using Mediator;
using Microsoft.EntityFrameworkCore;
using Musify.Application.Contracts;
using Musify.Application.Shared;
using Musify.Application.Users.Responses;

namespace Musify.Application.Users
{
    public record GetUsersQuery(int PageNumber, int PageSize, string? UsernameSearch, long? ViewerId = null)
        : IQuery<PaginatedResponse<UserSummaryResponse>>;

    public class GetUsersQueryHandler(IDatabase database)
        : IQueryHandler<GetUsersQuery, PaginatedResponse<UserSummaryResponse>>
    {
        public async ValueTask<PaginatedResponse<UserSummaryResponse>> Handle(GetUsersQuery request, CancellationToken cancellationToken)
        {
            var usersQuery = database.Users
                .AsNoTracking();

            if (!string.IsNullOrWhiteSpace(request.UsernameSearch))
            {
                var normalizedUsername = TextNormalizer.Normalize(request.UsernameSearch);
                usersQuery = usersQuery.Where(user => user.NormalizedName.Contains(normalizedUsername));
            }

            var viewerId = request.ViewerId;

            return await usersQuery
                .OrderBy(user => user.Name)
                .ThenBy(user => user.Id)
                .Select(user => new UserSummaryResponse(
                    user.Id,
                    user.Name,
                    user.FirstName,
                    user.SecondName,
                    user.ProfilePictureUrl,
                    viewerId != null && database.UserFollows.Any(f => f.FollowerId == viewerId && f.FollowedId == user.Id)))
                .ToPaginatedAsync(new PageRequest(request.PageNumber, request.PageSize), cancellationToken);
        }
    }
}