using System.Net;
using System.Security.Claims;
using System.Text.Encodings.Web;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Mvc.Testing;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Admin.Security;
using ZB.MOM.WW.OtOpcUa.Admin.Services;

namespace ZB.MOM.WW.OtOpcUa.Admin.Tests;

/// <summary>
///     End-to-end HTTP-pipeline tests for the Admin authorization layer — Admin-009.
///
///     Covers the four cases identified in the finding:
///     (a) anonymous access to every protected route is rejected (already in
///         <see cref="PageAuthorizationTests"/>; supplemented here with the mutating
///         POST surface).
///     (b) anonymous hub negotiate is rejected (already in
///         <see cref="AuthEndpointsTests"/>; complemented here).
///     (c) a signed-in FleetAdmin can reach pages gated by the fallback policy and
///         <c>CanPublish</c> pages.
///     (d) a <c>ConfigViewer</c> (no FleetAdmin role) is denied <c>CanPublish</c>-gated
///         pages while still being allowed through the fallback authenticated-user gate.
///
///     The test host uses a custom <see cref="RoleInjectingHandler"/> authentication scheme
///     so tests can assign any role set without going through LDAP. The <see cref="FleetStatusPoller"/>
///     background service is stripped out so the host starts clean without DB access.
/// </summary>
public sealed class AdminAuthPipelineTests : IClassFixture<AdminAuthPipelineTests.RoleInjectingAppFactory>
{
    private readonly RoleInjectingAppFactory _factory;

    public AdminAuthPipelineTests(RoleInjectingAppFactory factory) => _factory = factory;

    // ── (c) FleetAdmin is NOT rejected by the auth gate ──────────────────────────
    //
    // These tests verify that a FleetAdmin principal is not refused at the
    // authorization boundary. They do NOT assert that the page renders successfully
    // (the test host has no DB, so pages that hit the DB will 500 — that is an
    // application error, not an auth error). The assertions are:
    //   • Not 401 Unauthorized (auth failed — user not authenticated)
    //   • Not 403 Forbidden (auth failed — user lacks required role)
    //   • If 302/Found, the Location must NOT point to /login (bounced due to auth)
    // A 500 or 200 both mean the auth gate was cleared.

    public static readonly TheoryData<string> CanPublishPagesForPermitTest = new()
    {
        "/clusters/new",
        "/reservations",
        "/certificates",
        "/role-grants",
    };

    [Theory]
    [MemberData(nameof(CanPublishPagesForPermitTest))]
    public async Task FleetAdmin_is_permitted_CanPublish_gated_page(string route)
    {
        using var client = _factory.CreateClientWithRoles(AdminRoles.FleetAdmin);

        var response = await client.GetAsync(route);

        response.StatusCode.ShouldNotBe(HttpStatusCode.Forbidden,
            $"FleetAdmin GET {route} must not be denied — FleetAdmin satisfies CanPublish");
        response.StatusCode.ShouldNotBe(HttpStatusCode.Unauthorized,
            $"FleetAdmin GET {route} must not be denied");

        // May be 200, 500 (DB error — not auth error), or a redirect within session.
        if (response.StatusCode == HttpStatusCode.Redirect ||
            response.StatusCode == HttpStatusCode.Found)
        {
            response.Headers.Location!.OriginalString.ShouldNotContain("/login",
                Case.Insensitive, $"FleetAdmin GET {route} must not be bounced to login");
        }
    }

    // ── (d) ConfigViewer is denied CanPublish pages ───────────────────────────────

    public static readonly TheoryData<string> CanPublishPages = new()
    {
        "/clusters/new",        // [Authorize(Policy = "CanPublish")]
        "/reservations",        // [Authorize(Policy = "CanPublish")]
        "/role-grants",         // [Authorize(Policy = "CanPublish")]
        "/certificates",        // [Authorize(Policy = "CanPublish")]
    };

    [Theory]
    [MemberData(nameof(CanPublishPages))]
    public async Task ConfigViewer_is_denied_CanPublish_gated_page(string route)
    {
        // ConfigViewer has no FleetAdmin role, so the CanPublish policy must deny access.
        using var client = _factory.CreateClientWithRoles(AdminRoles.ConfigViewer);

        var response = await client.GetAsync(route);

        // A 403 Forbidden is the expected outcome for an authenticated user who lacks
        // the required role. A 302 to /login is also acceptable (the cookie scheme may
        // redirect, but the real gate is the role check, not authentication).
        response.StatusCode.ShouldNotBe(HttpStatusCode.OK,
            $"ConfigViewer GET {route} must be denied — CanPublish requires FleetAdmin");

        response.StatusCode.ShouldBeOneOf(
            HttpStatusCode.Forbidden, HttpStatusCode.Unauthorized,
            HttpStatusCode.Redirect, HttpStatusCode.Found);
    }

    // ── WebApplicationFactory plumbing ───────────────────────────────────────────

    /// <summary>
    ///     A <see cref="WebApplicationFactory{TEntryPoint}"/> that replaces the cookie
    ///     authentication scheme with a custom handler that stamps requests with a
    ///     caller-supplied role set. Tests obtain a per-role <see cref="HttpClient"/> via
    ///     <see cref="CreateClientWithRoles"/>.
    ///
    ///     Role injection works through a singleton <see cref="RoleContext"/> that holds a
    ///     simple <c>lock</c>-protected field. This avoids the <c>AsyncLocal</c>-does-not-flow-
    ///     into-TestServer pitfall and the stale-<c>[ThreadStatic]</c> pitfall.
    /// </summary>
    public sealed class RoleInjectingAppFactory : WebApplicationFactory<Program>
    {
        /// <summary>
        ///     Singleton shared by the factory and the <see cref="RoleInjectingHandler"/>.
        ///     Holds the roles that the next request should authenticate as.
        /// </summary>
        internal sealed class RoleContext
        {
            private readonly Lock _lock = new();
            private string[] _roles = [];

            public void SetRoles(string[] roles) { lock (_lock) { _roles = roles; } }
            public void Clear() { lock (_lock) { _roles = []; } }
            public string[] GetRoles() { lock (_lock) { return _roles; } }
        }

        // Initialized here so it is available before CreateHost is invoked (the factory
        // builds the host lazily on first client creation; _roleContext must not be null
        // at CreateClientWithRoles() time, and the singleton registered in CreateHost
        // must be the same instance as this field).
        private readonly RoleContext _roleContext = new();

        protected override IHost CreateHost(IHostBuilder builder)
        {
            var ctx = _roleContext;

            builder.ConfigureServices(services =>
            {
                // Remove the background poller: it would start a DB poll loop that fails
                // without the central SQL Server.
                var poller = services.SingleOrDefault(d =>
                    d.ImplementationType?.Name == "FleetStatusPoller");
                if (poller is not null) services.Remove(poller);

                // Remove the LDAP auth service to avoid accidental LDAP calls.
                var ldap = services.SingleOrDefault(d => d.ServiceType == typeof(ILdapAuthService));
                if (ldap is not null) services.Remove(ldap);
                services.AddScoped<ILdapAuthService, NullLdapAuthService>();

                // Register the shared RoleContext as a singleton so the handler can read it.
                services.AddSingleton(ctx);

                // Register the role-injecting test scheme and override the default schemes.
                services.AddAuthentication()
                    .AddScheme<AuthenticationSchemeOptions, RoleInjectingHandler>(
                        RoleInjectingHandler.SchemeName, _ => { });

                services.PostConfigure<AuthenticationOptions>(opt =>
                {
                    opt.DefaultAuthenticateScheme = RoleInjectingHandler.SchemeName;
                    opt.DefaultChallengeScheme = RoleInjectingHandler.SchemeName;
                    opt.DefaultForbidScheme = RoleInjectingHandler.SchemeName;
                });
            });
            return base.CreateHost(builder);
        }

        /// <summary>
        ///     Returns an <see cref="HttpClient"/> that authenticates every request with
        ///     the given <paramref name="roles"/>.
        /// </summary>
        public HttpClient CreateClientWithRoles(params string[] roles)
        {
            _roleContext!.SetRoles(roles);
            return CreateClient(new WebApplicationFactoryClientOptions { AllowAutoRedirect = false });
        }
    }

    /// <summary>
    ///     Authentication handler that stamps the current request with the roles stored in
    ///     the <see cref="RoleInjectingAppFactory.RoleContext"/> singleton.
    /// </summary>
    private sealed class RoleInjectingHandler(
        IOptionsMonitor<AuthenticationSchemeOptions> options,
        ILoggerFactory logger,
        UrlEncoder encoder,
        RoleInjectingAppFactory.RoleContext roleContext)
        : AuthenticationHandler<AuthenticationSchemeOptions>(options, logger, encoder)
    {
        public const string SchemeName = "RoleInjecting";

        protected override Task<AuthenticateResult> HandleAuthenticateAsync()
        {
            var roles = roleContext.GetRoles();
            if (roles.Length == 0)
                return Task.FromResult(AuthenticateResult.NoResult());

            var claims = new List<Claim>
            {
                new(ClaimTypes.Name, "test-operator"),
                new(ClaimTypes.NameIdentifier, "test-operator"),
            };
            foreach (var role in roles)
                claims.Add(new Claim(ClaimTypes.Role, role));

            var identity = new ClaimsIdentity(claims, SchemeName);
            var ticket = new AuthenticationTicket(new ClaimsPrincipal(identity), SchemeName);
            return Task.FromResult(AuthenticateResult.Success(ticket));
        }
    }

    /// <summary>Null LDAP auth service — never called in these tests.</summary>
    private sealed class NullLdapAuthService : ILdapAuthService
    {
        public Task<LdapAuthResult> AuthenticateAsync(string username, string password, CancellationToken ct = default) =>
            Task.FromResult(new LdapAuthResult(false, null, username, [], [], "LDAP disabled in auth-pipeline tests"));
    }
}