using System.Collections.Specialized;
using System.Net.Http.Headers;
using System.Text;
using DS.Module.Core.Extensions;
using Newtonsoft.Json;

namespace DS.Module.Core
{
    /// <summary>
    /// 提供对HTTP请求的低级别访问
    /// </summary>
    public class ApiFox : IDisposable
    {
        readonly HttpClient http;

        /// <summary>
        /// 基URI
        /// </summary>
        public Uri? BaseUri { get { return http.BaseAddress; } set { http.BaseAddress = value; } }

        /// <summary>
        /// 默认请求头
        /// </summary>
        public HttpRequestHeaders DefaultHeaders => http.DefaultRequestHeaders;

        /// <summary>
        /// 在发送网络请求之前的事件
        /// </summary>
        public event EventHandler<BeforeSendEventArgs>? BeforeSend;

        /// <summary>
        /// 在发送网络请求完成时的事件
        /// </summary>
        public event EventHandler<CompleteEventArgs>? Completed;


        /// <summary>
        /// 初始化
        /// </summary>
        /// <param name="pooledMinutes">连接池使用时间，默认为30分钟</param>
        public ApiFox(int pooledMinutes = 30)
        {
            var handler = new SocketsHttpHandler
            {
                PooledConnectionLifetime = TimeSpan.FromMinutes(pooledMinutes)
            };
            http = new(handler);
            http.DefaultRequestHeaders.Add("User-Agent", $"X-{nameof(ApiFox)}");
            http.DefaultRequestHeaders.Add("Accept", "application/json, text/plain");
        }

        /// <summary>
        /// 发起<see cref="HttpMethod.Get"/>请求
        /// </summary>
        /// <typeparam name="T">请求结果的类型</typeparam>
        /// <param name="url">请求Url</param>
        /// <param name="keyValues">查询字符串的键值对</param>
        /// <returns></returns>
        /// <exception cref="ArgumentException"><paramref name="url"/>为null或空字符串</exception>
        public async Task<DataResult<T>> GetAsync<T>(string url, NameValueCollection? keyValues = null)
        {
            string queryString = string.Empty;
            if (keyValues != null && keyValues.Count > 0)
            {
                StringBuilder sb = new StringBuilder();
                foreach (string key in keyValues.Keys)
                {
                    var values = keyValues.GetValues(key);
                    if (values?.Length > 0)
                    {
                        for (int i = 0; i < values.Length; i++)
                        {
                            sb.Append($"&{key}={values[i]}");
                        }
                    }
                }

                if (sb.Length > 0) //移除首个&符
                    sb.Remove(0, 1);

                queryString = sb.ToString();
            }

            if (!queryString.IsNullOrEmpty())
                url = url.LastOrDefault() == '?' ? url + queryString : url + "?" + queryString;

            var response = await SendRequestAsync(HttpMethod.Get, url);
            T? data = default;
            if (response != null)
            {
                string json = await response.Content.ReadAsStringAsync();
                data = JsonConvert.DeserializeObject<T>(json);
            }

            return DataResult<T>.Success(data);
        }

        /// <summary>
        /// 发起<see cref="HttpMethod.Post"/>请求
        /// </summary>
        /// <typeparam name="T">请求结果的类型</typeparam>
        /// <param name="url">请求Url</param>
        /// <param name="requestParams">请求参数对象</param>
        /// <returns></returns>
        /// <exception cref="ArgumentException"><paramref name="url"/>为null或空字符串</exception>
        public async Task<DataResult<T>> PostAsync<T>(string url, object? requestParams = null)
        {
            var response = await SendRequestAsync(HttpMethod.Post, url, requestParams);
            T? data = default;
            if (response != null)
            {
                string json = await response.Content.ReadAsStringAsync();
                data = JsonConvert.DeserializeObject<T>(json);
            }

            return DataResult<T>.Success(data);
        }

        /// <summary>
        /// 发起HTTP请求
        /// </summary>
        /// <param name="method">请求方法</param>
        /// <param name="url">请求Url</param>
        /// <param name="requestParams">请求参数</param>
        /// <returns></returns>
        /// <exception cref="ArgumentNullException"><paramref name="method"/>为null</exception>
        /// <exception cref="ArgumentException"><paramref name="url"/>为null或空字符串</exception>
        /// <exception cref="NotSupportedException"><paramref name="method"/>不等于 GET/POST/PUT/Delete 中的任何一个请求方法</exception>
        public async Task<HttpResponseMessage> SendRequestAsync(HttpMethod method, string url, object? requestParams = null)
        {
            ArgumentNullException.ThrowIfNull(method);
            ArgumentException.ThrowIfNullOrEmpty(url);

            Uri? reqUri = default;
            if (BaseUri == null)
            {
                if (!Uri.TryCreate(url, UriKind.RelativeOrAbsolute, out Uri? uri))
                    throw new ArgumentException("给定的URL格式无效", nameof(url));

                reqUri = new Uri(url);
            }
            else
            {
                reqUri = new(BaseUri, url);
            }

            OnBeforeSend(new BeforeSendEventArgs
            {
                RequestHeaders = http.DefaultRequestHeaders,
                RequestParameter = requestParams,
                RequestUri = reqUri
            });

            HttpResponseMessage? response = null;
            if (method == HttpMethod.Get)
            {
                response = await http.GetAsync(reqUri);
            }
            else if (method == HttpMethod.Post)
            {
                string json = JsonConvert.SerializeObject(requestParams);
                var jsonRequest = new StringContent(json, Encoding.UTF8, "application/json");
                response = await http.PostAsync(reqUri, jsonRequest);
            }
            else if (method == HttpMethod.Put)
            {
                string json = JsonConvert.SerializeObject(requestParams);
                var jsonRequest = new StringContent(json, Encoding.UTF8, "application/json");
                response = await http.PutAsync(reqUri, jsonRequest);
            }
            else if (method == HttpMethod.Delete)
            {
                response = await http.DeleteAsync(reqUri);
            }
            else
            {
                throw new NotSupportedException($"不支持的请求方法：{method.Method}");
            }

            OnCompleted(new CompleteEventArgs
            {
                RequestUri = reqUri,
                Response = response
            });

            return response;
        }

        /// <summary>
        /// 在发送网络请求之前调用
        /// </summary>
        /// <param name="e">事件参数</param>
        protected virtual void OnBeforeSend(BeforeSendEventArgs e)
        {
            BeforeSend?.Invoke(this, e);
        }

        /// <summary>
        /// 在发送网络请求完成时调用
        /// </summary>
        /// <param name="e">事件参数</param>
        protected virtual void OnCompleted(CompleteEventArgs e)
        {
            Completed?.Invoke(this, e);
        }

        /// <summary>
        /// 释放网络连接
        /// </summary>
        public void Dispose() => http?.Dispose();
    }

    /// <summary>
    /// 发送网络请求之前的事件参数
    /// </summary>
    public class BeforeSendEventArgs : EventArgs
    {
        /// <summary>
        /// 远程请求的URI
        /// </summary>
        public Uri RequestUri { get; internal set; }

        /// <summary>
        /// 请求标头
        /// </summary>
        public HttpRequestHeaders RequestHeaders { get; internal set; }

        /// <summary>
        /// 请求参数
        /// </summary>
        public object? RequestParameter { get; set; }
    }

    /// <summary>
    /// 发送网络请求完成的事件参数
    /// </summary>
    public class CompleteEventArgs : EventArgs
    {
        /// <summary>
        /// 远程请求的URI
        /// </summary>
        public Uri RequestUri { get; internal set; }

        /// <summary>
        /// 网络响应对象
        /// </summary>
        public HttpResponseMessage Response { get; internal set; }
    }
}