using LiteCqrs;
using Microsoft.EntityFrameworkCore;
using TeleWave.Application.Common.Interfaces;
using TeleWave.Application.Common.Models;
using TeleWave.Domain.Broadcast;

namespace TeleWave.Application.Broadcast.CreateOverride;

public sealed class CreateProgrammingOverrideCommandHandler(IAppDbContext dbContext)
    : ICommandHandler<CreateProgrammingOverrideCommand, Result<Guid>>
{
    public async Task<Result<Guid>> Handle(
        CreateProgrammingOverrideCommand command,
        CancellationToken cancellationToken
    )
    {
        var weekly = command.Recurrence == OverrideRecurrence.Weekly;
        if (weekly)
        {
            if (
                command.DayOfWeek is not (>= 0 and <= 6)
                || command.StartMinute is not { } sm
                || command.EndMinute is not { } em
                || em <= sm
                || sm < 0
                || em > 1440
            )
                return Result.Failure<Guid>(ChannelErrors.InvalidOverrideWindow);
        }
        else if (
            command.StartsAtUtc is not { } start
            || command.EndsAtUtc is not { } end
            || end <= start
        )
        {
            return Result.Failure<Guid>(ChannelErrors.InvalidOverrideWindow);
        }

        if (command.Shows.Count == 0)
            return Result.Failure<Guid>(ChannelErrors.OverrideNeedsShow);

        var channel = await dbContext
            .Channels.Include(c => c.Overrides)
                .ThenInclude(o => o.Shows)
            .FirstOrDefaultAsync(c => c.Id == command.ChannelId, cancellationToken);
        if (channel is null)
            return Result.Failure<Guid>(ChannelErrors.NotFound);

        var showIds = command.Shows.Select(s => s.ShowId).Distinct().ToList();
        var existingCount = await dbContext.Shows.CountAsync(
            s => showIds.Contains(s.Id),
            cancellationToken
        );
        if (existingCount != showIds.Count)
            return Result.Failure<Guid>(ChannelErrors.ShowNotFound);

        var ovr = weekly
            ? channel.AddWeeklyOverride(
                command.Mode,
                command.DayOfWeek!.Value,
                command.StartMinute!.Value,
                command.EndMinute!.Value
            )
            : channel.AddOverride(
                command.Mode,
                command.StartsAtUtc!.Value,
                command.EndsAtUtc!.Value
            );
        foreach (var show in command.Shows)
            ovr.AddShow(show.ShowId, show.Weight);

        return Result.Success(ovr.Id);
    }
}