<?php
// ─── DB-backed system settings with file-based cache ─────────────────────────
//
// Settings live in the `system_settings` table (key→value). To avoid a query
// on every page load, the full set is cached as a PHP array literal under
// config/cache/settings.cache.php — read via require, served from opcache
// in memory. The cache is invalidated (file deleted) on every db_update_setting().
//
// Public API:
//   setting($key, $default = null) — cached read
//   settings_all()                  — cached array
//   db_get_all_settings($pdo)       — bypasses cache
//   db_update_setting($pdo, $key, $value, $userId = null) — UPSERT + invalidate
//
// $pdo is read from the global scope only by db_*() helpers; setting() and
// settings_all() never touch the DB once the cache exists.

function _settings_cache_path(): string {
    return __DIR__ . '/cache/settings.cache.php';
}

function settings_cache_clear(): void {
    $path = _settings_cache_path();
    if (is_file($path)) {
        @unlink($path);
    }
}

function settings_cache_write(array $data): void {
    $path = _settings_cache_path();
    $dir  = dirname($path);
    if (!is_dir($dir)) {
        @mkdir($dir, 0775, true);
    }
    $tmp  = $path . '.' . bin2hex(random_bytes(4)) . '.tmp';
    $code = "<?php\nreturn " . var_export($data, true) . ";\n";
    if (@file_put_contents($tmp, $code, LOCK_EX) === false) {
        return;
    }
    @rename($tmp, $path);
    if (function_exists('opcache_invalidate')) {
        @opcache_invalidate($path, true);
    }
}

function db_get_all_settings(PDO $pdo): array {
    $rows = $pdo->query("SELECT setting_key, setting_value FROM system_settings")
                ->fetchAll(PDO::FETCH_KEY_PAIR);
    return $rows ?: [];
}

function settings_cache_load(): array {
    static $loaded = null;
    if ($loaded !== null) {
        return $loaded;
    }
    $path = _settings_cache_path();
    if (is_file($path)) {
        $data = @include $path;
        if (is_array($data)) {
            return $loaded = $data;
        }
    }
    global $pdo;
    if (!($pdo instanceof PDO)) {
        return $loaded = [];
    }
    $data = db_get_all_settings($pdo);
    settings_cache_write($data);
    return $loaded = $data;
}

function settings_all(): array {
    return settings_cache_load();
}

function setting(string $key, $default = null) {
    $data = settings_cache_load();
    return array_key_exists($key, $data) ? $data[$key] : $default;
}

function db_update_setting(PDO $pdo, string $key, string $value, ?int $userId = null): void {
    $s = $pdo->prepare(
        "INSERT INTO system_settings (setting_key, setting_value, updated_by)
         VALUES (?, ?, ?)
         ON DUPLICATE KEY UPDATE setting_value = VALUES(setting_value),
                                 updated_by    = VALUES(updated_by)"
    );
    $s->execute([$key, $value, $userId]);
    settings_cache_clear();
}