using System;
using System.Security.Cryptography;
using System.Text;
using LitJson;


namespace Sog.Crypto
{
    public enum HuaweiPaySignatureType
    {
        SHA256WithRSA = 1,
        SHA256WithRSA_PSS = 2,
    }

    public static class HuaweiPaySecurity
    {
        public static bool VerifyRsaSign(String content, String sign, String publicKey,
            HuaweiPaySignatureType sigType)
        {
            bool checkRet = false;
            using (var rsaProv = RSA.Create())
            {
                byte[] contentBytes = Encoding.UTF8.GetBytes(content);
                byte[] signBytes = Convert.FromBase64String(sign);
                byte[] publicKeyBytes = Convert.FromBase64String(publicKey);

                try
                {
                    int readBytes = 0;
                    rsaProv.ImportSubjectPublicKeyInfo(publicKeyBytes, out readBytes);

                    if (sigType == HuaweiPaySignatureType.SHA256WithRSA)
                    {
                        checkRet = rsaProv.VerifyData(contentBytes, signBytes,
                            HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);
                    }
                    else if (sigType == HuaweiPaySignatureType.SHA256WithRSA_PSS)
                    {
                        checkRet = rsaProv.VerifyData(contentBytes, signBytes,
                            HashAlgorithmName.SHA256, RSASignaturePadding.Pss);

                    }
                    else
                    {
                        TraceLog.Error("HuaweiPaySecurity.VerifyRsaSign invalid sign algorithm");
                    }
                }
                catch (CryptographicException e)
                {
                    TraceLog.Exception(e);
                }
                finally
                {
                    rsaProv.Clear();
                }
            }

            TraceLog.Debug("HuaweiPaySecurity.VerifyRsaSign {0} ret {1}", sigType, checkRet);
            return checkRet;
        }


        public static void GetOrderIdFromPurchaseData(string purchaseData, 
            out string orderId, out string orderId3rd)
        {
            orderId = null;
            orderId3rd = null;

            JsonData jsonData = JsonMapper.ToObject(purchaseData);
            if (jsonData == null)
            {
                return;
            }

            JsonData payload = jsonData["developerPayload"];
            if (payload != null)
            {
                orderId = payload.ToString();
            }

            JsonData order3rd = jsonData["orderId"];
            if (order3rd != null)
            {
                orderId3rd = order3rd.ToString();
            }
        }
    }
}