using CAPI.Custom.Data;
using CAPI.Custom.Domain.Quotes;
using CAPI.Custom.Entities;
using CAPI.Custom.Repositories;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CAPI.Custom.Services
{
    public class RequestItemsCalculator
    {
        private QuoteRepository repository;

        public RequestItemsCalculator(QuoteRepository service)
        {
            this.repository = service;
        }

        public IQueryable<QuoteRequestItem> Execute(int quoteId, string masterNumber)
        {
            var emptyResult = Enumerable.Empty<QuoteRequestItem>().AsQueryable();

            try
            {

                var requestItems = repository.GetRequestItems(quoteId)
                    .Where(p =>  masterNumber == p.MasterNumber)
                    .OrderBy(p => p.Sequence)
                    .ToList();

                // exit
                if (requestItems.IsEmpty())
                {
                    return emptyResult;
                }

                var quoteItems = repository.GetItems(quoteId)
                    .Where(p =>  masterNumber == p.MasterPartNumber)
                    .ToList();

                // exit
                if (quoteItems.IsEmpty())
                {
                    return emptyResult;
                }

                if (requestItems.Count == 1)
                {
                    var requestItem = requestItems.First();

                    requestItem.QuantitySelected
                        = quoteItems.Sum(p => p.QuantitySelected)
                        .GetValueOrDefault();

                    // outstanding = required - selected
                    requestItem.QuantityOutstanding =
                        requestItem.QuantityRequired
                        .GetValueOrDefault() -
                        requestItem.QuantitySelected
                        .GetValueOrDefault();
                }
                else
                {
                    int totalSelected = quoteItems
                        .Sum(p => p.QuantitySelected)
                        .GetValueOrDefault();

                    requestItems.ForEach(requestItem =>
                    {
                        int required = requestItem
                            .QuantityRequired
                            .GetValueOrDefault();

                        int selected = 0;
                        int outstanding = required - selected;

                        if (outstanding > 0)
                        {
                            if (totalSelected >= outstanding)
                            {
                                selected += outstanding;
                                totalSelected -= outstanding;
                                outstanding = 0;
                            }
                            else if (outstanding > totalSelected)
                            {
                                selected += totalSelected;
                                outstanding -= totalSelected;
                                totalSelected = 0;
                            }
                        }

                        requestItem.QuantitySelected = selected;
                        requestItem.QuantityOutstanding = outstanding;
                    });

                    // requested limit reached but still more to select
                    // will be added to the first found request item
                    if (totalSelected > 0)
                    {
                        var firstItem = requestItems.FirstOrDefault();

                        if (!firstItem.IsNull())
                        {
                            firstItem.QuantitySelected += totalSelected;
                            firstItem.QuantityOutstanding -= totalSelected;
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                BusinessUtils.HandleException(ex);
            }

            return emptyResult;
        }
    }
}