using Newtonsoft.Json;
using System.Net;
using System.Text;

namespace YLErp.App
{

    /// <summary>
    /// API请求帮助类
    /// </summary>
    static class ApiHelper
    {
        static readonly string BaseAddress = "";
        static readonly HttpClient httpClient;

        static ApiHelper()
        {
            var handler = new HttpClientHandler
            {
                AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate
            };

            httpClient = new HttpClient(handler)
            {
                Timeout = new TimeSpan(0, 3, 0),
                BaseAddress = new Uri(BaseAddress)
            };
            httpClient.DefaultRequestHeaders.Connection.Add("keep-alive");
            httpClient.DefaultRequestHeaders.Add("Keep-Alive", "600");
        }

        //获取访问令牌
        private static string GetAccessToken()
        {
            using (var request = new HttpRequestMessage()
            {
                Method = HttpMethod.Post,
                RequestUri = new Uri(httpClient.BaseAddress, "api/token"),
            })
            {
                var auth = Convert.ToBase64String(Encoding.UTF8.GetBytes("superA:123321"));
                request.Headers.Add("Authorization", "Basic " + auth);
                using (var response = httpClient.SendAsync(request).Result)
                {
                    var res = response.Content.ReadAsStringAsync().Result;
                    var model = JsonConvert.DeserializeObject<TokenRsp>(res);
                    if (model.errcode > 0)
                    {
                        throw new Exception(model.errmsg ?? "发生错误");
                    }
                    return model.accessToken;
                }
            }
        }

        /// <summary>
        /// 请求API
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="apiPath">api路径</param>
        /// <param name="postData">请求数据</param>
        /// <returns></returns>
        public static async Task<string> GetRequestAsync(string apiPath)
        {
            var accessToken = GetAccessToken();

            using (var request = new HttpRequestMessage()
            {
                Method = HttpMethod.Get,
                RequestUri = new Uri(httpClient.BaseAddress, apiPath.TrimStart('/')),
            })
            {
                request.Headers.Add("Authorization", "Bearer " + accessToken);
                var response = await httpClient.SendAsync(request);
                return await response.Content.ReadAsStringAsync();
            }
        }

        /// <summary>
        /// 请求API
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="apiPath">api路径</param>
        /// <param name="postData">请求数据</param>
        /// <returns></returns>
        public static async Task<T> RequestAsync<T>(string apiPath, object postData = null)
        {
            var json = await RequestAsync(apiPath, postData);
            return JsonConvert.DeserializeObject<T>(json);
        }

        /// <summary>
        /// 请求API
        /// </summary>
        /// <param name="apiPath">api路径</param>
        /// <param name="postData">请求数据</param>
        /// <returns></returns>
        public static async Task<string> RequestAsync(string apiPath, object postData = null)
        {
            var accessToken = GetAccessToken();

            using (var request = new HttpRequestMessage()
            {
                Method = HttpMethod.Post,
                RequestUri = new Uri(httpClient.BaseAddress, apiPath.TrimStart('/')),
            })
            {
                request.Headers.Add("Authorization", "Bearer " + accessToken);
                if (postData != null)
                {
                    var str = JsonConvert.SerializeObject(postData);
                    request.Content = new StringContent(str, Encoding.UTF8, "application/json");
                }

                var response = await httpClient.SendAsync(request);
                return await response.Content.ReadAsStringAsync();
            }
        }

        class ErrorRsp
        {
            public int errcode { get; set; }

            public string errmsg { get; set; }
        }

        class TokenRsp : ErrorRsp
        {
            public string tokenType { get; set; }

            public string accessToken { get; set; }

            public int expiresIn { get; set; }

            public string userName { get; set; }
        }
    }
}