HRCenter/Diligent.WebAPI.Business/Extensions/AdExtensions.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Diligent.WebAPI.Business.Extensions
{
    public static class AdExtensions
    {
        public static List<Ad> Filter(this List<Ad> query, AdFilterDto filters) =>
            query.FilterByExperience(filters.MinExperience, filters.MaxExperience).FilterByWorkType(filters.WorkHour).FilterByEmploymentType(filters.EmploymentType).ToList().FilterByTechnologies(filters.Technologies);

        public static List<Ad> FilterByExperience(this List<Ad> query, int minExperience, int maxExperience) =>
            minExperience >= maxExperience ? query.Where(x => x.MinimumExperience >= minExperience && x.MinimumExperience <= maxExperience).ToList()
                : query.Where(x => x.MinimumExperience >= minExperience && x.MinimumExperience <= maxExperience).ToList();
        public static List<Ad> FilterByWorkType(this List<Ad> query, string workHour) =>
           workHour.ToLower() == "parttime" ? query.Where(x => x.WorkHour == WorkHours.PartTime).ToList() : query.Where(x => x.WorkHour == WorkHours.FullTime).ToList();
        public static List<Ad> FilterByEmploymentType(this List<Ad> query, string employmentType) =>
           employmentType.ToLower() == "intership" ? query.Where(x => x.EmploymentType == EmploymentTypes.Intership).ToList() : query.Where(x => x.EmploymentType == EmploymentTypes.Work).ToList();

        public static List<Ad> FilterByTechnologies(this List<Ad> query, string[] technologies)
        {
            if (technologies == null || technologies.Length == 0)
            {
                return query;
            }

            List<Ad> filteredAds = new List<Ad>();
            

            for (int i = 0; i < query.Count(); i++)
            {
                for (int j = 0; j < query[i].Technologies.Count(); j++)
                {
                    var s = 0;

                    for (int k = 0; k < technologies.Length; k++)
                    {
                        if (query[i].Technologies[j].Name.ToLower() == technologies[k].ToLower())
                        {
                            s = 1;
                        }
                    }

                    if (s == 1)
                    {
                        filteredAds.Add(query[i]);
                        break;
                    }
                }
            }

            return filteredAds;
        }
    }
}