<?php
// $Id: cdn.basic.inc,v 1.1 2010-10-21 14:45:33 wimleers Exp $

/**
 * @file
 * Logic for basic mode ("Origin Pull mode" in the UI).
 */


//----------------------------------------------------------------------------
// Public functions.

/**
 * Gets the servers on which a file is available when basic mode is enabled.
 *
 * @param $path
 *   The path to get the servers for.
 */
function cdn_basic_get_servers($path) {
  static $mapping;
  $servers = array();

  // We only need to parse the textual CDN mapping once into a lookup table.
  if (!isset($mapping)) {
    $mapping = _cdn_basic_parse_raw_mapping(variable_get(CDN_BASIC_MAPPING_VARIABLE, ''));
  }

  // Parse the file extension from the given path.
  $file_extension = pathinfo($path, PATHINFO_EXTENSION);

  // Based on the file extension, determine which key should be used to find
  // the CDN URLs in the mapping lookup table, if any.
  if (array_key_exists($file_extension, $mapping)) {
    $key = $file_extension;
  }
  elseif (array_key_exists('*', $mapping)) {
    $key = '*';
  }
  else {
    $key = NULL;
  }

  // If there is a key to look up the CDN URLs in the mapping lookup table,
  // then build the list of servers.
  if (isset($key)) {
    $base_path = base_path();
    foreach ($mapping[$key] as $cdn_url) {
      $servers[] = array(
        'server' => $cdn_url,
        'url'    => $cdn_url . $base_path . $path,
      );
    }
  }

  return $servers;
}


//----------------------------------------------------------------------------
// Private functions.

/**
 * Parse the raw (textual) mapping into a lookup table, where the key is the
 * file extension and the value is a list of CDN URLs that serve the file.
 *
 * @param $mapping_raw
 *   A raw (textual) mapping.
 * @return
 *   The corresponding mapping lookup table.
 */
function _cdn_basic_parse_raw_mapping($mapping_raw) {
  $mapping = array();

  if (!empty($mapping_raw)) {
    $lines = preg_split("/[\n\r]+/", $mapping_raw, -1, PREG_SPLIT_NO_EMPTY);
    foreach ($lines as $line) {
      // Parse this line. It may or may not limit the CDN URL to a list of
      // file extensions.
      if (strpos($line, '|') !== FALSE) {
        $parts = explode('|', $line);
        $cdn_url    = rtrim(trim($parts[0]), '/'); // Remove whitespace and a trailing slash.
        $extensions = explode(' ', trim(str_replace('.', '', $parts[1]))); // Remove periods, whitespace and split on ' '.
      }
      else {
        $cdn_url    = trim($line);
        $extensions = array('*'); // Use the asterisk as a wildcard.
      }

      // Create the mapping lookup table.
      foreach ($extensions as $extension) {
        $mapping[$extension][] = $cdn_url;
      }
    }
  }

  return $mapping;
}