<?php
declare(strict_types=1);

const DB_MANUAL_CONFIG_FILE = __DIR__ . '/database.php';
const DB_INSTALLER_CONFIG_FILE = __DIR__ . '/installer-config.php';

function db_manual_config_relative_path(): string
{
    return 'db/database.php';
}

function db_normalize_settings(array $settings): array
{
    $host = trim((string)($settings['DB_HOST'] ?? ''));
    $port = trim((string)($settings['DB_PORT'] ?? ''));
    $name = trim((string)($settings['DB_NAME'] ?? ''));
    $user = trim((string)($settings['DB_USER'] ?? ''));
    $password = isset($settings['DB_PASS']) ? (string)$settings['DB_PASS'] : '';

    return [
        'DB_HOST' => $host !== '' ? $host : 'localhost',
        'DB_PORT' => $port !== '' ? $port : '3306',
        'DB_NAME' => $name,
        'DB_USER' => $user,
        'DB_PASS' => $password,
    ];
}

function db_export_settings_file(array $settings): string
{
    $settings = db_normalize_settings($settings);

    $payload = "<?php
";
    $payload .= "declare(strict_types=1);

";
    $payload .= "/**
";
    $payload .= " * Konfigurasi database manual.
";
    $payload .= " * Isi file ini langsung saat upload ke cPanel/shared hosting.
";
    $payload .= " * Untuk cPanel, DB_NAME dan DB_USER biasanya memakai prefix akun.
";
    $payload .= " */

";
    $payload .= 'return ' . var_export([
        'DB_HOST' => $settings['DB_HOST'],
        'DB_PORT' => $settings['DB_PORT'],
        'DB_NAME' => $settings['DB_NAME'],
        'DB_USER' => $settings['DB_USER'],
        'DB_PASS' => $settings['DB_PASS'],
    ], true) . ";
";

    return $payload;
}

function db_read_settings_file(string $path): array
{
    static $cache = [];

    if (array_key_exists($path, $cache)) {
        return $cache[$path];
    }

    $result = [
        'settings' => db_normalize_settings([]),
        'error' => null,
    ];

    if (!is_file($path)) {
        $cache[$path] = $result;
        return $result;
    }

    try {
        $loaded = include $path;
    } catch (Throwable $exception) {
        $result['error'] = $exception->getMessage();
        $cache[$path] = $result;
        return $result;
    }

    if (!is_array($loaded)) {
        $result['error'] = 'Format file konfigurasi harus return array.';
        $cache[$path] = $result;
        return $result;
    }

    $result['settings'] = db_normalize_settings($loaded);
    $cache[$path] = $result;

    return $result;
}

function db_env_settings(): array
{
    $settings = [];

    foreach (['DB_HOST', 'DB_PORT', 'DB_NAME', 'DB_USER', 'DB_PASS'] as $key) {
        $value = getenv($key);
        if ($value !== false) {
            $settings[$key] = $value;
        }
    }

    return db_normalize_settings($settings);
}

function db_manual_settings(): array
{
    return db_read_settings_file(DB_MANUAL_CONFIG_FILE)['settings'];
}

function db_manual_settings_error(): ?string
{
    return db_read_settings_file(DB_MANUAL_CONFIG_FILE)['error'];
}

function db_legacy_installer_settings(): array
{
    return db_read_settings_file(DB_INSTALLER_CONFIG_FILE)['settings'];
}

function db_legacy_installer_settings_error(): ?string
{
    return db_read_settings_file(DB_INSTALLER_CONFIG_FILE)['error'];
}

function db_settings_complete(array $settings): bool
{
    return $settings['DB_HOST'] !== ''
        && $settings['DB_NAME'] !== ''
        && $settings['DB_USER'] !== '';
}

function db_resolved_settings(): array
{
    static $settings = null;

    if (is_array($settings)) {
        return $settings;
    }

    $manual = db_manual_settings();
    if (db_settings_complete($manual)) {
        $manual['__source'] = 'manual_file';
        $settings = $manual;
        return $settings;
    }

    $env = db_env_settings();
    if (db_settings_complete($env)) {
        $env['__source'] = 'env';
        $settings = $env;
        return $settings;
    }

    $legacy = db_legacy_installer_settings();
    if (db_settings_complete($legacy)) {
        $legacy['__source'] = 'legacy_installer_file';
        $settings = $legacy;
        return $settings;
    }

    $settings = db_normalize_settings([]);
    $settings['__source'] = 'missing';

    return $settings;
}

$resolvedDbSettings = db_resolved_settings();
define('DB_HOST', $resolvedDbSettings['DB_HOST']);
define('DB_PORT', $resolvedDbSettings['DB_PORT']);
define('DB_NAME', $resolvedDbSettings['DB_NAME']);
define('DB_USER', $resolvedDbSettings['DB_USER']);
define('DB_PASS', $resolvedDbSettings['DB_PASS']);
unset($resolvedDbSettings);

function db_config_source(): string
{
    return db_resolved_settings()['__source'] ?? 'missing';
}

function db_configuration_problem(): ?string
{
    $manualError = db_manual_settings_error();
    if ($manualError !== null) {
        return 'Ada error di file ' . db_manual_config_relative_path() . ': ' . $manualError;
    }

    $legacyError = db_legacy_installer_settings_error();
    if ($legacyError !== null) {
        return 'Ada error di file lama db/installer-config.php: ' . $legacyError;
    }

    return null;
}

function db_has_required_config(): bool
{
    return db_settings_complete(db_resolved_settings());
}

function db_build_dsn(array $settings, bool $withDatabase = true): string
{
    $settings = db_normalize_settings($settings);
    $dsn = 'mysql:host=' . $settings['DB_HOST'] . ';port=' . $settings['DB_PORT'] . ';charset=utf8mb4';

    if ($withDatabase && $settings['DB_NAME'] !== '') {
        $dsn .= ';dbname=' . $settings['DB_NAME'];
    }

    return $dsn;
}

function db_create_pdo(array $settings, bool $withDatabase = true): PDO
{
    $settings = db_normalize_settings($settings);

    return new PDO(
        db_build_dsn($settings, $withDatabase),
        $settings['DB_USER'],
        $settings['DB_PASS'],
        [
            PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
            PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
            PDO::ATTR_TIMEOUT => 5,
        ]
    );
}

function db_test_connection(array $settings, bool $withDatabase = true, ?string &$error = null): bool
{
    try {
        db_create_pdo($settings, $withDatabase)->query('SELECT 1');
        $error = null;
        return true;
    } catch (Throwable $exception) {
        $error = $exception->getMessage();
        return false;
    }
}

function db_connection_error(?array $settings = null): ?string
{
    $settings = $settings !== null ? db_normalize_settings($settings) : db_resolved_settings();

    if (!db_settings_complete($settings)) {
        return 'Database belum dikonfigurasi lengkap.';
    }

    $error = null;
    db_test_connection($settings, true, $error);

    return $error;
}

function db(): PDO
{
    static $pdo = null;

    if ($pdo instanceof PDO) {
        return $pdo;
    }

    if (!db_has_required_config()) {
        throw new RuntimeException('Database belum dikonfigurasi. Isi file ' . db_manual_config_relative_path() . '.');
    }

    $pdo = db_create_pdo(db_resolved_settings(), true);
    return $pdo;
}

function db_error_is_missing_database(string $message): bool
{
    return stripos($message, 'Unknown database') !== false
        || str_contains($message, '[1049]');
}

function db_quote_identifier(string $identifier): string
{
    $identifier = trim($identifier);
    if ($identifier === '' || preg_match('/[[:cntrl:]]/', $identifier)) {
        throw new RuntimeException('Nama database tidak valid.');
    }

    return '`' . str_replace('`', '``', $identifier) . '`';
}

function db_create_database_if_missing(array $settings): void
{
    $settings = db_normalize_settings($settings);

    if ($settings['DB_NAME'] === '') {
        throw new RuntimeException('Nama database wajib diisi.');
    }

    $pdo = db_create_pdo($settings, false);
    $pdo->exec(
        'CREATE DATABASE IF NOT EXISTS ' . db_quote_identifier($settings['DB_NAME']) .
        ' CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci'
    );
}

function db_save_local_settings(array $settings): void
{
    $settings = db_normalize_settings($settings);
    $payload = db_export_settings_file($settings);

    $bytes = file_put_contents(DB_MANUAL_CONFIG_FILE, $payload, LOCK_EX);
    if ($bytes === false) {
        throw new RuntimeException('Gagal menyimpan file konfigurasi database. Pastikan folder db bisa ditulis.');
    }
}