class VideoStream {

	private $path = "";
	private $stream = "";
	private $buffer = 102400;
	private $start = - 1;
	private $end = - 1;
	private $size = 0;

	private $videoFormats;

	function __construct( $filePath ) {
		$this->videoFormats = apply_filters( 'dozent_video_types', [
			"mp4"  => "video/mp4",
			"webm" => "video/webm",
			"ogg"  => "video/ogg"
		] );

		$this->path = $filePath;
	}

	/**
	 * Open stream
	 */
	private function open() {
		if ( ! ( $this->stream = fopen( $this->path, 'rb' ) ) ) {
			die( 'Could not open stream for reading' );
		}
	}

	/**
	 * Set proper header to serve the video content
	 */
	private function setHeader() {
		ob_get_clean();

		header( "Content-Type: {$this->videoFormats[strtolower(pathinfo($this->path, PATHINFO_EXTENSION))]}" );
		header( "Cache-Control: max-age=2592000, public" );
		header( "Expires: " . gmdate( 'D, d M Y H:i:s', dozent_time() + 2592000 ) . ' GMT' );
		header( "Last-Modified: " . gmdate( 'D, d M Y H:i:s', @filemtime( $this->path ) ) . ' GMT' );
		$this->start = 0;
		$this->size  = filesize( $this->path );
		$this->end   = $this->size - 1;
		header( "Accept-Ranges: 0-" . $this->end );

		if ( isset( $_SERVER['HTTP_RANGE'] ) ) {
			$c_end = $this->end;
			list( , $range ) = explode( '=', $_SERVER['HTTP_RANGE'], 2 );

			if ( $range == '-' ) {
				$c_start = $this->size - substr( $range, 1 );
			} else {
				$range   = explode( '-', $range );
				$c_start = $range[0];

				$c_end = ( isset( $range[1] ) && is_numeric( $range[1] ) ) ? $range[1] : $c_end;
			}
			$c_end = ( $c_end > $this->end ) ? $this->end : $c_end;
			if ( $c_start > $c_end || $c_start > $this->size - 1 || $c_end >= $this->size ) {
				header( 'HTTP/1.1 416 Requested Range Not Satisfiable' );
				header( "Content-Range: bytes $this->start-$this->end/$this->size" );
				exit;
			}
			$this->start = $c_start;
			$this->end   = $c_end;
			$length      = $this->end - $this->start + 1;
			header( 'HTTP/1.1 206 Partial Content' );
			header( "Content-Length: " . $length );
			header( "Content-Range: bytes $this->start-$this->end/" . $this->size );
			header( "Accept-Ranges: bytes" );
		} else {
			header( "Content-Length: " . $this->size );
		}

	}

	/**
	 * close currently opened stream
	 */
	private function end() {
		fclose( $this->stream );
		exit;
	}

	/**
	 * perform the streaming of calculated range
	 */
	private function stream() {
		$i = $this->start;
		set_time_limit( 0 );
		while ( ! feof( $this->stream ) && $i <= $this->end ) {
			$bytesToRead = $this->buffer;
			if ( ( $i + $bytesToRead ) > $this->end ) {
				$bytesToRead = $this->end - $i + 1;
			}
			//$data = fread($this->stream, $bytesToRead);
			$data = @stream_get_contents( $this->stream, $bytesToRead, $i );
			echo $data;
			flush();
			$i += $bytesToRead;
		}
	}

	/**
	 * Start streaming lecture video content
	 */
	function start() {
		$this->open();
		$this->setHeader();
		$this->stream();
		$this->end();
	}
}