<?php
// GET  api/progress.php?video_id=N       -> saved progress for this user/video
// POST api/progress.php                  -> save progress
//      JSON body: {video_id, position, duration}
//      (also accepts form-encoded fields; used by navigator.sendBeacon)
require_once __DIR__ . '/../includes/auth.php';
require_once __DIR__ . '/../includes/functions.php';

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

if ($_SERVER['REQUEST_METHOD'] === 'GET') {
    $videoId = (int)($_GET['video_id'] ?? 0);
    $stmt = db()->prepare(
        'SELECT position_seconds, duration_seconds, completed
         FROM video_progress WHERE user_id = ? AND video_id = ?'
    );
    $stmt->execute([$userId, $videoId]);
    echo json_encode($stmt->fetch() ?: ['position_seconds' => 0, 'duration_seconds' => null, 'completed' => 0]);
    exit;
}

if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    http_response_code(405);
    echo json_encode(['error' => 'Method not allowed']);
    exit;
}

$raw  = file_get_contents('php://input');
$data = json_decode($raw, true);
if (!is_array($data)) {
    parse_str($raw, $data);          // sendBeacon posts form-encoded
}

$videoId  = (int)($data['video_id'] ?? 0);
$position = max(0, (float)($data['position'] ?? 0));
$duration = (float)($data['duration'] ?? 0);

if ($videoId <= 0 || !getVideo($videoId)) {
    http_response_code(400);
    echo json_encode(['error' => 'Unknown video']);
    exit;
}

$completed = ($duration > 0 && $position / $duration >= COMPLETE_THRESHOLD) ? 1 : 0;

$db = db();
$stmt = $db->prepare(
    'INSERT INTO video_progress (user_id, video_id, position_seconds, duration_seconds, completed)
     VALUES (?, ?, ?, ?, ?)
     ON DUPLICATE KEY UPDATE
        position_seconds = VALUES(position_seconds),
        duration_seconds = VALUES(duration_seconds),
        completed = GREATEST(completed, VALUES(completed))' // once complete, stays complete
);
$stmt->execute([$userId, $videoId, $position, $duration > 0 ? $duration : null, $completed]);

// Cache the duration on the video row so listings can show it without waiting
// for someone to play the video (and for files the scanner couldn't parse).
if ($duration > 0) {
    $db->prepare('UPDATE videos SET duration_seconds = ? WHERE id = ? AND duration_seconds IS NULL')
       ->execute([$duration, $videoId]);
}

echo json_encode(['ok' => true, 'completed' => (bool)$completed]);