APOD Widget [Flatpress]

<?php
/*
Plugin Name: Apod Widget
Version: 1.0
Plugin URI: http://www.vdfn.altervista.org/
Description: The APOD widget, like the wordpress one.
Author: Piero VDFN
Author URI: http://www.vdfn.altervista.org/
*/

/**
 * This is the file of the image URL cache.
 */
define('APOD_CACHE', CACHE_DIR.'apod.tmp');

/**
 * This is the thumb file.
 */
define('APOD_THUMB', IMAGES_DIR.'apod_thumb.jpg');

/**
 * This is the width of the thumbnail in pixels.
 */
define('APOD_THUMB_WIDTH', 150);

/**
 * This is the target attribute of the link of the widget.
 * It it breaks your validation, leave it void.
 */
define('APOD_TARGET', '');

/**
 * This is the an advanced function: if filemtime does
 * not work, set it to true.
 */
define('APOD_CLEARSTAT', false);

/**
 * This function returns the URL of the Apod Image.
 *
 * @return string: The URL
 */
function apod_geturl() {
    global $apod_image;

    if(!empty($apod_image)) {
        return $apod_image;
    }

    if(APOD_CLEARSTAT) {
        clearstatcache();
    }

    if(@filemtime(APOD_CACHE)>strtotime('today')) {
        $apod_image=io_load_file(APOD_CACHE);
        return $apod_image;
    }

    $baseurl='http://apod.nasa.gov/apod/';
    $pageurl=$baseurl.'ap'.date('ymd').'.html';

    // Get the page with cURL
    $ch=curl_init();
    curl_setopt($ch, CURLOPT_URL, $pageurl);
    curl_setopt($ch, CURLOPT_HEADER, false);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    $pagehtml=curl_exec($ch);
    curl_close($ch);

    // If we had an error with cURL...
    if($pagehtml===false) {
        return false;
    }

    // Get the image URL
    $searchfor='<IMG SRC="';
    $src_beg=strpos($pagehtml, $searchfor);

    if($src_beg===FALSE) {
        return false;
    }

    $src_beg+=strlen($searchfor);
    $src_end=strpos($pagehtml, '"', $src_beg);

    $url=$baseurl.substr($pagehtml, $src_beg, $src_end-$src_beg);
    $apod_image=$url;
    io_write_file(APOD_CACHE, $url);

    return $url;
}

/**
 * This function creates the thumbnail of the Apod Image.
 *
 * @return boolean: Is the thumb ok?
 */
function apod_thumb() {
    if(APOD_CLEARSTAT) {
        clearstatcache();
    }

    if(@filemtime(APOD_THUMB)>strtotime('today')) {
        return true;
    }

    if(file_exists(APOD_THUMB)) {
        @unlink(APOD_THUMB);
    }

    // Get the image URL
    @$image_url=apod_geturl();

    if($image_url===false) {
        return false;
    }

    // Download the image with cURL
    $ch=curl_init();
    curl_setopt($ch, CURLOPT_URL, $image_url);
    curl_setopt($ch, CURLOPT_HEADER, false);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    $image=curl_exec($ch);
    curl_close($ch);

    if($image===false) {
        return false;
    }

    // Save a temporary copy of the image to get its width
    $tmpfile=CACHE_DIR.'apod-tmp-'.mt_rand();
    if(!io_write_file($tmpfile, $image)) {
        $image='';
        unset($image);
        return false;
    }
    list($width, $height)=getimagesize($tmpfile);
    unlink($tmpfile);
    unset($tmpfile);

    // Save the new dimensions...
    $newwidth=APOD_THUMB_WIDTH;
    $newheight=$newwidth*$height/$width;

    // Make the thumb
    // @link http://it.php.net/manual/en/function.imagecopyresized.php
    $thumb=imagecreatetruecolor($newwidth, $newheight);
    $source=imagecreatefromstring($image);
    unset($image); // Free memory

    if($source===false) {
        return false;
    }

    imagecopyresized($thumb, $source, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
    $result=imagejpeg($thumb, APOD_THUMB);
    imagedestroy($thumb);
    imagedestroy($source);

    return $result;
}

/**
 * This function is the handler for the APOD Widget.
 *
 * @return array: The title and the content of the widget
 */
function apod_widget() {
    $fullurl=apod_geturl();
    $page='http://apod.nasa.gov/apod/ap'.date('ymd').'.html';

    if(apod_thumb()) {
        $image=BLOG_BASEURL.APOD_THUMB;
    } else {
        $image=$fullurl.'" style="width: 150px;" ';
    }

    if(APOD_TARGET!='') {
        $target=' target="'.APOD_TARGET.'"';
    }

    $content="<p>\n<a href=\"{$page}\"{$target}>\n"."<img src=\"{$image}\" ".
        "alt=\"Astronomy Picture of the Day\" title=\"Astronomy Picture of the Day\" />\n</a>\n</p>";

    return array(
        'subject'=>'APOD',
        'content'=>$content
    );
}
register_widget('apod', 'APOD', 'apod_widget');