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

namespace TeleWave.Application.Programming.Templates.Transfer;

public sealed class ExportGridQueryHandler(IAppDbContext dbContext)
    : IQueryHandler<ExportGridQuery, Result<GridConfig>>
{
    public async Task<Result<GridConfig>> Handle(
        ExportGridQuery query,
        CancellationToken cancellationToken
    )
    {
        var channel = await dbContext
            .Channels.AsNoTracking()
            .FirstOrDefaultAsync(c => c.Id == query.ChannelId, cancellationToken);
        if (channel is null)
            return Result.Failure<GridConfig>(ChannelErrors.NotFound);

        var template = await dbContext
            .ScheduleTemplates.AsNoTracking()
            .Include(t => t.Layers)
                .ThenInclude(l => l.Slots)
            .AsSplitQuery()
            .FirstOrDefaultAsync(t => t.ChannelId == query.ChannelId, cancellationToken);
        if (template is null)
            return Result.Failure<GridConfig>(ChannelErrors.TemplateNotFound);

        var groups = await dbContext
            .Groups.AsNoTracking()
            .ToDictionaryAsync(g => g.Id, g => g.Name, cancellationToken);
        var junctions = await dbContext
            .JunctionTemplates.AsNoTracking()
            .ToDictionaryAsync(j => j.Id, j => j.Name, cancellationToken);

        var layers = template
            .Layers.OrderBy(l => l.Priority)
            .Select(layer => new GridConfigLayer(
                layer.Name,
                layer.Priority,
                [
                    .. layer
                        .Slots.OrderBy(s => s.Weekday ?? -1)
                        .ThenBy(s => s.TargetStart)
                        .Select(slot => ToConfig(slot, groups, junctions)),
                ],
                layer.IsEnabled,
                layer.IsBackground,
                LayerApplicability.FromJson(layer.ApplicabilityJson)
            ))
            .ToList();

        return Result.Success(
            new GridConfig(
                layers,
                Channel: new GridConfigChannel(
                    channel.Name,
                    channel.DayStartTime,
                    channel.UtcOffsetMinutes
                ),
                Rules: PlanningRules.FromJson(template.RulesJson),
                FallbackGroup: Name(template.FallbackGroupId, groups),
                DefaultJunction: Name(template.DefaultJunctionId, junctions)
            )
        );
    }

    private static GridConfigSlot ToConfig(
        Slot slot,
        IReadOnlyDictionary<Guid, string> groups,
        IReadOnlyDictionary<Guid, string> junctions
    ) =>
        new(
            slot.Title,
            slot.TargetStart,
            slot.TargetDurationMinutes,
            slot.Daypart,
            slot.SlotKind,
            slot.Weekday,
            Name(slot.GroupId, groups),
            SlotStrategy.FromJson(slot.StrategyJson),
            RepeatSource.FromJson(slot.RepeatSourceJson),
            slot.BlockMode,
            slot.BlockValue,
            slot.OverflowPolicy,
            slot.IsAnchor,
            slot.MaxDriftMinutes,
            slot.SnapToMinutes,
            Name(slot.JunctionBetweenId, junctions),
            Name(slot.JunctionAfterId, junctions)
        );

    /// <summary>Имя по ссылке. Пропавшая ссылка выгружается пустой — файл важнее её сохранности.</summary>
    private static string? Name(Guid? id, IReadOnlyDictionary<Guid, string> names) =>
        id is { } value ? names.GetValueOrDefault(value) : null;
}