Beauty_Salon/BeautySalon/BeautySalonDBModels/Implements/ServiceDatabase.cs

using BeautySalonDBModels.Models;
using Npgsql;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace BeautySalonDBModels.Implements
{
    public class ServiceDatabase : AbstractWorkWithStorage<Service>
    {
        public override void Add(Service service)
        {
            using var conn = GetConnection();
            conn.Open();
            using var cmd = new NpgsqlCommand("INSERT INTO services (service_id, service_name, price, specialisation_id) " +
                "VALUES ((nextval('seq_service')), @ServiceName, @Price, @SpecialisationId)", conn);
            cmd.Parameters.AddWithValue("@ServiceName", service.ServiceName);
            cmd.Parameters.AddWithValue("@Price", service.Price);
            cmd.Parameters.AddWithValue("@SpecialisationId", service.SpecialisationId);
            cmd.ExecuteNonQuery();
        }

        public override Service? GetObject(int id)
        {
            using var conn = GetConnection();
            conn.Open();
            using var cmd = new NpgsqlCommand("SELECT * FROM services WHERE service_id = @id", conn);
            cmd.Parameters.AddWithValue("@id", id);
            using var reader = cmd.ExecuteReader();
            if (reader.Read())
            {
                return new Service
                {
                    ServiceId = reader.GetInt32(0),
                    ServiceName = reader.GetString(1),
                    Price = reader.GetDouble(2),
                    SpecialisationId = reader.GetInt32(3)
                };
            }
            return null;
        }

        public override List<Service> GetObjects()
        {
            var services = new List<Service>();
            using var conn = GetConnection();
            conn.Open();
            using var cmd = new NpgsqlCommand("SELECT * FROM services order by service_id", conn);
            using var reader = cmd.ExecuteReader();
            while (reader.Read())
            {
                services.Add(new Service
                {
                    ServiceId = reader.GetInt32(0),
                    ServiceName = reader.GetString(1),
                    Price = reader.GetDouble(2),
                    SpecialisationId = reader.GetInt32(3)
                });
            }
            return services;
        }

        public override Service? Remove(int id)
        {
            var service = GetObject(id);
            using var conn = GetConnection();
            conn.Open();
            using var cmd = new NpgsqlCommand("delete from services where service_id = @id", conn);
            cmd.Parameters.AddWithValue("@id", id);
            cmd.ExecuteNonQuery();
            return service;
        }

        public override void Update(Service service)
        {
            using var conn = GetConnection();
            conn.Open();
            using var cmd = new NpgsqlCommand("update services set service_name = @name, " +
                "price = @price, specialisation_id = @SpecialisationId where service_id = @id", conn);
            cmd.Parameters.AddWithValue("@name", service.ServiceName);
            cmd.Parameters.AddWithValue("@price", service.Price);
            cmd.Parameters.AddWithValue("@SpecialisationId", service.SpecialisationId);
            cmd.Parameters.AddWithValue("@id", service.ServiceId);
            cmd.ExecuteNonQuery();
        }

        public string GetNameSpecialisation(Service service)
        {
            SpecialisationDatabase db = new SpecialisationDatabase();
            int specId = service.SpecialisationId;
            List<Specialisation> specialisations = db.GetObjects();

            foreach (Specialisation specialisation in specialisations)
            {
                if (specialisation.SpecialisationId == specId) return specialisation.Name.ToString();
            }
            return string.Empty;
        }

        public List<Master> GetFilteredListByService(int serviceId)
        {
            var list = new List<Master>();
            var service = GetObject(serviceId);
            if(service != null)
            {
                int specId = service.SpecialisationId;
                using var conn = GetConnection();
                conn.Open();
                using var cmd = new NpgsqlCommand("select * from masters where specialisation_id = @specId", conn);
                cmd.Parameters.AddWithValue("@specId", specId);
                using var reader = cmd.ExecuteReader();
                while (reader.Read())
                {
                    list.Add(new Master
                    {
                        MasterId = reader.GetInt32(0),
                        SpecialisationId = reader.GetInt32(1),
                        FIO = reader.GetString(2)
                    });
                }
            }
            return list;
        }

        public void Clear()
        {
            using var conn = GetConnection();
            conn.Open();
            using var cmd = new NpgsqlCommand("drop sequence if exists seq_specialisation; " +
                "drop sequence if exists seq_service; " +
                "drop sequence if exists seq_master; " +
                "drop sequence if exists seq_client; " +
                "drop sequence if exists seq_reception; " +
                "drop sequence if exists seq_cheque; " +
                "create sequence seq_specialisation increment by 1 start with 1 minvalue 1; " +
                "create sequence seq_service increment by 1 start with 1 minvalue 1; " +
                "create sequence seq_master increment by 1 start with 1 minvalue 1;  " +
                "create sequence seq_client increment by 1 start with 1 minvalue 1;  " +
                "create sequence seq_reception increment by 1 start with 1 minvalue 1;  " +
                "create sequence seq_cheque increment by 1 start with 1 minvalue 1;  " +
                "delete from specialisations; " +
                "delete from services; " +
                "delete from masters; " +
                "delete from clients; " +
                "delete from cheques;", conn);
            cmd.ExecuteNonQuery();
        }
    }
}