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

namespace SqlSugar
{
    public class MySqlUpdateBuilder : UpdateBuilder
    {
        public override string SqlTemplateBatch
        {
            get
            {
                return @"UPDATE  {1} S {2}   INNER JOIN ${{0}}  SET {0} ";
            }
        }
        public override string SqlTemplateJoin
        {
            get
            {
                return @"            (
              {0}

            ) T ON {1}
                 ";
            }
        }
        protected override string TomultipleSqlString(List<IGrouping<int, DbColumnInfo>> groupList)
        {
            Check.Exception(PrimaryKeys == null || PrimaryKeys.Count == 0, " Update List<T> need Primary key");
            var pageSize = 200;
            var pageIndex = 1;
            var totalRecord = groupList.Count;
            var pageCount = (totalRecord + pageSize - 1) / pageSize;
            var batchUpdateSql = new StringBuilder();
            while (pageCount >= pageIndex)
            {
                var updateTable = new StringBuilder();
                var setValues = string.Join(",", groupList.First().Where(it => !it.IsPrimarykey && (!it.IsIdentity || (IsOffIdentity && it.IsIdentity))).Select(it =>
                {
                    if (SetValues.IsValuable())
                    {
                        var setValue = SetValues.Where(sv => sv.Key == Builder.GetTranslationColumnName(it.DbColumnName));
                        if (setValue != null && setValue.Any())
                        {
                            return setValue.First().Value;
                        }
                    }
                    var result = string.Format("S.{0}=T.{0}", Builder.GetTranslationColumnName(it.DbColumnName));
                    return result;
                }));
                batchUpdateSql.AppendFormat(SqlTemplateBatch.ToString(), setValues, GetTableNameStringNoWith, TableWithString);
                var i = 0;
                foreach (var columns in groupList.Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList())
                {
                    var isFirst = i == 0;
                    if (!isFirst)
                    {
                        updateTable.Append(SqlTemplateBatchUnion);
                    }
                    updateTable.Append("\r\n SELECT " + string.Join(",", columns.Select(it => string.Format(SqlTemplateBatchSelect, FormatValue(it.Value),this.Builder.GetTranslationColumnName(it.DbColumnName)))));
                    ++i;
                }
                pageIndex++;
                updateTable.Append("\r\n");
                string whereString = null;
                if (this.WhereValues.HasValue())
                {
                    foreach (var item in WhereValues)
                    {
                        var isFirst = whereString == null;
                        whereString += (isFirst ? null : " AND ");
                        whereString += item;
                    }
                }
                else if (PrimaryKeys.HasValue())
                {
                    foreach (var item in PrimaryKeys)
                    {
                        var isFirst = whereString == null;
                        whereString += (isFirst ? null : " AND ");
                        whereString += string.Format("S.{0}=T.{0}", Builder.GetTranslationColumnName(item));
                    }
                }
                var format= string.Format(SqlTemplateJoin, updateTable, whereString);
                batchUpdateSql.Replace("${0}",format);
                batchUpdateSql.Append(";");
            }
            return batchUpdateSql.ToString();
        }
    }
}