using System.Security.Claims;
using System.Text;
using System.Text.Json;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using RadicadeServer.API.Events;
using RadicadeServer.DB;
using RadicadeServer.RecNet.Events;
using RadicadeServer.RecNet.Rooms;
using Xunit;

namespace RadicadeServer.Tests;

/// <summary>
/// An event's start and end are the wall clock its creator picked, and the client posts them
/// with no zone on them. Treating that value as the instant itself made both this server and the
/// client file a fresh event as already finished: the Upcoming filters compare event windows to
/// UTC, and a zone-less timestamp on the wire is read as UTC by the client, so anything the
/// player scheduled "in twenty minutes" came back six hours in the past and was hidden. These
/// tests pin the conversion on the way in and the `Z` form on the way out.
/// </summary>
public class EventTimeTests
{
    private const long CreatorId = 42;

    private static RecDBContext CreateDb() => new(TestDbOptions.Create()
        .UseInMemoryDatabase(Guid.NewGuid().ToString())
        .Options);

    private static EventsAPI CreateController(RecDBContext db, string? jsonBody = null)
    {
        var identity = new ClaimsIdentity("TestAuth");
        identity.AddClaim(new Claim(ClaimTypes.NameIdentifier, CreatorId.ToString()));

        var controller = new EventsAPI(db)
        {
            ControllerContext = new ControllerContext
            {
                HttpContext = new Microsoft.AspNetCore.Http.DefaultHttpContext
                {
                    User = new ClaimsPrincipal(identity)
                }
            }
        };

        if (jsonBody != null)
        {
            var bytes = Encoding.UTF8.GetBytes(jsonBody);
            controller.HttpContext.Request.Body = new MemoryStream(bytes);
            controller.HttpContext.Request.ContentType = "application/json";
            controller.HttpContext.Request.ContentLength = bytes.Length;
        }

        return controller;
    }

    private static async Task<long> SeedRoomAsync(RecDBContext db)
    {
        var room = new RoomData { Name = "Event Room" };
        db.Rooms.Add(room);
        await db.SaveChangesAsync();
        return room.RoomId;
    }

    private static async Task<long> CreateAsync(RecDBContext db, long roomId, string startTime, string endTime)
    {
        var body =
            $$"""
            {
                "Name": "Time check",
                "RoomId": {{roomId}},
                "StartTime": "{{startTime}}",
                "EndTime": "{{endTime}}"
            }
            """;
        var created = Assert.IsType<OkObjectResult>(await CreateController(db, body).CreateEventV2());
        using var document = JsonDocument.Parse(JsonSerializer.Serialize(created.Value));
        return document.RootElement.GetProperty("PlayerEvent").GetProperty("PlayerEventId").GetInt64();
    }

    /// <summary>An event time with no zone, the way the game posts it.</summary>
    private static string WallClock(DateTime local) => local.ToString("yyyy-MM-dd'T'HH:mm:ss");

    /// <summary>The same instant with the sub-second ticks the wall-clock form drops.</summary>
    private static DateTime WholeSecond(DateTime value)
        => new(value.Ticks - value.Ticks % TimeSpan.TicksPerSecond, value.Kind);

    [Fact]
    public async Task APostedWallClockIsStoredAsTheUtcInstantItNames()
    {
        var db = CreateDb();
        var roomId = await SeedRoomAsync(db);
        var picked = new DateTime(2026, 10, 8, 20, 10, 0, DateTimeKind.Unspecified);

        await CreateAsync(db, roomId, WallClock(picked), WallClock(picked.AddMinutes(30)));

        var stored = await db.PlayerEvents.SingleAsync();
        var expected = TimeZoneInfo.ConvertTimeToUtc(picked, TimeZoneInfo.Local);
        Assert.Equal(expected, stored.StartTime);
        Assert.Equal(expected.AddMinutes(30), stored.EndTime);
    }

    [Fact]
    public async Task APostedUtcTimestampIsHonouredAsTheInstantItNames()
    {
        // A client that starts sending real UTC must not be shifted by the server's zone.
        var db = CreateDb();
        var roomId = await SeedRoomAsync(db);
        var instant = new DateTime(2026, 10, 9, 3, 10, 0, DateTimeKind.Utc);

        await CreateAsync(db, roomId, instant.ToString("o"), instant.AddMinutes(30).ToString("o"));

        var stored = await db.PlayerEvents.SingleAsync();
        Assert.Equal(instant, stored.StartTime);
    }

    [Fact]
    public async Task EventTimestampsGoOutAsUtcWithATrailingZ()
    {
        // Real RecNet serves every event time as `...Z`, and a zone-less value is read as UTC by
        // the client - so the read shape, the write envelope and the notification frame must all
        // carry the zone, or the client's own not-ended filter drops the event.
        var db = CreateDb();
        var roomId = await SeedRoomAsync(db);
        var picked = WholeSecond(DateTime.Now.AddMinutes(20));
        var eventId = await CreateAsync(db, roomId, WallClock(picked), WallClock(picked.AddHours(1)));

        var controller = CreateController(db);
        var read = await controller.GetEvent(eventId);
        var ok = Assert.IsType<OkObjectResult>(read.Result);
        using var document = JsonDocument.Parse(JsonSerializer.Serialize(ok.Value));

        var startTime = Assert.IsType<string>(document.RootElement.GetProperty("StartTime").GetString());
        var endTime = Assert.IsType<string>(document.RootElement.GetProperty("EndTime").GetString());

        Assert.EndsWith("Z", startTime);
        Assert.EndsWith("Z", endTime);
        Assert.Equal(TimeZoneInfo.ConvertTimeToUtc(picked, TimeZoneInfo.Local),
            DateTime.Parse(startTime, null, System.Globalization.DateTimeStyles.RoundtripKind));
    }

    [Fact]
    public async Task AnEventScheduledInTwentyMinutesIsUpcomingEverywhereTheClientLooks()
    {
        // The bug this guards: an event made "in twenty minutes" was stored as the wall clock and
        // compared to UTC now, so it was six hours finished as far as every Upcoming-shaped query
        // - and the client's own ended filter - were concerned.
        var db = CreateDb();
        var roomId = await SeedRoomAsync(db);
        var picked = DateTime.Now.AddMinutes(20);
        var eventId = await CreateAsync(db, roomId, WallClock(picked), WallClock(picked.AddHours(1)));
        var controller = CreateController(db);

        Assert.Contains(await controller.GetBrowseFeed(0, 50), e => e.PlayerEventId == eventId);
        Assert.Contains(await controller.GetUpcomingEvents(), e => e.PlayerEventId == eventId);
        Assert.Contains(await controller.SearchEvents(null, null), e => e.PlayerEventId == eventId);

        // What the client itself checks: the timestamp parsed as UTC is still in the future.
        var later = await controller.GetBrowseFeed(0, 50);
        var onWire = later.Single(e => e.PlayerEventId == eventId).StartTime;
        Assert.True(DateTimeOffset.Parse(EventClock.ToWire(onWire)) > DateTimeOffset.UtcNow);
    }

    [Fact]
    public async Task AnEventThatHasFinishedIsStillKeptOutOfTheUpcomingFeeds()
    {
        var db = CreateDb();
        var roomId = await SeedRoomAsync(db);
        var picked = DateTime.Now.AddHours(-4);
        var eventId = await CreateAsync(db, roomId, WallClock(picked), WallClock(picked.AddHours(2)));
        var controller = CreateController(db);

        Assert.DoesNotContain(await controller.GetBrowseFeed(0, 50), e => e.PlayerEventId == eventId);
        Assert.DoesNotContain(await controller.GetUpcomingEvents(), e => e.PlayerEventId == eventId);
    }

    [Fact]
    public void TheClockConvertsAWallClockAndPassesAUtcInstantThrough()
    {
        var wallClock = new DateTime(2026, 10, 8, 20, 10, 0, DateTimeKind.Unspecified);

        Assert.Equal(TimeZoneInfo.ConvertTimeToUtc(wallClock, TimeZoneInfo.Local),
            EventClock.FromPostedTime(wallClock));

        var utc = new DateTime(2026, 10, 9, 3, 10, 0, DateTimeKind.Utc);
        Assert.Equal(utc, EventClock.FromPostedTime(utc));
        Assert.Equal("2026-10-09T03:10:00.0000000Z", EventClock.ToWire(utc));

        // A value read back from the store carries no kind; it is already UTC and must not be
        // converted a second time.
        Assert.Equal("2026-10-09T03:10:00.0000000Z",
            EventClock.ToWire(new DateTime(2026, 10, 9, 3, 10, 0, DateTimeKind.Unspecified)));
    }
}