DocumentOrganizer/Diligent.WebAPI.Business/Extensions/PatternExtension.cs

using Diligent.WebAPI.Contracts.DTOs.Pattern;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Diligent.WebAPI.Business.Extensions
{
    [ExcludeFromCodeCoverage]
    public static class PatternExtension
    {
        public static List<Pattern> FilterApplicants(this List<Pattern> query, FilterPatternDto filterPatternDto)
        {
            return query.FilterByDate(filterPatternDto.FromDate, filterPatternDto.ToDate)
                        .FilterBySelectionLevels(filterPatternDto.SelectionLevels)
                        .ToList();
        }

        private static List<Pattern> FilterByDate(this List<Pattern> query, DateTime? fromDate, DateTime? toDate)
        {
            if(fromDate == null && toDate == null) return query;
            if(fromDate == null && toDate != null) return query.Where(x => x.CreatedAt <= toDate).ToList();
            if ((fromDate != null && toDate == null) || (fromDate > toDate)) return query.Where(x => x.CreatedAt >= fromDate).ToList();
            return query.Where(x => x.CreatedAt >= fromDate && x.CreatedAt < toDate).ToList();
        }

        private static List<Pattern> FilterBySelectionLevels(this List<Pattern> query, int[]? selectionLevels)
        {
            if (selectionLevels is null)
            {
                return query;
            }

            List<Pattern> filteredPatterns = new();

            for (int i = 0; i < query.Count; i++)
            {
                for(int j = 0; j < selectionLevels.Length; j++)
                {
                    if (query[i].SelectionLevelId == selectionLevels[j])
                    {
                        filteredPatterns.Add(query[i]);
                        break;
                    }
                }
            }

            return filteredPatterns;
        }
    }
}