using System;
using System.Collections.Generic;
using Microsoft.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace bnhtrade.Core.Data.Database.AmazonShipment
{
    public class ReadShipmentPrimaryKey : Connection
    {
        private bool enableCache = false;
        private Dictionary<string, int> shipmentPKByAmazonShipmentIdDic;
        private Dictionary<int, string> amazonShipmentIdByShipmentPKDic;

        public ReadShipmentPrimaryKey()
        { 
        }

        public bool CacheEnabled
        {
            get { return enableCache; }
            set
            {
                if (value && enableCache == false)
                {
                    shipmentPKByAmazonShipmentIdDic = new Dictionary<string, int>();
                    amazonShipmentIdByShipmentPKDic = new Dictionary<int, string>();
                }
                else
                {
                    shipmentPKByAmazonShipmentIdDic = null;
                    amazonShipmentIdByShipmentPKDic = null;
                }
            }
        }

        private void ClearCache()
        {
            if (CacheEnabled)
            {
                shipmentPKByAmazonShipmentIdDic.Clear();
                amazonShipmentIdByShipmentPKDic.Clear();
            }
        }

        private void DeleteCachedShipmentPK(int shipmentPrimaryKey)
        {
            if (CacheEnabled)
            {
                if (amazonShipmentIdByShipmentPKDic.ContainsKey(shipmentPrimaryKey))
                {
                    string amazonShipmentId = amazonShipmentIdByShipmentPKDic[shipmentPrimaryKey];
                    shipmentPKByAmazonShipmentIdDic.Remove(amazonShipmentId);
                    amazonShipmentIdByShipmentPKDic.Remove(shipmentPrimaryKey);
                }
            }
        }

        /// <summary>
        /// Retrives table primary key 'AmazonShipmentID' for tblAmazonShipment
        /// </summary>
        /// <param name="amazonShipmentId">Amazon's inbound FBA shipment Id.</param>
        /// <param name="forceDBQuery">Forces a database query when cache is enabled.</param>
        /// <returns>Primary key or -1 if match isn't found.</returns>
        public int ByAmazonShipmentId(string amazonShipmentId, bool forceDBQuery = false)
        {
            if (amazonShipmentId.Length < 5)
            {
                throw new Exception("Incorrect Amazon shipment if supplied '" + amazonShipmentId + "'");
            }

            // first, query class dictionary before sql call
            if (CacheEnabled 
                && forceDBQuery == false
                && shipmentPKByAmazonShipmentIdDic.ContainsKey(amazonShipmentId))
            {
                return shipmentPKByAmazonShipmentIdDic[amazonShipmentId];
            }

            int shipmentPK = -1;
            using (SqlConnection conn = new SqlConnection(SqlConnectionString))
            {
                conn.Open();

                using (SqlCommand cmd = new SqlCommand(@"
                    SELECT AmazonShipmentID
                    FROM tblAmazonShipment
                    WHERE (((tblAmazonShipment.ShipmentId)=@amazonShipmentId));
                    ", conn))
                {
                    cmd.Parameters.AddWithValue("@amazonShipmentId", amazonShipmentId);

                    object obj = cmd.ExecuteScalar();

                    if (obj == null || obj == DBNull.Value)
                    {
                        return shipmentPK;
                    }
                    else
                    {
                        shipmentPK = (int)obj;
                    }
                }
            }
            UpdateCache(shipmentPK, amazonShipmentId);
            return shipmentPK;
        }

        private void UpdateCache(int shipmentPK, string amazonShipmentId)
        {
            if (CacheEnabled)
            {
                DeleteCachedShipmentPK(shipmentPK);

                shipmentPKByAmazonShipmentIdDic.Add(amazonShipmentId, shipmentPK);
                amazonShipmentIdByShipmentPKDic.Add(shipmentPK, amazonShipmentId);
            }
        }
    }
}