using ErsatzTV.Application.Channels;
using ErsatzTV.Application.Configuration;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Domain.Filler;
using NUnit.Framework;
using Shouldly;

namespace ErsatzTV.Core.Tests.Channels;

// Issue #77 (XMLTV half): the clock-boundary Pad machinery snaps content to :00/:15/:30/:45 by emitting
// trailing PostRoll filler up to the boundary (proven at the builder level by
// PlayoutBuildGoldenTests.Classic_clock_padded). This test locks the OTHER half: that the guide
// projection — the single source of truth shared by the XMLTV cache builder and the JSON guide query —
// coalesces that trailing filler into the programme window, so each guide programme STOPS on the padded
// clock boundary. Together the two tests cover the full chain: schedule -> PlayoutItems -> guide.
[TestFixture]
public class ChannelGuideProjectorClockPadTests
{
    // Deterministic UTC instants mirroring the Classic_clock_padded golden shape: off-boundary content
    // (22/37/37-min) each followed by a single PostRoll filler run that ends exactly on the next :15 mark.
    private static readonly DateTime Anchor = new(2026, 1, 15, 0, 0, 0, DateTimeKind.Utc);

    [Test]
    public void Padded_programmes_stop_on_quarter_hour_boundary()
    {
        var items = new List<PlayoutItem>
        {
            // Programme 1: content 00:00-00:22, padded to 00:30 with PostRoll filler.
            Content(guideGroup: 1, start: T(0, 0), finish: T(0, 22), title: "Movie 01"),
            Pad(guideGroup: 1, start: T(0, 22), finish: T(0, 30)),

            // Programme 2: content 00:30-01:07, padded to 01:15.
            Content(guideGroup: 2, start: T(0, 30), finish: T(1, 7), title: "Movie 02"),
            Pad(guideGroup: 2, start: T(1, 7), finish: T(1, 15)),

            // Programme 3: content 01:15-01:52, padded to 02:00.
            Content(guideGroup: 3, start: T(1, 15), finish: T(1, 52), title: "Movie 03"),
            Pad(guideGroup: 3, start: T(1, 52), finish: T(2, 0))
        };

        List<ChannelGuideEntry> entries = ChannelGuideProjector
            .Project(PlayoutScheduleKind.Classic, items, XmltvTimeZone.Utc, XmltvBlockBehavior.UseActualTimes)
            .ToList();

        // One programme per content item; trailing filler is coalesced in, not surfaced as its own entry.
        entries.Count.ShouldBe(3);
        entries.ShouldAllBe(e => e.DisplayItem.FillerKind == FillerKind.None);

        // The #77 invariant: every programme STOPS on a :15 clock boundary (the padded target), and the
        // 2nd/3rd programmes also START on one (the previous programme padded up to it).
        foreach (ChannelGuideEntry entry in entries)
        {
            (entry.Stop.Minute % 15).ShouldBe(0, $"programme '{entry.DisplayItem.CustomTitle}' stops off-boundary at {entry.Stop:HH:mm:ss}");
            entry.Stop.Second.ShouldBe(0);
        }

        entries[0].Stop.ShouldBe(new DateTimeOffset(T(0, 30), TimeSpan.Zero));
        entries[1].Start.ShouldBe(new DateTimeOffset(T(0, 30), TimeSpan.Zero));
        entries[1].Stop.ShouldBe(new DateTimeOffset(T(1, 15), TimeSpan.Zero));
        entries[2].Start.ShouldBe(new DateTimeOffset(T(1, 15), TimeSpan.Zero));
        entries[2].Stop.ShouldBe(new DateTimeOffset(T(2, 0), TimeSpan.Zero));
    }

    private static DateTime T(int hour, int minute) => Anchor.AddHours(hour).AddMinutes(minute);

    private static PlayoutItem Content(int guideGroup, DateTime start, DateTime finish, string title) =>
        new()
        {
            Start = start,
            Finish = finish,
            FillerKind = FillerKind.None,
            GuideGroup = guideGroup,
            CustomTitle = title
        };

    private static PlayoutItem Pad(int guideGroup, DateTime start, DateTime finish) =>
        new()
        {
            Start = start,
            Finish = finish,
            FillerKind = FillerKind.PostRoll,
            GuideGroup = guideGroup
        };
}