using ErsatzTV.Core;
using ErsatzTV.Core.Domain.Scheduling;
using ErsatzTV.Infrastructure.Data;
using ErsatzTV.Infrastructure.Extensions;
using Microsoft.EntityFrameworkCore;

namespace ErsatzTV.Application.Scheduling;

public class UpdateDecoHandler(IDbContextFactory<TvContext> dbContextFactory)
    : IRequestHandler<UpdateDeco, Either<BaseError, DecoViewModel>>
{
    public async Task<Either<BaseError, DecoViewModel>> Handle(UpdateDeco request, CancellationToken cancellationToken)
    {
        await using TvContext dbContext = await dbContextFactory.CreateDbContextAsync(cancellationToken);
        Validation<BaseError, Deco> validation = await Validate(dbContext, request);
        return await validation.Apply(ps => ApplyUpdateRequest(dbContext, ps, request));
    }

    private static async Task<DecoViewModel> ApplyUpdateRequest(
        TvContext dbContext,
        Deco existing,
        UpdateDeco request)
    {
        existing.Name = request.Name;

        // watermark
        existing.WatermarkMode = request.WatermarkMode;
        existing.WatermarkId = request.WatermarkMode is DecoMode.Override ? request.WatermarkId : null;

        // default filler
        existing.DefaultFillerMode = request.DefaultFillerMode;
        existing.DefaultFillerCollectionType = request.DefaultFillerCollectionType;
        existing.DefaultFillerCollectionId = request.DefaultFillerMode is DecoMode.Override
            ? request.DefaultFillerCollectionId
            : null;
        existing.DefaultFillerMediaItemId = request.DefaultFillerMode is DecoMode.Override
            ? request.DefaultFillerMediaItemId
            : null;
        existing.DefaultFillerMultiCollectionId = request.DefaultFillerMode is DecoMode.Override
            ? request.DefaultFillerMultiCollectionId
            : null;
        existing.DefaultFillerSmartCollectionId = request.DefaultFillerMode is DecoMode.Override
            ? request.DefaultFillerSmartCollectionId
            : null;
        existing.DefaultFillerTrimToFit = request.DefaultFillerTrimToFit;

        // dead air fallback
        existing.DeadAirFallbackMode = request.DeadAirFallbackMode;
        existing.DeadAirFallbackCollectionType = request.DeadAirFallbackCollectionType;
        existing.DeadAirFallbackCollectionId = request.DeadAirFallbackMode is DecoMode.Override
            ? request.DeadAirFallbackCollectionId
            : null;
        existing.DeadAirFallbackMediaItemId = request.DeadAirFallbackMode is DecoMode.Override
            ? request.DeadAirFallbackMediaItemId
            : null;
        existing.DeadAirFallbackMultiCollectionId = request.DeadAirFallbackMode is DecoMode.Override
            ? request.DeadAirFallbackMultiCollectionId
            : null;
        existing.DeadAirFallbackSmartCollectionId = request.DeadAirFallbackMode is DecoMode.Override
            ? request.DeadAirFallbackSmartCollectionId
            : null;

        // break content
        existing.BreakContentMode = request.BreakContentMode;

        var toAdd = request.BreakContent.Filter(bc => bc.Id < 1).ToList();
        var toRemove = existing.BreakContent.Filter(bc => request.BreakContent.All(bc2 => bc2.Id != bc.Id)).ToList();
        var toUpdate = request.BreakContent.Except(toAdd).ToList();

        foreach (DecoBreakContent remove in toRemove)
        {
            existing.BreakContent.Remove(remove);
        }

        foreach (UpdateDecoBreakContent add in toAdd)
        {
            existing.BreakContent.Add(
                new DecoBreakContent
                {
                    CollectionType = add.CollectionType,
                    CollectionId = add.CollectionId,
                    MediaItemId = add.MediaItemId,
                    MultiCollectionId = add.MultiCollectionId,
                    SmartCollectionId = add.SmartCollectionId,
                    Placement = add.Placement
                });
        }

        foreach (UpdateDecoBreakContent update in toUpdate)
        {
            Option<DecoBreakContent> maybeExisting = existing.BreakContent.Find(bc => bc.Id == update.Id);
            foreach (DecoBreakContent bc in maybeExisting)
            {
                bc.CollectionType = update.CollectionType;
                bc.CollectionId = update.CollectionId;
                bc.MediaItemId = update.MediaItemId;
                bc.MultiCollectionId = update.MultiCollectionId;
                bc.SmartCollectionId = update.SmartCollectionId;
                bc.Placement = update.Placement;
            }
        }

        await dbContext.SaveChangesAsync();

        return Mapper.ProjectToViewModel(existing);
    }

    private static async Task<Validation<BaseError, Deco>> Validate(TvContext dbContext, UpdateDeco request) =>
        (await DecoMustExist(dbContext, request), await ValidateDecoName(dbContext, request))
        .Apply((deco, _) => deco);

    private static Task<Validation<BaseError, Deco>> DecoMustExist(
        TvContext dbContext,
        UpdateDeco request) =>
        dbContext.Decos
            .Include(d => d.BreakContent)
            .SelectOneAsync(d => d.Id, d => d.Id == request.DecoId)
            .Map(o => o.ToValidation<BaseError>("Deco does not exist"));

    private static async Task<Validation<BaseError, string>> ValidateDecoName(
        TvContext dbContext,
        UpdateDeco request)
    {
        if (request.Name.Length > 50)
        {
            return BaseError.New($"Deco name \"{request.Name}\" is invalid");
        }

        Option<Deco> maybeExisting = await dbContext.Decos
            .FirstOrDefaultAsync(
                d => d.Id != request.DecoId && d.DecoGroupId == request.DecoGroupId && d.Name == request.Name)
            .Map(Optional);

        return maybeExisting.IsSome
            ? BaseError.New($"A deco named \"{request.Name}\" already exists in that deco group")
            : Success<BaseError, string>(request.Name);
    }
}