<?php
/**
 * serve_media.php - Serves media files with proper headers for streaming + Range
 */
declare(strict_types=1);
require_once __DIR__ . '/auth.php';
require_auth(false); // plain text is fine for media endpoint
set_time_limit(0);


// ---- Config (prefer env vars in production) ----
$homeDir = getenv('HOME') ?: (getenv('USERPROFILE') ?: ('/home/' . get_current_user()));
$baseDir = rtrim($homeDir, DIRECTORY_SEPARATOR) . DIRECTORY_SEPARATOR . 'GDrive';

// ---- Input ----
$requested = $_GET['file'] ?? '';
if ($requested === '') {
    http_response_code(400);
    echo 'No file specified';
    exit;
}

// Normalize separators (avoid backslash weirdness)
$requested = str_replace(['\\'], '/', $requested);

// Compute real paths and enforce base directory containment
$realBase = realpath($baseDir);
$realFile = realpath($baseDir . DIRECTORY_SEPARATOR . $requested);

if ($realBase === false || $realFile === false) {
    http_response_code(404);
    echo 'File not found';
    exit;
}

$realBase = rtrim($realBase, DIRECTORY_SEPARATOR) . DIRECTORY_SEPARATOR;
if (strpos($realFile, $realBase) !== 0) {
    http_response_code(403);
    echo 'Access denied';
    exit;
}

if (!is_file($realFile) || !is_readable($realFile)) {
    http_response_code(404);
    echo 'File not found';
    exit;
}

// Disable output buffering to prevent Content-Length mismatch
while (ob_get_level() > 0) {
    ob_end_clean();
}

// Mime types (extend as needed)
$ext = strtolower(pathinfo($realFile, PATHINFO_EXTENSION));
$mime = [
    'mp4'  => 'video/mp4',
    'mkv'  => 'video/x-matroska',
    'avi'  => 'video/x-msvideo',
    'mov'  => 'video/quicktime',
    'wmv'  => 'video/x-ms-wmv',
    'flv'  => 'video/x-flv',
    'webm' => 'video/webm',
    'm4v'  => 'video/x-m4v',
    'mp3'  => 'audio/mpeg',
    'wav'  => 'audio/wav',
    'ogg'  => 'audio/ogg',
    'flac' => 'audio/flac',
    'm4a'  => 'audio/mp4',
    'aac'  => 'audio/aac',
    'wma'  => 'audio/x-ms-wma',
    'opus' => 'audio/opus',
][$ext] ?? 'application/octet-stream';

$size = filesize($realFile);
if ($size === false) {
    http_response_code(500);
    echo 'Failed to stat file';
    exit;
}

// Always advertise range support
header('Accept-Ranges: bytes');
header('Content-Type: ' . $mime);
// Optional caching (fine for local LAN usage)
header('Cache-Control: public, max-age=3600');

$rangeHeader = $_SERVER['HTTP_RANGE'] ?? '';
if ($rangeHeader === '') {
    // Full response
    header('Content-Length: ' . $size);
    http_response_code(200);

    $fp = fopen($realFile, 'rb');
    if ($fp === false) {
        http_response_code(500);
        echo 'Failed to open file';
        exit;
    }

    $buf = 1024 * 256; // 256KB chunks (fewer syscalls than 8KB)
    while (!feof($fp) && !connection_aborted()) {
        $data = fread($fp, $buf);
        if ($data === false) break;
        echo $data;
    }
    fclose($fp);
    exit;
}

// ---- Range response (single-range only) ----
// Examples:
//  - bytes=0-999
//  - bytes=1000-
//  - bytes=-500 (suffix range)
if (!preg_match('/^bytes=(\d*)-(\d*)$/', trim($rangeHeader), $m)) {
    http_response_code(416);
    header("Content-Range: bytes */{$size}");
    exit;
}

$startRaw = $m[1];
$endRaw   = $m[2];

if ($startRaw === '' && $endRaw === '') {
    http_response_code(416);
    header("Content-Range: bytes */{$size}");
    exit;
}

if ($startRaw === '') {
    // Suffix range: last N bytes
    $suffixLen = (int)$endRaw;
    if ($suffixLen <= 0) {
        http_response_code(416);
        header("Content-Range: bytes */{$size}");
        exit;
    }
    $start = max(0, $size - $suffixLen);
    $end   = $size - 1;
} else {
    $start = (int)$startRaw;
    $end   = ($endRaw === '') ? ($size - 1) : (int)$endRaw;
}

if ($start < 0 || $end < $start || $end >= $size) {
    http_response_code(416);
    header("Content-Range: bytes */{$size}");
    exit;
}

$length = $end - $start + 1;

http_response_code(206);
header("Content-Range: bytes {$start}-{$end}/{$size}");
header("Content-Length: {$length}");

$fp = fopen($realFile, 'rb');
if ($fp === false) {
    http_response_code(500);
    echo 'Failed to open file';
    exit;
}

if (fseek($fp, $start) !== 0) {
    fclose($fp);
    http_response_code(500);
    echo 'Failed to seek';
    exit;
}

$buf = 1024 * 256;
$remaining = $length;

while ($remaining > 0 && !feof($fp) && !connection_aborted()) {
    $read = min($buf, $remaining);
    $data = fread($fp, $read);
    if ($data === false || $data === '') break;
    echo $data;
    $remaining -= strlen($data);
}

fclose($fp);
exit;