using System;
using System.Collections.Concurrent;
using System.Net.Http;
using System.Threading.Tasks;
using Newtonsoft.Json;
using TeamAAS.Communication.Attributes;
using TeamAAS.Communication.Base;
using TeamAAS.Communication.Interfaces;

namespace TeamAAS.Communication.Devices
{
    /// <summary>
    /// Web 通讯（HTTP 客户端）。ReadValue(address) 为 GET 请求，
    /// WriteValue(address, value) 为 POST 请求，address 为相对路径。
    /// </summary>
    [Communication("Web", "基础通讯", "HTTP/WebApi 客户端")]
    public class WebCommunication : BindableCommunicationBase
    {
        [JsonIgnore]
        private static readonly HttpClient _http = new HttpClient();

        [JsonIgnore]
        private readonly ConcurrentQueue<string> _received = new ConcurrentQueue<string>();

        [JsonIgnore]
        private bool _connected;

        private string _baseUrl = "http://127.0.0.1:8000";

        public string BaseUrl
        {
            get { return _baseUrl; }
            set { SetProperty(ref _baseUrl, value); }
        }

        public override string EndpointUrl
        {
            get { return BaseUrl; }
            set
            {
                if (!string.IsNullOrWhiteSpace(value))
                    BaseUrl = value.TrimEnd('/');
            }
        }

        public override bool IsConnected
        {
            get { return _connected; }
        }

        public override event Action<object, bool> ConnectChangedEvent;
        public override event Action<object, string> DataReceivedEvent;

        public WebCommunication()
        {
        }

        public override void Connect()
        {
            if (string.IsNullOrWhiteSpace(BaseUrl))
                throw new InvalidOperationException("Web 基础地址不能为空。");

            _connected = true;
            Notify(nameof(IsConnected));
            ConnectChangedEvent?.Invoke(this, true);
            Notify(nameof(IsConnected));
        }

        public override Task ConnectAsync()
        {
            Connect();
            return Task.CompletedTask;
        }

        public override void Disconnect()
        {
            _connected = false;
            Notify(nameof(IsConnected));
            ConnectChangedEvent?.Invoke(this, false);
            Notify(nameof(IsConnected));
        }

        public override void Dispose()
        {
            Disconnect();
        }

        public override object ReadValue(string address)
        {
            try
            {
                var url = string.IsNullOrWhiteSpace(address) ? BaseUrl : $"{BaseUrl}/{address.TrimStart('/')}";
                return _http.GetStringAsync(url).GetAwaiter().GetResult();
            }
            catch (Exception ex)
            {
                return ex.Message;
            }
        }

        public override async Task<object> ReadValueAsync(string address)
        {
            try
            {
                var url = string.IsNullOrWhiteSpace(address) ? BaseUrl : $"{BaseUrl}/{address.TrimStart('/')}";
                return await _http.GetStringAsync(url);
            }
            catch (Exception ex)
            {
                return ex.Message;
            }
        }

        public override void WriteValue(string address, object value)
        {
            var url = string.IsNullOrWhiteSpace(address) ? BaseUrl : $"{BaseUrl}/{address.TrimStart('/')}";
            var content = new StringContent(value?.ToString() ?? string.Empty, System.Text.Encoding.UTF8, "application/json");
            _http.PostAsync(url, content).GetAwaiter().GetResult();
        }

        public override async Task WriteValueAsync(string address, object value)
        {
            var url = string.IsNullOrWhiteSpace(address) ? BaseUrl : $"{BaseUrl}/{address.TrimStart('/')}";
            var content = new StringContent(value?.ToString() ?? string.Empty, System.Text.Encoding.UTF8, "application/json");
            await _http.PostAsync(url, content);
        }
    }
}