using CsharpHttpHelper;
using AllBase.Model.Result;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;

namespace Work.Store.Api;

/// <summary>管理 API 的统一 HTTP 出口，负责 JSON、Bearer 认证和错误处理。</summary>
public sealed class ApiTransport
{
    private readonly string _baseUrl;
    private string _token;
    private LoginRequest _credentials;
    internal SemaphoreSlim SessionGate { get; } = new SemaphoreSlim(1, 1);

    // 调用方持有 SessionGate。
    internal void SetSession(string token, LoginRequest credentials)
    {
        _token = token;
        _credentials = credentials;
    }

    public ApiTransport(string baseUrl)
    {
        if (!Uri.TryCreate(baseUrl, UriKind.Absolute, out var uri) ||
            (uri.Scheme != "http" && uri.Scheme != "https") ||
            uri.UserInfo.Length != 0 || uri.Query.Length != 0 || uri.Fragment.Length != 0)
            throw new ArgumentException("必须提供无凭据、查询参数和片段的 HTTP(S) 根地址。", nameof(baseUrl));

        _baseUrl = uri.AbsoluteUri.TrimEnd('/') + "/";
    }

    /// <summary>仅存于内存；手动赋值会清除自动登录凭据，设为 null 退出本地会话。</summary>
    public string Token
    {
        get
        {
            SessionGate.Wait();
            try { return _token; }
            finally { SessionGate.Release(); }
        }
        set
        {
            if (value != null && (string.IsNullOrWhiteSpace(value) || value.IndexOfAny(new[] { '\r', '\n' }) >= 0))
                throw new ArgumentException("Token 不能为空白或包含换行。", nameof(value));
            SessionGate.Wait();
            try { SetSession(value, null); }
            finally { SessionGate.Release(); }
        }
    }

    public T Send<T>(string route, MethodType method, object body = null,
        IDictionary<string, string> query = null, bool authenticated = true,
        int timeoutMilliseconds = 30000)
    {
        var item = CreateRequest(route, method, body, query, timeoutMilliseconds);
        string token = null;
        if (authenticated)
        {
            //SessionGate.Wait();
            //try { token = _token ?? throw new HttpException("请先登录。") { IsOnline = false }; }
            //finally { SessionGate.Release(); }
        }
        for (int attempt = 0; ; attempt++)
        {
            if (token != null) item.Header["Authorization"] = "Bearer " + token;
            var response = HttpHelper.Request(item);
            try { return ReadResult<T>(response); }
            catch (HttpException ex) when (authenticated && !ex.IsOnline)
            {
                SessionGate.Wait();
                try
                {
                    if (_token == token)
                    {
                        _token = null;
                        if (attempt == 0 && _credentials != null)
                            _token = AuthApi.LoginCore(this, _credentials).Token;
                    }
                    if (attempt != 0 || _token == null) throw;
                    token = _token;
                }
                finally { SessionGate.Release(); }
            }
        }
    }

    public async Task<T> SendAsync<T>(string route, MethodType method, object body = null,
        IDictionary<string, string> query = null, bool authenticated = true,
        int timeoutMilliseconds = 30000)
    {
        var item = CreateRequest(route, method, body, query, timeoutMilliseconds);
        string token = null;
        if (authenticated)
        {
            //await SessionGate.WaitAsync().ConfigureAwait(false);
            //try { token = _token ?? throw new HttpException("请先登录。") { IsOnline = false }; }
            //finally { SessionGate.Release(); }
        }
        for (int attempt = 0; ; attempt++)
        {
            if (token != null) item.Header["Authorization"] = "Bearer " + token;
            var response = await HttpHelper.RequestAsync(item).ConfigureAwait(false);
            try { return ReadResult<T>(response); }
            catch (HttpException ex) when (authenticated && !ex.IsOnline)
            {
                await SessionGate.WaitAsync().ConfigureAwait(false);
                try
                {
                    if (_token == token)
                    {
                        _token = null;
                        if (attempt == 0 && _credentials != null)
                            _token = (await AuthApi.LoginCoreAsync(this, _credentials).ConfigureAwait(false)).Token;
                    }
                    if (attempt != 0 || _token == null) throw;
                    token = _token;
                }
                finally { SessionGate.Release(); }
            }
        }
    }

    private HttpItem CreateRequest(string route, MethodType method, object body,
        IDictionary<string, string> query, int timeoutMilliseconds)
    {
		string pathOnly = route?.Split('?', '#')[0];

		if (string.IsNullOrWhiteSpace(pathOnly) ||
            !Regex.IsMatch(pathOnly, @"\A[A-Za-z0-9_-]+(/[A-Za-z0-9_-]+)*\z"))
            throw new ArgumentException("接口必须使用相对路由，例如 Auth/Login。", nameof(route));
        if (body != null) Validator.ValidateObject(body, new ValidationContext(body), true);
        if (timeoutMilliseconds <= 0) throw new ArgumentOutOfRangeException(nameof(timeoutMilliseconds));
        var url = new StringBuilder(_baseUrl).Append(route);
        if (query != null)
        {
            bool first = true;
            foreach (var pair in query)
            {
                if (pair.Value == null) continue;
                url.Append(first ? '?' : '&').Append(Uri.EscapeDataString(pair.Key))
                    .Append('=').Append(Uri.EscapeDataString(pair.Value));
                first = false;
            }
        }
        return new HttpItem
        {
            URL = url.ToString(),
            Method = method,
            ContentType = "application/json; charset=utf-8",
            Accept = "application/json",
            PostDataType = PostDataType.Byte,
            PostdataByte = body == null ? null : Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(body)),
            Encoding = Encoding.UTF8,
            Timeout = timeoutMilliseconds,
            ReadWriteTimeout = timeoutMilliseconds,
            Allowautoredirect = false
        };
    }

    private static T ReadResult<T>(HttpResult response)
    {
        int status = (int)response.StatusCode;
        if (status == 0) throw new HttpException("无法连接服务器或请求超时。");

        Result<JToken> result = null;
        JsonException parseError = null;
        try { result = JsonConvert.DeserializeObject<Result<JToken>>(response.Html ?? ""); }
        catch (JsonException ex) { parseError = ex; }

        if (status == 401 || (result?.Success == false && result.Code == 401))
            throw new HttpException(result?.Msg ?? "登录已失效，请重新登录。") { IsOnline = false };
        // 统一错误响应即使使用 HTTP 4xx/5xx，也保留业务码、数据和追踪 ID。
        if (result?.Success == false)
            throw new ApiException("请求失败：" + (result.Msg ?? $"业务码 {result.Code}。"),
                result.Code, result.Data, result.TraceId);
        if (status < 200 || status >= 300)
            throw new HttpException($"请求失败（HTTP {status}）：{result?.Msg}");
        if (result?.Success == null)
            throw new HttpException("服务器响应不是有效的 Result 格式。", parseError);
        if (result.Data == null || result.Data.Type == JTokenType.Null) return default;
        try { return result.Data.ToObject<T>(); }
        catch (JsonException ex) { throw new HttpException("服务器响应 data 格式无效。", ex); }
    }

    public T GetRequired<T>(string route, MethodType method, object body = null,
        IDictionary<string, string> query = null, bool authenticated = true,
        int timeoutMilliseconds = 30000) where T : class
        => Send<T>(route, method, body, query, authenticated, timeoutMilliseconds)
           ?? throw new HttpException("服务器响应缺少 data。");

    public async Task<T> GetRequiredAsync<T>(string route, MethodType method, object body = null,
        IDictionary<string, string> query = null, bool authenticated = true,
        int timeoutMilliseconds = 30000) where T : class
        => await SendAsync<T>(route, method, body, query, authenticated, timeoutMilliseconds).ConfigureAwait(false)
           ?? throw new HttpException("服务器响应缺少 data。");
}