<?php

namespace Server\Protocol;


class WebSocket extends Protocol
{


	//
	public function decode($received): ?string
	{
		$decoded = null;
		$buffer = $received;
		$len = ord($buffer[1]) & 127;
		if ($len === 126) {
			$masks = substr($buffer, 4, 4);
			$data = substr($buffer, 8);
		} else {
			if ($len === 127) {
				$masks = substr($buffer, 10, 4);
				$data = substr($buffer, 14);
			} else {
				$masks = substr($buffer, 2, 4);
				$data = substr($buffer, 6);
			}
		}
		for ($index = 0; $index < strlen($data); $index++) {
			$decoded .= $data[$index] ^ $masks[$index % 4];
		}

		return $decoded;
	}

	const BINARY_TYPE_BLOB = "\x81";


	public function encode($buffer): string
	{
		$len = strlen($buffer);

		$first_byte = self::BINARY_TYPE_BLOB;

		if ($len <= 125) {
			$encode_buffer = $first_byte . chr($len) . $buffer;
		} else {
			if ($len <= 65535) {
				$encode_buffer = $first_byte . chr(126) . pack("n", $len) . $buffer;
			} else {
				//pack("xxxN", $len)pack函数只处理2的32次方大小的文件，实际上2的32次方已经4G了。
				$encode_buffer = $first_byte . chr(127) . pack("xxxxN", $len) . $buffer;
			}
		}

		return $encode_buffer;
	}


	/**
	 * @param $data
	 * @return string
	 */
	private function getWebSocketProtocol($data): string
	{
		[$http_protocol, $body] = $this->resolveProtocol($data);
		$key = base64_encode(sha1($http_protocol['Sec-WebSocket-Key'] . '258EAFA5-E914-47DA-95CA-C5AB0DC85B11', TRUE));
		$headers = [
			'HTTP/1.1 101 Switching Protocols',
			'Upgrade: websocket',
			'Connection: Upgrade',
			'Sec-WebSocket-Accept: ' . $key,
			'Sec-WebSocket-Version: 13',
		];
		if (isset($http_protocol['Sec-WebSocket-Protocol'])) {
			$headers[] = 'Sec-WebSocket-Protocol: ' . $http_protocol['Sec-WebSocket-Protocol'];
		}
		return implode("\r\n", $headers) . "\r\n\r\n";
	}


}