using System.Net.Http.Headers;
using System.Text;
using System.Text.Json.Nodes;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting.Server;
using Microsoft.AspNetCore.Hosting.Server.Features;
using Microsoft.Extensions.DependencyInjection;
using MoShiro.Backend.Application;
using MoShiro.TestSupport;

namespace MoShiro.Backend.Tests;

/// <summary>首次启动种入的默认线路任务模板数：udp_echo、tcp_echo、connect。</summary>
internal static class Defaults
{
    public const int TaskCount = 3;
}

/// <summary>
/// 在真实的 Kestrel 端口上启动整个后端（真实的 SQLite 与段文件，只是用临时目录和较快的轮询），
/// 并提供管理员客户端（Bearer 令牌）和假 Agent。
/// </summary>
public class BackendFixture : IAsyncLifetime
{
    public const string AdminUser = "admin";
    public const string AdminPassword = "correct horse battery";

    private readonly List<AgentSimulator> _agents = [];
    private string _adminToken = "";
    private int _counter;

    /// <summary>所有测试都从同一个回环地址登录，所以共享的后端放宽限流；专门测试限流的类用 <see cref="StrictLoginFixture"/>。</summary>
    protected virtual int LoginAttemptsPerMinute => 1000;

    public WebApplication App { get; private set; } = null!;

    public Uri BaseAddress { get; private set; } = null!;

    public string DataDirectory { get; private set; } = "";

    public HttpClient Anonymous { get; private set; } = null!;

    /// <summary>带 admin 作用域的 API 令牌的客户端。</summary>
    public HttpClient Admin { get; private set; } = null!;

    public IServiceProvider Services => App.Services;

    /// <summary>夹具创建的默认 Probe：合成块（<see cref="ChunkFactory"/>）和单线路的查询都用它。</summary>
    public string DefaultProbeId { get; private set; } = "";

    /// <summary>默认 Probe 与这个 Agent 组成的线路 id（<c>agent~probe</c>）。</summary>
    public string Line(Fleet.Core.NodeId agent) => $"{agent.Value}~{DefaultProbeId}";

    public string Line(string agentId) => $"{agentId}~{DefaultProbeId}";

    /// <summary>在后端创建一个新的 Probe 身份，返回响应里的 JSON（含私钥，只此一次）。</summary>
    public async Task<JsonNode> CreateProbeAsync(string? name = null)
    {
        using HttpResponseMessage response = await Admin.PostAsync("/api/admin/probes", Json(new JsonObject { ["name"] = name ?? UniqueName("probe") }));
        string body = await response.Content.ReadAsStringAsync();
        Assert.True(response.IsSuccessStatusCode, body);
        return JsonNode.Parse(body)!;
    }

    public async ValueTask InitializeAsync()
    {
        DataDirectory = Path.Combine(Path.GetTempPath(), "moshiro-tests-" + Guid.NewGuid().ToString("N"));
        await StartAsync();
        _adminToken = await CreateAdminTokenAsync();
        CreateClients();
        DefaultProbeId = (await CreateProbeAsync("default"))["probe_id"]!.GetValue<string>();
    }

    public async ValueTask DisposeAsync()
    {
        GC.SuppressFinalize(this);
        foreach (AgentSimulator agent in _agents)
        {
            await agent.DisposeAsync();
        }

        Anonymous.Dispose();
        Admin.Dispose();
        await StopAsync();
        try
        {
            Directory.Delete(DataDirectory, recursive: true);
        }
        catch (IOException)
        {
            // 临时目录清理失败不影响测试结果
        }
    }

    /// <summary>重启后端（保留数据目录）：用来验证数据是否真的落盘。</summary>
    public async Task RestartAsync()
    {
        Anonymous.Dispose();
        Admin.Dispose();
        await StopAsync();
        await StartAsync();
        CreateClients(); // 新的端口：HttpClient 的 BaseAddress 只能在第一次请求之前设置
    }

    /// <summary>用同一个身份重新连接一个已经断开的假 Agent。</summary>
    public async Task<AgentSimulator> ReconnectAsync(AgentSimulator previous)
    {
        AgentSimulator agent = AgentSimulator.Restore(previous.ExportedKey, previous.NodeId);
        agent.ProbeForChunks = new MoShiro.Protocol.ProbeId(DefaultProbeId);
        _agents.Add(agent);
        await agent.ConnectAsync(BaseAddress);
        return agent;
    }

    private void CreateClients()
    {
        Anonymous = NewClient();
        Admin = NewClient();
        Admin.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", _adminToken);
    }

    public HttpClient NewClient() => new() { BaseAddress = BaseAddress };

    public string UniqueName(string prefix) => $"{prefix}-{Interlocked.Increment(ref _counter)}";

    public async Task<string> CreateJoinTokenAsync(bool autoApprove = true, int maxUses = 1, int expiresInHours = 1)
    {
        using HttpResponseMessage response = await Admin.PostAsync("/api/admin/join-tokens", Json(new JsonObject { ["auto_approve"] = autoApprove, ["max_uses"] = maxUses, ["expires_in_hours"] = expiresInHours }));
        response.EnsureSuccessStatusCode();
        return JsonNode.Parse(await response.Content.ReadAsStringAsync())!["plaintext"]!.GetValue<string>();
    }

    /// <summary>注册并连接一个假 Agent。</summary>
    public async Task<AgentSimulator> ConnectAgentAsync(string? name = null, bool autoApprove = true, string[]? kinds = null, bool hello = true)
    {
        string token = await CreateJoinTokenAsync(autoApprove);
        AgentSimulator agent = await AgentSimulator.EnrollAsync(Anonymous, token, name ?? UniqueName("agent"), kinds);
        agent.ProbeForChunks = new MoShiro.Protocol.ProbeId(DefaultProbeId);
        _agents.Add(agent);
        await agent.ConnectAsync(BaseAddress, hello, kinds);
        return agent;
    }

    public async Task<AgentSimulator> EnrollOnlyAsync(string? name = null, bool autoApprove = true)
    {
        string token = await CreateJoinTokenAsync(autoApprove);
        AgentSimulator agent = await AgentSimulator.EnrollAsync(Anonymous, token, name ?? UniqueName("agent"));
        _agents.Add(agent);
        return agent;
    }

    public async Task<JsonNode> GetJsonAsync(HttpClient client, string url)
    {
        using HttpResponseMessage response = await client.GetAsync(url);
        string text = await response.Content.ReadAsStringAsync();
        Assert.True(response.IsSuccessStatusCode, $"GET {url} -> {(int)response.StatusCode} {text}");
        return JsonNode.Parse(text)!;
    }

    public static StringContent Json(JsonNode node, string mediaType = "application/json") =>
        new(node.ToJsonString(), Encoding.UTF8, mediaType);

    public async Task SiteMustBePublicAsync()
    {
        using HttpResponseMessage response = await Admin.PatchAsync("/api/admin/settings", Json(new JsonObject { ["site.public"] = true }, "application/merge-patch+json"));
        response.EnsureSuccessStatusCode();
    }

    /// <summary>轮询直到条件成立（后台分析、状态推送都是异步的）。</summary>
    public static async Task EventuallyAsync(Func<Task<bool>> condition, TimeSpan? timeout = null, string? because = null)
    {
        long started = TimeProvider.System.GetTimestamp();
        TimeSpan limit = timeout ?? TimeSpan.FromSeconds(15);
        while (TimeProvider.System.GetElapsedTime(started) < limit)
        {
            if (await condition())
            {
                return;
            }

            await Task.Delay(50);
        }

        Assert.Fail("condition was not met in time" + (because is null ? "" : ": " + because));
    }

    private async Task StartAsync()
    {
        App = BackendHost.Build(
            ["--urls", "http://127.0.0.1:0", "--Logging:LogLevel:Default=Warning"],
            options =>
            {
                options.DataDirectory = DataDirectory;
                options.Pbkdf2Iterations = 1000;
                options.SecureCookies = false;
                options.WindowGrace = TimeSpan.Zero;
                options.AnalysisPollInterval = TimeSpan.FromMilliseconds(100);
                options.InitialAdminUser = AdminUser;
                options.InitialAdminPassword = AdminPassword;
                options.LoginAttemptsPerMinute = LoginAttemptsPerMinute;
                options.GeoLookupUrl = string.Empty; // 测试里不访问外部服务
                options.PhaseDurationScale = 0.2; // 端到端测试里 connect、hold 这些固定 30 秒的阶段缩成 6 秒
            });
        await App.StartAsync();
        string address = App.Services.GetRequiredService<IServer>().Features.Get<IServerAddressesFeature>()!.Addresses.First();
        BaseAddress = new Uri(address);
    }

    private async Task StopAsync()
    {
        await App.StopAsync();
        await App.DisposeAsync();
    }

    private async Task<string> CreateAdminTokenAsync()
    {
        using HttpClient session = NewClient();
        using HttpResponseMessage login = await session.PostAsync(
            "/api/admin/auth/login", Json(new JsonObject { ["username"] = AdminUser, ["password"] = AdminPassword }));
        login.EnsureSuccessStatusCode();
        JsonNode body = JsonNode.Parse(await login.Content.ReadAsStringAsync())!;
        string cookie = login.Headers.GetValues("Set-Cookie").First().Split(';')[0];

        using var request = new HttpRequestMessage(HttpMethod.Post, "/api/admin/api-tokens") { Content = Json(new JsonObject { ["name"] = "tests", ["scope"] = "admin" }) };
        request.Headers.Add("Cookie", cookie);
        request.Headers.Add("X-CSRF-Token", body["csrf_token"]!.GetValue<string>());
        using HttpResponseMessage created = await session.SendAsync(request);
        created.EnsureSuccessStatusCode();
        return JsonNode.Parse(await created.Content.ReadAsStringAsync())!["plaintext"]!.GetValue<string>();
    }
}

/// <summary>登录限流为每分钟 10 次（默认值）的独立后端。</summary>
public sealed class StrictLoginFixture : BackendFixture
{
    protected override int LoginAttemptsPerMinute => 10;
}