using Mapster;

namespace Dpz.Core.Service.Mediator;

public static class PageExtensions
{
    /// <param name="source">包含所有要分页数据的IMongoQueryable对象。</param>
    /// <typeparam name="TSource">原类型</typeparam>
    extension<TSource>(IQueryable<TSource> source)
    {
        /// <summary>
        /// 根据当前页索引pageIndex及每页记录数pageSize获取要分页的ViewModel数据对象。
        /// </summary>
        /// <typeparam name="TDestination">目标类型</typeparam>
        /// <param name="pageIndex">当前页索引。</param>
        /// <param name="pageSize">每页显示的记录数。</param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task<IPagedList<TDestination>> ToPagedListAsync<TDestination>(
            int pageIndex,
            int pageSize,
            CancellationToken cancellationToken = default
        )
        {
            if (pageIndex < 1)
            {
                pageIndex = 1;
            }

            var itemIndex = (pageIndex - 1) * pageSize;
            var totalItemCount = await source.CountAsync(cancellationToken: cancellationToken);
            while (totalItemCount <= itemIndex && pageIndex > 1)
            {
                itemIndex = (--pageIndex - 1) * pageSize;
            }

            var pageOfItems = source.Skip(itemIndex).Take(pageSize);
            var data = (await pageOfItems.ToListAsync(cancellationToken: cancellationToken)).Adapt<
                List<TDestination>
            >();
            return new PagedList<TDestination>(data, pageIndex, pageSize, totalItemCount);
        }
    }

    extension<TSource>(IQueryable<TSource> source)
    {
        public async Task<List<TDestination>> ToListAsync<TDestination>(
            CancellationToken cancellationToken = default
        )
        {
            var data = await source.ToListAsync(cancellationToken: cancellationToken);
            return data.Adapt<List<TDestination>>();
        }

        public async Task<IPagedList<TSource>> ToPagedListAsync(
            int pageIndex,
            int pageSize,
            CancellationToken cancellationToken = default
        )
        {
            if (pageIndex < 1)
            {
                pageIndex = 1;
            }

            var itemIndex = (pageIndex - 1) * pageSize;
            var totalItemCount = await source.CountAsync(cancellationToken: cancellationToken);
            while (totalItemCount <= itemIndex && pageIndex > 1)
            {
                itemIndex = (--pageIndex - 1) * pageSize;
            }

            var pageOfItems = source.Skip(itemIndex).Take(pageSize);
            var data = await pageOfItems.ToListAsync(cancellationToken: cancellationToken);
            return new PagedList<TSource>(data, pageIndex, pageSize, totalItemCount);
        }

        public async Task<IPagedList<TDestination>> ToPagedListAsync<TDestination>(
            int pageIndex,
            int pageSize,
            Func<TSource, TDestination> func,
            CancellationToken cancellationToken = default
        )
        {
            if (pageIndex < 1)
            {
                pageIndex = 1;
            }

            var itemIndex = (pageIndex - 1) * pageSize;
            var totalItemCount = await source.CountAsync(cancellationToken: cancellationToken);
            while (totalItemCount <= itemIndex && pageIndex > 1)
            {
                itemIndex = (--pageIndex - 1) * pageSize;
            }

            var pageOfItems = source.Skip(itemIndex).Take(pageSize);
            var data = await pageOfItems.ToListAsync(cancellationToken: cancellationToken);
            return new PagedList<TDestination>(
                data.Select(func),
                pageIndex,
                pageSize,
                totalItemCount
            );
        }
    }

    extension<TSource>(IFindFluent<TSource, TSource> source)
    {
        public async Task<PagedList<TDestination>> ToPagedListAsync<TDestination>(
            int pageIndex,
            int pageSize,
            CancellationToken cancellationToken = default
        )
        {
            if (pageIndex < 1)
            {
                pageIndex = 1;
            }

            var itemIndex = (pageIndex - 1) * pageSize;
            var totalItemCount = checked((int)await source.CountDocumentsAsync(cancellationToken));
            while (totalItemCount <= itemIndex && pageIndex > 1)
            {
                itemIndex = (--pageIndex - 1) * pageSize;
            }

            var pageOfItems = source.Skip(itemIndex).Limit(pageSize);
            var data = (await pageOfItems.ToListAsync(cancellationToken: cancellationToken)).Adapt<
                List<TDestination>
            >();
            return new PagedList<TDestination>(data, pageIndex, pageSize, totalItemCount);
        }

        public async Task<PagedList<TSource>> ToPagedListAsync(
            int pageIndex,
            int pageSize,
            CancellationToken cancellationToken = default
        )
        {
            if (pageIndex < 1)
            {
                pageIndex = 1;
            }

            var itemIndex = (pageIndex - 1) * pageSize;
            var totalItemCount = checked((int)await source.CountDocumentsAsync(cancellationToken));
            while (totalItemCount <= itemIndex && pageIndex > 1)
            {
                itemIndex = (--pageIndex - 1) * pageSize;
            }

            var pageOfItems = source.Skip(itemIndex).Limit(pageSize);
            var data = await pageOfItems.ToListAsync(cancellationToken: cancellationToken);
            return new PagedList<TSource>(data, pageIndex, pageSize, totalItemCount);
        }
    }

    public static IPagedList<T> ToPagedList<T>(
        this IEnumerable<T> source,
        int pageIndex,
        int pageSize,
        int totalItem
    )
    {
        return new PagedList<T>(source, pageIndex, pageSize, totalItem);
    }
}