using System.Collections.Concurrent;
using System.IdentityModel.Tokens.Jwt;
using System.Net;
using System.Net.Http.Json;
using System.Net.Http.Headers;
using System.Security.Claims;
using System.Text;
using Campaign_Tracker.Server.Audit;
using Campaign_Tracker.Server.Authentication;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc.Testing;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.IdentityModel.Tokens;

namespace Campaign_Tracker.Server.Tests;

/// <summary>
/// Custom factory that replaces the file-backed IAuditService with an in-memory
/// passthrough so integration tests have no file-system dependency.
/// Keycloak configuration is also applied here so all tests inherit it without
/// repeating SetEnvironmentVariable calls in every test constructor.
/// </summary>
public sealed class AuthIntegrationTestFactory : WebApplicationFactory<Program>
{
    private const string Issuer = "http://kci-app01.ntp.kentcommunications.com:8180/realms/KCI";
    private const string ClientId = "canopy-web";
    private const string SigningKey = "test-signing-key-with-at-least-32-characters";

    protected override void ConfigureWebHost(IWebHostBuilder builder)
    {
        // Apply Keycloak test configuration before the host builds.
        builder.UseSetting("Keycloak:Authority", Issuer);
        builder.UseSetting("Keycloak:ValidIssuer", Issuer);
        builder.UseSetting("Keycloak:PublicAuthority", Issuer);
        builder.UseSetting("Keycloak:ClientId", ClientId);
        builder.UseSetting("Keycloak:DisableHttpsMetadata", "true");
        builder.UseSetting("Keycloak:TestSigningKey", SigningKey);

        builder.ConfigureServices(services =>
        {
            // Replace the file-backed IAuditService with an in-memory passthrough.
            // File persistence is validated in AuditServiceTests; integration tests
            // should not depend on file-system state.
            var descriptor = services.SingleOrDefault(d => d.ServiceType == typeof(IAuditService));
            if (descriptor is not null)
            {
                services.Remove(descriptor);
            }

            services.AddSingleton<IAuditService, InMemoryPassthroughAuditService>();
        });
    }

    public static string CreateToken(string subject, string role, string audience = ClientId)
    {
        var credentials = new SigningCredentials(
            new SymmetricSecurityKey(Encoding.UTF8.GetBytes(SigningKey)),
            SecurityAlgorithms.HmacSha256);
        var token = new JwtSecurityToken(
            issuer: Issuer,
            audience: audience,
            claims:
            [
                new Claim(JwtRegisteredClaimNames.Sub, subject),
                new Claim(ClaimTypes.Name, subject),
                new Claim(ClaimTypes.Role, role),
            ],
            expires: DateTime.UtcNow.AddMinutes(10),
            signingCredentials: credentials);

        return new JwtSecurityTokenHandler().WriteToken(token);
    }

    private sealed class InMemoryPassthroughAuditService : IAuditService
    {
        private readonly ConcurrentQueue<AuditEvent> _events = new();

        public void Record(AuditEvent auditEvent) => _events.Enqueue(auditEvent);

        public IReadOnlyCollection<AuditEvent> GetRecent(int maxCount = 200)
        {
            if (maxCount < 0)
            {
                throw new ArgumentOutOfRangeException(nameof(maxCount));
            }

            if (maxCount == 0)
            {
                return [];
            }

            var events = _events.ToArray();
            return events.Length > maxCount ? events[^maxCount..] : events;
        }
    }
}

public class AuthEndpointTests : IClassFixture<AuthIntegrationTestFactory>
{
    private readonly AuthIntegrationTestFactory _factory;

    public AuthEndpointTests(AuthIntegrationTestFactory factory)
    {
        _factory = factory;
    }

    [Fact]
    public async Task SessionEndpoint_WithoutToken_ReturnsUnauthorized()
    {
        using var client = _factory.CreateClient();

        var response = await client.GetAsync("/api/auth/session");

        Assert.Equal(HttpStatusCode.Unauthorized, response.StatusCode);
    }

    [Fact]
    public async Task SessionEndpoint_WithValidToken_ReturnsRoleWorkspaceAndAuditsSuccess()
    {
        using var client = _factory.CreateClient();
        client.DefaultRequestHeaders.Authorization =
            new AuthenticationHeaderValue("Bearer", AuthIntegrationTestFactory.CreateToken("daniel@example.test", "client-services"));

        var httpResponse = await client.GetAsync("/api/auth/session");
        var auditStore = _factory.Services.GetRequiredService<IAuthenticationAuditStore>();
        Assert.True(httpResponse.IsSuccessStatusCode, string.Join("; ", auditStore.Events.Select(audit => audit.Reason)));

        var response = await httpResponse.Content.ReadFromJsonAsync<AuthSessionResponse>();

        Assert.NotNull(response);
        Assert.Equal("daniel@example.test", response.UserName);
        Assert.Contains("ClientServices", response.Roles);
        Assert.Equal("/workspace/client-services", response.WorkspacePath);
        Assert.Contains(auditStore.Events, audit =>
            audit.EventType == AuthenticationAuditEventType.Success &&
            audit.Subject == "daniel@example.test");
    }

    [Fact]
    public async Task SessionEndpoint_WithKeycloakDefaultAudience_IsAccepted()
    {
        // Keycloak's default access tokens carry aud="account" (the realm's
        // built-in account client) rather than the resource-server's ClientId.
        // The bearer middleware must accept "account" in addition to "canopy-web",
        // otherwise every real-world login fails with SecurityTokenInvalidAudienceException.
        using var client = _factory.CreateClient();
        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue(
            "Bearer",
            AuthIntegrationTestFactory.CreateToken(
                "daniel@example.test",
                "client-services",
                audience: "account"));

        var response = await client.GetAsync("/api/auth/session");

        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
    }

    [Fact]
    public async Task SessionEndpoint_WithInvalidToken_ReturnsUnauthorizedAndAuditsFailure()
    {
        using var client = _factory.CreateClient();
        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", "invalid.jwt.value");

        var response = await client.GetAsync("/api/auth/session");
        var auditStore = _factory.Services.GetRequiredService<IAuthenticationAuditStore>();

        Assert.Equal(HttpStatusCode.Unauthorized, response.StatusCode);
        Assert.Contains(auditStore.Events, audit =>
            audit.EventType == AuthenticationAuditEventType.Failure &&
            audit.Reason.Contains("invalid", StringComparison.OrdinalIgnoreCase));
    }

    [Fact]
    public async Task TokenExchange_WhenSuccessful_RecordsSharedAuditEvent()
    {
        var stubFactory = _factory.WithWebHostBuilder(builder =>
        {
            builder.ConfigureServices(services =>
            {
                var descriptor = services.SingleOrDefault(
                    d => d.ServiceType == typeof(IKeycloakTokenClient));
                if (descriptor is not null)
                {
                    services.Remove(descriptor);
                }

                services.AddSingleton<IKeycloakTokenClient, StubKeycloakTokenClient>();
            });
        });

        using var client = stubFactory.CreateClient();
        var response = await client.PostAsJsonAsync("/api/auth/token/exchange", new
        {
            code = "code",
            redirectUri = "https://app.example.test/auth/callback",
        });
        var auditService = stubFactory.Services.GetRequiredService<IAuditService>();

        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
        Assert.Contains(auditService.GetRecent(), audit =>
            audit.EventType == AuditEventType.SessionLogin &&
            audit.ActorIdentity == "alice@example.test" &&
            audit.Resource == "authentication/token/exchange");
    }

    [Fact]
    public async Task TokenRefresh_WhenKeycloakRejects_RecordsSharedAuditFailure()
    {
        var rejectingFactory = _factory.WithWebHostBuilder(builder =>
        {
            builder.ConfigureServices(services =>
            {
                var descriptor = services.SingleOrDefault(
                    d => d.ServiceType == typeof(IKeycloakTokenClient));
                if (descriptor is not null)
                {
                    services.Remove(descriptor);
                }

                services.AddSingleton<IKeycloakTokenClient, RejectingKeycloakTokenClient>();
            });
        });

        using var client = rejectingFactory.CreateClient();
        var response = await client.PostAsJsonAsync("/api/auth/token/refresh", new
        {
            refreshToken = "expired-refresh-token",
        });
        var auditService = rejectingFactory.Services.GetRequiredService<IAuditService>();

        Assert.Equal(HttpStatusCode.Unauthorized, response.StatusCode);
        Assert.Contains(auditService.GetRecent(), audit =>
            audit.EventType == AuditEventType.SessionRefreshFailure &&
            audit.Resource == "authentication/token/refresh");
    }

    [Fact]
    public async Task LogoutEndpoint_WithValidIdTokenHint_Returns200AndAuditsSuccessfulLogout()
    {
        var stubFactory = _factory.WithWebHostBuilder(builder =>
        {
            builder.ConfigureServices(services =>
            {
                var descriptor = services.SingleOrDefault(
                    d => d.ServiceType == typeof(IKeycloakTokenClient));
                if (descriptor is not null)
                {
                    services.Remove(descriptor);
                }

                services.AddSingleton<IKeycloakTokenClient, StubKeycloakTokenClient>();
            });
        });

        using var client = stubFactory.CreateClient();
        var idToken = AuthIntegrationTestFactory.CreateToken("alice@example.test", "client-services");
        client.DefaultRequestHeaders.Authorization =
            new AuthenticationHeaderValue("Bearer", idToken);
        var response = await client.PostAsJsonAsync("/api/auth/logout", new { idTokenHint = idToken });
        var auditStore = stubFactory.Services.GetRequiredService<IAuthenticationAuditStore>();

        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
        Assert.Contains(auditStore.Events, audit =>
            audit.EventType == AuthenticationAuditEventType.Logout &&
            audit.Subject == "alice@example.test" &&
            audit.Resource == "authentication/logout");
    }

    [Fact]
    public async Task LogoutEndpoint_WhenKeycloakUnreachable_StillReturns200AndAuditsFailure()
    {
        var throwingFactory = _factory.WithWebHostBuilder(builder =>
        {
            builder.ConfigureServices(services =>
            {
                var descriptor = services.SingleOrDefault(
                    d => d.ServiceType == typeof(IKeycloakTokenClient));
                if (descriptor is not null)
                {
                    services.Remove(descriptor);
                }

                services.AddSingleton<IKeycloakTokenClient, ThrowingKeycloakTokenClient>();
            });
        });

        using var client = throwingFactory.CreateClient();

        var idToken = AuthIntegrationTestFactory.CreateToken("bob@example.test", "production");
        client.DefaultRequestHeaders.Authorization =
            new AuthenticationHeaderValue("Bearer", idToken);
        var response = await client.PostAsJsonAsync("/api/auth/logout", new { idTokenHint = idToken });
        var auditStore = throwingFactory.Services.GetRequiredService<IAuthenticationAuditStore>();

        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
        Assert.Contains(auditStore.Events, audit =>
            audit.EventType == AuthenticationAuditEventType.Logout &&
            audit.Resource == "authentication/logout");
    }

    [Fact]
    public async Task LogoutEndpoint_WithEmptyIdTokenHint_ReturnsBadRequest()
    {
        using var client = _factory.CreateClient();
        client.DefaultRequestHeaders.Authorization =
            new AuthenticationHeaderValue("Bearer", AuthIntegrationTestFactory.CreateToken("alice@example.test", "client-services"));

        var response = await client.PostAsJsonAsync("/api/auth/logout", new { idTokenHint = "" });

        Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
    }

    [Fact]
    public async Task LogoutEndpoint_WithMissingBody_ReturnsBadRequest()
    {
        using var client = _factory.CreateClient();
        client.DefaultRequestHeaders.Authorization =
            new AuthenticationHeaderValue("Bearer", AuthIntegrationTestFactory.CreateToken("alice@example.test", "client-services"));

        var response = await client.PostAsync("/api/auth/logout", null);

        Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
    }

    [Fact]
    public async Task SessionEndpoint_WhenAuditServiceUnavailable_BlocksAction_AC5()
    {
        var failingAuditFactory = _factory.WithWebHostBuilder(builder =>
        {
            builder.ConfigureServices(services =>
            {
                var descriptor = services.SingleOrDefault(d => d.ServiceType == typeof(IAuditService));
                if (descriptor is not null)
                {
                    services.Remove(descriptor);
                }

                services.AddSingleton<IAuditService, AlwaysFailingAuditService>();
            });
        });

        using var client = failingAuditFactory.CreateClient();
        client.DefaultRequestHeaders.Authorization =
            new AuthenticationHeaderValue("Bearer", AuthIntegrationTestFactory.CreateToken("alice@example.test", "client-services"));

        var response = await client.GetAsync("/api/auth/session");

        // Action must be blocked — not silently succeed (AC #5).
        Assert.NotEqual(HttpStatusCode.OK, response.StatusCode);
    }

    private sealed class AuthSessionResponse
    {
        public string UserName { get; init; } = string.Empty;
        public string[] Roles { get; init; } = [];
        public string WorkspacePath { get; init; } = string.Empty;
    }

    private sealed class StubKeycloakTokenClient : IKeycloakTokenClient
    {
        public Task<AuthTokenSetResponse> ExchangeAuthorizationCodeAsync(
            string code, string redirectUri, CancellationToken cancellationToken) =>
            Task.FromResult(new AuthTokenSetResponse(
                AuthIntegrationTestFactory.CreateToken("alice@example.test", "client-services"),
                "refresh",
                9999));

        public Task<AuthTokenSetResponse> RefreshAccessTokenAsync(
            string refreshToken, CancellationToken cancellationToken) =>
            Task.FromResult(new AuthTokenSetResponse(
                AuthIntegrationTestFactory.CreateToken("alice@example.test", "client-services"),
                "refresh",
                9999));

        public Task EndSessionAsync(string idTokenHint, CancellationToken cancellationToken) =>
            Task.CompletedTask;
    }

    private sealed class ThrowingKeycloakTokenClient : IKeycloakTokenClient
    {
        public Task<AuthTokenSetResponse> ExchangeAuthorizationCodeAsync(
            string code, string redirectUri, CancellationToken cancellationToken) =>
            Task.FromResult(new AuthTokenSetResponse("access", "refresh", 9999));

        public Task<AuthTokenSetResponse> RefreshAccessTokenAsync(
            string refreshToken, CancellationToken cancellationToken) =>
            Task.FromResult(new AuthTokenSetResponse("access", "refresh", 9999));

        public Task EndSessionAsync(string idTokenHint, CancellationToken cancellationToken) =>
            throw new HttpRequestException("Simulated Keycloak outage.");
    }

    private sealed class RejectingKeycloakTokenClient : IKeycloakTokenClient
    {
        public Task<AuthTokenSetResponse> ExchangeAuthorizationCodeAsync(
            string code, string redirectUri, CancellationToken cancellationToken) =>
            throw new KeycloakTokenRequestException(HttpStatusCode.BadRequest, "invalid_grant");

        public Task<AuthTokenSetResponse> RefreshAccessTokenAsync(
            string refreshToken, CancellationToken cancellationToken) =>
            throw new KeycloakTokenRequestException(HttpStatusCode.BadRequest, "invalid_grant");

        public Task EndSessionAsync(string idTokenHint, CancellationToken cancellationToken) =>
            Task.CompletedTask;
    }

    private sealed class AlwaysFailingAuditService : IAuditService
    {
        public void Record(AuditEvent auditEvent) =>
            throw new AuditServiceUnavailableException("Audit service unavailable (test stub).",
                new IOException("Simulated disk failure"));

        public IReadOnlyCollection<AuditEvent> GetRecent(int maxCount = 200) => [];
    }
}