using Gridify;
using Gridify.EntityFramework;

namespace GerbilManagerWebAPI.Common
{
    /// <summary>Standard paged list envelope returned by every list endpoint.</summary>
    public record PagedResult<T>(IReadOnlyList<T> Items, int TotalCount, int Page, int PageSize);

    public static class QueryableExtensions
    {
        /// <summary>
        /// Apply a Gridify query (filter/order/page) to an EF query and project each
        /// row to a DTO, returning the standard paged envelope. Filter/orderBy names
        /// are the ENTITY property names (case-insensitive), e.g. "status==Active",
        /// "orderBy=dateOfBirth", "litterId==...".
        /// </summary>
        public static async Task<PagedResult<TDto>> ToPagedResultAsync<TEntity, TDto>(
            this IQueryable<TEntity> source,
            GridifyQuery query,
            Func<TEntity, TDto> map)
        {
            query.Page = query.Page <= 0 ? 1 : query.Page;
            query.PageSize = query.PageSize <= 0 ? 20 : query.PageSize;

            Paging<TEntity> paging = await source.GridifyAsync(query);
            var items = paging.Data.Select(map).ToList();
            return new PagedResult<TDto>(items, paging.Count, query.Page, query.PageSize);
        }
    }
}