PHP API proxy with caching build in.

apiproxy.php

<?php
// apiproxy [atree 12/18/2012] 
// In order for the cache to work properly,
// there needs to be a folder under this script's folder
// named temp with the 777 permissions set.
// Don't fret if you don't have this, it will just continue on
//
// this cache will write to here every 12 hours (default)
//

    // settings //
    $cache_file = 'temp/api-cache.txt';
    $recreate_cache = false;
    $show_cache = false;
    $timestamp = time();
    $cached_hours = 12;

    // if we have the cache, use it.. if it has expired set flag to recreate it // 
    if (file_exists($cache_file)) {
        $show_cache = true;
        $fh = fopen($cache_file, 'r');
        $cur_cache = fgets($fh);
        if (($timestamp - $cur_cache) > (3600*$cached_hours) ) { // 3600 == 1 hour, default cache is 12 hours
          $recreate_cache = true;
        } 
    } else {
        // we don't have one created // 
        $recreate_cache = true;
    }

    // if we should show, lets show //
    if ($show_cache) {
        $cache = fgets($fh);
        header("Connection: close");
        header("Content-Length: " . mb_strlen($cache));
        echo trim($cache);
        fclose($fh);
        flush(); // flush to the browser [try to get response to browser before doing anything else] //
    }

    // if we need to create it, let's do that here // 
    if ($recreate_cache) {
      $fh = fopen($cache_file, 'w');
      fwrite($fh, $timestamp ."\n");

        $base_url = "awesome-product-url-returning-json"; 
        $product_list = array(105,106,107,108,109,110,115,166,149,184);
        $product_data = array();
        $brand_id = 100;
        $agent= 'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.0.3705; .NET CLR 1.1.4322)';

        $api_data = "[";
        foreach($product_list as $product_id => $pid) {
            $ch = curl_init();
            $extended_url = $base_url . $pid . "/" . $brand_id . "/";
            curl_setopt($ch, CURLOPT_URL, $extended_url);
            curl_setopt($ch, CURLOPT_USERAGENT, $agent);
            curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
            $json = curl_exec($ch);
            $api_data = $api_data . $json;
            if ($pid != end($product_list))
              $api_data = $api_data . ',';
        }
        $api_data = $api_data . ']';
        fwrite($fh, $api_data);
        fclose($fh);
    }

    // if we didn't show (didn't have one) but created something, show what we created. [don't return empty] //
    if (!$show_cache && $recreate_cache) {
        echo $api_data;
    }
?>