<?php

/**
* User: djunny
* Date: 2016-04-29
* Time: 17:18
* Mail: [email protected]
* 支援斷點下載的類
*/
class downloader {

/**
* download file to local path
*
* @param       $url
* @param       $save_file
* @param int   $speed
* @param array $headers
* @param int   $timeout
* @return bool
* @throws Exception
*/
static function
 
 get($url, $save_file, 
    $speed = 10240, $headers = array(), $timeout = 10) {
        $url_info = self::parse_url($url);
if (!$url_info['host']) {
throw new Exception('Url is Invalid');
        }

// default header
        $def_headers = array(
'Accept'          => '*/*',
'User-Agent'      => 'Mozilla/4.0 (compatible;
 MSIE 8.0; Windows NT 5.1; Trident/4.0)'
 
,
'Accept-Encoding' => 'gzip, deflate',
'Host'            => $url_info['host'],
'Connection'      => 'Close',
'Accept-Language' => 'zh-cn',
        );

// merge heade
        $headers = array_merge($def_headers,
         $headers);
// get content length
        $content_length = self::get_content_size(
        $url_info['host'
 
], $url_info['port'], 
        $url_info['request'], $headers, $timeout);

// content length not exist
if (!$content_length) {
throw new Exception('Content-Length is 
Not Exists');
        }
// get exists length
        $exists_length = is_file($save_file) ? 
        filesize($save_file) : 0;
// get tmp data file
        $data_file = $save_file . '.data';
// get tmp data
        $exists_data = is_file($data_file) ? 
        json_decode(file_get_contents($data_file), 1) 
        : array();
// check file is valid
if ($exists_length == $content_length) {
            $exists_data && @unlink($data_file);
            return true;
        }
// check file is expire
if ($exists_data['length'] != $content_length 
|| $exists_length > $content_length) {
            $exists_data = array(
'length' => $content_length,
            );
        }
// write exists data
        file_put_contents($data_file, json_encode(
        $exists_data));

try {
            $download_status = self::download_content(
            $url_info['host'], $url_info['port'], 
            $url_info['request'], $save_file, 
            $content_length, $exists_length, $speed, 
            $headers, $timeout);
if ($download_status) {
                @unlink($data_file);
            }
        } catch (Exception $e) {
throw new Exception($e->getMessage());
        }
        return true;
    }

/**
* parse url
*
* @param $url
* @return bool|mixed
*/
static function parse_url($url) {
        $url_info = parse_url($url);
        var_dump($url_info);
        if (!$url_info['host']) {
            return false;
        }


        if (!isset($url_info['port']))
            $url_info['port'] = 80;
        if (!isset($url_info['query']))
            $url_info['query'] = '';
        $url_info['request'] = $url_info['path'] . $url_info['query'];


        return $url_info;
    }

/**
* download content by chunk
*
* @param $host
* @param $port
* @param $url_path
* @param $headers
* @param $timeout
*/
static function download_content($host, 
    $port, $url_path, $save_file, $content_length,
     $range_start, $speed, &$headers, $timeout) {
        $request = self::build_header('GET', 
        $url_path, $headers, $range_start);
        $fsocket = @fsockopen($host, $port, 
        $errno, $errstr, $timeout);
        stream_set_blocking($fsocket, TRUE);
        stream_set_timeout($fsocket, $timeout);
        fwrite($fsocket, $request);
        $status = stream_get_meta_data($fsocket);
if ($status['timed_out']) {
throw new Exception('Socket Connect Timeout');
        }
        $is_header_end = 0;
        $total_size    = $range_start;
        $file_fp       = fopen($save_file, 'a+');
while (!feof($fsocket)) {
if (!$is_header_end) {
                $line = @fgets($fsocket);
if (in_array($line, array("\n", "\r\n"))) {
                    $is_header_end = 1;
                }
continue;
            }
            $resp        = fread($fsocket, $speed);
            $read_length = strlen($resp);
if ($resp === false || $content_length 
< $total_size + $read_length) {
                fclose($fsocket);
                fclose($file_fp);
throw new Exception('Socket I/O 
Error Or File Was Changed');
            }
            $total_size += $read_length;
            fputs($file_fp, $resp);
// check file end
if ($content_length == $total_size) {
break;
            }
            sleep(1);
// for test
//break;
        }
        fclose($fsocket);
        fclose($file_fp);
        return true;

    }

/**
* get content length
*
* @param $host
* @param $port
* @param $url_path
* @param $headers
* @param $timeout
* @return int
*/
static function get_content_size($host, 
    $port, $url_path, &$headers, $timeout) {
        $request = self::build_header('HEAD', 
        $url_path, $headers);
        $fsocket = @fsockopen($host, $port, 
        $errno, $errstr, $timeout);
        stream_set_blocking($fsocket, TRUE);
        stream_set_timeout($fsocket, $timeout);
        fwrite($fsocket, $request);
        $status = stream_get_meta_data($fsocket);
        $length = 0;
if ($status['timed_out']) {
            return 0;
        }
while (!feof($fsocket)) {
            $line = @fgets($fsocket);
if (in_array($line, array("\n", "\r\n"))) {
break;
            }
            $line = strtolower($line);
// get location
if (substr($line, 0, 9) == 'location:') {
                $location = trim(substr($line, 9));
                $url_info = self::parse_url($location);
if (!$url_info['host']) {
                    return 0;
                }
                fclose($fsocket);
                return self::get_content_size($url_info['host'], 
                $url_info['port'], $url_info['request'], 
                $headers, $timeout);
            }
// get content length
if (strpos($line, 'content-length:') !== false) {
list(, $length) = explode('content-length:', 
                $line);
                $length = (int)trim($length);
            }
        }
        fclose($fsocket);
        return $length;

    }

/**
* build header for socket
*
* @param     $action
* @param     $url_path
* @param     $headers
* @param int $range_start
* @return string
*/
static function build_header($action, $url_path, 
&$headers, $range_start = -1) {
        $out = $action . " {$url_path} HTTP/1.0\r\n";
foreach ($headers as $hkey => $hval) {
            $out .= $hkey . ': ' . $hval . "\r\n";
        }
if ($range_start > -1) {
            $out .= "Accept-Ranges: bytes\r\n";
            $out .= "Range: bytes={$range_start}-\r\n";
        }
        $out .= "\r\n";

        return $out;
    }
}


#use age
/*
try {
if (downloader::get('http://dzs.aqtxt.com/files/
11/23636/201604230358308081.rar', 'test.rar')) {
//todo
echo 'Download Succ';
}
} catch (Exception $e) {
echo 'Download Failed';
}
*/
?>