<?php
declare(strict_types=1);

final class PhpMyAdminSso
{
    private Settings $settings;
    private DirectAdminUser $daUser;
    private MySQLService $db;

    public function __construct(Settings $settings, DirectAdminUser $daUser, MySQLService $db)
    {
        $this->settings = $settings;
        $this->daUser = $daUser;
        $this->db = $db;
    }

    /**
     * @return array{target:string,auth:array<string,string|int>}
     */
    public function issueLoginPayload(?string $requestedDatabase = null): array
    {
        if (!$this->settings->enableAdminer()) {
            throw new RuntimeException('Integracja phpMyAdmin jest wyłączona.');
        }

        $this->db->cleanupExpiredAdminerRoles();

        $databaseRows = $this->db->listDatabasesForUser($this->daUser->username(), false);
        if (empty($databaseRows)) {
            throw new RuntimeException('Użytkownik nie ma żadnej bazy MySQL do otwarcia w phpMyAdmin.');
        }

        $databaseNames = [];
        foreach ($databaseRows as $row) {
            $name = (string)($row['name'] ?? '');
            if ($name !== '') {
                $databaseNames[] = $name;
            }
        }
        $databaseNames = array_values(array_unique($databaseNames));

        $targetDatabase = '';
        if ($requestedDatabase !== null) {
            $requestedDatabase = trim($requestedDatabase);
            if ($requestedDatabase !== '') {
                if (!in_array($requestedDatabase, $databaseNames, true)) {
                    throw new RuntimeException('Wskazana baza danych nie należy do zalogowanego użytkownika.');
                }
                $targetDatabase = $requestedDatabase;
            }
        }
        if ($targetDatabase === '') {
            $targetDatabase = $databaseNames[0];
        }

        $roleTtl = max($this->settings->adminerRoleTtl(), $this->settings->adminerSessionTtl() + 120);
        $role = $this->generateTemporaryRoleName();
        $password = $this->generateSecret(32);
        $expiresAt = time() + $roleTtl;

        $this->db->createTemporaryRole($role, $password, $expiresAt);
        try {
            foreach ($databaseNames as $dbName) {
                $this->db->grantTemporaryAdminerAccess($dbName, $role);
            }
        } catch (Throwable $e) {
            try {
                $this->db->dropTemporaryRole($role);
            } catch (Throwable $ignored) {
            }
            throw new RuntimeException('Nie udało się przygotować sesji phpMyAdmin: ' . $e->getMessage(), 0, $e);
        }

        $auth = [
            'user' => $role,
            'password' => $password,
            'host' => $this->db->connectionEndpoint()['host'],
            'port' => $this->db->connectionEndpoint()['port'],
            'db' => $targetDatabase,
        ];
        $ticket = $this->writeLoginTicket($auth, $targetDatabase);

        return [
            'target' => $this->buildPhpMyAdminLoginUrl($targetDatabase, $ticket),
            'auth' => $auth,
        ];
    }

    private function buildPhpMyAdminLoginUrl(string $database, string $ticket): string
    {
        $query = http_build_query([
            'ticket' => $ticket,
            'route' => '/database/structure',
            'db' => $database,
        ]);

        return $this->phpMyAdminBaseUrl() . '/da_login.php?' . $query;
    }

    private function phpMyAdminBaseUrl(): string
    {
        $path = $this->settings->adminerUrlPath();
        $customBase = $this->settings->adminerPublicBaseUrl();
        if ($customBase !== '') {
            return $customBase . $path;
        }

        $scheme = 'http';
        $https = strtolower(Http::server('HTTPS'));
        if ($https !== '' && $https !== 'off' && $https !== '0') {
            $scheme = 'https';
        } elseif (strtolower(Http::server('HTTP_X_FORWARDED_PROTO')) === 'https') {
            $scheme = 'https';
        } elseif (strtolower(Http::server('REQUEST_SCHEME')) === 'https') {
            $scheme = 'https';
        }

        $host = Http::server('HTTP_HOST');
        if ($host === '') {
            $host = Http::server('SERVER_NAME', 'localhost');
        }
        $host = preg_replace('/:\d+$/', '', $host) ?? $host;

        return $scheme . '://' . $host . $path;
    }

    /**
     * @param array<string,string|int> $auth
     */
    private function writeLoginTicket(array $auth, string $database): string
    {
        $ticketDir = rtrim($this->settings->adminerSsoDir(), '/') . '/tickets';
        if (!is_dir($ticketDir) && !@mkdir($ticketDir, 0755, true) && !is_dir($ticketDir)) {
            throw new RuntimeException('Nie można utworzyć katalogu ticketów phpMyAdmin: ' . $ticketDir);
        }

        $this->cleanupExpiredTickets($ticketDir);

        $token = bin2hex(random_bytes(32));
        $payload = [
            'version' => 1,
            'created_at' => time(),
            'expires_at' => time() + $this->settings->adminerTicketTtl(),
            'auth' => $auth,
            'route' => '/database/structure',
            'db' => $database,
        ];
        $encoded = json_encode($payload, JSON_UNESCAPED_SLASHES);
        if (!is_string($encoded) || $encoded === '') {
            throw new RuntimeException('Nie udało się zakodować ticketu phpMyAdmin.');
        }

        $path = $ticketDir . '/' . $token . '.json';
        $tmpPath = $path . '.tmp.' . bin2hex(random_bytes(4));
        if (@file_put_contents($tmpPath, $encoded, LOCK_EX) === false) {
            throw new RuntimeException('Nie udało się zapisać ticketu phpMyAdmin.');
        }
        @chmod($tmpPath, 0644);
        if (!@rename($tmpPath, $path)) {
            @unlink($tmpPath);
            throw new RuntimeException('Nie udało się aktywować ticketu phpMyAdmin.');
        }

        return $token;
    }

    private function cleanupExpiredTickets(string $ticketDir): void
    {
        foreach (glob($ticketDir . '/*.json') ?: [] as $path) {
            if (!is_file($path)) {
                continue;
            }
            $raw = @file_get_contents($path);
            $decoded = is_string($raw) ? json_decode($raw, true) : null;
            $expiresAt = is_array($decoded) ? (int)($decoded['expires_at'] ?? 0) : 0;
            if ($expiresAt > 0 && $expiresAt >= time()) {
                continue;
            }
            @unlink($path);
        }
    }

    private function generateTemporaryRoleName(): string
    {
        $base = strtolower($this->daUser->username());
        $base = preg_replace('/[^a-z0-9_]+/', '_', $base) ?? 'user';
        $base = trim($base, '_');
        if ($base === '') {
            $base = 'user';
        }

        for ($i = 0; $i < 5; $i++) {
            $suffix = bin2hex(random_bytes(6));
            $maxBaseLen = NamePolicy::MAX_IDENTIFIER_LEN - strlen('da_tmp_phpmyadmin_') - 1 - strlen($suffix);
            if ($maxBaseLen < 1) {
                $maxBaseLen = 1;
            }
            $safeBase = substr($base, 0, $maxBaseLen);
            $role = 'da_tmp_phpmyadmin_' . $safeBase . '_' . $suffix;
            if (!$this->db->roleExists($role)) {
                return $role;
            }
        }

        throw new RuntimeException('Nie udało się wygenerować unikalnego tymczasowego użytkownika dla phpMyAdmin.');
    }

    private function generateSecret(int $len): string
    {
        $value = rtrim(strtr(base64_encode(random_bytes(48)), '+/', 'AZ'), '=');
        if (strlen($value) >= $len) {
            return substr($value, 0, $len);
        }
        return str_pad($value, $len, 'x');
    }
}