<?php

require_once __DIR__ . '/db.php';

function normalize_merchant_text(string $text): string
{
    $text = trim($text);
    $text = mb_strtolower($text, 'UTF-8');

    $removeWords = [
        '주식회사',
        '(주)',
        '㈜',
        '유한회사',
        '영농조합법인',
        '농업회사법인',
        '사단법인',
        '재단법인',
        '법인',
        '카드',
        '체크',
        '승인',
        '취소',
        '일시불',
        '할부',
        '누적',
        '잔액',
    ];

    foreach ($removeWords as $word) {
        $text = str_replace($word, '', $text);
    }

    $replace = [
        ' ' => '',
        '-' => '',
        '_' => '',
        '(' => '',
        ')' => '',
        '[' => '',
        ']' => '',
        '{' => '',
        '}' => '',
        '.' => '',
        ',' => '',
        ':' => '',
        ';' => '',
        '/' => '',
        '\\' => '',
        '|' => '',
        '\'' => '',
        '"' => '',
        "\t" => '',
        "\n" => '',
        "\r" => '',
    ];

    $text = strtr($text, $replace);

    // 금액/시간/승인번호처럼 추천에 방해되는 숫자 덩어리 완화
    $text = preg_replace('/\d{4,}/u', '', $text);

    return trim((string)$text);
}

function map_transaction_type_to_category_type(string $transactionType): string
{
    if ($transactionType === 'income') {
        return 'income';
    }

    if ($transactionType === 'expense') {
        return 'expense';
    }

    return 'transfer';
}

function merchant_starts_with(string $haystack, string $needle): bool
{
    if ($needle === '') {
        return false;
    }

    return mb_substr($haystack, 0, mb_strlen($needle, 'UTF-8'), 'UTF-8') === $needle;
}

function suggest_category_from_merchant(int $userId, string $merchantText, string $transactionType): ?array
{
    $pdo = db();

    $merchantText = trim($merchantText);
    if ($merchantText === '') {
        return null;
    }

    $normalized = normalize_merchant_text($merchantText);
    if ($normalized === '') {
        return null;
    }

    $categoryType = map_transaction_type_to_category_type($transactionType);

    $stmt = $pdo->prepare("
        SELECT
            r.id,
            r.pattern_text,
            r.normalized_pattern,
            r.match_type,
            r.priority,
            r.confidence,
            c.id AS category_id,
            c.name AS category_name,
            c.category_type
        FROM merchant_pattern_rules r
        JOIN categories c
          ON c.id = r.category_id
         AND c.user_id = r.user_id
        WHERE r.user_id = ?
          AND r.is_active = 1
          AND c.is_active = 1
          AND c.category_type = ?
          AND r.normalized_pattern IS NOT NULL
          AND r.normalized_pattern <> ''
        ORDER BY
          CASE r.match_type
            WHEN 'exact' THEN 1
            WHEN 'prefix' THEN 2
            ELSE 3
          END ASC,
          r.priority ASC,
          CHAR_LENGTH(r.normalized_pattern) DESC,
          r.id ASC
    ");
    $stmt->execute([$userId, $categoryType]);
    $rows = $stmt->fetchAll();

    foreach ($rows as $row) {
        $pattern = (string)$row['normalized_pattern'];

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

        $matched = false;

        if ($row['match_type'] === 'exact') {
            $matched = ($normalized === $pattern);
        } elseif ($row['match_type'] === 'prefix') {
            $matched = merchant_starts_with($normalized, $pattern);
        } else {
            $matched = mb_strpos($normalized, $pattern, 0, 'UTF-8') !== false;
        }

        if ($matched) {
            return [
                'rule_id' => (int)$row['id'],
                'pattern_text' => (string)$row['pattern_text'],
                'keyword' => (string)$row['pattern_text'],
                'match_type' => (string)$row['match_type'],
                'priority' => (int)$row['priority'],
                'confidence' => (float)$row['confidence'],
                'category_id' => (int)$row['category_id'],
                'category_name' => (string)$row['category_name'],
                'category_type' => (string)$row['category_type'],
                'normalized_input' => $normalized,
            ];
        }
    }

    return null;
}