using System.Net;
using System.Net.Http.Headers;
using System.Reflection;
using GameList.Infrastructure;
using GameList.Endpoints;
using GameList.Tests.Support;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.HttpOverrides;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.TestHost;
using Microsoft.Extensions.Configuration;
using System.Text.Json;
using System.Net.Http.Json;

namespace GameList.Tests;

public class HelperTests
{
    [Fact]
    public void PasswordHasher_roundtrip_and_empty_guard()
    {
        var (hash, salt) = PasswordHasher.HashPassword("secret");
        Assert.True(PasswordHasher.Verify("secret", hash, salt));
        Assert.False(PasswordHasher.Verify("other", hash, salt));
        Assert.Throws<ArgumentException>(() => PasswordHasher.HashPassword(""));
    }

    [Fact]
    public void Program_does_not_include_runtime_index_rewrite_hook()
    {
        var hasRewriteMethod = typeof(Program).GetMethods(BindingFlags.Static | BindingFlags.NonPublic | BindingFlags.Public).Any(m => m.Name.Contains("UpdateIndexMetaBase", StringComparison.Ordinal));
        Assert.False(hasRewriteMethod);
    }

    [Fact]
    public async Task IsReachableImageAsync_rejects_redirect_and_accepts_image()
    {
        Assert.True(await EndpointHelpers.IsReachableImageAsync(null, new StubHttpClientFactory(new StubHttpMessageHandler())));
        Assert.False(await EndpointHelpers.IsReachableImageAsync("http://127.0.0.1/img.png", new StubHttpClientFactory(new StubHttpMessageHandler())));
    }

    [Fact]
    public async Task IsReachableImageAsync_handles_head_success_redirect_and_size_guard()
    {
        var handler = new StubHttpMessageHandler();
        handler.SetResponder(req =>
        {
            if (req.Method == HttpMethod.Head)
            {
                var resp = new HttpResponseMessage(HttpStatusCode.OK);
                resp.Content = new ByteArrayContent([]);
                resp.Content.Headers.ContentType = new MediaTypeHeaderValue("image/png");
                resp.Content.Headers.ContentLength = 100;
                return resp;
            }

            return new HttpResponseMessage(HttpStatusCode.OK)
            {
                Content = new ByteArrayContent([])
                {
                    Headers =
                    {
                        ContentType = new MediaTypeHeaderValue("image/png"),
                        ContentLength = 100
                    }
                }
            };
        });

        var ok = await EndpointHelpers.IsReachableImageAsync("http://example.com/img.png", new StubHttpClientFactory(handler), handler);
        Assert.True(ok);

        handler.SetResponder(_ =>
        {
            var resp = new HttpResponseMessage(HttpStatusCode.Redirect);
            resp.Headers.Location = new Uri("http://example.com/other");
            return resp;
        });
        var redirect = await EndpointHelpers.IsReachableImageAsync("http://example.com/img.png", new StubHttpClientFactory(handler), handler);
        Assert.False(redirect);

        handler.SetResponder(_ =>
        {
            var resp = new HttpResponseMessage(HttpStatusCode.OK);
            resp.Content = new ByteArrayContent(new byte[10]);
            resp.Content.Headers.ContentType = new MediaTypeHeaderValue("image/png");
            resp.Content.Headers.ContentLength = 6 * 1024 * 1024; // over 5 MB
            return resp;
        });
        var tooLarge = await EndpointHelpers.IsReachableImageAsync("http://example.com/img.png", new StubHttpClientFactory(handler), handler);
        Assert.False(tooLarge);
    }

    [Fact]
    public async Task IsReachableImageAsync_rejects_followed_redirect_chain()
    {
        var handler = new RedirectFollowingHandler();
        var reachable = await EndpointHelpers.IsReachableImageAsync("http://example.com/img.png", new StubHttpClientFactory(new StubHttpMessageHandler()), handler);
        Assert.False(reachable);
    }

    [Fact]
    public async Task IsReachableImageAsync_rejects_non_image_content()
    {
        var handler = new StubHttpMessageHandler();
        handler.SetResponder(_ =>
        {
            var resp = new HttpResponseMessage(HttpStatusCode.OK);
            resp.Content = new ByteArrayContent("not image"u8.ToArray());
            resp.Content.Headers.ContentType = new MediaTypeHeaderValue("text/plain");
            resp.Content.Headers.ContentLength = 9;
            return resp;
        });

        var result = await EndpointHelpers.IsReachableImageAsync("http://example.com/img.png", new StubHttpClientFactory(handler), handler);
        Assert.False(result);
    }

    [Fact]
    public async Task IsReachableImageAsync_rejects_private_and_reserved_ranges()
    {
        var factory = new StubHttpClientFactory(new StubHttpMessageHandler());
        var blockedUrls = new[]
        {
            "http://0.0.0.1/img.png",
            "http://10.0.0.1/img.png",
            "http://100.64.1.1/img.png",
            "http://169.254.169.254/img.png",
            "http://192.168.0.20/img.png",
            "http://198.51.100.2/img.png",
            "http://203.0.113.8/img.png",
            "http://[::1]/img.png",
            "http://[fc00::1]/img.png",
            "http://[::ffff:127.0.0.1]/img.png"
        };

        foreach (var url in blockedUrls)
        {
            var reachable = await EndpointHelpers.IsReachableImageAsync(url, factory);
            Assert.False(reachable);
        }
    }

    [Fact]
    public void Link_root_helpers_handle_groups()
    {
        var roots = EndpointHelpers.BuildLinkRoots([(1, null), (2, 1), (3, null)]);
        Assert.Equal(1, roots[1]);
        Assert.Equal(1, roots[2]);
        Assert.Equal(3, roots[3]);

        var linked = EndpointHelpers.LinkedIdsFor(2, roots);
        Assert.Contains(1, linked);
        Assert.Contains(2, linked);
    }

    [Fact]
    public void Url_validation_rules()
    {
        Assert.True(EndpointHelpers.IsValidImageUrl("https://x.com/img.png"));
        Assert.False(EndpointHelpers.IsValidImageUrl("ftp://x/img.png"));
        Assert.True(EndpointHelpers.IsValidHttpUrl("http://x"));
        Assert.False(EndpointHelpers.IsValidHttpUrl("file://x"));
    }

    [Fact]
    public void Find_root_handles_cycles()
    {
        var parentMap = new Dictionary<int, int?>
        {
            { 1, 2 },
            { 2, 3 },
            { 3, 1 }
        };

        var root = EndpointHelpers.FindRootId(1, parentMap);
        Assert.Equal(3, root); // cycle breaks on revisit
    }

    [Fact]
    public async Task Global_exception_handler_returns_json_error()
    {
        await using var factory = new TestWebApplicationFactory().WithWebHostBuilder(builder =>
        {
            builder.Configure(app =>
            {
                app.UseGlobalExceptionLogging();
                app.UseRouting();
                app.UseEndpoints(endpoints => { endpoints.MapGet("/boom", _ => throw new InvalidOperationException("boom")); });
            });
        });

        var client = factory.CreateClient();
        var resp = await client.GetAsync("/boom");
        Assert.Equal(HttpStatusCode.InternalServerError, resp.StatusCode);
        var json = await resp.Content.ReadFromJsonAsync<JsonElement>();
        Assert.Equal("Unexpected server error", json.GetProperty("error").GetString());
    }

    [Fact]
    public void BuildForwardedHeadersOptions_reads_only_valid_proxies_and_networks()
    {
        var config = new ConfigurationBuilder().AddInMemoryCollection(new Dictionary<string, string?>
        {
            ["ForwardedHeaders:KnownProxies:0"] = "203.0.113.10",
            ["ForwardedHeaders:KnownProxies:1"] = "not-an-ip",
            ["ForwardedHeaders:KnownNetworks:0"] = "10.20.0.0/16",
            ["ForwardedHeaders:KnownNetworks:1"] = "invalid"
        }).Build();

        var options = BuildForwardedHeadersOptionsForTest(config);

        Assert.Single(options.KnownProxies);
        Assert.Single(options.KnownIPNetworks);
    }

    [Fact]
    public async Task Forwarded_headers_are_ignored_for_untrusted_proxy()
    {
        var config = new ConfigurationBuilder().AddInMemoryCollection(new Dictionary<string, string?>
        {
            ["ForwardedHeaders:KnownProxies:0"] = "203.0.113.10"
        }).Build();
        var options = BuildForwardedHeadersOptionsForTest(config);

        var builder = WebApplication.CreateBuilder();
        builder.WebHost.UseTestServer();

        await using var app = builder.Build();
        app.Use((ctx, next) =>
        {
            ctx.Connection.RemoteIpAddress = IPAddress.Parse("198.51.100.25");
            return next();
        });
        app.UseForwardedHeaders(options);
        app.MapGet("/scheme", (HttpContext ctx) => ctx.Request.Scheme);

        await app.StartAsync();
        try
        {
            var request = new HttpRequestMessage(HttpMethod.Get, "/scheme");
            request.Headers.TryAddWithoutValidation("X-Forwarded-Proto", "https");
            var response = await app.GetTestClient().SendAsync(request);
            var scheme = await response.Content.ReadAsStringAsync();

            Assert.Equal("http", scheme);
        }
        finally
        {
            await app.StopAsync();
        }
    }

    [Fact]
    public async Task Security_headers_are_applied_to_responses()
    {
        await using var factory = new TestWebApplicationFactory();
        var client = factory.CreateClient();

        var response = await client.GetAsync("/health");
        response.EnsureSuccessStatusCode();

        Assert.Equal("nosniff", response.Headers.GetValues("X-Content-Type-Options").Single());
        Assert.Equal("DENY", response.Headers.GetValues("X-Frame-Options").Single());
        Assert.Equal("no-referrer", response.Headers.GetValues("Referrer-Policy").Single());
        Assert.Contains("default-src 'self'", response.Headers.GetValues("Content-Security-Policy").Single());
    }

    [Fact]
    public async Task Auth_endpoints_are_rate_limited()
    {
        await using var factory = new TestWebApplicationFactory();
        var client = factory.CreateClientWithCookies();
        await client.RegisterAsync("ratelimit-user");

        HttpResponseMessage? last = null;
        for (var i = 0; i < 8; i++)
        {
            last = await client.PostAsJsonAsync("/api/auth/login", new
            {
                Username = "ratelimit-user",
                Password = "wrong-pass"
            });
        }

        Assert.NotNull(last);
        Assert.Equal(HttpStatusCode.TooManyRequests, last!.StatusCode);
    }

    [Fact]
    public async Task Admin_endpoints_are_rate_limited()
    {
        await using var factory = new TestWebApplicationFactory();
        var admin = factory.CreateClientWithCookies();
        await admin.RegisterAsync("ratelimit-admin", admin: true);

        HttpResponseMessage? last = null;
        for (var i = 0; i < 25; i++)
        {
            last = await admin.GetAsync("/api/admin/vote-status");
            if (last.StatusCode == HttpStatusCode.TooManyRequests)
                break;
        }

        Assert.NotNull(last);
        Assert.Equal(HttpStatusCode.TooManyRequests, last!.StatusCode);
    }

    [Fact]
    public void Frontend_regressions_prevent_modal_html_interpolation_for_untrusted_values()
    {
        var root = Path.GetFullPath(Path.Combine(AppContext.BaseDirectory, "..", "..", "..", ".."));
        var modalJsPath = Path.Combine(root, "wwwroot", "js", "modals-ui.js");
        var adminJsPath = Path.Combine(root, "wwwroot", "js", "admin-ui.js");

        var modalJs = File.ReadAllText(modalJsPath);
        var adminJs = File.ReadAllText(adminJsPath);

        Assert.DoesNotContain("<h3>${title}</h3>", modalJs, StringComparison.Ordinal);
        Assert.DoesNotContain("<p>${body}</p>", modalJs, StringComparison.Ordinal);
        Assert.Contains("heading.textContent = title ?? \"\";", modalJs, StringComparison.Ordinal);
        Assert.Contains("bodyText.textContent = body ?? \"\";", modalJs, StringComparison.Ordinal);
        Assert.DoesNotContain("data-name=\"${v.name}\"", adminJs, StringComparison.Ordinal);
    }

    private static ForwardedHeadersOptions BuildForwardedHeadersOptionsForTest(IConfiguration config)
    {
        var method = typeof(Program).GetMethods(BindingFlags.Static | BindingFlags.NonPublic | BindingFlags.Public).First(m => m.Name.Contains("BuildForwardedHeadersOptions"));
        return (ForwardedHeadersOptions)method.Invoke(null, [config])!;
    }

    private sealed class RedirectFollowingHandler : HttpMessageHandler
    {
        private static readonly Uri Source = new("http://example.com/img.png");
        private static readonly Uri Destination = new("http://example.com/final.png");

        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
        {
            if (request.RequestUri != Source)
            {
                return Task.FromResult(new HttpResponseMessage(HttpStatusCode.NotFound) { RequestMessage = request });
            }

            var redirectedRequest = new HttpRequestMessage(request.Method, Destination);
            var response = new HttpResponseMessage(HttpStatusCode.OK)
            {
                RequestMessage = redirectedRequest,
                Content = new ByteArrayContent("PNG"u8.ToArray())
            };
            response.Content.Headers.ContentType = new MediaTypeHeaderValue("image/png");
            response.Content.Headers.ContentLength = 3;

            return Task.FromResult(response);
        }
    }
}