using System.Diagnostics;
using System.Net;
using System.Net.Http.Json;
using System.Text.Json;
using Azaion.E2E.Helpers;
using FluentAssertions;
using Xunit;

namespace Azaion.E2E.Tests;

[Collection("E2E")]
public sealed class ResilienceTests
{
    private static readonly JsonSerializerOptions ResponseJsonOptions = new()
    {
        PropertyNameCaseInsensitive = true
    };

    private const string TestUserPassword = "TestPass1234";
    private const string MalformedJwtUnsigned =
        "eyJhbGciOiJub25lIn0.eyJ0ZXN0IjoiMSJ9.";

    private readonly TestFixture _fixture;

    public ResilienceTests(TestFixture fixture) => _fixture = fixture;

    [Fact]
    public async Task Malformed_authorization_headers_return_401_and_system_remains_operational()
    {
        // Arrange
        var baseUrl = _fixture.Settings.ApiBaseUrl;
        var headers = new[]
        {
            "Bearer invalidtoken123",
            $"Bearer {MalformedJwtUnsigned}",
            "NotBearer somevalue",
            "Bearer "
        };

        using var http = new HttpClient { BaseAddress = new Uri(baseUrl, UriKind.Absolute), Timeout = TimeSpan.FromMinutes(5) };

        // Act
        foreach (var h in headers)
        {
            using var request = new HttpRequestMessage(HttpMethod.Get, "/users/current");
            request.Headers.TryAddWithoutValidation("Authorization", h);
            using var response = await http.SendAsync(request);

            // Assert
            response.StatusCode.Should().Be(HttpStatusCode.Unauthorized);
        }

        // Arrange
        using var client = _fixture.CreateApiClient();

        // Act
        var token = await client.LoginAsync(_fixture.AdminEmail, _fixture.AdminPassword);

        // Assert
        token.Should().NotBeNullOrWhiteSpace();
    }

    [Fact]
    public async Task Concurrent_hardware_binding_same_hardware_has_no_500_and_state_consistent()
    {
        // Arrange
        string? email = null;
        var hardware =
            $"CPU: ConcCPU. GPU: ConcGPU. Memory: 8192. DriveSerial: {Guid.NewGuid():N}.";

        try
        {
            var candidateEmail = $"resilience-hw-{Guid.NewGuid()}@azaion.com";
            using (var adminClient = _fixture.CreateAuthenticatedClient(_fixture.AdminToken))
            {
                using var createResp = await adminClient.PostAsync("/users",
                    new { Email = candidateEmail, Password = TestUserPassword, Role = 10 });
                createResp.EnsureSuccessStatusCode();
            }

            email = candidateEmail;

            using var loginClient = _fixture.CreateApiClient();
            var userToken = await loginClient.LoginAsync(email, TestUserPassword);
            using var userClient = _fixture.CreateAuthenticatedClient(userToken);

            // Act
            var concurrentTasks = Enumerable.Range(0, 5)
                .Select(_ => userClient.PostAsync("/resources/check", new { Hardware = hardware }))
                .ToArray();
            var concurrentResponses = await Task.WhenAll(concurrentTasks);

            // Assert
            foreach (var r in concurrentResponses)
            {
                using (r)
                {
                    r.StatusCode.Should().NotBe(HttpStatusCode.InternalServerError);
                }
            }

            // Act
            using var followUp = await userClient.PostAsync("/resources/check", new { Hardware = hardware });

            // Assert
            followUp.StatusCode.Should().Be(HttpStatusCode.OK);
            var body = await followUp.Content.ReadFromJsonAsync<bool>(ResponseJsonOptions);
            body.Should().BeTrue();
        }
        finally
        {
            if (email is not null)
            {
                using var adminCleanup = _fixture.CreateAuthenticatedClient(_fixture.AdminToken);
                using var del = await adminCleanup.DeleteAsync($"/users/{Uri.EscapeDataString(email)}");
                del.EnsureSuccessStatusCode();
            }
        }
    }

    [Fact]
    public async Task Login_p95_latency_under_500ms_after_warmup()
    {
        // Arrange
        using var client = _fixture.CreateApiClient();
        for (var i = 0; i < 5; i++)
        {
            using var w = await client.PostAsync("/login",
                new { email = _fixture.UploaderEmail, password = _fixture.UploaderPassword });
            w.EnsureSuccessStatusCode();
        }

        var samples = new List<double>(100);

        // Act
        for (var i = 0; i < 100; i++)
        {
            var sw = Stopwatch.StartNew();
            using var resp = await client.PostAsync("/login",
                new { email = _fixture.UploaderEmail, password = _fixture.UploaderPassword });
            sw.Stop();
            resp.EnsureSuccessStatusCode();
            samples.Add(sw.Elapsed.TotalMilliseconds);
        }

        var sorted = samples.OrderBy(x => x).ToArray();
        var p95Index = (int)Math.Ceiling(0.95 * sorted.Length) - 1;
        if (p95Index < 0)
            p95Index = 0;
        var p95 = sorted[p95Index];

        // Assert
        p95.Should().BeLessThan(500);
    }

    [Fact]
    [Trait("Category", "ResourceLimit")]
    public async Task Max_file_upload_200_mb_accepted()
    {
        // Arrange
        const string folder = "testfolder";
        const string fileName = "max.bin";
        var payload = new byte[200 * 1024 * 1024 - 4096];

        try
        {
            using var adminClient = _fixture.CreateAuthenticatedClient(_fixture.AdminToken);

            // Act
            using var response = await adminClient.UploadFileAsync($"/resources/{folder}", payload, fileName);

            // Assert
            response.StatusCode.Should().Be(HttpStatusCode.OK);
        }
        finally
        {
            using var adminCleanup = _fixture.CreateAuthenticatedClient(_fixture.AdminToken);
            using var clear = await adminCleanup.PostAsync($"/resources/clear/{folder}", new { });
            clear.EnsureSuccessStatusCode();
        }
    }

    [Fact]
    [Trait("Category", "ResourceLimit")]
    public async Task Over_max_upload_201_mb_rejected_or_connection_aborted()
    {
        // Arrange
        const string folder = "testfolder";
        const string fileName = "over.bin";
        var payload = new byte[201 * 1024 * 1024];

        using var adminClient = _fixture.CreateAuthenticatedClient(_fixture.AdminToken);

        // Act
        var outcome = await TryUploadAsync(adminClient, $"/resources/{folder}", payload, fileName);

        // Assert
        outcome.Acceptable.Should().BeTrue();

        using (var adminCleanup = _fixture.CreateAuthenticatedClient(_fixture.AdminToken))
        {
            using var clear = await adminCleanup.PostAsync($"/resources/clear/{folder}", new { });
            clear.EnsureSuccessStatusCode();
        }
    }

    private static async Task<(bool Acceptable, HttpStatusCode? Status)> TryUploadAsync(
        ApiClient adminClient, string url, byte[] payload, string fileName)
    {
        try
        {
            using var response = await adminClient.UploadFileAsync(url, payload, fileName);
            if (response.StatusCode == HttpStatusCode.RequestEntityTooLarge)
                return (true, response.StatusCode);
            return (false, response.StatusCode);
        }
        catch (Exception ex) when (IsConnectionRelated(ex))
        {
            return (true, null);
        }
    }

    private static bool IsConnectionRelated(Exception ex)
    {
        if (ex is HttpRequestException or TaskCanceledException or IOException)
            return true;
        return ex.InnerException is not null && IsConnectionRelated(ex.InnerException);
    }
}