KJD/Work/Store.Api/ApiTransport.cs

using CsharpHttpHelper;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Text;
using System.Text.RegularExpressions;

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 Func<string> _login;
    internal object SessionGate { get; } = new object();

    internal void SetSession(string token, Func<string> login)
    {
        lock (SessionGate)
        {
            _token = token;
            _login = login;
        }
    }

    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 { lock (SessionGate) return _token; }
        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));
            SetSession(value, null);
        }
    }

    /// <summary>同步请求；无 data 时返回 default(T)，界面调用需放在后台线程。</summary>
    public T Send<T>(string route, MethodType method, object body = null,
        IDictionary<string, string> query = null, bool authenticated = true,
        int timeoutMilliseconds = 30000)
    {
        if (string.IsNullOrWhiteSpace(route) ||
            !Regex.IsMatch(route, @"\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));
        string token = authenticated ? Token : null;
        if (authenticated && token == null)
            throw new HttpException("请先登录。") { IsOnline = false };

        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;
            }
        }
        var item = 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
        };
        for (int attempt = 0; ; attempt++)
        {
            if (token != null) item.Header["Authorization"] = "Bearer " + token;
            var response = HttpHelper.Request(item);
            int status = (int)response.StatusCode;
            if (status == 0) throw new HttpException("无法连接服务器或请求超时。");

            JObject result = null;
            JsonException parseError = null;
            try { result = JObject.Parse(response.Html ?? ""); }
            catch (JsonException ex) { parseError = ex; }

            var code = result?["code"];
            if (status == 401 || (code?.Type == JTokenType.Integer && code.ToString() == "401"))
            {
                if (authenticated)
                {
                    lock (SessionGate)
                    {
                        // 并发旧请求复用已更新的 Token；同一请求最多重新发送一次。
                        if (_token == token)
                        {
                            _token = null;
                            if (attempt == 0 && _login != null)
                                _token = _login();
                        }
                        if (attempt == 0 && _token != null)
                        {
                            token = _token;
                            continue;
                        }
                    }
                }
                throw new HttpException(result?["msg"]?.ToString() ?? "登录已失效，请重新登录。") { IsOnline = false };
            }
            if (status < 200 || status >= 300)
                throw new HttpException($"请求失败（HTTP {status}）：{result?["msg"]}");
            if (result == null)
                throw new HttpException("服务器响应不是有效的 JSON 对象。", parseError);
            // 先检查业务码，避免错误响应的 data 结构掩盖服务端错误。
            if (code?.Type != JTokenType.Integer || code.ToString() != "200")
                throw new ApiException("请求失败：" + (result["msg"]?.ToString() ?? "响应缺少成功状态码。"),
                    code?.Type == JTokenType.Integer && int.TryParse(code.ToString(), out var businessCode) ? businessCode : (int?)null,
                    result["data"]);
            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。");
}