using System.Text;
using System.Web;
using Common;
using Infrastructure;

namespace Filters
{
    public class DecryptMiddleware
    {
        public static int Do(HttpContext context)
        {
            var request = context.Request;
            string cipherText = "";
            try
            {
                if(request.Method.ToLower() == "get")
                {
                    cipherText = request.Query["value"];
                    cipherText = HttpUtility.UrlDecode(cipherText);
                    cipherText = Decrypt(cipherText);
                    cipherText = HttpUtility.UrlDecode(cipherText);
                }
                else if(request.Method.ToLower() == "delete")
                {
                    string path = request.Path.Value;
                    string value = path.Substring(path.LastIndexOf("/") + 1);
                    path = path.Substring(0, path.LastIndexOf("/") + 1);
                    value = Decrypt(value);
                    path += value;
                    request.Path = new PathString(path);
                    request.RouteValues["id"] = value;
                }
                else
                {
                    using var reader = new StreamReader(request.Body, leaveOpen: true);
                    cipherText = reader.ReadToEnd();
                    if(cipherText.StartsWith("value=")) 
                    {
                        cipherText = cipherText.Replace("value=", "");
                    }
                    cipherText = Decrypt(cipherText);
                }
                if (string.IsNullOrWhiteSpace(cipherText))
                {
                    return 1;
                }

                if(request.Method.ToLower() == "get")
                {
                    cipherText = GetParams(cipherText);
                    var queryDict = Microsoft.AspNetCore.WebUtilities.QueryHelpers.ParseQuery(cipherText);
                    var newQuery = new QueryCollection(queryDict);
                    request.Query = newQuery;
                    request.QueryString = new QueryString("?" + cipherText);
                }
                else if(request.Method.ToLower() == "delete") {}
                else
                {
                    var bytes = Encoding.UTF8.GetBytes(cipherText);
                    var ms = new MemoryStream(bytes);
                    request.Body = ms;        // 替换为明文
                    request.ContentLength = bytes.Length;
                    ms.Position = 0;
                }
            }
            catch (Exception ex)
            {
                context.Response.StatusCode = StatusCodes.Status400BadRequest;
                Utils.WriteLog(ex.ToString(), "解密异常");
                return 2;
            }
            return 0;
        }

        public static string Decrypt(string str)
        {
            if(string.IsNullOrEmpty(str)) return "";
            str = str.Trim('"');
            str = Encoding.UTF8.GetString(Convert.FromBase64String(str));
            var options = App.OptionsSetting;
            var aes = options.Aes;
            return Dbconn.AesDecrypt(str, aes.EncodeKey, aes.EncodeIv, aes.EncodeMode, aes.EncodePadding);
        }

        #region 接口通用DES解密

        public static string DesDecrypt(string content)
        {
            content = HttpUtility.UrlDecode(content);
            return Dbconn.DesDecrypt(content, "&L^kg4N9");
        }

        #endregion

        public static string GetParam(string content, string key)
        {
            if(content.StartsWith("?")) content = content.Substring(1);
            string[] data = content.Split('&');
            foreach(string sub in data)
            {
                if(sub.StartsWith(key + "="))
                {
                    return sub.Substring(sub.IndexOf("=") + 1);
                }
            }
            return "";
        }

        public static string GetParams(string content)
        {
            SortedList<string, string> req = Newtonsoft.Json.JsonConvert.DeserializeObject<SortedList<string, string>>(content);
            return Function.BuildQueryString(req);
        }
    }
}