<?php
/**
 * API: Spielstaende speichern/laden
 * GET  /api/saves?key=klimawaechter-save
 * POST /api/saves {key, data, version}
 *
 * Bootstrap: idempotent, falls direkt über /php/api/saves.php aufgerufen.
 */
require_once __DIR__ . '/../config/app.php';
require_once __DIR__ . '/../lib/Database.php';
require_once __DIR__ . '/../lib/Session.php';
require_once __DIR__ . '/../lib/Response.php';

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

if ($method === 'GET') {
    $sessionId = Session::studentId();
    if (!$sessionId) Response::json(['data' => null]);

    $key = $_GET['key'] ?? '';
    if (!$key || strlen($key) > 100) Response::error('key fehlt oder zu lang');

    // Optional: module_id mitgeben → erlaubt es, Saves bei aktivem
    // Lehrer-Auftrag (mode='teacher_started') zu unterdrücken, damit der
    // Schüler frisch in den Auftrag startet. Sobald der Auftrag durch ein
    // assessment-Eintrag (submitted_at > started_at) abgeschlossen ist,
    // greift wieder der normale Save-Resume.
    $moduleId = $_GET['module_id'] ?? '';
    if ($moduleId !== '' && strlen($moduleId) <= 32) {
        $session = $db->fetchOne(
            'SELECT class_id FROM student_sessions WHERE id = ?', [$sessionId]
        );
        if ($session && $session['class_id']) {
            $cm = $db->fetchOne(
                'SELECT mode, started_at FROM class_modules WHERE class_id = ? AND module_id = ?',
                [$session['class_id'], $moduleId]
            );
            if ($cm && $cm['mode'] === 'teacher_started' && $cm['started_at']) {
                $completed = $db->fetchOne(
                    'SELECT 1 FROM assessments WHERE session_id = ? AND sim_id = ? AND submitted_at > ? LIMIT 1',
                    [$sessionId, $moduleId, $cm['started_at']]
                );
                if (!$completed) {
                    // Aktiver, noch nicht erledigter Lehrer-Auftrag → frisch starten.
                    Response::json(['data' => null, 'version' => null, 'fresh' => 'teacher_started']);
                }
            }
        }
    }

    $row = $db->fetchOne(
        'SELECT save_data, save_version FROM game_saves WHERE session_id = ? AND save_key = ?',
        [$sessionId, $key]
    );
    Response::json(['data' => $row ? $row['save_data'] : null, 'version' => $row ? (int)$row['save_version'] : null]);
}

if ($method === 'POST') {
    $sessionId = Session::requireStudent();
    $body = json_decode(file_get_contents('php://input'), true);
    // Klima 2D/3D senden 'save_key'/'save_data', historische Sims 'key'/'data'.
    $key  = $body['key']  ?? $body['save_key']  ?? null;
    $data = $body['data'] ?? $body['save_data'] ?? null;
    if (!$body || $key === null || $data === null) {
        Response::error('key und data erforderlich');
    }
    if (!is_string($data)) $data = json_encode($data, JSON_UNESCAPED_UNICODE);
    if (strlen($key) > 100 || strlen($data) > 500000) {
        Response::error('Payload zu gross', 413);
    }

    $db->execute(
        'INSERT INTO game_saves (session_id, save_key, save_data, save_version)
         VALUES (?, ?, ?, ?)
         ON DUPLICATE KEY UPDATE save_data = VALUES(save_data), save_version = VALUES(save_version)',
        [$sessionId, $key, $data, $body['version'] ?? 2]
    );
    Response::ok();
}

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