using System.Net.Http.Json;

namespace HSchool.AppHost.Tests;

/// <summary>
/// The main menu's HTTP surface: list, create, delete. Tests share one AppHost, so each of them
/// starts from an empty list rather than assuming one.
/// </summary>
[Collection(AppHostCollection.Name)]
public class SchoolApiTests(AppHostFixture fixture)
{
    private static readonly DateTime ExpectedDefaultStart = new(2012, 4, 3, 6, 0, 0, DateTimeKind.Utc);

    [Fact]
    public async Task Schools_ReportTheConfiguredLimitAndDefaultStartDate()
    {
        using var client = fixture.App.CreateHttpClient("server");
        await ResetAsync(client);

        var state = await GetSchoolsAsync(client);

        Assert.Equal(6, state.MaxSchools);
        Assert.Equal(ExpectedDefaultStart, state.DefaultStartDate);

        // Without the "Z" the browser would read the start date in its own time zone and the
        // creation form would offer the wrong hour.
        Assert.Equal(DateTimeKind.Utc, state.DefaultStartDate.Kind);
        Assert.Equal(5d, state.GameMinutesPerRealSecond);
        Assert.Empty(state.Schools);
    }

    [Fact]
    public async Task CreateSchool_StartsAtTheRequestedDateAndRunning()
    {
        using var client = fixture.App.CreateHttpClient("server");
        await ResetAsync(client);

        var created = await CreateAsync(client, "Гимназия у моря", ExpectedDefaultStart);

        Assert.Equal("Гимназия у моря", created.Name);
        Assert.Equal(ExpectedDefaultStart, created.GameTime);

        // Schools live from the moment they exist, whether or not anybody is inside.
        Assert.True(created.Running);

        var state = await GetSchoolsAsync(client);
        Assert.Contains(state.Schools, school => school.Id == created.Id);
    }

    [Fact]
    public async Task CreateSchool_BeyondTheLimit_IsRejected()
    {
        using var client = fixture.App.CreateHttpClient("server");
        await ResetAsync(client);

        var state = await GetSchoolsAsync(client);
        for (var i = 0; i < state.MaxSchools; i++)
        {
            await CreateAsync(client, $"Школа {i + 1}", ExpectedDefaultStart);
        }

        using var response = await PostAsync(client, "Лишняя", ExpectedDefaultStart);

        Assert.Equal(HttpStatusCode.Conflict, response.StatusCode);
        Assert.Equal("school-limit-reached", await ProblemCodeAsync(response));
        Assert.Equal(state.MaxSchools, (await GetSchoolsAsync(client)).Schools.Count);
    }

    [Theory]
    [InlineData("")]
    [InlineData("   ")]
    public async Task CreateSchool_WithABlankName_IsRejected(string name)
    {
        using var client = fixture.App.CreateHttpClient("server");
        await ResetAsync(client);

        using var response = await PostAsync(client, name, ExpectedDefaultStart);

        Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
        Assert.Equal("invalid-name", await ProblemCodeAsync(response));
    }

    [Fact]
    public async Task CreateSchool_WithAnImpossibleStartDate_IsRejected()
    {
        using var client = fixture.App.CreateHttpClient("server");
        await ResetAsync(client);

        using var response = await PostAsync(client, "Школа", new DateTime(1500, 1, 1, 0, 0, 0, DateTimeKind.Utc));

        Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
        Assert.Equal("invalid-start-date", await ProblemCodeAsync(response));
    }

    [Fact]
    public async Task DeleteSchool_RemovesItAndFreesASlot()
    {
        using var client = fixture.App.CreateHttpClient("server");
        await ResetAsync(client);
        var created = await CreateAsync(client, "На удаление", ExpectedDefaultStart);

        using var response = await client.DeleteAsync($"/api/schools/{created.Id}", TestContext.Current.CancellationToken);

        Assert.Equal(HttpStatusCode.NoContent, response.StatusCode);
        Assert.DoesNotContain((await GetSchoolsAsync(client)).Schools, school => school.Id == created.Id);
    }

    [Fact]
    public async Task DeleteSchool_ThatDoesNotExist_IsNotFound()
    {
        using var client = fixture.App.CreateHttpClient("server");

        using var response = await client.DeleteAsync("/api/schools/999999", TestContext.Current.CancellationToken);

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

    [Fact]
    public async Task RandomName_IsUsableAsIs()
    {
        using var client = fixture.App.CreateHttpClient("server");
        await ResetAsync(client);

        var suggestion = await client.GetFromJsonAsync<RandomNameResponse>(
            "/api/schools/random-name",
            TestContext.Current.CancellationToken);

        Assert.NotNull(suggestion);
        Assert.False(string.IsNullOrWhiteSpace(suggestion.Name));

        var created = await CreateAsync(client, suggestion.Name, ExpectedDefaultStart);
        Assert.Equal(suggestion.Name, created.Name);
    }

    [Fact]
    public async Task Status_ReportsTheLoopAndTheLimit()
    {
        using var client = fixture.App.CreateHttpClient("server");

        var status = await client.GetFromJsonAsync<StatusResponse>("/api/status", TestContext.Current.CancellationToken);

        Assert.NotNull(status);
        Assert.Equal(20, status.TickRate);
        Assert.Equal(6, status.MaxSchools);
        Assert.True(status.Tick > 0, "The loop should have ticked by now.");
    }

    [Fact]
    public async Task ReloadFromDisk_RestoresCreatedSchools()
    {
        using var client = fixture.App.CreateHttpClient("server");
        await ResetAsync(client);
        var created = await CreateAsync(client, "После перезагрузки", ExpectedDefaultStart);

        using var reload = await client.PostAsync("/api/dev/reload-schools", content: null, TestContext.Current.CancellationToken);
        reload.EnsureSuccessStatusCode();

        var restored = (await GetSchoolsAsync(client)).Schools.Single(school => school.Id == created.Id);
        Assert.Equal(created.Name, restored.Name);
        Assert.True(restored.Running);
    }

    internal static async Task ResetAsync(HttpClient client)
    {
        var state = await GetSchoolsAsync(client);

        foreach (var school in state.Schools)
        {
            using var response = await client.DeleteAsync($"/api/schools/{school.Id}", TestContext.Current.CancellationToken);
            response.EnsureSuccessStatusCode();
        }
    }

    internal static async Task<SchoolsResponse> GetSchoolsAsync(HttpClient client)
    {
        var state = await client.GetFromJsonAsync<SchoolsResponse>("/api/schools", TestContext.Current.CancellationToken);
        Assert.NotNull(state);
        return state;
    }

    internal static async Task<SchoolResponse> CreateAsync(HttpClient client, string name, DateTime startDate)
    {
        using var response = await PostAsync(client, name, startDate);
        response.EnsureSuccessStatusCode();

        var created = await response.Content.ReadFromJsonAsync<SchoolResponse>(TestContext.Current.CancellationToken);
        Assert.NotNull(created);
        return created;
    }

    private static Task<HttpResponseMessage> PostAsync(HttpClient client, string name, DateTime startDate) =>
        client.PostAsJsonAsync(
            "/api/schools",
            new { name, startDate },
            TestContext.Current.CancellationToken);

    private static async Task<string?> ProblemCodeAsync(HttpResponseMessage response)
    {
        var problem = await response.Content.ReadFromJsonAsync<ProblemResponse>(TestContext.Current.CancellationToken);
        return problem?.Code;
    }

    internal sealed record SchoolResponse(int Id, string Name, DateTime GameTime, bool Running, byte SpeedIndex);

    internal sealed record SchoolsResponse(
        int MaxSchools,
        DateTime DefaultStartDate,
        double GameMinutesPerRealSecond,
        IReadOnlyList<SchoolResponse> Schools);

    private sealed record RandomNameResponse(string Name);

    private sealed record ProblemResponse(string? Code);

    private sealed record StatusResponse(uint Tick, int TickRate, int Schools, int MaxSchools, int Connections);
}