1) . '...'
        : $value;
}

function human_seconds(int $s): string
{
    $d = intdiv($s, 86400);
    $s %= 86400;

    $h = intdiv($s, 3600);
    $s %= 3600;

    $m = intdiv($s, 60);

    return ($d > 0 ? $d . 'd ' : '') . sprintf('%02dh %02dm', $h, $m);
}

function human_remaining_seconds(int $seconds): string
{
    if ($seconds <= 0) {
        return '-';
    }

    $hours = intdiv($seconds, 3600);
    $minutes = intdiv($seconds % 3600, 60);

    if ($hours > 0) {
        return sprintf('%dh %02dm', $hours, $minutes);
    }

    return sprintf('%dm', max(1, $minutes));
}

function dmesg_log(): array
{
    $path = '/tmp/dmesg.log';

    if (!is_readable($path)) {
        return [
            'path' => $path,
            'available' => false,
            'lines' => [],
            'line_count' => 0,
            'size_bytes' => 0,
            'updated_at' => null,
            'message' => 'dmesg log is not available yet.',
        ];
    }

    $size = filesize($path) ?: 0;
    $chunk = file_get_contents($path);
    if ($chunk === false) {
        return [
            'path' => $path,
            'available' => false,
            'lines' => [],
            'line_count' => 0,
            'size_bytes' => $size,
            'updated_at' => null,
            'message' => 'failed to open dmesg log.',
        ];
    }

    $lines = array_values(array_filter(
        preg_split('/\R/', $chunk) ?: [],
        static fn($line): bool => trim((string)$line) !== ''
    ));

    return [
        'path' => $path,
        'available' => true,
        'lines' => array_reverse($lines),
        'line_count' => count($lines),
        'size_bytes' => $size,
        'updated_at' => date('Y-m-d H:i:s', filemtime($path) ?: time()),
    ];
}

function throttled_event_status(?int $flags, string $raw, int $activeBit, int $seenBit, string $statePath): array
{
    $now = time();
    $windowSeconds = 600;
    $recoverySeconds = 300;
    $active = $flags !== null && (bool)($flags & $activeBit);
    $seen = $flags !== null && (bool)($flags & $seenBit);

    if (is_file($statePath) && !is_writable($statePath)) {
        @chmod($statePath, 0666);
    }

    $state = [
        'active' => false,
        'active_since' => null,
        'last_detected_at' => null,
        'last_cleared_at' => null,
        'last_duration_seconds' => 0,
        'updated_at' => null,
        'events' => [],
    ];

    $fp = @fopen($statePath, 'c+');
    if ($fp !== false) {
        @chmod($statePath, 0666);
        @flock($fp, LOCK_EX);
        $saved = stream_get_contents($fp);
        $decoded = json_decode((string)$saved, true);
        if (is_array($decoded)) {
            $state = array_merge($state, array_intersect_key($decoded, $state));
        }
        $state['events'] = array_values(array_filter(
            is_array($state['events'] ?? null) ? $state['events'] : [],
            static fn($event): bool => is_array($event) && is_numeric($event['start'] ?? null)
        ));

        $wasActive = !empty($state['active']);
        $activeSince = is_numeric($state['active_since'] ?? null) ? (int)$state['active_since'] : null;

        if ($flags !== null) {
            if ($active) {
                if (!$wasActive || $activeSince === null) {
                    $activeSince = $now;
                    $state['last_detected_at'] = $now;
                    $state['events'][] = [
                        'start' => $now,
                        'end' => null,
                        'duration_seconds' => 0,
                    ];
                }
                $state['active'] = true;
                $state['active_since'] = $activeSince;
            } else {
                if ($wasActive && $activeSince !== null) {
                    $state['last_cleared_at'] = $now;
                    $state['last_duration_seconds'] = max(0, $now - $activeSince);
                    $lastIndex = count($state['events']) - 1;
                    if ($lastIndex >= 0 && empty($state['events'][$lastIndex]['end'])) {
                        $state['events'][$lastIndex]['end'] = $now;
                        $state['events'][$lastIndex]['duration_seconds'] = $state['last_duration_seconds'];
                    } else {
                        $state['events'][] = [
                            'start' => $activeSince,
                            'end' => $now,
                            'duration_seconds' => $state['last_duration_seconds'],
                        ];
                    }
                }
                $state['active'] = false;
                $state['active_since'] = null;
            }

            $keepAfter = $now - 86400;
            $state['events'] = array_slice(array_values(array_filter(
                $state['events'],
                static function ($event) use ($keepAfter, $now): bool {
                    $start = (int)($event['start'] ?? 0);
                    $end = is_numeric($event['end'] ?? null) ? (int)$event['end'] : $now;
                    return $start > 0 && max($start, $end) >= $keepAfter;
                }
            )), -200);

            $state['updated_at'] = $now;
            ftruncate($fp, 0);
            rewind($fp);
            fwrite($fp, json_encode($state, JSON_UNESCAPED_SLASHES));
            fflush($fp);
            @chmod($statePath, 0666);
        }

        @flock($fp, LOCK_UN);
        fclose($fp);
    }

    $duration = 0;
    if ($active && is_numeric($state['active_since'] ?? null)) {
        $duration = max(0, $now - (int)$state['active_since']);
    } elseif (is_numeric($state['last_duration_seconds'] ?? null)) {
        $duration = max(0, (int)$state['last_duration_seconds']);
    }

    $dateValue = static fn($ts): ?string => is_numeric($ts) && (int)$ts > 0
        ? date('Y-m-d H:i:s', (int)$ts)
        : null;

    $windowStart = $now - $windowSeconds;
    $recentCount = 0;
    $recentActiveSeconds = 0;
    $events = is_array($state['events'] ?? null) ? $state['events'] : [];
    foreach ($events as $event) {
        if (!is_array($event) || !is_numeric($event['start'] ?? null)) {
            continue;
        }
        $start = (int)$event['start'];
        $end = is_numeric($event['end'] ?? null) ? (int)$event['end'] : $now;
        if ($end < $windowStart || $start > $now) {
            continue;
        }
        $overlapStart = max($start, $windowStart);
        $overlapEnd = min(max($end, $overlapStart), $now);
        if ($overlapEnd > $overlapStart) {
            $recentCount++;
            $recentActiveSeconds += $overlapEnd - $overlapStart;
        }
    }

    $lastClearedAt = is_numeric($state['last_cleared_at'] ?? null) ? (int)$state['last_cleared_at'] : null;
    $recovering = !$active && $lastClearedAt !== null && ($now - $lastClearedAt) <= $recoverySeconds;
    $repeated = $recentCount >= 2;
    $stateLabel = 'normal';
    if ($active) {
        $stateLabel = 'active';
    } elseif ($repeated) {
        $stateLabel = 'repeated';
    } elseif ($recovering) {
        $stateLabel = 'recovering';
    }

    return [
        'available' => $flags !== null,
        'raw' => $raw,
        'flags' => $flags,
        'active' => $active,
        'seen_since_boot' => $seen,
        'active_since' => $dateValue($state['active_since'] ?? null),
        'last_detected_at' => $dateValue($state['last_detected_at'] ?? null),
        'last_cleared_at' => $dateValue($state['last_cleared_at'] ?? null),
        'duration_seconds' => $duration,
        'last_duration_seconds' => (int)($state['last_duration_seconds'] ?? 0),
        'updated_at' => $dateValue($state['updated_at'] ?? null),
        'state_label' => $stateLabel,
        'recovering' => $recovering,
        'repeated_recently' => $repeated,
        'recovery_window_seconds' => $recoverySeconds,
        'recent_window_seconds' => $windowSeconds,
        'recent_event_count' => $recentCount,
        'recent_active_seconds' => $recentActiveSeconds,
        'recent_active_percent' => round($recentActiveSeconds / $windowSeconds * 100, 1),
    ];
}

function read_throttled_flags(): array
{
    $result = sh(['/usr/bin/vcgencmd', 'get_throttled'], false, 3);
    $raw = trim((string)$result['out']);
    $flags = null;
    $source = 'direct';

    if ((int)$result['code'] === 0 && preg_match('/throttled=0x([0-9a-f]+)/i', $raw, $m)) {
        $flags = hexdec($m[1]);
    }

    if ($flags === null) {
        $sudoResult = sh(['/usr/bin/vcgencmd', 'get_throttled'], true, 3);
        $sudoRaw = trim((string)$sudoResult['out']);
        if ((int)$sudoResult['code'] === 0 && preg_match('/throttled=0x([0-9a-f]+)/i', $sudoRaw, $m)) {
            $result = $sudoResult;
            $raw = $sudoRaw;
            $flags = hexdec($m[1]);
            $source = 'sudo';
        }
    }

    return [
        'result' => $result,
        'raw' => $raw,
        'flags' => $flags,
        'source' => $source,
    ];
}

function throttled_statuses(): array
{
    $read = read_throttled_flags();
    $raw = (string)$read['raw'];
    $flags = $read['flags'];
    $source = (string)$read['source'];

    $lowVoltage = throttled_event_status($flags, $raw, 0x1, 0x10000, '/tmp/control-low-voltage-state.json');
    $throttling = throttled_event_status($flags, $raw, 0x4, 0x40000, '/tmp/control-throttling-state.json');

    $lowVoltage['source'] = $source;
    $lowVoltage['freq_capped'] = $flags !== null && (bool)($flags & 0x2);
    $lowVoltage['throttled'] = $flags !== null && (bool)($flags & 0x4);
    $lowVoltage['soft_temp_limit'] = $flags !== null && (bool)($flags & 0x8);
    $throttling['source'] = $source;
    $throttling['low_voltage'] = $flags !== null && (bool)($flags & 0x1);
    $throttling['freq_capped'] = $flags !== null && (bool)($flags & 0x2);
    $throttling['soft_temp_limit'] = $flags !== null && (bool)($flags & 0x8);

    return [
        'low_voltage' => $lowVoltage,
        'throttling' => $throttling,
    ];
}

function low_voltage_status(): array
{
    return throttled_statuses()['low_voltage'];
}

function fan_paths(): array
{
    $candidates = glob('/sys/devices/platform/cooling_fan/hwmon/hwmon*/pwm1') ?: [];
    $candidates = array_merge(
        $candidates,
        glob('/sys/class/hwmon/hwmon*/pwm1') ?: []
    );

    foreach ($candidates as $pwm) {
        $dir = dirname($pwm);

        return [
            'base' => $dir,
            'pwm' => $pwm,
            'enable' => $dir . '/pwm1_enable',
            'rpm' => $dir . '/fan1_input',
            'name' => first_readable([$dir . '/name']) ?: 'cooling_fan',
        ];
    }

    return [
        'base' => 'N/A',
        'pwm' => 'N/A',
        'enable' => 'N/A',
        'rpm' => 'N/A',
        'name' => 'N/A',
    ];
}

function read_int_file(string $file): int
{
    if ($file === '' || $file === 'N/A' || !is_readable($file)) {
        return 0;
    }

    $raw = trim((string)@file_get_contents($file));

    return is_numeric($raw) ? (int)$raw : 0;
}

function cpu_temp(): float
{
    $raw = first_readable([
        '/sys/class/thermal/thermal_zone0/temp',
        '/sys/devices/virtual/thermal/thermal_zone0/temp',
    ]);

    if ($raw !== '' && is_numeric($raw)) {
        return round(((float)$raw) / 1000, 2);
    }

    $vc = sh(['/usr/bin/vcgencmd', 'measure_temp'], false, 3)['out'];

    if (preg_match('/([0-9.]+)/', $vc, $m)) {
        return round((float)$m[1], 2);
    }

    return 0.0;
}

function fan_target_pwm(float $temp): int
{
    if ($temp >= 80) {
        return 255;
    }

    if ($temp <= 50) {
        return 0;
    }

    $ratio = ($temp - 50) / 30;

    return max(0, min(255, (int)round($ratio * 255)));
}

function fan_ramped_pwm(int $current, int $desired, float $temp): int
{
    if ($temp >= 80) {
        return $desired;
    }

    if ($desired > $current) {
        return min($desired, $current + 2);
    }

    if ($desired < $current) {
        return max($desired, $current - 2);
    }

    return $desired;
}

function write_sys_value(string $path, int $value): bool
{
    if ($path === '' || $path === 'N/A') {
        return false;
    }

    if (@file_put_contents($path, $value . "\n", LOCK_EX) !== false) {
        return true;
    }

    $cmd = 'printf ' . escapeshellarg($value . "\n") . ' > ' . escapeshellarg($path);
    return sh(['/bin/sh', '-lc', $cmd], true, 5)['code'] === 0;
}

function apply_fan_policy(): array
{
    $state = get_control_state();
    $paths = fan_paths();

    $temp = cpu_temp();

    $mode = (string)($state['mode'] ?? 'auto');
    if (!in_array($mode, ['auto', 'manual', 'off'], true)) {
        $mode = 'auto';
    }

    $manualPwm = max(0, min(255, (int)($state['manual_pwm'] ?? 120)));

    $currentPwm = read_int_file($paths['pwm']);
    $desired = match ($mode) {
        'manual' => $manualPwm,
        'off' => 0,
        default => fan_target_pwm($temp),
    };
    $target = $mode === 'auto'
        ? fan_ramped_pwm($currentPwm, $desired, $temp)
        : $desired;

    $enableOk = write_sys_value($paths['enable'], $mode === 'off' ? 0 : 1);
    $pwmOk = write_sys_value($paths['pwm'], $target);

    usleep(60000);

    $actualPwm = read_int_file($paths['pwm']);

    $rpm = read_int_file($paths['rpm']);

    return [
        'mode' => $mode,
        'target_pwm' => $target,
        'actual_pwm' => $actualPwm,
        'temp_c' => $temp,
        'rpm' => $rpm,
        'ok' => $enableOk && $pwmOk,
        'paths' => $paths,
        'enable_value' => first_readable([$paths['enable']]) ?: 'N/A',
    ];
}

function mem_info(): array
{
    $rows = [];

    foreach (@file('/proc/meminfo', FILE_IGNORE_NEW_LINES) ?: [] as $line) {
        if (preg_match('/^([^:]+):\s+(\d+)/', $line, $m)) {
            $rows[$m[1]] = (int)$m[2];
        }
    }

    $total = (int)($rows['MemTotal'] ?? 0);
    $available = (int)($rows['MemAvailable'] ?? 0);
    $used = max(0, $total - $available);

    $swapTotal = (int)($rows['SwapTotal'] ?? 0);
    $swapFree = (int)($rows['SwapFree'] ?? 0);

    return [
        'total_mb' => round($total / 1024),
        'used_mb' => round($used / 1024),
        'free_mb' => round($available / 1024),
        'percent' => $total > 0 ? round($used / $total * 100, 1) : 0,
        'swap_total_mb' => round($swapTotal / 1024),
        'swap_used_mb' => round(max(0, $swapTotal - $swapFree) / 1024),
    ];
}

function disk_info(string $path = '/var/www/control'): array
{
    $total = @disk_total_space($path) ?: 0;
    $free = @disk_free_space($path) ?: 0;

    if ($total <= 0 || $free <= 0) {
        $out = trim(sh(['/bin/df', '-kP', $path], false, 3)['out']);
        $lines = preg_split('/\R/', $out);
        $parts = isset($lines[1]) ? preg_split('/\s+/', trim($lines[1])) : [];

        if (count($parts) >= 6) {
            $total = (int)$parts[1] * 1024;
            $free = (int)$parts[3] * 1024;
        }
    }

    $used = max(0, $total - $free);

    return [
        'path' => '/',
        'total_kb' => (int)round($total / 1024),
        'used_kb' => (int)round($used / 1024),
        'free_kb' => (int)round($free / 1024),
        'percent' => $total > 0 ? round($used / $total * 100, 1) : 0,
    ];
}

function active_user_info(): array
{
    $out = trim(sh(['/usr/bin/who'], false, 3)['out']);

    if ($out === '') {
        return [
            'users' => 0,
            'sessions' => 0,
            'names' => '',
            'display' => '0 users / 0 sessions',
        ];
    }

    $lines = preg_split('/\R/', $out) ?: [];
    $lines = array_values(array_filter($lines, fn($line) => trim($line) !== ''));

    $names = [];

    foreach ($lines as $line) {
        $parts = preg_split('/\s+/', trim($line));
        if (!empty($parts[0])) {
            $names[$parts[0]] = true;
        }
    }

    $userNames = array_keys($names);

    return [
        'users' => count($userNames),
        'sessions' => count($lines),
        'names' => implode(', ', $userNames),
        'display' => count($userNames) . ' users / ' . count($lines) . ' sessions',
    ];
}

function os_info(): array
{
    $os = [];

    foreach (@file('/etc/os-release', FILE_IGNORE_NEW_LINES) ?: [] as $line) {
        if (preg_match('/^([A-Z_]+)=(.*)$/', $line, $m)) {
            $os[$m[1]] = trim($m[2], '"');
        }
    }

    $uptimeRaw = trim((string)@file_get_contents('/proc/uptime'));
    $uptimeSec = $uptimeRaw !== ''
        ? (int)floor((float)explode(' ', $uptimeRaw)[0])
        : 0;

    return [
        'hostname' => gethostname() ?: 'N/A',
        'os' => $os['PRETTY_NAME'] ?? 'N/A',
        'kernel' => php_uname('r'),
        'arch' => php_uname('m'),
        'model' => trim(@file_get_contents('/proc/device-tree/model') ?: '') ?: 'N/A',
        'uptime' => human_seconds($uptimeSec),
        'uptime_seconds' => $uptimeSec,
    ];
}

function network_info(): array
{
    $rows = [];

    foreach (glob('/sys/class/net/*') ?: [] as $dir) {
        $name = basename($dir);

        if ($name === 'lo') {
            continue;
        }

        $rx = (int)first_readable([$dir . '/statistics/rx_bytes']);
        $tx = (int)first_readable([$dir . '/statistics/tx_bytes']);

        $rows[] = [
            'name' => $name,
            'state' => first_readable([$dir . '/operstate']) ?: 'unknown',
            'carrier' => first_readable([$dir . '/carrier']) === '1' ? 'up' : 'down',
            'mac' => first_readable([$dir . '/address']) ?: 'N/A',
            'mtu' => first_readable([$dir . '/mtu']) ?: 'N/A',
            'rx_bytes' => $rx,
            'tx_bytes' => $tx,
            'rx_human' => bytes_human($rx),
            'tx_human' => bytes_human($tx),
            'ipv4' => trim(sh(['/usr/sbin/ip', '-4', '-o', 'addr', 'show', 'dev', $name], false, 3)['out']) ?: 'N/A',
        ];
    }

    return $rows;
}

function latest_sensor(): array
{
    $stmt = db()->query("
        SELECT *
        FROM sensor_logs
        ORDER BY id DESC
        LIMIT 1
    ");

    return $stmt->fetch() ?: [];
}

function sensor_history(int $limit = 240): array
{
    $limit = max(1, min(1500, $limit));

    $stmt = db()->query("
        SELECT
            sl.recorded_at AS time,
            sl.cpu_temp_c AS temp_c,
            sl.fan_rpm,
            sl.fan_efficiency,
            sl.rp1_temp_c,
            sl.cpu_voltage,
            sl.cpu_watts,
            sl.battery_voltage,
            sl.battery_percent,
            sl.pwm_value AS fan_pwm,
            sl.pwm_percent,
            sl.pwm_mode,
            sl.cpu_load_1,
            sl.cpu_load_5,
            sl.cpu_load_15,
            sl.disk_total_kb,
            sl.disk_used_kb,
            sl.disk_free_kb,
            sl.mem_total_mb,
            sl.mem_used_mb,
            CASE
                WHEN sl.mem_total_mb > 0 THEN ROUND(sl.mem_used_mb / sl.mem_total_mb * 100, 1)
                ELSE 0
            END AS mem_percent
        FROM sensor_logs sl
        ORDER BY sl.id DESC
        LIMIT {$limit}
    ");

    return array_reverse($stmt->fetchAll());
}

function numeric_median(array $values): ?float
{
    $numbers = [];
    foreach ($values as $value) {
        if ($value !== null && $value !== '' && is_numeric($value)) {
            $numbers[] = (float)$value;
        }
    }

    if ($numbers === []) {
        return null;
    }

    sort($numbers, SORT_NUMERIC);
    $count = count($numbers);
    $mid = intdiv($count, 2);

    return ($count % 2) === 1
        ? $numbers[$mid]
        : ($numbers[$mid - 1] + $numbers[$mid]) / 2;
}

function numeric_trimmed_average(array $values, float $trimRatio = 0.1): ?float
{
    $numbers = [];
    foreach ($values as $value) {
        if ($value !== null && $value !== '' && is_numeric($value)) {
            $number = (float)$value;
            if ($number > 0) {
                $numbers[] = $number;
            }
        }
    }

    if ($numbers === []) {
        return null;
    }

    sort($numbers, SORT_NUMERIC);
    $trim = (int)floor(count($numbers) * max(0.0, min(0.4, $trimRatio)));
    if ($trim > 0 && count($numbers) > ($trim * 2 + 2)) {
        $numbers = array_slice($numbers, $trim, count($numbers) - ($trim * 2));
    }

    return array_sum($numbers) / count($numbers);
}

function clamp_float(float $value, float $min, float $max): float
{
    return max($min, min($max, $value));
}

function battery_trend_history(int $hours = 24): array
{
    $hours = max(1, min(48, $hours));
    static $cache = [];
    $cacheKey = (string)$hours;
    $now = time();

    if (
        isset($cache[$cacheKey])
        && ($now - (int)$cache[$cacheKey]['time']) < 55
        && is_array($cache[$cacheKey]['rows'])
    ) {
        return $cache[$cacheKey]['rows'];
    }

    $stmt = db()->query("
        SELECT
            FLOOR(UNIX_TIMESTAMP(recorded_at) / 60) AS bucket,
            MIN(recorded_at) AS time,
            AVG(battery_percent) AS battery_percent,
            AVG(battery_voltage) AS battery_voltage,
            AVG(cpu_watts) AS cpu_watts,
            AVG(cpu_load_1) AS cpu_load_1,
            COUNT(*) AS samples
        FROM sensor_logs FORCE INDEX (idx_recorded_at)
        WHERE recorded_at >= DATE_SUB(NOW(), INTERVAL {$hours} HOUR)
            AND battery_percent IS NOT NULL
        GROUP BY bucket
        ORDER BY bucket ASC
    ");

    $rows = [];
    foreach ($stmt->fetchAll() as $row) {
        $time = strtotime((string)($row['time'] ?? ''));
        if ($time <= 0 || !is_numeric($row['battery_percent'] ?? null)) {
            continue;
        }

        $rows[] = [
            'time' => $time,
            'battery_percent' => (float)$row['battery_percent'],
            'battery_voltage' => is_numeric($row['battery_voltage'] ?? null) ? (float)$row['battery_voltage'] : null,
            'cpu_watts' => is_numeric($row['cpu_watts'] ?? null) ? (float)$row['cpu_watts'] : null,
            'cpu_load_1' => is_numeric($row['cpu_load_1'] ?? null) ? (float)$row['cpu_load_1'] : null,
            'samples' => (int)($row['samples'] ?? 0),
        ];
    }

    $cache[$cacheKey] = [
        'time' => $now,
        'rows' => $rows,
    ];

    return $rows;
}

function battery_profile_history(int $days = 45): array
{
    $days = max(3, min(90, $days));
    static $cache = [];
    $cacheKey = (string)$days;
    $now = time();
    $cacheFile = sys_get_temp_dir() . '/control-battery-profile-' . $days . 'd.json';

    if (
        isset($cache[$cacheKey])
        && ($now - (int)$cache[$cacheKey]['time']) < 600
        && is_array($cache[$cacheKey]['rows'])
    ) {
        return $cache[$cacheKey]['rows'];
    }

    if (is_readable($cacheFile)) {
        $raw = @file_get_contents($cacheFile);
        $decoded = is_string($raw) ? json_decode($raw, true) : null;
        if (
            is_array($decoded)
            && isset($decoded['created_at'], $decoded['rows'])
            && is_array($decoded['rows'])
            && ($now - (int)$decoded['created_at']) < 21600
        ) {
            $cache[$cacheKey] = [
                'time' => $now,
                'rows' => $decoded['rows'],
            ];
            return $decoded['rows'];
        }
    }

    $maxId = (int)db()->query("SELECT MAX(id) FROM sensor_logs")->fetchColumn();
    $minId = max(1, $maxId - 3000000);

    $stmt = db()->query("
        SELECT
            recorded_at AS time,
            battery_percent,
            battery_voltage,
            cpu_watts,
            cpu_load_1,
            1 AS samples
        FROM sensor_logs FORCE INDEX (idx_recorded_at)
        WHERE recorded_at >= DATE_SUB(NOW(), INTERVAL {$days} DAY)
            AND battery_percent IS NOT NULL
            AND id >= {$minId}
            AND MOD(id, 300) = 0
        ORDER BY recorded_at ASC
    ");

    $rows = [];
    foreach ($stmt->fetchAll() as $row) {
        $time = strtotime((string)($row['time'] ?? ''));
        if ($time <= 0 || !is_numeric($row['battery_percent'] ?? null)) {
            continue;
        }

        $rows[] = [
            'time' => $time,
            'battery_percent' => (float)$row['battery_percent'],
            'battery_voltage' => is_numeric($row['battery_voltage'] ?? null) ? (float)$row['battery_voltage'] : null,
            'cpu_watts' => is_numeric($row['cpu_watts'] ?? null) ? (float)$row['cpu_watts'] : null,
            'cpu_load_1' => is_numeric($row['cpu_load_1'] ?? null) ? (float)$row['cpu_load_1'] : null,
            'samples' => (int)($row['samples'] ?? 0),
        ];
    }

    $cache[$cacheKey] = [
        'time' => $now,
        'rows' => $rows,
    ];
    @file_put_contents(
        $cacheFile,
        json_encode([
            'created_at' => $now,
            'days' => $days,
            'rows' => $rows,
        ], JSON_UNESCAPED_UNICODE)
    );

    return $rows;
}

function battery_trend_candidate(array $trendRows, float $currentPercent, int $windowSeconds, ?float $recentWatts): ?array
{
    if (count($trendRows) < 6) {
        return null;
    }

    $lastTime = (int)$trendRows[count($trendRows) - 1]['time'];
    $rows = array_values(array_filter($trendRows, static function (array $row) use ($lastTime, $windowSeconds): bool {
        return (int)$row['time'] >= ($lastTime - $windowSeconds)
            && is_numeric($row['battery_percent'] ?? null);
    }));

    $count = count($rows);
    if ($count < 6) {
        return null;
    }

    $first = $rows[0];
    $last = $rows[$count - 1];
    $elapsed = max(1, (int)$last['time'] - (int)$first['time']);
    if ($elapsed < 600) {
        return null;
    }

    $edgeCount = max(3, min(10, (int)floor($count * 0.12)));
    $startSoc = numeric_median(array_column(array_slice($rows, 0, $edgeCount), 'battery_percent'));
    $endSoc = numeric_median(array_column(array_slice($rows, -$edgeCount), 'battery_percent'));
    if ($startSoc === null || $endSoc === null) {
        return null;
    }

    $drop = $startSoc - $endSoc;
    $minDrop = $windowSeconds <= 3600 ? 0.12 : 0.22;
    if ($drop < $minDrop) {
        return null;
    }

    $rate = $drop / $elapsed;
    if ($rate <= 0) {
        return null;
    }

    $windowWatts = numeric_trimmed_average(array_column($rows, 'cpu_watts'), 0.1);
    $loadFactor = 1.0;
    if ($recentWatts !== null && $recentWatts > 0 && $windowWatts !== null && $windowWatts > 0) {
        $loadFactor = 1 + ((clamp_float($recentWatts / $windowWatts, 0.65, 1.75) - 1) * 0.45);
        $rate *= $loadFactor;
    }

    $seconds = (int)round($currentPercent / $rate);
    if ($seconds <= 0) {
        return null;
    }

    $confidence = min(1.0, $elapsed / $windowSeconds)
        * min(1.0, $drop / 1.2)
        * min(1.0, $count / 90);

    return [
        'seconds' => $seconds,
        'rate_per_second' => $rate,
        'drop_percent' => round($drop, 3),
        'elapsed_seconds' => $elapsed,
        'window_seconds' => $windowSeconds,
        'sample_count' => $count,
        'confidence' => round($confidence, 4),
        'weight' => max(0.05, $confidence),
        'avg_watts' => $windowWatts === null ? null : round($windowWatts, 3),
        'load_factor' => round($loadFactor, 3),
        'source' => 'recent_window',
    ];
}

function battery_learned_profile_candidate(array $profileRows, float $currentPercent, ?float $recentWatts): ?array
{
    if (count($profileRows) < 24) {
        return null;
    }

    $now = time();
    $rates = [];
    $dropSum = 0.0;
    $sampleSum = 0;
    $socBuckets = [];
    $minSoc = max(0.0, $currentPercent - 70.0);
    $maxSoc = min(100.0, $currentPercent + 8.0);

    for ($i = 1, $count = count($profileRows); $i < $count; $i++) {
        $prev = $profileRows[$i - 1];
        $row = $profileRows[$i];
        $elapsed = (int)$row['time'] - (int)$prev['time'];
        if ($elapsed < 240 || $elapsed > 900) {
            continue;
        }

        $startSoc = (float)$prev['battery_percent'];
        $endSoc = (float)$row['battery_percent'];
        $avgSoc = ($startSoc + $endSoc) / 2;
        if ($avgSoc < $minSoc || $avgSoc > $maxSoc) {
            continue;
        }

        $drop = $startSoc - $endSoc;
        if ($drop < 0.03 || $drop > 8.0) {
            continue;
        }

        $avgWatts = numeric_trimmed_average([$prev['cpu_watts'] ?? null, $row['cpu_watts'] ?? null], 0.0);
        $loadFactor = 1.0;
        if ($recentWatts !== null && $recentWatts > 0 && $avgWatts !== null && $avgWatts > 0) {
            $loadFactor = 1 + ((clamp_float($recentWatts / $avgWatts, 0.55, 1.95) - 1) * 0.5);
        }

        $socDistance = abs($currentPercent - $avgSoc);
        $socWeight = 1 / (1 + ($socDistance / 18));
        $ageDays = max(0.0, ($now - (int)$row['time']) / 86400);
        $recencyWeight = 1 / (1 + ($ageDays / 45));
        $sampleWeight = min(1.0, max(1, ((int)$prev['samples'] + (int)$row['samples']) / 2) / 30);
        $weight = max(0.01, $socWeight * $recencyWeight * $sampleWeight);

        $rates[] = [
            'rate' => ($drop / $elapsed) * $loadFactor,
            'weight' => $weight,
            'soc' => $avgSoc,
            'drop' => $drop,
            'watts' => $avgWatts,
        ];
        $dropSum += $drop;
        $sampleSum += (int)$prev['samples'] + (int)$row['samples'];
        $bucket = (int)(floor($avgSoc / 10) * 10);
        $socBuckets[$bucket] = true;
    }

    if (count($rates) < 12 || $dropSum < 1.0) {
        return null;
    }

    $weightedRate = 0.0;
    $weightSum = 0.0;
    foreach ($rates as $row) {
        $weightedRate += (float)$row['rate'] * (float)$row['weight'];
        $weightSum += (float)$row['weight'];
    }

    if ($weightedRate <= 0 || $weightSum <= 0) {
        return null;
    }

    $rate = $weightedRate / $weightSum;
    $seconds = (int)round($currentPercent / $rate);
    if ($seconds <= 0) {
        return null;
    }

    $watts = numeric_trimmed_average(array_column($rates, 'watts'), 0.1);
    $confidence = min(1.0, count($rates) / 240)
        * min(1.0, $dropSum / 18)
        * min(1.0, count($socBuckets) / 5);

    return [
        'seconds' => $seconds,
        'rate_per_second' => $rate,
        'drop_percent' => round($dropSum, 3),
        'elapsed_seconds' => null,
        'window_seconds' => null,
        'sample_count' => $sampleSum,
        'confidence' => round($confidence, 4),
        'weight' => max(0.05, $confidence * 0.9),
        'avg_watts' => $watts === null ? null : round($watts, 3),
        'load_factor' => null,
        'source' => 'learned_profile',
        'intervals' => count($rates),
        'soc_buckets' => count($socBuckets),
    ];
}

function battery_power_fallback_estimate(float $percent, array $history): array
{
    $wattValues = [];

    foreach (array_slice($history, -180) as $row) {
        $watts = $row['cpu_watts'] ?? null;
        if ($watts !== null && $watts !== '' && is_numeric($watts) && (float)$watts > 0) {
            $wattValues[] = (float)$watts;
        }
    }

    $avgWatts = numeric_trimmed_average($wattValues, 0.12);
    if (BATTERY_CAPACITY_WH > 0 && $avgWatts !== null && $avgWatts > 0) {
        $remainingWh = BATTERY_CAPACITY_WH * ($percent / 100);
        $seconds = (int)round(($remainingWh / $avgWatts) * 3600);

        return [
            'display' => human_remaining_seconds($seconds),
            'seconds' => $seconds,
            'source' => 'capacity_power_fallback',
            'avg_watts' => round($avgWatts, 3),
            'capacity_wh' => BATTERY_CAPACITY_WH,
        ];
    }

    return [
        'display' => '-',
        'seconds' => null,
        'source' => BATTERY_CAPACITY_WH > 0 ? 'avg_watts_missing' : 'battery_capacity_missing',
        'avg_watts' => $avgWatts === null ? null : round($avgWatts, 3),
    ];
}

function battery_remaining_estimate(array $battery, array $history, array $trendRows = [], array $profileRows = []): array
{
    $percent = $battery['percent'] ?? null;
    if ($percent === null || $percent === '' || !is_numeric($percent)) {
        return [
            'display' => '-',
            'seconds' => null,
            'source' => 'battery_soc_missing',
            'avg_watts' => null,
        ];
    }

    $percent = max(0.0, min(100.0, (float)$percent));
    $recentWatts = numeric_trimmed_average(array_column(array_slice($trendRows, -10), 'cpu_watts'), 0.1)
        ?? numeric_trimmed_average(array_column(array_slice($history, -90), 'cpu_watts'), 0.1);

    $candidates = [];
    foreach ([1800, 3600, 10800, 21600, 43200, 86400] as $windowSeconds) {
        $candidate = battery_trend_candidate($trendRows, $percent, $windowSeconds, $recentWatts);
        if ($candidate !== null) {
            $candidates[] = $candidate;
        }
    }

    $learned = battery_learned_profile_candidate($profileRows, $percent, $recentWatts);
    if ($learned !== null) {
        $candidates[] = $learned;
    }

    if ($candidates !== []) {
        $weightedRate = 0.0;
        $weightSum = 0.0;
        foreach ($candidates as $candidate) {
            $weight = (float)$candidate['weight'];
            $weightedRate += (float)$candidate['rate_per_second'] * $weight;
            $weightSum += $weight;
        }

        if ($weightedRate > 0 && $weightSum > 0) {
            $rate = $weightedRate / $weightSum;
            $seconds = (int)round($percent / $rate);
            $avgWatts = numeric_trimmed_average(array_column($candidates, 'avg_watts'), 0.0);

            return [
                'display' => human_remaining_seconds($seconds),
                'seconds' => $seconds,
                'source' => 'soc_multi_window',
                'avg_watts' => $avgWatts === null ? null : round($avgWatts, 3),
                'recent_watts' => $recentWatts === null ? null : round($recentWatts, 3),
                'drop_per_hour' => round($rate * 3600, 3),
                'confidence' => round(array_sum(array_column($candidates, 'confidence')) / count($candidates), 3),
                'sources' => array_values(array_unique(array_column($candidates, 'source'))),
                'windows' => array_map(static function (array $candidate): array {
                    return [
                        'source' => $candidate['source'],
                        'minutes' => $candidate['window_seconds'] === null ? null : (int)round($candidate['window_seconds'] / 60),
                        'drop_percent' => $candidate['drop_percent'],
                        'confidence' => $candidate['confidence'],
                        'load_factor' => $candidate['load_factor'],
                        'intervals' => $candidate['intervals'] ?? null,
                        'soc_buckets' => $candidate['soc_buckets'] ?? null,
                    ];
                }, $candidates),
            ];
        }
    }

    return battery_power_fallback_estimate($percent, $history);
}

function add_battery_remaining_history(array $history): array
{
    $wattWindow = [];
    $socWindow = [];

    foreach ($history as $index => $row) {
        $watts = $row['cpu_watts'] ?? null;
        if ($watts !== null && $watts !== '' && is_numeric($watts) && (float)$watts > 0) {
            $wattWindow[] = (float)$watts;
            if (count($wattWindow) > 180) {
                array_shift($wattWindow);
            }
        }

        $percent = $row['battery_percent'] ?? null;
        $time = strtotime((string)($row['time'] ?? ''));
        if ($percent !== null && $percent !== '' && is_numeric($percent) && $time > 0) {
            $socWindow[] = [
                'time' => $time,
                'soc' => (float)$percent,
            ];
            if (count($socWindow) > 240) {
                array_shift($socWindow);
            }
        }

        $history[$index]['battery_remaining_seconds'] = null;
        if (!is_numeric($percent)) {
            continue;
        }

        $safePercent = max(0.0, min(100.0, (float)$percent));
        if (count($socWindow) >= 30) {
            $first = $socWindow[0];
            $last = $socWindow[count($socWindow) - 1];
            $elapsed = max(1, (int)$last['time'] - (int)$first['time']);
            $drop = (float)$first['soc'] - (float)$last['soc'];
            if ($elapsed >= 120 && $drop >= 0.12) {
                $history[$index]['battery_remaining_seconds'] = (int)round($safePercent / ($drop / $elapsed));
                continue;
            }
        }

        $avgWatts = numeric_trimmed_average($wattWindow, 0.12);
        if (BATTERY_CAPACITY_WH > 0 && $avgWatts !== null && $avgWatts > 0) {
            $safePercent = max(0.0, min(100.0, (float)$percent));
            $remainingWh = BATTERY_CAPACITY_WH * ($safePercent / 100);
            $history[$index]['battery_remaining_seconds'] = (int)round(($remainingWh / $avgWatts) * 3600);
        }
    }

    return $history;
}

function process_service_name(int $pid): string
{
    $cgroup = @file('/proc/' . $pid . '/cgroup', FILE_IGNORE_NEW_LINES) ?: [];

    foreach ($cgroup as $line) {
        if (preg_match('/([^\/:]+\.service)(?:\/|$)/', $line, $m)) {
            return $m[1];
        }
    }

    return 'N/A';
}

function process_args(int $pid): string
{
    $raw = @file_get_contents('/proc/' . $pid . '/cmdline');

    if (is_string($raw) && $raw !== '') {
        return command_short(str_replace("\0", ' ', trim($raw, "\0")));
    }

    $comm = trim((string)@file_get_contents('/proc/' . $pid . '/comm'));

    return $comm !== '' ? $comm : 'N/A';
}

function process_resource_data(int $limit = 6): array
{
    $limit = max(3, min(12, $limit));

    $ps = sh([
        '/bin/ps',
        '-eo',
        'pid=,ppid=,user=,pcpu=,pmem=,rss=,comm=,args=',
        '--sort=-pcpu',
    ], false, 4)['out'];

    $cpu = [];
    $mem = [];

    foreach (preg_split('/\R/', trim($ps)) ?: [] as $line) {
        $line = trim($line);

        if ($line === '') {
            continue;
        }

        $parts = preg_split('/\s+/', $line, 8);

        if (count($parts) < 8 || !ctype_digit($parts[0])) {
            continue;
        }

        $pid = (int)$parts[0];
        $row = [
            'pid' => $pid,
            'ppid' => (int)$parts[1],
            'user' => $parts[2],
            'cpu_percent' => round((float)$parts[3], 1),
            'mem_percent' => round((float)$parts[4], 1),
            'rss_mb' => round(((int)$parts[5]) / 1024, 1),
            'name' => $parts[6],
            'service' => process_service_name($pid),
            'command' => command_short($parts[7]),
        ];

        if ($row['cpu_percent'] > 0 || count($cpu) < $limit) {
            $cpu[] = $row;
        }

        $mem[] = $row;
    }

    usort($mem, fn($a, $b) => ($b['mem_percent'] <=> $a['mem_percent']) ?: ($b['rss_mb'] <=> $a['rss_mb']));

    return [
        'cpu' => array_slice($cpu, 0, $limit),
        'memory' => array_slice($mem, 0, $limit),
    ];
}

function notice_process_signature(array $processes): string
{
    $cpu = null;
    foreach (($processes['cpu'] ?? []) as $row) {
        if (!is_array($row)) {
            continue;
        }

        $command = (string)($row['command'] ?? $row['name'] ?? '');
        $service = (string)($row['service'] ?? '');
        if (
            str_contains($command, '/bin/ps')
            || str_contains($command, 'api.php')
            || str_contains($command, 'php-fpm')
            || $service === 'fanpanel-apply.service'
        ) {
            continue;
        }

        $cpu = $row;
        break;
    }

    $mem = null;
    foreach (($processes['memory'] ?? []) as $row) {
        if (!is_array($row)) {
            continue;
        }

        $mem = $row;
        break;
    }

    return hash('sha256', json_encode([
        'cpu' => $cpu === null ? null : [
            'pid' => $cpu['pid'] ?? null,
            'service' => $cpu['service'] ?? null,
            'command' => $cpu['command'] ?? $cpu['name'] ?? null,
        ],
        'mem' => $mem === null ? null : [
            'pid' => $mem['pid'] ?? null,
            'service' => $mem['service'] ?? null,
            'command' => $mem['command'] ?? $mem['name'] ?? null,
        ],
    ], JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES));
}

function trimmed_average(array $values, float $fallback): float
{
    $values = array_values(array_filter(
        $values,
        fn($value) => is_numeric($value) && (float)$value > 0
    ));

    if (count($values) < 5) {
        return $fallback;
    }

    sort($values, SORT_NUMERIC);
    $trim = (int)floor(count($values) * 0.1);
    if ($trim > 0 && count($values) > $trim * 2) {
        $values = array_slice($values, $trim, count($values) - ($trim * 2));
    }

    return array_sum($values) / max(1, count($values));
}

function notice_rolling_baseline(array $history, float $temp, float $rpm, float $pwm, array $state = []): array
{
    $rows = array_slice($history, -180);
    if (count($rows) > 3) {
        $rows = array_slice($rows, 0, -3);
    }

    $temps = [];
    $rpms = [];
    $pwms = [];

    foreach ($rows as $row) {
        $rowTemp = (float)($row['temp_c'] ?? 0);
        $rowRpm = (float)($row['fan_rpm'] ?? 0);
        $rowPwm = (float)($row['fan_pwm'] ?? 0);

        if ($rowTemp > 0) $temps[] = $rowTemp;
        if ($rowRpm > 0) $rpms[] = $rowRpm;
        if ($rowPwm > 0) $pwms[] = $rowPwm;
    }

    $fallbackTemp = (float)($state['baseline_temp'] ?? 0) > 0 ? (float)$state['baseline_temp'] : $temp;
    $fallbackRpm = (float)($state['baseline_rpm'] ?? 0) > 0 ? (float)$state['baseline_rpm'] : $rpm;
    $fallbackPwm = (float)($state['baseline_pwm'] ?? 0) > 0 ? (float)$state['baseline_pwm'] : $pwm;

    return [
        'temp' => trimmed_average($temps, $fallbackTemp),
        'rpm' => trimmed_average($rpms, $fallbackRpm),
        'pwm' => trimmed_average($pwms, $fallbackPwm),
        'samples' => count($rows),
    ];
}

function fan_spike_analysis(array $history, array $fan, array $system, array $processes = []): array
{
    $rpm = (float)($fan['rpm'] ?? 0);
    $pwm = (float)($fan['pwm'] ?? 0);
    $temp = (float)($system['temp_c'] ?? 0);
    $state = system_notice_state();
    $rollingBaseline = notice_rolling_baseline($history, $temp, $rpm, $pwm, $state);

    $currentState = (string)($state['state'] ?? 'normal');
    if (!in_array($currentState, ['normal', 'alert'], true)) {
        $currentState = 'normal';
    }

    $bootEpoch = (int)(time() - max(0, (int)($system['uptime_seconds'] ?? 0)));
    $alertStartedEpoch = strtotime((string)($state['alert_started_at'] ?? '')) ?: 0;
    if ($currentState === 'alert' && $bootEpoch > 0 && ($alertStartedEpoch === 0 || $alertStartedEpoch < $bootEpoch)) {
        $currentState = 'normal';
    }

    $rpmAvg = $currentState === 'alert' ? (float)($state['baseline_rpm'] ?? 0) : (float)$rollingBaseline['rpm'];
    $pwmAvg = $currentState === 'alert' ? (float)($state['baseline_pwm'] ?? 0) : (float)$rollingBaseline['pwm'];
    $tempAvg = $currentState === 'alert' ? (float)($state['baseline_temp'] ?? 0) : (float)$rollingBaseline['temp'];

    if ($rpmAvg <= 0) $rpmAvg = $rpm;
    if ($pwmAvg <= 0) $pwmAvg = $pwm;
    if ($tempAvg <= 0) $tempAvg = $temp;

    $rpmDelta = $rpm - $rpmAvg;
    $pwmDelta = $pwm - $pwmAvg;
    $tempDelta = $temp - $tempAvg;
    $rollingRpmDelta = $rpm - (float)$rollingBaseline['rpm'];
    $rollingTempDelta = $temp - (float)$rollingBaseline['temp'];

    $mode = (string)($fan['mode'] ?? '');
    if ($mode === 'off') {
        $offBaselineReason = 'fan_off_baseline';
        $hasOffBaseline = (string)($state['active_reason'] ?? '') === $offBaselineReason;

        $tempAvg = $hasOffBaseline && (float)($state['baseline_temp'] ?? 0) > 0
            ? (float)$state['baseline_temp']
            : $temp;
        $rpmAvg = $hasOffBaseline && (float)($state['baseline_rpm'] ?? 0) >= 0
            ? (float)$state['baseline_rpm']
            : $rpm;
        $pwmAvg = $hasOffBaseline && (float)($state['baseline_pwm'] ?? 0) >= 0
            ? (float)$state['baseline_pwm']
            : $pwm;

        if (!$hasOffBaseline) {
            save_system_notice_state('normal', $tempAvg, $rpmAvg, $pwmAvg, $offBaselineReason);
        }

        return [
            'active' => false,
            'summary' => 'Fan off baseline is fixed.',
            'rpm_delta' => round($rpm - $rpmAvg, 1),
            'pwm_delta' => round($pwm - $pwmAvg, 1),
            'temp_delta' => round($temp - $tempAvg, 1),
            'rpm_avg' => round($rpmAvg, 1),
            'pwm_avg' => round($pwmAvg, 1),
            'temp_avg' => round($tempAvg, 1),
            'notice_state' => 'normal',
            'baseline_source' => 'frozen_off',
            'baseline_samples' => (int)$rollingBaseline['samples'],
        ];
    }

    $rpmExpected = $mode !== 'off' && ($pwm >= 20 || $pwmAvg >= 20);

    $reasons = [];
    if ($rpmExpected && abs($rpmDelta) >= 1000) $reasons[] = 'RPM ' . signed_delta_text($rpmDelta);
    if (abs($tempDelta) >= 3.0) $reasons[] = 'TEMP ' . signed_delta_text($tempDelta, 'C');

    $spiking = false;

    if ($currentState === 'normal') {
        $spiking = $reasons !== [];
        if ($spiking) {
            save_system_notice_state(
                'alert',
                $tempAvg,
                $rpmAvg,
                $pwmAvg,
                implode(', ', $reasons),
                true,
                $tempDelta,
                $rpmDelta,
                notice_process_signature($processes)
            );
        } else {
            save_system_notice_state('normal', $rollingBaseline['temp'], $rollingBaseline['rpm'], $rollingBaseline['pwm']);
        }
    } else {
        $recovered = (abs($rpmDelta) <= 500 && abs($tempDelta) <= 1.5)
            || (abs($rollingRpmDelta) <= 500 && abs($rollingTempDelta) <= 1.5);
        if ($recovered || $reasons === []) {
            $currentState = 'normal';
            save_system_notice_state('normal', $rollingBaseline['temp'], $rollingBaseline['rpm'], $rollingBaseline['pwm']);
            $tempAvg = (float)$rollingBaseline['temp'];
            $rpmAvg = (float)$rollingBaseline['rpm'];
            $pwmAvg = (float)$rollingBaseline['pwm'];
            $rpmDelta = $rpm - $rpmAvg;
            $pwmDelta = $pwm - $pwmAvg;
            $tempDelta = $temp - $tempAvg;
        } else {
            save_system_notice_state(
                'alert',
                $tempAvg,
                $rpmAvg,
                $pwmAvg,
                implode(', ', $reasons),
                false,
                $tempDelta,
                $rpmDelta,
                notice_process_signature($processes)
            );
        }
    }

    $summary = 'No system notice detected in recent samples.';
    if ($spiking) {
        $summary = 'System notice: ' . implode(', ', $reasons);
    } elseif ($currentState === 'alert' && $reasons !== []) {
        $summary = 'System notice active: ' . implode(', ', $reasons);
    }

    return [
        'active' => $spiking,
        'summary' => $summary,
        'rpm_delta' => round($rpmDelta, 1),
        'pwm_delta' => round($pwmDelta, 1),
        'temp_delta' => round($tempDelta, 1),
        'rpm_avg' => round($rpmAvg, 1),
        'pwm_avg' => round($pwmAvg, 1),
        'temp_avg' => round($tempAvg, 1),
        'notice_state' => $spiking ? 'alert' : $currentState,
        'baseline_source' => $currentState === 'alert' ? 'frozen_alert' : 'rolling',
        'baseline_samples' => (int)$rollingBaseline['samples'],
    ];
}

function system_notice_state(): array
{
    $stmt = db()->query("
        SELECT
            state,
            baseline_temp,
            baseline_rpm,
            baseline_pwm,
            active_reason,
            active_temp_delta,
            active_rpm_delta,
            process_signature,
            alert_started_at,
            last_alert_at,
            updated_at
        FROM system_notice_state
        WHERE id = 1
        LIMIT 1
    ");

    return $stmt->fetch() ?: [];
}

function save_system_notice_state(
    string $state,
    float $baselineTemp,
    float $baselineRpm,
    float $baselinePwm,
    ?string $reason = null,
    bool $alertStarted = false,
    float $activeTempDelta = 0.0,
    float $activeRpmDelta = 0.0,
    ?string $processSignature = null
): void {
    $stmt = db()->prepare("
        INSERT INTO system_notice_state (
            id,
            state,
            baseline_temp,
            baseline_rpm,
            baseline_pwm,
            active_reason,
            active_temp_delta,
            active_rpm_delta,
            process_signature,
            alert_started_at,
            last_alert_at
        ) VALUES (
            1,
            :state,
            :baseline_temp,
            :baseline_rpm,
            :baseline_pwm,
            :active_reason,
            :active_temp_delta,
            :active_rpm_delta,
            :process_signature,
            IF(:alert_started = 1, CURRENT_TIMESTAMP, NULL),
            IF(:alert_started_last = 1, CURRENT_TIMESTAMP, NULL)
        )
        ON DUPLICATE KEY UPDATE
            state = VALUES(state),
            baseline_temp = VALUES(baseline_temp),
            baseline_rpm = VALUES(baseline_rpm),
            baseline_pwm = VALUES(baseline_pwm),
            active_reason = VALUES(active_reason),
            active_temp_delta = VALUES(active_temp_delta),
            active_rpm_delta = VALUES(active_rpm_delta),
            process_signature = VALUES(process_signature),
            alert_started_at = IF(:alert_started_update = 1, CURRENT_TIMESTAMP, alert_started_at),
            last_alert_at = IF(:alert_started_last_update = 1, CURRENT_TIMESTAMP, last_alert_at),
            updated_at = CURRENT_TIMESTAMP
    ");

    $stmt->execute([
        ':state' => in_array($state, ['normal', 'alert'], true) ? $state : 'normal',
        ':baseline_temp' => round($baselineTemp, 2),
        ':baseline_rpm' => round($baselineRpm, 2),
        ':baseline_pwm' => round($baselinePwm, 2),
        ':active_reason' => $reason,
        ':active_temp_delta' => round($activeTempDelta, 2),
        ':active_rpm_delta' => round($activeRpmDelta, 2),
        ':process_signature' => $processSignature,
        ':alert_started' => $alertStarted ? 1 : 0,
        ':alert_started_last' => $alertStarted ? 1 : 0,
        ':alert_started_update' => $alertStarted ? 1 : 0,
        ':alert_started_last_update' => $alertStarted ? 1 : 0,
    ]);
}

function add_fan_spike_log(array $spike, array $fan, array $system, array $processes): int
{
    $summary = (string)($spike['summary'] ?? '');
    $rpmDelta = round((float)($spike['rpm_delta'] ?? 0), 1);
    $pwmDelta = round((float)($spike['pwm_delta'] ?? 0), 1);
    $tempDelta = round((float)($spike['temp_delta'] ?? 0), 1);
    $spikeKey = 'fan:' . date('YmdHi');
    $loggedProcesses = notice_downward_only($tempDelta, $rpmDelta)
        ? ['cpu' => [], 'memory' => []]
        : $processes;

    $stmt = db()->prepare("
        INSERT IGNORE INTO fan_spike_logs (
            spike_key,
            summary,
            rpm_delta,
            pwm_delta,
            temp_delta,
            current_rpm,
            current_pwm,
            current_temp,
            cpu_process,
            memory_process
        ) VALUES (
            :spike_key,
            :summary,
            :rpm_delta,
            :pwm_delta,
            :temp_delta,
            :current_rpm,
            :current_pwm,
            :current_temp,
            :cpu_process,
            :memory_process
        )
    ");

    $stmt->execute([
        ':spike_key' => $spikeKey,
        ':summary' => $summary !== '' ? $summary : null,
        ':rpm_delta' => $rpmDelta,
        ':pwm_delta' => $pwmDelta,
        ':temp_delta' => $tempDelta,
        ':current_rpm' => $fan['rpm'] ?? null,
        ':current_pwm' => $fan['pwm'] ?? null,
        ':current_temp' => $system['temp_c'] ?? null,
        ':cpu_process' => json_encode($loggedProcesses['cpu'] ?? [], JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES),
        ':memory_process' => json_encode($loggedProcesses['memory'] ?? [], JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES),
    ]);

    if ($stmt->rowCount() <= 0) {
        return 0;
    }

    return (int)db()->lastInsertId();
}

function signed_delta_text(float $value, string $suffix = ''): string
{
    $sign = $value >= 0 ? '+' : '';

    return $sign . number_format($value, 1) . $suffix;
}

function signed_delta_compact(float $value, int $decimals, string $suffix = ''): string
{
    $sign = $value >= 0 ? '+' : '';

    return $sign . number_format($value, $decimals) . $suffix;
}

function display_process_name(array $row): string
{
    $service = (string)($row['service'] ?? '');
    if ($service !== '' && $service !== 'N/A') {
        return $service;
    }

    $command = (string)($row['command'] ?? $row['name'] ?? '');

    if (
        str_contains($command, '/codex ')
        || str_contains($command, '/codex')
        || str_contains($command, 'codex app-server')
    ) {
        return 'codex';
    }

    if (str_contains($command, '.vscode-server')) {
        return 'vscode-server';
    }

    if (str_contains($command, 'python3 -m homeassistant')) {
        return 'homeassistant';
    }

    if (str_contains($command, 'firefox')) {
        return 'firefox';
    }

    if ($command === '') {
        $command = (string)($row['name'] ?? '');
    }

    return $command !== '' ? $command : 'N/A';
}

function process_identity(array $row): string
{
    return implode('|', [
        (string)($row['pid'] ?? ''),
        (string)($row['service'] ?? ''),
        (string)($row['command'] ?? $row['name'] ?? ''),
    ]);
}

function expected_process_text(array $processes): string
{
    $cpu = null;
    foreach (($processes['cpu'] ?? []) as $row) {
        if (!is_array($row)) {
            continue;
        }

        $command = (string)($row['command'] ?? $row['name'] ?? '');
        $service = (string)($row['service'] ?? '');
        if (
            str_contains($command, '/bin/ps')
            || str_contains($command, 'api.php')
            || str_contains($command, 'php-fpm')
            || $service === 'fanpanel-apply.service'
        ) {
            continue;
        }

        $cpu = $row;
        break;
    }

    if ($cpu !== null && (float)($cpu['cpu_percent'] ?? 0) >= 1.0) {
        return 'CPU ' . display_process_name($cpu);
    }

    $mem = null;
    foreach (($processes['memory'] ?? []) as $row) {
        if (!is_array($row)) {
            continue;
        }

        $mem = $row;
        break;
    }

    if ($mem !== null) {
        return 'MEM ' . display_process_name($mem);
    }

    return 'CPU/MEM 원인 후보 없음';
}

function expected_process_detail_text(array $processes): string
{
    $cpu = null;
    foreach (($processes['cpu'] ?? []) as $row) {
        if (!is_array($row)) {
            continue;
        }

        $command = (string)($row['command'] ?? $row['name'] ?? '');
        $service = (string)($row['service'] ?? '');
        if (
            str_contains($command, '/bin/ps')
            || str_contains($command, 'api.php')
            || str_contains($command, 'php-fpm')
            || $service === 'fanpanel-apply.service'
        ) {
            continue;
        }

        $cpu = $row;
        break;
    }

    $mem = null;
    foreach (($processes['memory'] ?? []) as $row) {
        if (!is_array($row)) {
            continue;
        }

        $mem = $row;
        break;
    }

    if ($cpu !== null && $mem !== null && process_identity($mem) === process_identity($cpu)) {
        return display_process_name($cpu);
    }

    $parts = [];

    if ($cpu !== null) {
        $parts[] = sprintf('CPU %.1f%% %s', (float)($cpu['cpu_percent'] ?? 0), display_process_name($cpu));
    }

    if ($mem !== null) {
        $parts[] = sprintf('RAM %.1f%% %s', (float)($mem['mem_percent'] ?? 0), display_process_name($mem));
    }

    return $parts === [] ? '원인 후보 없음' : implode(' / ', $parts);
}

function delta_state_text(float $value): string
{
    return $value >= 0 ? '높음' : '낮음';
}

function notice_downward_only(float $tempDelta, float $rpmDelta): bool
{
    $tempTriggered = abs($tempDelta) >= 3.0;
    $rpmTriggered = abs($rpmDelta) >= 1000;

    if (!$tempTriggered && !$rpmTriggered) {
        return false;
    }

    if ($tempTriggered && $tempDelta >= 0) {
        return false;
    }

    if ($rpmTriggered && $rpmDelta >= 0) {
        return false;
    }

    return true;
}

function send_fan_spike_notify(array $spike, array $fan, array $system, array $processes): array
{
    $tempDelta = (float)($spike['temp_delta'] ?? 0);
    $rpmDelta = (float)($spike['rpm_delta'] ?? 0);
    $tempAvg = (float)($spike['temp_avg'] ?? 0);
    $rpmAvg = (float)($spike['rpm_avg'] ?? 0);
    $pwmAvg = (float)($spike['pwm_avg'] ?? 0);
    $reasons = [];

    if (abs($tempDelta) >= 3.0) {
        $reasons[] = '온도 평균보다 ' . ($tempDelta >= 0 ? '상승' : '하강');
    }

    if (abs($rpmDelta) >= 1000) {
        $reasons[] = '팬RPM 평균보다 ' . ($rpmDelta >= 0 ? '상승' : '하강');
    }

    if ($reasons === []) {
        $reasons[] = '순간 변화';
    }

    $body = '기록된 이유: '
        . implode(', ', $reasons)
        . "\n평균: "
        . number_format($tempAvg, 1)
        . '°C / '
        . number_format($rpmAvg, 0)
        . ' RPM / PWM '
        . number_format($pwmAvg, 0)
        . "\n현재: "
        . number_format((float)($system['temp_c'] ?? 0), 1)
        . '°C / '
        . number_format((float)($fan['rpm'] ?? 0), 0)
        . ' RPM / PWM '
        . number_format((float)($fan['pwm'] ?? 0), 0)
        . (notice_downward_only($tempDelta, $rpmDelta) ? '' : "\n원인 후보: " . expected_process_detail_text($processes));

    return send_ha_notify([
        'title' => '시스템 유의사항',
        'message' => $body,
        'level' => 'warning',
        'url' => '/',
        'tag' => 'control-system-notice',
        'data' => [
            'channel' => 'control_system',
            'notification_icon' => 'mdi:fan-alert',
            'color' => '#f59e0b',
            'sticky' => 'false',
            'renotify' => 'true',
            'summary' => $spike['summary'] ?? '',
            'rpm_delta' => $spike['rpm_delta'] ?? 0,
            'pwm_delta' => $spike['pwm_delta'] ?? 0,
            'temp_delta' => $spike['temp_delta'] ?? 0,
            'expected_process' => expected_process_text($processes),
        ],
    ]);
}

function latest_system_notice_notify_epoch(): int
{
    return latest_ha_notify_epoch_by_tag('control-system-notice');
}

function fan_spike_history(int $limit = 100): array
{
    $limit = max(1, min(500, $limit));

    $stmt = db()->query("
        SELECT
            id,
            created_at,
            summary,
            rpm_delta,
            pwm_delta,
            temp_delta,
            current_rpm,
            current_pwm,
            current_temp,
            cpu_process,
            memory_process
        FROM fan_spike_logs
        WHERE id IN (
            SELECT MAX(id)
            FROM fan_spike_logs
            GROUP BY DATE_FORMAT(created_at, '%Y-%m-%d %H:%i')
        )
        ORDER BY id DESC
        LIMIT {$limit}
    ");

    $rows = $stmt->fetchAll();

    foreach ($rows as &$row) {
        $row['cpu_process'] = json_decode((string)($row['cpu_process'] ?? '[]'), true) ?: [];
        $row['memory_process'] = json_decode((string)($row['memory_process'] ?? '[]'), true) ?: [];
    }

    unset($row);

    return $rows;
}

function dnsmasq_leases(): array
{
    $map = [];

    foreach (@file('/var/lib/misc/dnsmasq.leases', FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES) ?: [] as $line) {
        $p = preg_split('/\s+/', trim($line));

        if (count($p) >= 4) {
            $mac = strtolower($p[1]);

            $map[$mac] = [
                'expire_ts' => (int)$p[0],
                'mac' => $mac,
                'ip' => $p[2],
                'hostname' => $p[3] === '*' ? 'N/A' : $p[3],
            ];
        }
    }

    return $map;
}

function wifi_client_aliases(): array
{
    try {
        $rows = db()->query("SELECT mac, hostname FROM wifi_client_aliases")->fetchAll();
    } catch (Throwable) {
        return [];
    }

    $aliases = [];
    foreach ($rows as $row) {
        $mac = strtolower((string)($row['mac'] ?? ''));
        $hostname = trim((string)($row['hostname'] ?? ''));
        if (wifi_valid_mac($mac) && $hostname !== '') {
            $aliases[$mac] = $hostname;
        }
    }

    return $aliases;
}

function save_wifi_client_alias(string $mac, string $hostname): array
{
    $mac = strtolower(trim($mac));
    $hostname = trim(preg_replace('/\s+/', ' ', $hostname) ?? '');

    if (!wifi_valid_mac($mac)) {
        throw new InvalidArgumentException('bad_mac');
    }
    if ($hostname === '' || mb_strlen($hostname) > 80) {
        throw new InvalidArgumentException('bad_hostname');
    }

    $stmt = db()->prepare("
        INSERT INTO wifi_client_aliases (mac, hostname)
        VALUES (:mac, :hostname)
        ON DUPLICATE KEY UPDATE
            hostname = VALUES(hostname),
            updated_at = CURRENT_TIMESTAMP
    ");
    $stmt->execute([
        ':mac' => $mac,
        ':hostname' => $hostname,
    ]);

    return [
        'mac' => $mac,
        'hostname' => $hostname,
    ];
}

function iw_station_dump(string $iface): string
{
    if (!preg_match('/^[A-Za-z0-9_.:-]+$/', $iface)) {
        return '';
    }

    return sh(['/usr/sbin/iw', 'dev', $iface, 'station', 'dump'], true, 4)['out'];
}

function parse_live_wifi_rows(string $iface, string $band, string $text, array $leases, array $aliases): array
{
    $rows = [];
    $cur = null;

    foreach (explode("\n", $text) as $line) {
        $t = trim($line);

        if (preg_match('/^Station\s+([0-9a-f:]+)/i', $t, $m)) {
            if ($cur !== null) {
                $rows[] = $cur;
            }

            $mac = strtolower($m[1]);
            $lease = $leases[$mac] ?? [];
            $leaseHostname = (string)($lease['hostname'] ?? 'N/A');
            $aliasHostname = $aliases[$mac] ?? null;
            $hostname = $aliasHostname ?: $leaseHostname;
            $hostnameSource = $aliasHostname ? 'alias' : ($leaseHostname === 'N/A' ? 'generated' : 'lease');
            $cur = [
                'band' => $band,
                'iface' => $iface,
                'mac' => $mac,
                'ip' => $lease['ip'] ?? 'N/A',
                'hostname' => $hostname === 'N/A' ? '기기-' . strtoupper(substr(str_replace(':', '', $mac), -6)) : $hostname,
                'hostname_source' => $hostnameSource,
                'name' => $hostname === 'N/A' ? $mac : $hostname,
                'signal' => 'N/A',
                'tx_bitrate' => 'N/A',
                'rx_bitrate' => 'N/A',
                'signal_source' => 'missing',
                'tx_bitrate_source' => 'missing',
                'rx_bitrate_source' => 'missing',
                'connected_time' => 'N/A',
                'inactive_time' => 'N/A',
                'rx_bytes' => 0,
                'tx_bytes' => 0,
                'rx_packets' => 0,
                'tx_packets' => 0,
                'tx_failed' => 0,
            ];
            continue;
        }

        if ($cur === null) {
            continue;
        }

        if (preg_match('/^signal:\s+(.+)/', $t, $m)) {
            $cur['signal'] = $m[1];
            $cur['signal_source'] = 'iw';
        } elseif (preg_match('/^tx bitrate:\s+(.+)/', $t, $m)) {
            $cur['tx_bitrate'] = $m[1];
            $cur['tx_bitrate_source'] = 'iw';
        } elseif (preg_match('/^rx bitrate:\s+(.+)/', $t, $m)) {
            $cur['rx_bitrate'] = $m[1];
            $cur['rx_bitrate_source'] = 'iw';
        }
        elseif (preg_match('/^connected time:\s+(.+)/', $t, $m)) $cur['connected_time'] = $m[1];
        elseif (preg_match('/^inactive time:\s+(.+)/', $t, $m)) $cur['inactive_time'] = $m[1];
        elseif (preg_match('/^rx bytes:\s+(\d+)/', $t, $m)) $cur['rx_bytes'] = (int)$m[1];
        elseif (preg_match('/^tx bytes:\s+(\d+)/', $t, $m)) $cur['tx_bytes'] = (int)$m[1];
        elseif (preg_match('/^rx packets:\s+(\d+)/', $t, $m)) $cur['rx_packets'] = (int)$m[1];
        elseif (preg_match('/^tx packets:\s+(\d+)/', $t, $m)) $cur['tx_packets'] = (int)$m[1];
        elseif (preg_match('/^tx failed:\s+(\d+)/', $t, $m)) $cur['tx_failed'] = (int)$m[1];
    }

    if ($cur !== null) {
        $rows[] = $cur;
    }

    return $rows;
}

function wifi_time_ms(string $value): int
{
    if (preg_match('/(\d+)/', $value, $m)) {
        return (int)$m[1];
    }

    return PHP_INT_MAX;
}

function wifi_unknown(mixed $value): bool
{
    $text = strtoupper(trim((string)$value));
    return $text === '' || $text === 'N/A' || $text === '-';
}

function wifi_bitrate_mbps(mixed $value): ?float
{
    if (preg_match('/([0-9]+(?:\.[0-9]+)?)/', (string)$value, $m)) {
        return (float)$m[1];
    }

    return null;
}

function wifi_signal_dbm(string $value): int
{
    if (preg_match('/-?\d+/', $value, $m)) {
        return (int)$m[0];
    }

    return -999;
}

function estimate_wifi_rate_from_signal(string $band, int $dbm): float
{
    if ($band === '5G') {
        if ($dbm >= -50) return 1300.0;
        if ($dbm >= -58) return 866.7;
        if ($dbm >= -66) return 585.0;
        if ($dbm >= -73) return 390.0;
        if ($dbm >= -80) return 173.3;
        return 54.0;
    }

    if ($dbm >= -50) return 300.0;
    if ($dbm >= -58) return 144.4;
    if ($dbm >= -66) return 72.2;
    if ($dbm >= -73) return 39.0;
    if ($dbm >= -80) return 19.5;
    return 6.5;
}

function estimate_wifi_signal_from_rate(string $band, float $mbps): int
{
    if ($band === '5G') {
        if ($mbps >= 900) return -48;
        if ($mbps >= 600) return -55;
        if ($mbps >= 350) return -63;
        if ($mbps >= 150) return -71;
        if ($mbps >= 54) return -79;
        return -84;
    }

    if ($mbps >= 250) return -48;
    if ($mbps >= 120) return -56;
    if ($mbps >= 65) return -64;
    if ($mbps >= 30) return -72;
    if ($mbps >= 10) return -80;
    return -86;
}

function format_estimated_mbps(float $mbps): string
{
    $value = abs($mbps - round($mbps)) < 0.05
        ? (string)(int)round($mbps)
        : number_format($mbps, 1);

    return $value . ' MBit/s (추정)';
}

function apply_wifi_estimates(array $clients): array
{
    foreach ($clients as &$client) {
        $band = (string)($client['band'] ?? '2.4G');
        $signalDbm = wifi_signal_dbm((string)($client['signal'] ?? ''));
        $txMbps = wifi_bitrate_mbps($client['tx_bitrate'] ?? null);
        $rxMbps = wifi_bitrate_mbps($client['rx_bitrate'] ?? null);

        if (wifi_unknown($client['signal'] ?? null)) {
            $sourceRate = max($txMbps ?? 0.0, $rxMbps ?? 0.0);
            $signalDbm = $sourceRate > 0
                ? estimate_wifi_signal_from_rate($band, $sourceRate)
                : ($band === '5G' ? -67 : -70);
            $client['signal'] = $signalDbm . ' dBm (추정)';
            $client['signal_source'] = $sourceRate > 0 ? 'estimated_from_rate' : 'estimated_default';
        }

        if (wifi_unknown($client['tx_bitrate'] ?? null)) {
            $base = $rxMbps ?? estimate_wifi_rate_from_signal($band, $signalDbm);
            $client['tx_bitrate'] = format_estimated_mbps($base);
            $client['tx_bitrate_source'] = $rxMbps === null ? 'estimated_from_signal' : 'estimated_from_rx';
        }

        if (wifi_unknown($client['rx_bitrate'] ?? null)) {
            $base = $txMbps ?? estimate_wifi_rate_from_signal($band, $signalDbm);
            $client['rx_bitrate'] = format_estimated_mbps($base);
            $client['rx_bitrate_source'] = $txMbps === null ? 'estimated_from_signal' : 'estimated_from_tx';
        }
    }
    unset($client);

    return $clients;
}

function dedupe_wifi_clients(array $clients): array
{
    $deduped = [];

    foreach ($clients as $client) {
        $mac = strtolower((string)($client['mac'] ?? ''));
        $key = $mac !== '' && $mac !== 'n/a'
            ? 'mac:' . $mac
            : 'row:' . ($client['band'] ?? '') . ':' . ($client['ip'] ?? '') . ':' . ($client['hostname'] ?? '');

        if (!isset($deduped[$key])) {
            $deduped[$key] = $client;
            continue;
        }

        $currentInactive = wifi_time_ms((string)($deduped[$key]['inactive_time'] ?? ''));
        $nextInactive = wifi_time_ms((string)($client['inactive_time'] ?? ''));
        $currentSignal = wifi_signal_dbm((string)($deduped[$key]['signal'] ?? ''));
        $nextSignal = wifi_signal_dbm((string)($client['signal'] ?? ''));

        if ($nextInactive < $currentInactive || ($nextInactive === $currentInactive && $nextSignal > $currentSignal)) {
            $deduped[$key] = $client;
        }
    }

    return array_values($deduped);
}

function wifi_connected_time_missing(mixed $value): bool
{
    $text = strtoupper(trim((string)$value));
    return $text === '' || $text === 'N/A' || $text === '-';
}

function wifi_valid_mac(string $mac): bool
{
    return preg_match('/^[0-9a-f]{2}(?::[0-9a-f]{2}){5}$/', strtolower($mac)) === 1;
}

function prune_observed_wifi_sessions(PDO $pdo, array $visibleMacs): void
{
    $visibleMacs = array_values(array_unique(array_filter(
        array_map(static fn($mac) => strtolower((string)$mac), $visibleMacs),
        static fn($mac) => wifi_valid_mac($mac)
    )));

    if ($visibleMacs === []) {
        $pdo->exec("DELETE FROM wifi_observed_sessions WHERE band = '5G'");
        return;
    }

    $placeholders = implode(',', array_fill(0, count($visibleMacs), '?'));
    $stmt = $pdo->prepare("
        DELETE FROM wifi_observed_sessions
        WHERE band = '5G'
          AND mac NOT IN ($placeholders)
    ");
    $stmt->execute($visibleMacs);
}

function observed_wifi_duration_seconds(array $clients): array
{
    $targets = [];
    $visible5gMacs = [];

    foreach ($clients as $client) {
        $band = (string)($client['band'] ?? '');
        $mac = strtolower((string)($client['mac'] ?? ''));

        if ($band !== '5G' || !wifi_valid_mac($mac)) {
            continue;
        }

        $visible5gMacs[] = $mac;

        if (!wifi_connected_time_missing($client['connected_time'] ?? null)) {
            continue;
        }

        $targets[$mac] = [
            'mac' => $mac,
            'band' => $band,
            'iface' => (string)($client['iface'] ?? ''),
            'ip' => (string)($client['ip'] ?? ''),
            'hostname' => (string)($client['hostname'] ?? ''),
        ];
    }

    try {
        $pdo = db();
        $pdo->beginTransaction();
        prune_observed_wifi_sessions($pdo, $visible5gMacs);

        if ($targets === []) {
            $pdo->commit();
            return [];
        }

        $upsert = $pdo->prepare("
            INSERT INTO wifi_observed_sessions
                (mac, band, iface, first_seen_at, last_seen_at, last_ip, hostname)
            VALUES
                (:mac, :band, :iface, NOW(3), NOW(3), :last_ip, :hostname)
            ON DUPLICATE KEY UPDATE
                band = VALUES(band),
                iface = VALUES(iface),
                last_seen_at = NOW(3),
                last_ip = VALUES(last_ip),
                hostname = VALUES(hostname)
        ");

        foreach ($targets as $target) {
            $upsert->execute([
                ':mac' => $target['mac'],
                ':band' => $target['band'],
                ':iface' => $target['iface'],
                ':last_ip' => $target['ip'] === 'N/A' ? null : $target['ip'],
                ':hostname' => $target['hostname'] === 'N/A' ? null : $target['hostname'],
            ]);
        }

        $placeholders = implode(',', array_fill(0, count($targets), '?'));
        $stmt = $pdo->prepare("
            SELECT
                mac,
                GREATEST(0, TIMESTAMPDIFF(SECOND, first_seen_at, NOW(3))) AS observed_seconds
            FROM wifi_observed_sessions
            WHERE mac IN ($placeholders)
        ");
        $stmt->execute(array_keys($targets));
        $rows = $stmt->fetchAll();

        $pdo->commit();

        $seconds = [];
        foreach ($rows as $row) {
            $seconds[strtolower((string)$row['mac'])] = (int)$row['observed_seconds'];
        }

        return $seconds;
    } catch (Throwable) {
        if (isset($pdo) && $pdo instanceof PDO && $pdo->inTransaction()) {
            $pdo->rollBack();
        }

        return [];
    }
}

function apply_observed_wifi_connected_time(array $clients): array
{
    $observedSeconds = observed_wifi_duration_seconds($clients);

    if ($observedSeconds === []) {
        return $clients;
    }

    foreach ($clients as &$client) {
        $mac = strtolower((string)($client['mac'] ?? ''));

        if (($client['band'] ?? '') !== '5G'
            || !wifi_connected_time_missing($client['connected_time'] ?? null)
            || !array_key_exists($mac, $observedSeconds)
        ) {
            continue;
        }

        $client['connected_time'] = (string)$observedSeconds[$mac];
        $client['connected_time_source'] = 'observed';
    }
    unset($client);

    return $clients;
}

function wifi_data(): array
{
    $leases = dnsmasq_leases();
    $aliases = wifi_client_aliases();
    $clients = [];

    foreach (['wlan0' => '2.4G', 'wlan1' => '5G'] as $iface => $band) {
        $clients = array_merge(
            $clients,
            parse_live_wifi_rows($iface, $band, iw_station_dump($iface), $leases, $aliases)
        );
    }

    $clients = dedupe_wifi_clients($clients);
    $clients = apply_wifi_estimates($clients);
    $clients = apply_observed_wifi_connected_time($clients);

    return [
        'clients' => $clients,
        'count24' => count(array_filter($clients, fn($c) => $c['band'] === '2.4G')),
        'count5' => count(array_filter($clients, fn($c) => $c['band'] === '5G')),
        'leases' => array_values($leases),
    ];
}

function action_rows(int $limit = 80): array
{
    $limit = max(1, min(300, $limit));

    $stmt = db()->query("
        SELECT
            created_at AS ts,
            action_type AS action,
            CONCAT(
                action_type,
                IF(pwm_mode IS NULL, '', CONCAT(' ', pwm_mode)),
                IF(pwm_value IS NULL, '', CONCAT(' pwm ', pwm_value)),
                IF(note IS NULL OR note = '', '', CONCAT(' / ', note))
            ) AS message,
            success,
            actor_ip
        FROM fan_actions
        ORDER BY id DESC
        LIMIT {$limit}
    ");

    return $stmt->fetchAll();
}

function custom_systemd_service_names(): array
{
    $paths = glob('/etc/systemd/system/*.service') ?: [];
    $names = [];

    foreach ($paths as $path) {
        if (is_link($path)) {
            continue;
        }

        $name = basename($path);
        if (preg_match('/^[A-Za-z0-9_.@:-]+\.service$/', $name)) {
            $names[] = $name;
        }
    }

    sort($names, SORT_NATURAL | SORT_FLAG_CASE);
    return $names;
}

function parse_systemctl_show_records(string $out): array
{
    $records = [];
    $current = [];

    foreach (preg_split('/\R/', trim($out)) as $line) {
        if ($line === '') {
            if (!empty($current['Id'])) {
                $records[$current['Id']] = $current;
            }
            $current = [];
            continue;
        }

        $parts = explode('=', $line, 2);
        if (count($parts) === 2) {
            $current[$parts[0]] = $parts[1];
        }
    }

    if (!empty($current['Id'])) {
        $records[$current['Id']] = $current;
    }

    return $records;
}

function systemd_service_logs(string $unit, int $limit = 12): array
{
    $limit = max(1, min(50, $limit));
    $cmd = [
        '/usr/bin/journalctl',
        '-u',
        $unit,
        '-n',
        (string)$limit,
        '--no-pager',
        '--output=short-iso',
    ];

    $result = sh($cmd, false, 4);
    if ((int)$result['code'] !== 0) {
        $result = sh($cmd, true, 4);
    }

    $lines = array_values(array_filter(
        preg_split('/\R/', trim((string)$result['out'])),
        static fn($line) => trim((string)$line) !== ''
    ));

    return [
        'ok' => (int)$result['code'] === 0,
        'lines' => $lines,
        'error' => (int)$result['code'] === 0 ? '' : (string)$result['out'],
    ];
}

function custom_systemd_services(): array
{
    $cachePath = '/tmp/control-custom-services.json';
    if (is_file($cachePath) && filemtime($cachePath) >= time() - 5) {
        $cached = json_decode((string)@file_get_contents($cachePath), true);
        if (is_array($cached)) {
            return $cached;
        }
    }

    $names = custom_systemd_service_names();
    if (!$names) {
        return [];
    }

    $show = sh(array_merge([
        '/usr/bin/systemctl',
        'show',
    ], $names, [
        '--no-pager',
        '-p',
        'Id',
        '-p',
        'LoadState',
        '-p',
        'ActiveState',
        '-p',
        'SubState',
        '-p',
        'UnitFileState',
        '-p',
        'Description',
        '-p',
        'FragmentPath',
        '-p',
        'ActiveEnterTimestamp',
        '-p',
        'InactiveEnterTimestamp',
        '-p',
        'ExecMainPID',
        '-p',
        'NRestarts',
    ]), false, 6);

    $records = parse_systemctl_show_records((string)$show['out']);
    $rows = [];

    foreach ($names as $name) {
        $record = $records[$name] ?? [];
        $logs = systemd_service_logs($name, 12);

        $rows[] = [
            'name' => $name,
            'description' => (string)($record['Description'] ?? ''),
            'load' => (string)($record['LoadState'] ?? ''),
            'active' => (string)($record['ActiveState'] ?? 'unknown'),
            'sub' => (string)($record['SubState'] ?? ''),
            'enabled' => (string)($record['UnitFileState'] ?? ''),
            'pid' => (int)($record['ExecMainPID'] ?? 0),
            'restarts' => (int)($record['NRestarts'] ?? 0),
            'active_enter' => (string)($record['ActiveEnterTimestamp'] ?? ''),
            'inactive_enter' => (string)($record['InactiveEnterTimestamp'] ?? ''),
            'fragment' => (string)($record['FragmentPath'] ?? ''),
            'logs' => $logs['lines'],
            'logs_ok' => $logs['ok'],
            'logs_error' => $logs['ok'] ? '' : $logs['error'],
        ];
    }

    @file_put_contents($cachePath, json_encode($rows, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES));

    return $rows;
}

function collect_snapshot(bool $applyFan = true): array
{
    if ($applyFan) {
        $policy = apply_fan_policy();
    } else {
        $state = get_control_state();
        $policy = [
            'mode' => (string)($state['mode'] ?? 'auto'),
            'target_pwm' => (int)($state['manual_pwm'] ?? 120),
            'actual_pwm' => 0,
            'temp_c' => 0.0,
            'rpm' => 0,
            'ok' => true,
            'paths' => [],
            'enable_value' => 'N/A',
        ];
    }

    $latest = latest_sensor();

    $pwm = isset($latest['pwm_value']) ? (int)$latest['pwm_value'] : 0;
    if ($latest === false || $latest === [] || !isset($latest['pwm_value'])) {
        $pwm = (int)$policy['actual_pwm'];
    }

    $rpm = (int)($latest['fan_rpm'] ?? 0);
    if ($rpm <= 0) {
        $rpm = (int)$policy['rpm'];
    }

    $temp = (float)($latest['cpu_temp_c'] ?? 0);
    if ($temp <= 0) {
        $temp = (float)$policy['temp_c'];
    }

    $load = sys_getloadavg() ?: [0, 0, 0];
    $mem = mem_info();
    $disk = disk_info('/');
    $os = os_info();
    $throttledStatuses = throttled_statuses();
    $cpuPower = $applyFan ? cpu_power_status() : [
        'voltage' => isset($latest['cpu_voltage']) ? (float)$latest['cpu_voltage'] : null,
        'watts' => isset($latest['cpu_watts']) ? (float)$latest['cpu_watts'] : null,
    ];
    $battery = $applyFan ? battery_status() : [
        'voltage' => isset($latest['battery_voltage']) ? (float)$latest['battery_voltage'] : null,
        'percent' => isset($latest['battery_percent']) ? (float)$latest['battery_percent'] : null,
    ];

    if ($applyFan) {
        add_sensor_log([
            'cpu_temp_c' => $temp,
            'fan_rpm' => $rpm,
            'fan_efficiency' => fan_efficiency($rpm, $temp, $cpuPower['watts'] ?? null),
            'rp1_temp_c' => rp1_temp_c(),
            'cpu_voltage' => $cpuPower['voltage'],
            'cpu_watts' => $cpuPower['watts'],
            'battery_voltage' => $battery['voltage'],
            'battery_percent' => $battery['percent'],
            'pwm_value' => $pwm,
            'pwm_percent' => round($pwm / 255 * 100, 2),
            'pwm_mode' => $policy['mode'],
            'cpu_load_1' => round((float)$load[0], 2),
            'cpu_load_5' => round((float)$load[1], 2),
            'cpu_load_15' => round((float)$load[2], 2),
            'mem_total_mb' => $mem['total_mb'],
            'mem_used_mb' => $mem['used_mb'],
            'mem_free_mb' => $mem['free_mb'],
            'disk_total_kb' => $disk['total_kb'],
            'disk_used_kb' => $disk['used_kb'],
            'disk_free_kb' => $disk['free_kb'],
            'uptime_seconds' => $os['uptime_seconds'],
            'hostname' => $os['hostname'],
        ]);
    }

    $fan = [
        'mode' => $policy['mode'],
        'pwm' => $pwm,
        'percent' => round($pwm / 255 * 100, 1),
        'rpm' => $rpm,
        'enable' => $policy['enable_value'],
        'target_pwm' => $policy['target_pwm'],
        'policy_ok' => $policy['ok'],
        'paths' => $policy['paths'],
    ];

    $system = array_merge($os, [
        'temp_c' => $temp,
        'load' => [
            round((float)$load[0], 2),
            round((float)$load[1], 2),
            round((float)$load[2], 2),
        ],
        'active_users' => active_user_info(),
        'memory' => $mem,
        'disk' => $disk,
        'low_voltage' => $throttledStatuses['low_voltage'],
        'throttling' => $throttledStatuses['throttling'],
    ]);

    $history = add_battery_remaining_history(sensor_history(240));
    $batteryTrend = battery_trend_history(24);
    $batteryProfile = battery_profile_history(45);
    $battery['remaining'] = battery_remaining_estimate($battery, $history, $batteryTrend, $batteryProfile);

    $processes = process_resource_data(6);
    $fanSpike = fan_spike_analysis($history, $fan, $system, $processes);

    if (!empty($fanSpike['active'])) {
        $latestNoticeNotify = latest_system_notice_notify_epoch();
        $spikeLogId = add_fan_spike_log($fanSpike, $fan, $system, $processes);
        if ($spikeLogId > 0) {
            $fanSpike['log_id'] = $spikeLogId;
            if ($latestNoticeNotify <= 0 || time() - $latestNoticeNotify >= HA_NOTIFY_SYSTEM_NOTICE_COOLDOWN) {
                $fanSpike['notify'] = send_fan_spike_notify($fanSpike, $fan, $system, $processes);
            } else {
                $fanSpike['notify'] = [
                    'sent' => 0,
                    'failed' => 0,
                    'skipped' => 'system_notice_cooldown',
                    'cooldown_seconds' => HA_NOTIFY_SYSTEM_NOTICE_COOLDOWN,
                ];
            }
        }
    }

    $snapshot = [
        'ok' => true,
        'generated_at' => date('Y-m-d H:i:s'),
        'time_ms' => (int)round(microtime(true) * 1000),

        'fan' => $fan,
        'system' => $system,
        'battery' => $battery,

        'wifi' => wifi_data(),
        'history' => $history,
        'processes' => $processes,
        'custom_services' => custom_systemd_services(),
        'fan_spike' => $fanSpike,
        'fan_spike_history' => fan_spike_history(100),
        'ha_notify_history' => ha_notify_log_rows(20),
    ];

    return $snapshot;
}

function control_api_dispatch(): void
{
    $action = $_GET['action'] ?? $_POST['action'] ?? 'status';

    if (($_SERVER['REQUEST_METHOD'] ?? 'GET') === 'POST') {
        require_csrf();
    }

    try {
        if ($action === 'dmesg') {
            json_out([
                'ok' => true,
                'data' => dmesg_log(),
            ]);
        }

        if ($action === 'status') {
            json_out([
                'ok' => true,
                'data' => collect_snapshot(false),
            ]);
        }

        if ($action === 'fan') {
            $mode = (string)($_POST['mode'] ?? 'auto');
            $pwm = max(0, min(255, (int)($_POST['pwm'] ?? 120)));

            if (!in_array($mode, ['auto', 'manual', 'off'], true)) {
                json_out([
                    'ok' => false,
                    'error' => 'bad_mode',
                ], 400);
            }

            set_control_state($mode, $pwm);

            add_fan_action(
                'fan_set',
                $mode,
                $pwm,
                'web fan control',
                true
            );

            $data = collect_snapshot(true);

            json_out([
                'ok' => true,
                'data' => $data,
            ]);
        }

        if ($action === 'reboot') {
            $phrase = trim((string)($_POST['phrase'] ?? ''));
            $password = (string)($_POST['password'] ?? '');

            if ($phrase !== '재부팅') {
                json_out([
                    'ok' => false,
                    'error' => 'bad_reboot_phrase',
                    'message' => '재부팅 확인 단어가 올바르지 않습니다.',
                ], 400);
            }

            if (!hash_equals(APP_PASSWORD, $password)) {
                json_out([
                    'ok' => false,
                    'error' => 'bad_reboot_password',
                    'message' => '관리자 암호가 올바르지 않습니다.',
                ], 403);
            }

            add_fan_action(
                'system_reboot',
                null,
                null,
                'web reboot requested',
                true
            );

            $result = sh(['/usr/sbin/reboot'], true, 5);
            if ($result['code'] !== 0) {
                json_out([
                    'ok' => false,
                    'error' => 'reboot_failed',
                    'message' => trim($result['out']) !== '' ? trim($result['out']) : 'reboot command failed',
                ], 500);
            }

            json_out([
                'ok' => true,
                'data' => [
                    'message' => 'reboot_requested',
                ],
            ]);
        }

        if ($action === 'wifi') {
            $verb = (string)($_POST['verb'] ?? '');
            $unit = (string)($_POST['unit'] ?? '');
            $allowedUnits = [
                'hostapd-24g.service',
                'hostapd-5g.service',
                'dnsmasq.service',
            ];

            if (
                !in_array($unit, $allowedUnits, true)
                || !in_array($verb, ['restart', 'reload'], true)
            ) {
                json_out([
                    'ok' => false,
                    'error' => 'bad_wifi_request',
                ], 400);
            }

            $result = sh(['/usr/bin/systemctl', $verb, $unit], true, 25);
            $out = $result['out'];

            add_fan_action(
                'wifi_' . $verb,
                null,
                null,
                $unit . "\n" . mb_substr($out, 0, 1000),
                true
            );

            json_out([
                'ok' => true,
                'output' => $out,
                'data' => collect_snapshot(false),
            ]);
        }

        if ($action === 'wifi_alias') {
            $alias = save_wifi_client_alias(
                (string)($_POST['mac'] ?? ''),
                (string)($_POST['hostname'] ?? '')
            );

            json_out([
                'ok' => true,
                'data' => [
                    'alias' => $alias,
                    'status' => collect_snapshot(false),
                ],
            ]);
        }

        if ($action === 'collect') {
            json_out([
                'ok' => true,
                'data' => collect_snapshot(true),
            ]);
        }

        json_out([
            'ok' => false,
            'error' => 'unknown_action',
        ], 404);
    } catch (Throwable $e) {
        json_out([
            'ok' => false,
            'error' => 'exception',
            'message' => $e->getMessage(),
        ], 500);
    }
}

if (!$controlApiLibrary) {
    control_api_dispatch();
}