<?php
declare(strict_types=1);

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

function local_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' => '',
        'pwm' => '',
        'enable' => '',
        'rpm' => '',
        'name' => '',
    ];
}

function local_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 local_target(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 local_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 local_mem(): 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);

    return [
        'total_mb' => (int)round($total / 1024),
        'used_mb' => (int)round($used / 1024),
        'free_mb' => (int)round($available / 1024),
    ];
}

function local_disk(string $path = '/'): array
{
    $total = @disk_total_space($path) ?: 0;
    $free = @disk_free_space($path) ?: 0;
    $used = max(0, $total - $free);

    return [
        'total_kb' => (int)round($total / 1024),
        'used_kb' => (int)round($used / 1024),
        'free_kb' => (int)round($free / 1024),
    ];
}

function local_uptime_seconds(): int
{
    $raw = trim((string)@file_get_contents('/proc/uptime'));

    if ($raw === '') {
        return 0;
    }

    return (int)floor((float)explode(' ', $raw)[0]);
}

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

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

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

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

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

function dmesg_log(string $message): void
{
    $line = '<6>fanpanel: ' . $message . "\n";
    @file_put_contents('/dev/kmsg', $line, FILE_APPEND);
}

function dmesg_log_throttled(string $key, string $message, int $seconds = 30): void
{
    $file = '/tmp/fanpanel_dmesg_' . preg_replace('/[^a-zA-Z0-9_.-]/', '_', $key) . '.last';
    $now = time();
    $last = is_file($file) ? (int)trim((string)@file_get_contents($file)) : 0;

    if (($now - $last) < $seconds) {
        return;
    }

    @file_put_contents($file, (string)$now, LOCK_EX);
    dmesg_log($message);
}

try {
    $state = get_control_state();

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

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

    $paths = local_fan_paths();
    $temp = local_temp();

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

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

    usleep(80000);

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

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

    $load = sys_getloadavg() ?: [0, 0, 0];
    $mem = local_mem();
    $disk = local_disk('/');
    $cpuPower = cpu_power_status();
    $battery = battery_status();

    $ok = $enableOk && $pwmOk;

    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' => $actualPwm,
        'pwm_percent' => round($actualPwm / 255 * 100, 2),
        'pwm_mode' => $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' => local_uptime_seconds(),

        'hostname' => gethostname() ?: null,
    ]);

    send_battery_low_push_if_needed($battery);

    if (!$ok) {
        add_fan_action(
            'apply_policy_failed',
            $mode,
            $target,
            'enable=' . ($enableOk ? 'ok' : 'fail')
                . ', pwm=' . ($pwmOk ? 'ok' : 'fail')
                . ', path=' . ($paths['pwm'] ?: 'N/A'),
            false
        );
    }

    exit($ok ? 0 : 1);
} catch (Throwable $e) {
    try {
        add_fan_action(
            'apply_policy_exception',
            null,
            null,
            $e->getMessage(),
            false
        );
    } catch (Throwable) {
    }

    fwrite(STDERR, $e->getMessage() . PHP_EOL);
    exit(1);
}