using AutoMapper;
using MediatR;
using ExpenseTracker.Application.Common.Extensions;
using ExpenseTracker.Application.Common.Interfaces.Repositories;
using ExpenseTracker.Application.Common.Models;
using ExpenseTracker.Domain.Entities;

namespace ExpenseTracker.Application.Transactions.Queries.GetWithPagination;

public class GetTransactionsWithPaginationQueryHandler : IRequestHandler<GetTransactionsWithPaginationQuery, PaginatedList<TransactionDto>>
{
    private readonly IMapper _mapper;
    private readonly ITransactionRepository _transactionRepository;

    public GetTransactionsWithPaginationQueryHandler(
        IMapper mapper,
        ITransactionRepository repository)
    {
        _mapper = mapper;
        _transactionRepository = repository;
    }

    public async Task<PaginatedList<TransactionDto>> Handle(
        GetTransactionsWithPaginationQuery request,
        CancellationToken cancellationToken)
    {
        // TODO: This is unoptimized. Pagination is being applied
        // on the side of the application
        // and not on the side of the database

        Func<Transaction, DateTimeOffset> func = t => t.Time;
        
        var entities = _transactionRepository.Queryable
            .Where(e => e.AccountId == request.AccountId)
            .OrderByDescending(func)
            .AsQueryable();


        return entities
            .ProjectToPaginatedList<Transaction, TransactionDto>(request.PageNumber, request.PageSize, _mapper.ConfigurationProvider);
    }
}