using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Text;
using System.Configuration;
using System.Threading.Tasks;
using Dapper;
using MySql.Data.MySqlClient;
using Winsoft.GOV.Framework.Model;

namespace Winsoft.GOV.Framework.Provider
{
    public abstract class BaseProvider<T>
    {
        #region instance
        protected County _county;
        private static object lockObj = new object();
        protected static void CreateInstance<K>(ref K singleInstance) where K : BaseProvider<T>, new()
        {
            if (singleInstance == null)
            {
                lock (lockObj)
                {
                    if (singleInstance == null)
                    {
                        singleInstance = new K();
                    }
                }
            }
        }
        #endregion

        #region        connection

        protected string connectionString;

        public BaseProvider(County county)
        {
            _county = county;
            connectionString = "gov_" + _county.ToString();
        }

        /// <summary>
        /// </summary>
        /// <param name="connectionStr"></param>
        /// <returns></returns>
        protected IDbConnection GetDbConnection()
        {

            string connectionStr = ConfigurationManager.ConnectionStrings[connectionString].ConnectionString;

            var connection = new MySqlConnection
            {
                ConnectionString = connectionStr
            };
            connection.Open();
            return connection;
        }

        protected string BuildTotalSQL(string sql)
        {
            var selectCount = new StringBuilder("SELECT COUNT(1) from (");
            return
                selectCount.Append(sql + ") as t")
                    .ToString();
        }
        /// <summary>
        /// </summary>
        /// <param name="total"></param>
        /// <param name="sql"></param>
        /// <param name="pageIndex">内部索引从0开始，页码从1开始</param>
        /// <code>
        ///   if (pageIndex - 1 >= 0)
        ///   {
        ///       pageIndex = pageIndex - 1;
        ///   }
        /// </code>
        /// <param name="pageSize"></param>
        /// <param name="param"></param>
        /// <param name="areaCode"></param>
        /// <returns></returns>
        protected PagedResult<T> GetPagedList(string sql, int pageIndex, int pageSize, object param = null)
        {
            long total = 0;
            if (pageIndex < 0)
            {
                pageIndex = 0;
            }
            if (pageSize <= 0)
            {
                pageSize = 20;
            }
            using (IDbConnection connection = GetDbConnection())
            {
                string totalSql = BuildTotalSQL(sql);
                total = connection.Query<long>(totalSql, param).FirstOrDefault();
                var list = connection.Query<T>(String.Format(sql + " limit {0},{1}", pageIndex * pageSize, pageSize), param);

                return new PagedResult<T>()
                {
                    Data = list,
                    Index = pageIndex,
                    Size = pageSize,
                    Total = total
                };

            }
        }

        protected IEnumerable<T> GetItemList(string sql, int itemIndex, int pageSize, object param = null)
        {
            if (itemIndex < 0)
            {
                itemIndex = 0;
            }
            if (pageSize <= 0)
            {
                pageSize = 20;
            }
            using (IDbConnection connection = GetDbConnection())
            {
                var list = connection.Query<T>(String.Format(sql + " limit {0},{1}", itemIndex, pageSize), param);
                return list;
            }
        }
        #endregion
    }
}