<?php
  ini_set('always_populate_raw_post_data', 'On');

  define('UPLOAD_DIR', '/var/www/blog/htdocs/uploaded/');
  define('UPLOAD_LOCATION', '/uploaded/');

  if($_SERVER['REQUEST_METHOD'] != 'POST')
    die_msg('Invalid request.');

  $fname = tempnam(sys_get_temp_dir(), "img_upload");
  if(save_to_file($fname) === false)
    die_msg('Failed to save file.');

  $mime = mime_content_type($fname);
  if(!preg_match('#^image/(.+)#', $mime, $ext)){
    unlink($fname);
    die_msg('Unable to determine file type.');
  }

  $ext = '.'.$ext[1];
  while(file_exists($path = UPLOAD_DIR . ($name = uniqid(). $ext)));

  if(!rename($fname, $path)){
    unlink($fname);
    die_msg('Unable to rename file.');
  }

  header('Image-Link: ' . build_url_for(UPLOAD_LOCATION, $name));

  function die_msg($msg){
    header('Error-Message: ' . $msg, true, 500);
    exit;
  }

  function save_to_file($name, $size_hint = 16384){
    if(!($src = fopen('php://input', 'rb')))
      return false;

    if(!($dst = fopen($name, 'wb'))){
      fclose($src);
      return false;
    }

    $wrote = 0;

    while(!feof($src)){
      if(($buf = fread($src, $size_hint)) === false || ($t = fwrite($dst, $buf)) === false){
        $wrote = false;
        break;
      }

      $wrote += $t;
    }

    fclose($src);
    fclose($dst);

    if($wrote === false)
      unlink($name);

    return $wrote;
  }

  function build_url_for($name){
    $args = func_get_args();

    $args = preg_replace('#/{2,}#', '/', implode('/', $args));
    if(substr($args, 0, 1) != '/')
      $args = '/' . $args;

    $is_https = isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] != 'off';

    $url = 'http';

    if($is_https)
      $url .= 's';

    $url .= '://';

    if(isset($_SERVER['PHP_AUTH_USER']) || isset($_SERVER['PHP_AUTH_PW'])){
      $url .= (isset($_SERVER['PHP_AUTH_USER']) ? $_SERVER['PHP_AUTH_USER'] : '') .
              ':' . (isset($_SERVER['PHP_AUTH_PW']) ? $_SERVER['PHP_AUTH_PW'] : '');
    }

    $url .= $_SERVER['HTTP_HOST'];

    if(($is_https && $_SERVER['SERVER_PORT'] != 443) || (!$is_https && $_SERVER['SERVER_PORT'] != 80))
      $url .= ':' . $_SERVER['SERVER_PORT'];

    return $url . $args;
  }