monorepo/LCU.WebApps.Indirect.ReserveManagementSystem/Api/ReserveManagementSystemLib/Models/PaginatedListResponse.cs

namespace ReserveManagementSystemLib.Models
{
    public class PaginatedListResponse
    {
        public List<Loan> LoanList { get; set; }

        public int PageIndex { get; set; }

        public int TotalPages { get; set; }

        public int TotalItems { get; set; }

        public int FirstPage { get; set; }

        public int LastPage { get; set; }

        public int PageRangeSize { get; set; }

        public PaginatedListResponse() {}

        public void SetFirstAndLastPageToShow()
        {
            if (TotalPages < PageRangeSize) { PageRangeSize = TotalPages; }
            var half = PageRangeSize / 2; //this should be set to an odd number to evenly set page range
            if (PageIndex - half <= 0)
            {
                FirstPage = 1;
                LastPage = (PageRangeSize > TotalPages) ? TotalPages : PageRangeSize;
            }
            else if (PageIndex == TotalPages || PageIndex + half > TotalPages)
            {
                FirstPage = TotalPages - PageRangeSize + 1;
                LastPage = TotalPages;
            }
            else //increment page range slightly by the half difference
            {
                FirstPage = PageIndex - half;
                LastPage = PageIndex + half;
            }
        }

        public PaginatedListResponse(List<Loan> items, int count, int pageIndex, int pageSize, int pageRangeSize)
        {
            PageIndex = pageIndex;
            TotalItems = count;
            TotalPages = (int)Math.Ceiling(count / (double)pageSize);
            PageRangeSize = pageRangeSize;

            SetFirstAndLastPageToShow();
            List<Loan> loanList = new List<Loan>();
            loanList.AddRange(items);
            LoanList = loanList;
        }

        public bool HasPreviousPage
        {
            get
            {
                return (PageIndex > 1);
            }
        }

        public bool HasNextPage
        {
            get
            {
                return (PageIndex < TotalPages);
            }
        }

        public static async Task<PaginatedListResponse> CreateListAsync(IQueryable<Loan> source, int pageIndex, int pageSize, int pageRangeSize)
        {
            var count = source.Count();
            var items = await source.Skip((pageIndex - 1) * pageSize).Take(pageSize).ToListAsync();
            return new PaginatedListResponse(items, count, pageIndex, pageSize, pageRangeSize);
        }
    }
}