using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using LitJson;

namespace Sog.Crypto
{
    public static class HeroUSDKSecurity
    {
        public static MD5 _md5 = MD5.Create();

        // 生成http请求中的data字段
        public static string CreateData(Dictionary<string, string> dataParam)
        {
            JsonData data = new JsonData();
            foreach (KeyValuePair<string, string> pair in dataParam)
            {
                data[pair.Key] = new JsonData(pair.Value);
            }

            string jsonStr = data.ToJson();
            string finalData = Convert.ToBase64String(Encoding.ASCII.GetBytes(jsonStr));

            if (finalData.Length > 51)
            {
                char[] array = finalData.ToCharArray();
                SwapChar(array, 1, 33);
                SwapChar(array, 10, 42);
                SwapChar(array, 18, 50);
                SwapChar(array, 19, 51);
                finalData = new string(array);
            }

            return finalData;
        }

        // 传入按字母排序后的请求参数, 不包含_appKey, 返回签名
        public static string CalcSign(string appKey, Dictionary<string, string> allParam)
        {
            var str = CreateParamsStr(appKey, allParam, true);

            byte[] md5Hash = _md5.ComputeHash(Encoding.UTF8.GetBytes(str));
            string md5Str = BitConverter.ToString(md5Hash).Replace("-", "").ToLower();
            //if (md5Str.Length > 23)
            //{
            //    char[] array = md5Str.ToCharArray();
            //    SwapChar(array, 1, 13);
            //    SwapChar(array, 5, 17);
            //    SwapChar(array, 7, 23);
            //    md5Str = new string(array);
            //}

            TraceLog.Trace("HeroUSDKSecurity.CalcSign str {0}, md5 {1}", str, md5Str);
            return md5Str;
        }

        private static void SwapChar(char[] str, int idx1, int idx2)
        {
            if (idx1 >= 0 && idx2 >= 0 && str.Length > Math.Max(idx1, idx2))
            {
                char tmp = str[idx1];
                str[idx1] = str[idx2];
                str[idx2] = tmp;
            }
        }

        private static string CreateParamsStr(string appKey, Dictionary<string, string> allParam, bool sortParam)
        {
            // sign不参与签名
            allParam.Remove("sign");

            StringBuilder sb = new StringBuilder();

            // 生成签名串, "k1=v1&k2=v2...&_appKey"
            if (sortParam)
            {
                var sortPairs = from pair in allParam orderby pair.Key select pair;
                foreach (KeyValuePair<string, string> pair in sortPairs)
                {
                    sb.Append(pair.Key).Append('=').Append(pair.Value).Append('&');
                }
            }
            else
            {
                foreach (KeyValuePair<string, string> pair in allParam)
                {
                    sb.Append(pair.Key).Append('=').Append(pair.Value).Append('&');
                }
            }

            sb.Append(appKey);

            return sb.ToString();
        }
    }
}