using HSchool.People;
using HSchool.Schedule;
using HSchool.Server.Game;
using HSchool.Simulation;

namespace HSchool.Server.Api;

/// <summary>
/// Diagnostic HTTP that exists only when <c>HSchool:AllowSaveReload</c> is on. Never mapped in
/// production by default.
/// </summary>
internal static class DevEndpoints
{
    private static readonly TimeSpan CommandTimeout = TimeSpan.FromSeconds(5);

    public static void MapDevEndpoints(this IEndpointRouteBuilder builder)
    {
        builder.MapGet("/api/dev/schools/{id:int}/dump", async (
            int id,
            GameLoopService loop,
            GameCommandQueue commands,
            CancellationToken cancellationToken) =>
        {
            var published = loop.FindPeople(id);
            if (published is null)
            {
                return Problem(StatusCodes.Status404NotFound, "unknown-school", "That school does not exist.");
            }

            var command = new GameCommand.DumpSchool(id, NewCompletion<SchoolLiveDump?>());
            commands.Enqueue(command);
            var live = await command.Result.Task.WaitAsync(CommandTimeout, cancellationToken);
            if (live is null)
            {
                return Problem(StatusCodes.Status404NotFound, "unknown-school", "That school does not exist.");
            }

            return Results.Ok(MapDump(published, live));
        })
        .WithName("DumpSchool");

        builder.MapPost("/api/dev/schools/{id:int}/notices", async (
            int id,
            PostDevNoticeRequest? request,
            GameLoopService loop,
            GameCommandQueue commands,
            CancellationToken cancellationToken) =>
        {
            if (loop.FindSchool(id) is null)
            {
                return Problem(StatusCodes.Status404NotFound, "unknown-school", "That school does not exist.");
            }

            var defName = request?.DefName?.Trim() ?? "";
            if (defName.Length == 0)
            {
                return Problem(StatusCodes.Status400BadRequest, "invalid-query", "defName is required.");
            }

            var command = new GameCommand.PostSchoolNotice(
                id,
                defName,
                request?.Person?.Trim() ?? "",
                request?.Kind?.Trim() ?? "",
                NewCompletion<PostedNotice?>());
            commands.Enqueue(command);
            var posted = await command.Result.Task.WaitAsync(CommandTimeout, cancellationToken);
            if (posted is null)
            {
                return Problem(
                    StatusCodes.Status409Conflict,
                    "notice-rejected",
                    "Unknown event def or the sticky notice ceiling is full.");
            }

            return Results.Ok(new { id = posted.Id, defName = posted.DefName, pause = posted.Pause });
        })
        .WithName("PostDevNotice");
    }

    private static SchoolDumpResponse MapDump(PublishedSchoolPeople published, SchoolLiveDump live)
    {
        var byId = live.Presence.ToDictionary(row => row.PersonId, StringComparer.Ordinal);
        var people = published.Roster?.People
            .OrderBy(person => person.Id, StringComparer.Ordinal)
            .Select(person => Person(person, byId, live.Needs))
            .ToArray() ?? [];

        var lessons = (published.Timetable?.Lessons ?? [])
            .Select(Lesson)
            .ToArray();
        var now = live.Now.Select(Lesson).ToArray();

        return new SchoolDumpResponse(
            published.School.Id,
            published.School.Name,
            live.GameTime,
            live.Running,
            people,
            now,
            lessons);
    }

    private static SchoolDumpPersonResponse Person(
        Person person,
        IReadOnlyDictionary<string, PresenceSnapshot> presence,
        IReadOnlyDictionary<string, IReadOnlyDictionary<string, float>> needs)
    {
        string? nodeId = null;
        if (presence.TryGetValue(person.Id, out var row))
        {
            nodeId = row.NodeId;
        }

        IReadOnlyDictionary<string, float> values = person.Needs;
        if (needs.TryGetValue(person.Id, out var live))
        {
            values = live;
        }

        return new SchoolDumpPersonResponse(person.Id, person.Name.Full, nodeId, values);
    }

    private static SchoolDumpLessonResponse Lesson(LessonPlacement lesson) =>
        new(lesson.ClassId, lesson.Subject, lesson.TeacherId, lesson.RoomId, lesson.Day, lesson.Period);

    private static TaskCompletionSource<T> NewCompletion<T>() =>
        new(TaskCreationOptions.RunContinuationsAsynchronously);

    private static IResult Problem(int statusCode, string code, string detail) =>
        Results.Problem(detail: detail, statusCode: statusCode, title: code, extensions: new Dictionary<string, object?> { ["code"] = code });
}

internal sealed record SchoolDumpResponse(
    int Id,
    string Name,
    DateTime GameTime,
    bool Running,
    IReadOnlyList<SchoolDumpPersonResponse> People,
    IReadOnlyList<SchoolDumpLessonResponse> Now,
    IReadOnlyList<SchoolDumpLessonResponse> Lessons);

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

internal sealed record SchoolDumpLessonResponse(
    string ClassId,
    string Subject,
    string TeacherId,
    string RoomId,
    int Day,
    int Period);

internal sealed record PostDevNoticeRequest(string? DefName, uint PersonId = 0, string? Person = null, string? Kind = null);