using ErsatzTV.Core.Domain;
using ErsatzTV.Infrastructure.Data;
using Microsoft.EntityFrameworkCore;
using static ErsatzTV.Application.MediaCollections.Mapper;

namespace ErsatzTV.Application.MediaCollections;

public class GetPagedMultiCollectionsHandler(IDbContextFactory<TvContext> dbContextFactory)
    : IRequestHandler<GetPagedMultiCollections, PagedMultiCollectionsViewModel>
{
    public async Task<PagedMultiCollectionsViewModel> Handle(
        GetPagedMultiCollections request,
        CancellationToken cancellationToken)
    {
        await using TvContext dbContext = await dbContextFactory.CreateDbContextAsync(cancellationToken);
        IQueryable<MultiCollection> query = dbContext.MultiCollections
            .AsNoTracking()
            .Where(mc => mc.OwnedByChannelId == null);

        if (!string.IsNullOrWhiteSpace(request.Query))
        {
            query = query.Where(mc => EF.Functions.Like(mc.Name, $"%{request.Query}%"));
        }

        // count the SAME query the page is taken from, so the two cannot drift (issues #690, #758)
        int count = await query.CountAsync(cancellationToken);

        List<MultiCollectionViewModel> page = await query
            .OrderBy(mc => mc.Name)
            .Skip(request.PageNum * request.PageSize)
            .Take(request.PageSize)
            .Include(mc => mc.MultiCollectionItems)
            .ThenInclude(i => i.Collection)
            .ToListAsync(cancellationToken)
            .Map(list => list.Map(ProjectToViewModel).ToList());

        return new PagedMultiCollectionsViewModel(count, page);
    }
}