using System.Net.Http.Json;
using System.Text.Json;
using System.Text.Json.Nodes;

namespace HSchool.AppHost.Tests;

[Collection(AppHostCollection.Name)]
public class ServiceabilityTests(AppHostFixture fixture)
{
    private static readonly DateTime TuesdayMorning = new(2012, 4, 3, 10, 20, 0, DateTimeKind.Utc);

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

        try
        {
            InstallGolden(directory, "current");
            var path = Path.Combine(directory, "1.json");
            BumpFormat(path, 99);
            var before = File.ReadAllBytes(path);

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

            var state = await SchoolApiTests.GetSchoolsAsync(client);
            Assert.Empty(state.Schools);
            var broken = Assert.Single(state.Others);
            Assert.Equal(1, broken.Id);

            using var people = await client.GetAsync(
                $"/api/schools/{broken.Id}/people?pageSize=1",
                TestContext.Current.CancellationToken);
            Assert.Equal(HttpStatusCode.NotFound, people.StatusCode);

            Assert.Equal(before, File.ReadAllBytes(path));
        }
        finally
        {
            DeleteSchoolFiles(directory, 1);
            using var cleanup = await client.PostAsync("/api/dev/reload-schools", content: null, TestContext.Current.CancellationToken);
            cleanup.EnsureSuccessStatusCode();
        }
    }

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

        try
        {
            InstallGolden(directory, "current");
            var path = Path.Combine(directory, "1.json");
            BumpFormat(path, 3);
            var before = File.ReadAllBytes(path);

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

            var state = await SchoolApiTests.GetSchoolsAsync(client);
            Assert.Empty(state.Schools);
            var broken = Assert.Single(state.Others);
            Assert.Equal(1, broken.Id);

            using var people = await client.GetAsync(
                $"/api/schools/{broken.Id}/people?pageSize=1",
                TestContext.Current.CancellationToken);
            Assert.Equal(HttpStatusCode.NotFound, people.StatusCode);

            Assert.Equal(before, File.ReadAllBytes(path));
        }
        finally
        {
            DeleteSchoolFiles(directory, 1);
            using var cleanup = await client.PostAsync("/api/dev/reload-schools", content: null, TestContext.Current.CancellationToken);
            cleanup.EnsureSuccessStatusCode();
        }
    }

    [Fact]
    public async Task MissingModFolder_LeavesTheSchoolUnstartedAndTheFileUntouched()
    {
        using var client = fixture.App.CreateHttpClient("server");
        await SchoolApiTests.ResetAsync(client);
        var created = await SchoolApiTests.CreateAsync(client, "Без папки мода", TuesdayMorning);
        var directory = await SavesDirectoryAsync(client);
        var path = Path.Combine(directory, $"{created.Id}.json");
        var node = JsonNode.Parse(File.ReadAllText(path))
            ?? throw new InvalidOperationException($"Save {path} parsed to nothing.");
        var mods = node["modIds"] as JsonArray
            ?? throw new InvalidOperationException($"Save {path} has no modIds.");
        mods.Add("missing-pack-slice1-recheck");
        var patched = node.ToJsonString(new JsonSerializerOptions { WriteIndented = true });

        try
        {
            await SchoolApiTests.ResetAsync(client);
            File.WriteAllText(path, patched);
            var before = File.ReadAllBytes(path);

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

            Assert.Equal(before, File.ReadAllBytes(path));

            var state = await SchoolApiTests.GetSchoolsAsync(client);
            var mine = state.Schools.FirstOrDefault(school => school.Id == created.Id);
            var other = state.Others.FirstOrDefault(school => school.Id == created.Id);
            Assert.True(mine is not null || other is not null);
            Assert.False(mine?.Running ?? other?.Running ?? true);

            using var people = await client.GetAsync(
                $"/api/schools/{created.Id}/people?pageSize=1",
                TestContext.Current.CancellationToken);
            Assert.Equal(HttpStatusCode.NotFound, people.StatusCode);
        }
        finally
        {
            DeleteSchoolFiles(directory, created.Id);
            using var cleanup = await client.PostAsync("/api/dev/reload-schools", content: null, TestContext.Current.CancellationToken);
            cleanup.EnsureSuccessStatusCode();
        }
    }

    [Fact]
    public async Task Dump_ReturnsPeopleNodesAndTimetable()
    {
        using var client = fixture.App.CreateHttpClient("server");
        await SchoolApiTests.ResetAsync(client);
        var school = await SchoolApiTests.CreateAsync(client, "Дамп", TuesdayMorning);
        // Create starts the clock. Presence still goes out while paused (often empty); waiting
        // for people then hangs. Hire, keep time moving, then dump.
        Assert.True(school.Running);
        await HireMathAsync(client, school.Id);

        var dump = await WaitUntilSomeoneIsOnANodeAsync(client, school.Id);

        Assert.Equal(school.Id, dump.Id);
        Assert.True(dump.Running);
        Assert.NotEmpty(dump.People);
        Assert.Contains(dump.People, person => !string.IsNullOrWhiteSpace(person.NodeId));
        Assert.All(dump.People, person =>
        {
            Assert.False(string.IsNullOrWhiteSpace(person.Id));
            Assert.False(string.IsNullOrWhiteSpace(person.FullName));
            Assert.NotEmpty(person.Needs);
        });
        Assert.Contains(dump.Lessons, lesson => lesson.Subject == "Mathematics");
    }

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

        using var response = await client.GetAsync("/api/dev/schools/999999/dump", TestContext.Current.CancellationToken);
        Assert.Equal(HttpStatusCode.NotFound, response.StatusCode);
        Assert.Equal("unknown-school", await ProblemCodeAsync(response));
    }

    /// <summary>
    /// Polls the dump while the clock is moving. A paused school would keep answering with empty
    /// occupancy; fail immediately instead of waiting that out.
    /// </summary>
    private static async Task<SchoolDumpResponse> WaitUntilSomeoneIsOnANodeAsync(HttpClient client, int schoolId)
    {
        SchoolDumpResponse? dump = null;
        for (var attempt = 0; attempt < 120; attempt++)
        {
            dump = await client.GetFromJsonAsync<SchoolDumpResponse>(
                $"/api/dev/schools/{schoolId}/dump",
                TestContext.Current.CancellationToken);
            Assert.NotNull(dump);
            if (!dump.Running)
            {
                Assert.Fail("Clock is paused; occupancy stays empty and this wait would hang.");
            }

            if (dump.People.Any(person => !string.IsNullOrWhiteSpace(person.NodeId)))
            {
                return dump;
            }

            await Task.Delay(250, TestContext.Current.CancellationToken);
        }

        throw new InvalidOperationException(
            $"Nobody had a NodeId after hire with the clock running at {dump?.GameTime:HH:mm}.");
    }

    private static async Task HireMathAsync(HttpClient client, int schoolId)
    {
        var staffing = await client.GetFromJsonAsync<StaffingResponse>(
            $"/api/schools/{schoolId}/staffing",
            TestContext.Current.CancellationToken);
        Assert.NotNull(staffing);
        var applicant = Assert.Single(staffing.Applicants.Take(1));

        using var hire = await client.PostAsJsonAsync(
            $"/api/schools/{schoolId}/staff/hire",
            new { personId = applicant.Id, position = "Teacher" },
            TestContext.Current.CancellationToken);
        hire.EnsureSuccessStatusCode();

        using var assign = await client.PostAsJsonAsync(
            $"/api/schools/{schoolId}/staff/{Uri.EscapeDataString(applicant.Id)}/subjects",
            new { subject = "Mathematics" },
            TestContext.Current.CancellationToken);
        assign.EnsureSuccessStatusCode();
    }

    private static async Task<string> SavesDirectoryAsync(HttpClient client)
    {
        var payload = await client.GetFromJsonAsync<SavesDirectoryResponse>(
            "/api/dev/saves-directory",
            TestContext.Current.CancellationToken);
        Assert.NotNull(payload);
        Assert.False(string.IsNullOrWhiteSpace(payload.Path));
        return payload.Path;
    }

    private static void InstallGolden(string directory, string folder)
    {
        var source = Path.Combine(AppContext.BaseDirectory, "golden", folder);
        foreach (var file in Directory.EnumerateFiles(source))
        {
            File.Copy(file, Path.Combine(directory, Path.GetFileName(file)), overwrite: true);
        }
    }

    private static void BumpFormat(string path, int format)
    {
        var node = JsonNode.Parse(File.ReadAllText(path))
            ?? throw new InvalidOperationException($"Save {path} parsed to nothing.");
        node["format"] = format;
        File.WriteAllText(path, node.ToJsonString(new JsonSerializerOptions { WriteIndented = true }));
    }

    private static void DeleteSchoolFiles(string directory, int id)
    {
        foreach (var name in new[] { $"{id}.json", $"{id}.people.json", $"{id}.timetable.json" })
        {
            var path = Path.Combine(directory, name);
            if (File.Exists(path))
            {
                File.Delete(path);
            }
        }
    }

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

    private sealed record SavesDirectoryResponse(string Path);

    private sealed record ProblemResponse(string? Code);

    private sealed record StaffingResponse(IReadOnlyList<ApplicantResponse> Applicants);

    private sealed record ApplicantResponse(string Id);

    private sealed record SchoolDumpResponse(
        int Id,
        string Name,
        DateTime GameTime,
        bool Running,
        IReadOnlyList<DumpPersonResponse> People,
        IReadOnlyList<DumpLessonResponse> Now,
        IReadOnlyList<DumpLessonResponse> Lessons);

    private sealed record DumpPersonResponse(
        string Id,
        string FullName,
        string? NodeId,
        IReadOnlyDictionary<string, float> Needs);

    private sealed record DumpLessonResponse(
        string ClassId,
        string Subject,
        string TeacherId,
        string RoomId,
        int Day,
        int Period);
}