Download Youtube Thumbnail

YoutubeThumbs.php

<?php

/**
* Get Preview Image from Youtube video link (not from embeded code) and download it if video exist
* @author Maxim Ishchenko <maxim.ishchenko@gmail.com>
* @version 1.0* 
* @uses 
* 
*     $getThumbs = new YoutubeThumbs('https://youtu.be/xxxxxxxxxxx', 'quality', 'directory');
*     echo '<img src="'.$getThumbs->getThumbnail().'"/>';
* 
* 		xxxxxxxxxxx - youtube video ID
* 		quality - image quality (default, hqdefault, mqdefault, sddefault)
* 		directory - path to save thumbnails
* 
* @property string $url
* @property string $size
* @property string $path
*/
class YoutubeThumbs
{	
	/**
	 * @access public
	 * @property string $youtubeThumbsPath
	 * @property string $youtubeUrl
	 * @property string $youtubeThumbsPath
	 */
	public $youtubeThumbsPath;
	public $youtubeUrl;
	public $youtubeThumbnailSize;

	function __construct($url, $size, $path)
	{
		$this->youtubeUrl = $url;
		$this->youtubeThumbnailSize = $size;
		$this->youtubeThumbsPath = $path;
	}

	/**
	 * Check if Youtube Url Exist
	 * @var string $videoJson formated url from class agruments
	 * @var array $headers headers url from $videoJson
	 * @var integer $code parsed http-status code from $headers array
	 * @access private
	 * @return true|false
	 */
	private function isValidYoutubeUrl()
	{
		$videoJson = "http://www.youtube.com/oembed?url=$this->youtubeUrl&format=json";
		$headers = get_headers($videoJson);
		$code = substr($headers[0], 9, 3);
		return ($code != "404") ? true : false;
	}

	/**
	 * @var string $youtubeThumbnailSize return index for Youtube image url from quality name. Return default quality if index incorrect.
	 * @access private
	 * @return integer return image index from size string
	 */
	private function getThumbsSize()
	{
		switch ($this->youtubeThumbnailSize) {
			case 'default':
				return 0;
				break;
			case 'hqdefault':
				return 1;
				break;
			case 'mqdefault':
				return 2;
				break;
			case 'sddefault':
				return 3;
				break;
			
			// Return default quality if quality from class argument is incorrect
			default:
				return 0;
				break;
		}
	}

	/**
	 * @var array $urlArr get array from url class argument, "/" - delimiter
	 * @var integer $urlArrNum count $urlArr elements
	 * @var string $thumbURL thumbnail url
	 * @access private
	 * @return string $thumbURL
	 */
	private function getThumbsUrl()
	{
		// Parse Youtube video URL
		$urlArr = explode("/",$this->youtubeUrl);
		$urlArrNum = count($urlArr);

		// Get Youtube video ID
		$youtubeVideoId = $urlArr[$urlArrNum - 1];

		// Generate youtube thumbnail url
		$thumbURL = 'http://img.youtube.com/vi/'.$youtubeVideoId.'/'.$this->getThumbsSize($this->youtubeThumbnailSize).'.jpg';

		// Return thumbnail image url
		return $thumbURL;
	}

	/**
	 * @uses string $youtubeThumbsPath path to save thumbnails from class argument
	 * @var string $youtubeImageFileName generate md5 hash string from current time with .jpg extension for filename
	 * @var string $thumbnailPath concatename directory path from class argument and filename from $youtubeImageFileName
	 * @access private
	 * @return string|Exception return path to save thumbnails of Exception if path incorrect
	 */
	private function getThumbnailPath()
	{
		if(is_dir($this->youtubeThumbsPath))
		{
			$youtubeImageFileName = md5(time()).'.jpg';
			$thumbnailPath = $this->youtubeThumbsPath . '/' . $youtubeImageFileName;
		}
		else
		{
			throw new Exception("Incorrect Path", 1);
		}
		return $thumbnailPath;
	}

	/**
	 * Download thumbnails and return full path to image
	 * 
	 * @uses string $url youtube video url
	 * @throws Exception return an exception if url is incorrect
	 * @access public
	 * @return string|Exception return thumbs url if exist or set Exception
	 */
	public function getThumbnail()
	{
		if($this->isValidYoutubeUrl())
		{
			$thumbsPath = $this->getThumbnailPath();
			file_put_contents($thumbsPath, fopen($this->getThumbsUrl($this->youtubeUrl, $this->youtubeThumbnailSize), 'r'));
			return $thumbsPath;
		}
		else
		{
			throw new Exception("Incorrect URL", 1);
		}
	}

}

?>