<?php
/**
 * API: Logistik-Sessions (Durchgangs-Tracking)
 *
 * POST /api/logistik-sessions {action: "start", levelId: 2}
 *   -> legt einen aktiven Durchgang an, liefert attempt_id zurueck
 *
 * POST /api/logistik-sessions {action: "end", attemptId, finalBalance, success, stats}
 *   -> schliesst den Durchgang ab
 *
 * GET  /api/logistik-sessions?action=status
 *   -> liefert aktiven Durchgang der aktuellen Schueler-Session (oder null)
 *
 * Persistenz: nutzt game_saves (save_key = "logistik:active-attempt" +
 * "logistik:history") — keine eigene Tabelle noetig.
 *
 * Security: Session-ID aus Cookie wird gegen student_sessions validiert.
 */

$method = $_SERVER['REQUEST_METHOD'];
$db = Database::get();

/** Student-Session validieren (nicht nur Cookie-Praesenz, sondern DB-Existenz). */
function lg_requireValidStudent(): string {
    $sid = Session::requireStudent();
    $db = Database::get();
    $row = $db->fetchOne('SELECT id FROM student_sessions WHERE id = ?', [$sid]);
    if (!$row) {
        http_response_code(401);
        echo json_encode(['error' => 'Session ungueltig']);
        exit;
    }
    return $sid;
}

function lg_uuid(): string {
    return sprintf('%s-%s-%s-%s-%s',
        bin2hex(random_bytes(4)),
        bin2hex(random_bytes(2)),
        bin2hex(random_bytes(2)),
        bin2hex(random_bytes(2)),
        bin2hex(random_bytes(6))
    );
}

if ($method === 'GET') {
    $action = $_GET['action'] ?? 'status';
    if ($action !== 'status') Response::error('Unbekannte Aktion', 400);

    $sid = lg_requireValidStudent();
    $row = $db->fetchOne(
        'SELECT save_data FROM game_saves WHERE session_id = ? AND save_key = ?',
        [$sid, 'logistik:active-attempt']
    );
    if (!$row) Response::ok(['active' => null]);
    $payload = json_decode($row['save_data'], true);
    Response::ok(['active' => $payload]);
}

if ($method === 'POST') {
    $body = json_decode(file_get_contents('php://input'), true);
    if (!is_array($body)) Response::error('Body fehlt oder kein JSON', 400);
    $action = $body['action'] ?? '';
    $sid = lg_requireValidStudent();

    if ($action === 'start') {
        $levelId = (int)($body['levelId'] ?? 0);
        if ($levelId < 1) Response::error('levelId fehlt oder ungueltig', 400);

        $attemptId = lg_uuid();
        $payload = [
            'attemptId'  => $attemptId,
            'levelId'    => $levelId,
            'startedAt'  => gmdate('c'),
            'status'     => 'active',
        ];

        $db->execute(
            'INSERT INTO game_saves (session_id, save_key, save_data, save_version)
             VALUES (?, ?, ?, ?)
             ON DUPLICATE KEY UPDATE save_data = VALUES(save_data), save_version = VALUES(save_version)',
            [$sid, 'logistik:active-attempt', json_encode($payload), 1]
        );

        Response::ok(['attemptId' => $attemptId, 'levelId' => $levelId]);
    }

    if ($action === 'end') {
        $attemptId = trim($body['attemptId'] ?? '');
        if (strlen($attemptId) < 8) Response::error('attemptId fehlt', 400);

        $row = $db->fetchOne(
            'SELECT save_data FROM game_saves WHERE session_id = ? AND save_key = ?',
            [$sid, 'logistik:active-attempt']
        );
        if (!$row) Response::error('Kein aktiver Durchgang', 404);
        $active = json_decode($row['save_data'], true);
        if (($active['attemptId'] ?? null) !== $attemptId) {
            Response::error('attemptId passt nicht zum aktiven Durchgang', 409);
        }

        $finalBalance = (int)($body['finalBalance'] ?? 0);
        $success      = (bool)($body['success'] ?? false);
        $stats        = is_array($body['stats'] ?? null) ? $body['stats'] : [];

        $closed = array_merge($active, [
            'status'       => $success ? 'success' : 'fail',
            'finalBalance' => $finalBalance,
            'endedAt'      => gmdate('c'),
            'stats'        => $stats,
        ]);

        // Aktiven Slot leeren, Historie anhaengen (letzte 20 Durchgaenge)
        $db->execute(
            'DELETE FROM game_saves WHERE session_id = ? AND save_key = ?',
            [$sid, 'logistik:active-attempt']
        );

        $hist = $db->fetchOne(
            'SELECT save_data FROM game_saves WHERE session_id = ? AND save_key = ?',
            [$sid, 'logistik:history']
        );
        $list = $hist ? (json_decode($hist['save_data'], true) ?: []) : [];
        $list[] = $closed;
        if (count($list) > 20) $list = array_slice($list, -20);

        $db->execute(
            'INSERT INTO game_saves (session_id, save_key, save_data, save_version)
             VALUES (?, ?, ?, ?)
             ON DUPLICATE KEY UPDATE save_data = VALUES(save_data), save_version = VALUES(save_version)',
            [$sid, 'logistik:history', json_encode($list), 1]
        );

        Response::ok(['closed' => $closed]);
    }

    Response::error('Unbekannte Aktion', 400);
}

Response::error('Methode nicht erlaubt', 405);