using System.Text.Json;
using Microsoft.Playwright;

namespace ZB.MOM.WW.ScadaBridge.CentralUI.PlaywrightTests;

[Collection("Playwright")]
public class LoginTests
{
    private readonly PlaywrightFixture _fixture;

    /// <summary>Initializes the tests with the shared Playwright fixture.</summary>
    /// <param name="fixture">The shared Playwright fixture.</param>
    public LoginTests(PlaywrightFixture fixture)
    {
        _fixture = fixture;
    }

    /// <summary>Verifies that an unauthenticated user is redirected to the login page.</summary>
    /// <returns>A task that represents the asynchronous operation.</returns>
    [Fact]
    public async Task UnauthenticatedUser_RedirectsToLogin()
    {
        var page = await _fixture.NewPageAsync();

        await page.GotoAsync(PlaywrightFixture.BaseUrl);

        Assert.Contains("/login", page.Url);
        // The kit's LoginCard renders the heading "<Product> — sign in" with the
        // product token in its own .login-product span; the submit button reads
        // "Sign in".
        await Expect(page.Locator(".login-product")).ToHaveTextAsync("ScadaBridge");
        await Expect(page.Locator("#username")).ToBeVisibleAsync();
        await Expect(page.Locator("#password")).ToBeVisibleAsync();
        await Expect(page.Locator("button[type='submit']")).ToHaveTextAsync("Sign in");
    }

    /// <summary>Verifies that valid credentials authenticate the user successfully.</summary>
    /// <returns>A task that represents the asynchronous operation.</returns>
    [Fact]
    public async Task ValidCredentials_AuthenticatesSuccessfully()
    {
        var page = await _fixture.NewAuthenticatedPageAsync();

        // Should be on the dashboard, not the login page
        Assert.DoesNotContain("/login", page.Url);
    }

    /// <summary>Verifies that invalid credentials show an error on the login page.</summary>
    /// <returns>A task that represents the asynchronous operation.</returns>
    [Fact]
    public async Task InvalidCredentials_ShowsError()
    {
        var page = await _fixture.NewPageAsync();

        await page.GotoAsync($"{PlaywrightFixture.BaseUrl}/login");
        await page.WaitForLoadStateAsync(LoadState.DOMContentLoaded);

        // POST invalid credentials via fetch
        var status = await page.EvaluateAsync<int>(@"
            async () => {
                const resp = await fetch('/auth/login', {
                    method: 'POST',
                    headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
                    body: 'username=baduser&password=badpass&__RequestVerificationToken=' + encodeURIComponent(document.querySelector('input[name=__RequestVerificationToken]').value),
                    redirect: 'follow'
                });
                return resp.status;
            }
        ");

        // The login endpoint redirects to /login?error=... on failure.
        // Reload the page to see the error state.
        await page.ReloadAsync();
        Assert.Equal(200, status); // redirect followed to login page
    }

    /// <summary>
    /// Verifies that the token endpoint returns a JWT for valid credentials. Skipped when the
    /// rig runs with <c>DisableLogin</c>, where <c>/auth/token</c> deliberately answers 404.
    /// </summary>
    /// <returns>A task that represents the asynchronous operation.</returns>
    [SkippableFact]
    public async Task TokenEndpoint_ReturnsJwt()
    {
        var page = await OpenLoginPageAsync();
        Skip.If(await TokenEndpointDisabledAsync(page),
            "Login is disabled on this rig: POST /auth/token answers 404 by design, so no JWT is issued.");

        var result = await page.EvaluateAsync<JsonElement>(@"
            async () => {
                const resp = await fetch('/auth/token', {
                    method: 'POST',
                    headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
                    body: 'username=multi-role&password=password'
                });
                const json = await resp.json();
                return { status: resp.status, hasToken: !!json.access_token, username: json.username || '' };
            }
        ");

        Assert.Equal(200, result.GetProperty("status").GetInt32());
        Assert.True(result.GetProperty("hasToken").GetBoolean());
        Assert.Equal("multi-role", result.GetProperty("username").GetString());
    }

    /// <summary>
    /// Verifies that the token endpoint rejects invalid credentials: HTTP 401 with login
    /// enabled, or HTTP 404 under <c>DisableLogin</c> (the exchange is closed entirely, so
    /// even bad credentials can never reach a credential check).
    /// </summary>
    /// <returns>A task that represents the asynchronous operation.</returns>
    [Fact]
    public async Task TokenEndpoint_InvalidCredentials_Returns401()
    {
        var page = await OpenLoginPageAsync();
        var disabled = await TokenEndpointDisabledAsync(page);

        var status = await PostTokenAsync(page, "baduser", "badpass");

        Assert.Equal(disabled ? 404 : 401, status);
    }

    private async Task<IPage> OpenLoginPageAsync()
    {
        var page = await _fixture.NewPageAsync();
        await page.GotoAsync($"{PlaywrightFixture.BaseUrl}/login");
        await page.WaitForLoadStateAsync(LoadState.DOMContentLoaded);
        return page;
    }

    /// <summary>
    /// Probes whether the rig runs with <c>DisableLogin</c>: the token exchange then answers
    /// 404 for any request (AuthEndpoints.HandleTokenAsync), while with login enabled a
    /// valid-credential POST is a 200 and never a 404.
    /// </summary>
    private static async Task<bool> TokenEndpointDisabledAsync(IPage page) =>
        await PostTokenAsync(page, PlaywrightFixture.TestUsername, PlaywrightFixture.TestPassword) == 404;

    private static Task<int> PostTokenAsync(IPage page, string username, string password) =>
        page.EvaluateAsync<int>(@"
            async ([u, p]) => {
                const resp = await fetch('/auth/token', {
                    method: 'POST',
                    headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
                    body: new URLSearchParams({ username: u, password: p }).toString()
                });
                return resp.status;
            }
        ", new object[] { username, password });

    private static ILocatorAssertions Expect(ILocator locator) =>
        Assertions.Expect(locator);
}