<?php
/**
 * Video Streaming with Range Request Support
 * Enables proper video seeking in browsers
 */

$videoDir = __DIR__ . '/generated_videos';

// Get the requested video file
$file = isset($_GET['file']) ? basename($_GET['file']) : null;

if (!$file) {
    http_response_code(400);
    die('No file specified');
}

$filePath = $videoDir . '/' . $file;

// Security: ensure file is within video directory
$realPath = realpath($filePath);
$realVideoDir = realpath($videoDir);

if ($realPath === false || strpos($realPath, $realVideoDir) !== 0) {
    http_response_code(404);
    die('File not found');
}

if (!file_exists($filePath)) {
    http_response_code(404);
    die('File not found');
}

$fileSize = filesize($filePath);
$mimeType = 'video/mp4';

// Check for Range header
$range = isset($_SERVER['HTTP_RANGE']) ? $_SERVER['HTTP_RANGE'] : null;

if ($range) {
    // Parse Range header
    list($unit, $rangeSpec) = explode('=', $range, 2);

    if ($unit !== 'bytes') {
        http_response_code(416);
        header("Content-Range: bytes */$fileSize");
        die('Invalid range unit');
    }

    // Parse the range values
    $ranges = explode(',', $rangeSpec);
    $rangeSpec = trim($ranges[0]); // Only handle first range

    list($start, $end) = explode('-', $rangeSpec);

    $start = $start === '' ? 0 : intval($start);
    $end = $end === '' ? $fileSize - 1 : intval($end);

    // Validate range
    if ($start < 0 || $start >= $fileSize || $end >= $fileSize || $start > $end) {
        http_response_code(416);
        header("Content-Range: bytes */$fileSize");
        die('Invalid range');
    }

    $length = $end - $start + 1;

    // Send partial content headers
    http_response_code(206);
    header('Content-Type: ' . $mimeType);
    header('Accept-Ranges: bytes');
    header("Content-Range: bytes $start-$end/$fileSize");
    header("Content-Length: $length");
    header('Cache-Control: public, max-age=86400');

    // Output the requested range
    $fp = fopen($filePath, 'rb');
    fseek($fp, $start);

    $bytesRemaining = $length;
    $bufferSize = 8192;

    while ($bytesRemaining > 0 && !feof($fp)) {
        $readSize = min($bufferSize, $bytesRemaining);
        echo fread($fp, $readSize);
        $bytesRemaining -= $readSize;
        flush();
    }

    fclose($fp);
} else {
    // No range requested - send full file
    header('Content-Type: ' . $mimeType);
    header('Accept-Ranges: bytes');
    header("Content-Length: $fileSize");
    header('Cache-Control: public, max-age=86400');

    readfile($filePath);
}