<?php
// GET api/library.php?view=home              -> courses + continue-watching
// GET api/library.php?view=folder&id=N       -> folder contents + progress
// GET api/library.php?view=video&id=N        -> video + playlist + resume info
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)
    );
}

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

switch ($view) {
    case 'home':
        echo json_encode([
            'courses' => array_map(fn($c) => folderSummary($c, $userId), childFolders(null)),
            'continue' => array_map(fn($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)),
        ]);
        break;

    case 'folder':
        $folder = getFolder((int)($_GET['id'] ?? 0));
        if (!$folder) {
            http_response_code(404);
            echo json_encode(['error' => 'Folder not found']);
            break;
        }
        echo json_encode([
            'folder'      => ['id' => (int)$folder['id'], 'name' => $folder['name']],
            'breadcrumbs' => crumbList($folder),
            'progress'    => folderProgress($userId, $folder['path']),
            'subfolders'  => array_map(fn($f) => folderSummary($f, $userId),
                                       childFolders((int)$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);

        $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' => $video['name']],
            'folder'      => ['id' => (int)$folder['id'], 'name' => $folder['name']],
            'breadcrumbs' => crumbList($folder),
            'playlist'    => array_map('videoSummary', $playlist),
            'resume_at'   => $resumeAt,
            'prev_id'     => $prevId,
            'next_id'     => $nextId,
            'stream_url'  => 'stream.php?id=' . (int)$video['id'],
        ]);
        break;

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