<?php
// GET api/library.php?view=meta                -> sidebar/header chrome: totals, shelves, last scan
// GET api/library.php?view=home                -> resume card, stats, in progress, recent additions
// GET api/library.php?view=library             -> every course, grouped into shelves
// GET api/library.php?view=folder&id=N         -> folder contents + progress
// GET api/library.php?view=video&id=N          -> video + playlist + resume info
// GET api/library.php?view=search&q=text       -> matching folders, videos, quizzes
// GET api/library.php?view=settings            -> library paths, thresholds, progress summary
require_once __DIR__ . '/../includes/auth.php';
require_once __DIR__ . '/../includes/functions.php';

header('Content-Type: application/json');
$userId = requireLoginApi();

function folderSummary(array $f, int $userId): array
{
    return [
        'id'       => (int)$f['id'],
        'name'     => $f['name'],
        'progress' => folderProgress($userId, $f['path']),
    ];
}

function videoSummary(array $v): array
{
    $duration = $v['duration_seconds'] ?? $v['watched_duration'] ?? null;
    $position = (float)($v['position_seconds'] ?? 0);
    return [
        'id'        => (int)$v['id'],
        'name'      => $v['name'],
        'filename'  => $v['filename'],
        'duration'  => $duration !== null ? (float)$duration : null,
        'position'  => $position,
        'completed' => (bool)($v['completed'] ?? false),
        'percent'   => ($duration ?? 0) > 0 ? min(100, (int)round(100 * $position / $duration)) : 0,
    ];
}

function quizSummary(array $q): array
{
    return [
        'id'         => (int)$q['id'],
        'name'       => $q['name'],
        'filename'   => $q['filename'],
        'questions'  => (int)$q['num_questions'],
        'attempts'   => (int)($q['attempts'] ?? 0),
        'best_score' => (int)($q['best_score'] ?? 0),
        'completed'  => (bool)($q['completed'] ?? false),
    ];
}

function crumbList(array $folder): array
{
    return array_map(
        fn($c) => ['id' => (int)$c['id'], 'name' => $c['name']],
        folderBreadcrumbs($folder)
    );
}

/** The three shelves the library groups courses into. */
function shelveCourses(array $courses): array
{
    $shelves = [
        ['key' => 'progress', 'name' => 'In progress',  'courses' => []],
        ['key' => 'finished', 'name' => 'Finished',     'courses' => []],
        ['key' => 'fresh',    'name' => 'Not started',  'courses' => []],
    ];
    foreach ($courses as $c) {
        foreach ($shelves as $i => $shelf) {
            if ($shelf['key'] === $c['state']) {
                $shelves[$i]['courses'][] = $c;
            }
        }
    }
    return array_values(array_filter($shelves, fn($s) => $s['courses']));
}

$view = $_GET['view'] ?? 'home';

switch ($view) {
    case 'meta':
        $courses = courseCards($userId);
        $counts  = ['progress' => 0, 'finished' => 0, 'fresh' => 0];
        foreach ($courses as $c) {
            $counts[$c['state']]++;
        }
        echo json_encode([
            'totals'    => libraryTotals(),
            'shelves'   => [
                ['key' => 'progress', 'name' => 'In progress', 'count' => $counts['progress']],
                ['key' => 'finished', 'name' => 'Finished',    'count' => $counts['finished']],
                ['key' => 'fresh',    'name' => 'Not started', 'count' => $counts['fresh']],
            ],
            'last_scan' => appMetaGet('last_scan_at'),
            'username'  => currentUsername(),
        ]);
        break;

    case 'home':
        $courses = courseCards($userId);
        $resume  = continueWatching($userId, 1);
        $resumeCourseId = null;
        if ($resume) {
            $resumeFolder = getFolder((int)$resume[0]['folder_id']);
            if ($resumeFolder) $resumeCourseId = courseIdOf($resumeFolder);
        }
        echo json_encode([
            'stats'       => userStats($userId, $courses),
            'resume'      => $resume ? [
                'id'          => (int)$resume[0]['id'],
                'course_id'   => $resumeCourseId,
                'name'        => $resume[0]['name'],
                'folder_path' => $resume[0]['folder_path'],
                'position'    => (float)$resume[0]['position_seconds'],
                'duration'    => $resume[0]['duration_seconds'] !== null
                    ? (float)$resume[0]['duration_seconds'] : null,
            ] : null,
            'continue'    => array_map(fn($r) => [
                'id'          => (int)$r['id'],
                'name'        => $r['name'],
                'folder_path' => $r['folder_path'],
                'position'    => (float)$r['position_seconds'],
                'duration'    => $r['duration_seconds'] !== null ? (float)$r['duration_seconds'] : null,
            ], continueWatching($userId)),
            'in_progress' => array_values(array_filter($courses, fn($c) => $c['state'] === 'progress')),
            'recent'      => recentCourses($userId),
            'courses'     => $courses,
        ]);
        break;

    case 'library':
        $courses = courseCards($userId);
        echo json_encode([
            'courses' => $courses,
            'shelves' => shelveCourses($courses),
            'totals'  => libraryTotals(),
        ]);
        break;

    case 'folder':
        $folder = getFolder((int)($_GET['id'] ?? 0));
        if (!$folder) {
            http_response_code(404);
            echo json_encode(['error' => 'Folder not found']);
            break;
        }
        $crumbs = crumbList($folder);
        echo json_encode([
            'folder'      => ['id' => (int)$folder['id'], 'name' => $folder['name'],
                              'path' => $folder['path']],
            'course_id'   => $crumbs ? $crumbs[0]['id'] : (int)$folder['id'],
            'breadcrumbs' => $crumbs,
            'rollup'      => folderRollup($userId, $folder['path']),
            'progress'    => folderProgress($userId, $folder['path']),
            'subfolders'  => array_map(fn($f) => courseSummary($userId, $f),
                                       childFolders((int)$folder['id'])),
            'videos'      => array_map('videoSummary',
                                       folderVideos((int)$folder['id'], $userId)),
            'quizzes'     => array_map('quizSummary',
                                       folderQuizzes((int)$folder['id'], $userId)),
        ]);
        break;

    case 'video':
        $video = getVideo((int)($_GET['id'] ?? 0));
        if (!$video) {
            http_response_code(404);
            echo json_encode(['error' => 'Video not found']);
            break;
        }
        $folder   = getFolder((int)$video['folder_id']);
        $playlist = folderVideos((int)$folder['id'], $userId);
        $crumbs   = crumbList($folder);

        $stmt = db()->prepare(
            'SELECT position_seconds, completed FROM video_progress
             WHERE user_id = ? AND video_id = ?'
        );
        $stmt->execute([$userId, (int)$video['id']]);
        $saved = $stmt->fetch() ?: null;
        $resumeAt = ($saved && !$saved['completed'] && $saved['position_seconds'] > 5)
            ? (float)$saved['position_seconds'] : 0;

        $prevId = $nextId = null;
        foreach ($playlist as $i => $p) {
            if ((int)$p['id'] === (int)$video['id']) {
                $prevId = isset($playlist[$i - 1]) ? (int)$playlist[$i - 1]['id'] : null;
                $nextId = isset($playlist[$i + 1]) ? (int)$playlist[$i + 1]['id'] : null;
                break;
            }
        }

        echo json_encode([
            'video'       => ['id' => (int)$video['id'], 'name' => $video['name'],
                              'duration' => $video['duration_seconds'] !== null
                                  ? (float)$video['duration_seconds'] : null],
            'folder'      => ['id' => (int)$folder['id'], 'name' => $folder['name']],
            'course_id'   => $crumbs ? $crumbs[0]['id'] : (int)$folder['id'],
            'breadcrumbs' => $crumbs,
            'playlist'    => array_map('videoSummary', $playlist),
            'quizzes'     => array_map('quizSummary', folderQuizzes((int)$folder['id'], $userId)),
            'resume_at'   => $resumeAt,
            'prev_id'     => $prevId,
            'next_id'     => $nextId,
            'stream_url'  => 'stream.php?id=' . (int)$video['id'],
            'captions_url' => srtFilePath($video) !== null
                ? 'captions.php?id=' . (int)$video['id'] : null,
        ]);
        break;

    case 'search':
        $q = trim((string)($_GET['q'] ?? ''));
        if ($q === '') {
            echo json_encode(['query' => '', 'folders' => [], 'videos' => [], 'quizzes' => []]);
            break;
        }
        $withPath = fn(array $row, array $summary) =>
            $summary + ['folder_path' => $row['folder_path']];

        echo json_encode([
            'query'   => $q,
            'folders' => array_map(
                fn($f) => courseSummary($userId, $f),
                searchFolders($q)
            ),
            'videos'  => array_map(
                fn($v) => $withPath($v, videoSummary($v)),
                searchVideos($userId, $q)
            ),
            'quizzes' => array_map(
                fn($q2) => $withPath($q2, quizSummary($q2)),
                searchQuizzes($userId, $q)
            ),
        ]);
        break;

    case 'settings':
        $courses  = courseCards($userId);
        $withSome = array_values(array_filter($courses, fn($c) => $c['progress']['percent'] > 0));
        echo json_encode([
            'root'               => rtrim(VIDEOS_ROOT, '/'),
            'root_exists'        => is_dir(VIDEOS_ROOT),
            'totals'             => libraryTotals(),
            'last_scan'          => appMetaGet('last_scan_at'),
            'complete_threshold' => (int)round(100 * COMPLETE_THRESHOLD),
            'registration_open'  => (bool)ALLOW_REGISTRATION,
            'username'           => currentUsername(),
            'progress_courses'   => count($withSome),
            'courses'            => count($courses),
        ]);
        break;

    default:
        http_response_code(400);
        echo json_encode(['error' => 'Unknown view']);
}