<?php
/**
 * API: Modulfreigabe (Klasse + individuell pro Schüler)
 * GET  /api/modules?class_id=X              → Modulstatus für Klasse
 * GET  /api/modules?class_id=X&matrix=1     → Matrix: alle Schüler × alle Module
 * POST /api/modules {action}                → Modul freigeben/sperren
 */

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

$ALL_MODULES = [
    ['id' => 'sim-05',    'name' => 'Klimawächter 2D',        'desc' => 'Treibhauseffekt-Simulation',     'icon' => '🌡️'],
    ['id' => 'sim-05-3d', 'name' => 'Klimawächter 3D',        'desc' => '3D-Klimasimulation',             'icon' => '🌊'],
    ['id' => 'sim-07',    'name' => 'Erdbeben',                'desc' => 'Plattentektonik & Stadtplanung', 'icon' => '🌋'],
    ['id' => 'sim-09',    'name' => 'Energiemix',              'desc' => 'Energiewende planen',            'icon' => '⚡'],
    ['id' => 'sim-10',    'name' => 'Lieferketten',            'desc' => 'Globale Lieferketten',           'icon' => '👕'],
    ['id' => 'sim-11',    'name' => 'Regenwald',               'desc' => 'Regenwald-Expedition',           'icon' => '🌴'],
    ['id' => 'sim-12',    'name' => 'Flussmanagement',         'desc' => 'Fluss & Hochwasserschutz',       'icon' => '🏞️'],
    ['id' => 'sim-13',    'name' => 'Stadt & Raumplanung',     'desc' => 'Stadtsimulation mit Kacheln',    'icon' => '🏗️'],
    ['id' => 'sim-14',    'name' => 'Helikopter-Navigation',  'desc' => 'Rettungshubschrauber steuern', 'icon' => '🚁'],
];

if ($method === 'GET') {
    // Schüler*innen-Ansicht: welche Module sind für mich freigeschaltet?
    if (isset($_GET['student']) && $_GET['student'] === '1') {
        $sessionId = Session::requireStudent();
        $session = $db->fetchOne('SELECT class_id FROM student_sessions WHERE id = ?', [$sessionId]);
        if (!$session || !$session['class_id']) {
            // Kein Klasse = alle Module frei (Autodidakt)
            $result = [];
            foreach ($ALL_MODULES as $mod) {
                $result[] = ['id' => $mod['id'], 'name' => $mod['name'], 'icon' => $mod['icon'], 'mode' => 'free'];
            }
            Response::ok($result);
        }
        $classId = $session['class_id'];
        $classMap = [];
        $settings = $db->fetchAll('SELECT module_id, mode FROM class_modules WHERE class_id = ?', [$classId]);
        foreach ($settings as $s) $classMap[$s['module_id']] = $s['mode'];

        // Individuelle Overrides für diesen Schüler
        // Finde student_id aus session
        $studentRow = $db->fetchOne(
            'SELECT s.id FROM students s JOIN student_sessions ss ON ss.class_id = s.class_id AND ss.display_name = s.display_name WHERE ss.id = ?',
            [$sessionId]
        );
        $overrides = [];
        if ($studentRow) {
            $rows = $db->fetchAll('SELECT module_id, mode FROM student_modules WHERE student_id = ?', [$studentRow['id']]);
            foreach ($rows as $r) $overrides[$r['module_id']] = $r['mode'];
        }

        $result = [];
        foreach ($ALL_MODULES as $mod) {
            $mode = $overrides[$mod['id']] ?? $classMap[$mod['id']] ?? 'locked';
            $result[] = ['id' => $mod['id'], 'name' => $mod['name'], 'icon' => $mod['icon'], 'mode' => $mode];
        }
        Response::ok($result);
    }

    $teacherId = Session::requireTeacher();
    $classId = (int)($_GET['class_id'] ?? 0);
    if (!$classId) Response::error('class_id erforderlich');

    $class = $db->fetchOne('SELECT id FROM classes WHERE id = ? AND teacher_id = ?', [$classId, $teacherId]);
    if (!$class) Response::error('Klasse nicht gefunden', 404);

    // Klassen-Defaults laden
    $settings = $db->fetchAll('SELECT module_id, mode FROM class_modules WHERE class_id = ?', [$classId]);
    $classMap = [];
    foreach ($settings as $s) $classMap[$s['module_id']] = $s['mode'];

    // Matrix-Modus: alle Schüler × alle Module
    if (isset($_GET['matrix']) && $_GET['matrix'] === '1') {
        $students = $db->fetchAll(
            'SELECT id, username, display_name, emoji_avatar FROM students WHERE class_id = ? ORDER BY username',
            [$classId]
        );

        // Individuelle Overrides laden
        $studentIds = array_column($students, 'id');
        $overrides = [];
        if (!empty($studentIds)) {
            $placeholders = implode(',', array_fill(0, count($studentIds), '?'));
            $rows = $db->fetchAll(
                "SELECT student_id, module_id, mode FROM student_modules WHERE student_id IN ($placeholders)",
                $studentIds
            );
            foreach ($rows as $r) {
                $overrides[$r['student_id']][$r['module_id']] = $r['mode'];
            }
        }

        // Matrix aufbauen
        $matrix = [];
        foreach ($students as $s) {
            $row = [
                'id' => (int)$s['id'],
                'username' => $s['username'],
                'displayName' => $s['display_name'] ?: $s['username'],
                'emoji' => $s['emoji_avatar'] ?: '🧑‍🎓',
                'modules' => [],
            ];
            foreach ($ALL_MODULES as $mod) {
                $row['modules'][$mod['id']] = $overrides[$s['id']][$mod['id']] ?? $classMap[$mod['id']] ?? 'locked';
            }
            $matrix[] = $row;
        }

        // Modul-Infos mit Klassen-Defaults
        $modulesInfo = [];
        foreach ($ALL_MODULES as $mod) {
            $modulesInfo[] = [
                'id' => $mod['id'],
                'name' => $mod['name'],
                'desc' => $mod['desc'],
                'icon' => $mod['icon'],
                'classMode' => $classMap[$mod['id']] ?? 'locked',
            ];
        }

        Response::ok(['modules' => $modulesInfo, 'students' => $matrix]);
    }

    // Standard: nur Klassen-Defaults
    $result = [];
    foreach ($ALL_MODULES as $mod) {
        $result[] = [
            'id' => $mod['id'],
            'name' => $mod['name'],
            'desc' => $mod['desc'],
            'icon' => $mod['icon'],
            'mode' => $classMap[$mod['id']] ?? 'locked',
        ];
    }
    Response::ok($result);
}

if ($method === 'POST') {
    $teacherId = Session::requireTeacher();
    $body = json_decode(file_get_contents('php://input'), true);
    $action = $body['action'] ?? '';
    $classId = (int)($body['classId'] ?? 0);
    $moduleId = $body['moduleId'] ?? '';

    if (!$classId || !$moduleId) Response::error('classId und moduleId erforderlich');

    $class = $db->fetchOne('SELECT id FROM classes WHERE id = ? AND teacher_id = ?', [$classId, $teacherId]);
    if (!$class) Response::error('Klasse nicht gefunden', 404);

    // Klassen-Default setzen
    if ($action === 'set_mode') {
        $mode = $body['mode'] ?? 'locked';
        if (!in_array($mode, ['locked', 'free', 'teacher_started'])) Response::error('Ungültiger Modus');

        $db->execute(
            'INSERT INTO class_modules (class_id, module_id, enabled, mode)
             VALUES (?, ?, 1, ?)
             ON DUPLICATE KEY UPDATE mode = VALUES(mode), enabled = 1',
            [$classId, $moduleId, $mode]
        );
        Response::ok();
    }

    // Individuell pro Schüler setzen
    if ($action === 'set_student_mode') {
        $studentId = (int)($body['studentId'] ?? 0);
        $mode = $body['mode'] ?? 'locked';
        if (!$studentId) Response::error('studentId erforderlich');
        if (!in_array($mode, ['locked', 'free', 'teacher_started'])) Response::error('Ungültiger Modus');

        // Prüfen dass Schüler zur Klasse gehört
        $student = $db->fetchOne('SELECT id FROM students WHERE id = ? AND class_id = ?', [$studentId, $classId]);
        if (!$student) Response::error('Schüler nicht in dieser Klasse');

        $db->execute(
            'INSERT INTO student_modules (student_id, module_id, mode)
             VALUES (?, ?, ?)
             ON DUPLICATE KEY UPDATE mode = VALUES(mode)',
            [$studentId, $moduleId, $mode]
        );
        Response::ok();
    }

    // Klassen-Default für ALLE Schüler übernehmen (reset overrides)
    if ($action === 'reset_overrides') {
        $db->execute(
            'DELETE sm FROM student_modules sm JOIN students s ON s.id = sm.student_id WHERE s.class_id = ? AND sm.module_id = ?',
            [$classId, $moduleId]
        );
        Response::ok();
    }

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

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