cached_url.php

<?php

function is_online() {
    if (!@fopen("http://example.com/", "r")) {
        return false;
    }
    return true;
}

function is_recent($filepath, $max_age) {
    $then = filemtime($filepath);
    $now  = time();
    $diff = $now - $then;
    if ($diff < $max_age) {
        return true;
    }
    return false;
}

function cached_url($url, $filepath, $max_age) {
    $content = null;
    if (file_exists($filepath)) {
        if (!is_recent($filepath, $max_age) && is_online()) {
            unlink($filepath);
            $content = file_get_contents($url);
            file_put_contents($filepath, $content);
        } else {
            $content = file_get_contents($filepath);
        }
    } else {
        $content = file_get_contents($url);
        file_put_contents($filepath, $content);
    }
    return $content;
}

function cached_parsed_url($url, $raw_path, $cached_path, $max_age, $parse_callback) {
    $raw_content    = null;
    $cached_content = null;
    if (file_exists($cached_path)) {
        if (!is_recent($cached_path, $max_age) && is_online()) {
            @unlink($raw_path);
            unlink($cached_path);
            $raw_content = file_get_contents($url);
            file_put_contents($raw_path, $raw_content);
            $cached_content = $parse_callback($raw_content);
            file_put_contents($cached_path, $cached_content);
        } else {
            $cached_content = file_get_contents($cached_path);
        }
    } else {
        if (file_exists($raw_path)) {
            if (!is_recent($raw_path, $max_age) && is_online()) {
                $raw_content = file_get_contents($url);
                file_put_contents($raw_path, $raw_content);
            } else {
                $raw_content = file_get_contents($raw_path);
            }
        } else {
            $raw_content = file_get_contents($url);
            file_put_contents($raw_path, $raw_content);
        }
        $cached_content = $parse_callback($raw_content);
        file_put_contents($cached_path, $cached_content);
    }
    return $cached_content;
}