<?php


namespace common;


class Decode
{

	private $sessionKey;
	private $iv;
	private $encryptedData;
	private $appId;


	private $OK = 0;
	private $IllegalAesKey = -41001;
	private $IllegalIv = -41002;
	private $IllegalBuffer = -41003;
	private $DecodeBase64Error = -41004;

	/**
	 * @param mixed $sessionKey
	 * @return Decode
	 */
	public function setSessionKey($sessionKey)
	{
		$this->sessionKey = $sessionKey;
		return $this;
	}

	/**
	 * @param mixed $iv
	 * @return Decode
	 */
	public function setIv($iv)
	{
		$this->iv = $iv;
		return $this;
	}

	/**
	 * @param mixed $encryptedData
	 * @return Decode
	 */
	public function setEncryptedData($encryptedData)
	{
		$this->encryptedData = $encryptedData;
		return $this;
	}

	/**
	 * @param mixed $appId
	 * @return Decode
	 */
	public function setAppId($appId)
	{
		$this->appId = $appId;
		return $this;
	}


	/**
	 * @param $asArray
	 * @return array|mixed
	 * @throws \Exception
	 */
	public function decode($asArray)
	{
		if (strlen($this->sessionKey) != 24) {
			throw new \Exception('encodingAesKey 非法', $this->IllegalAesKey);
		}

		$aesKey = base64_decode($this->sessionKey);
		if (strlen($this->iv) != 24) {
			throw new \Exception('base64解密失败', $this->IllegalIv);
		}

		$aesIV = base64_decode($this->iv);
		$aesCipher = base64_decode($this->encryptedData);
		$result = openssl_decrypt($aesCipher, "AES-128-CBC", $aesKey, OPENSSL_RAW_DATA, $aesIV);
		if ($result === false) {
			throw new \Exception('aes 解密失败', $this->IllegalBuffer);
		}

		$dataObj = json_decode($result);
		if ($dataObj->watermark->appid != $this->appId) {
			throw new \Exception('aes 解密失败', $this->IllegalBuffer);
		}

		if ($asArray) {
			return get_object_vars($dataObj);
		}

		return $dataObj;

	}

}