<?php
/**
 * GET /api/modules/available
 *
 * Liefert für die eingeloggte Schüler*in zwei Listen:
 *   - assignments: aktuelle Modulaufträge der Klasse (fixe Schwierigkeit)
 *   - freeModules: Module, die für die Klasse generell freigegeben sind
 *
 * Liest Modul-Stammdaten aus module_info_v2 (V2-Registrierung).
 * Aufträge aus class_assignments_v2.
 * Freigaben aus V1-class_modules (wird in V2 weiter genutzt).
 */

declare(strict_types=1);
require_once __DIR__ . '/../../bootstrap.php';

v2_validate_method('GET');
$auth = v2_auth_require('student');
$studentId = (int) ($auth['sub'] ?? 0);
$classId = (int) ($auth['class_id'] ?? 0);

// ─── Aktive Aufträge (V2) ────────────────────────────────────────
$assignmentsRaw = v2_db_all("
    SELECT a.id, a.module_slug, a.difficulty, a.starts_at, a.ends_at,
           mi.display_name, mi.display_name_easy, mi.icon, mi.card_image_url,
           mi.short_description, mi.short_description_easy,
           mi.estimated_duration_min
    FROM class_assignments_v2 a
    LEFT JOIN module_info_v2 mi ON mi.slug = a.module_slug
    WHERE a.class_id = :cid AND a.active = 1
      AND a.starts_at <= NOW()
      AND (a.ends_at IS NULL OR a.ends_at > NOW())
    ORDER BY a.created_at DESC
", [':cid' => $classId]);

// ─── Freie Module (V1-Freigaben weiter genutzt) ──────────────────
// V1: class_modules.module_id matcht module_info_v2.slug
$freeRaw = [];
try {
    $freeRaw = v2_db_all("
        SELECT mi.slug, mi.display_name, mi.display_name_easy,
               mi.icon, mi.card_image_url, mi.short_description,
               mi.short_description_easy, mi.estimated_duration_min,
               mi.status
        FROM module_info_v2 mi
        WHERE mi.status IN ('beta', 'stable')
          AND mi.slug IN (
              SELECT module_id FROM class_modules WHERE class_id = :cid AND enabled = 1
          )
        ORDER BY mi.display_name
    ", [':cid' => $classId]);
} catch (Throwable $e) {
    // Fallback: alle 'stable' V2-Module wenn class_modules nicht existiert / leer ist
    $freeRaw = v2_db_all("
        SELECT slug, display_name, display_name_easy, icon, card_image_url,
               short_description, short_description_easy,
               estimated_duration_min, status
        FROM module_info_v2
        WHERE status IN ('beta', 'stable')
        ORDER BY display_name
    ");
}

// ─── Level-Unlocks ───────────────────────────────────────────────
$unlocks = v2_db_all("
    SELECT module_slug, highest_unlocked_level, highest_completed_level
    FROM student_level_unlock_v2
    WHERE student_id = :sid
", [':sid' => $studentId]);
$unlocksBySlug = [];
foreach ($unlocks as $u) {
    $unlocksBySlug[$u['module_slug']] = [
        'highestUnlocked' => $u['highest_unlocked_level'],
        'highestCompleted' => $u['highest_completed_level'],
    ];
}

// ─── Output formen ───────────────────────────────────────────────
$assignments = array_map(function ($a) {
    return [
        'assignmentId' => (int) $a['id'],
        'moduleSlug' => $a['module_slug'],
        'difficulty' => $a['difficulty'],
        'displayName' => $a['display_name'] ?? $a['module_slug'],
        'displayNameEasy' => $a['display_name_easy'] ?? $a['module_slug'],
        'icon' => $a['icon'] ?? '📘',
        'cardImageUrl' => $a['card_image_url'],
        'shortDescription' => $a['short_description'] ?? '',
        'shortDescriptionEasy' => $a['short_description_easy'] ?? '',
        'estimatedDurationMin' => (int) ($a['estimated_duration_min'] ?? 0),
        'endsAt' => $a['ends_at'],
    ];
}, $assignmentsRaw);

$freeModules = array_map(function ($m) use ($unlocksBySlug) {
    return [
        'slug' => $m['slug'],
        'displayName' => $m['display_name'],
        'displayNameEasy' => $m['display_name_easy'],
        'icon' => $m['icon'] ?? '📘',
        'cardImageUrl' => $m['card_image_url'],
        'shortDescription' => $m['short_description'] ?? '',
        'shortDescriptionEasy' => $m['short_description_easy'] ?? '',
        'estimatedDurationMin' => (int) ($m['estimated_duration_min'] ?? 0),
        'status' => $m['status'],
        'unlocked' => $unlocksBySlug[$m['slug']] ?? ['highestUnlocked' => 'L1', 'highestCompleted' => null],
    ];
}, $freeRaw);

v2_response_ok([
    'assignments' => $assignments,
    'freeModules' => $freeModules,
]);