using System.Data;
using System;
using System.Data.Common;

namespace Mesnac.Codd.Session
{
    /// <summary>
    /// 数据库操作类
    /// </summary>
    public class DbHelper
    {
        public DbHelper(DbSession dbSession)
        {
            this.dbSession = dbSession;
        }

        #region 私有变量
        private bool closeByHandle = false;

        private DbSession dbSession = null;
        private DbTransaction transaction = null;
        #endregion

        #region 属性
        public DbSession DbSession
        {
            get { return this.dbSession; }
        }
        public CommandType CommandType
        {
            get
            {
                return this.dbSession.Command.CommandType;
            }
            set
            {
                this.dbSession.Command.CommandType = value;
            }
        }
        public string CommandText
        {
            get
            {
                return this.dbSession.Command.CommandText;
            }
            set
            {
                this.dbSession.Command.CommandText = value;
            }
        }
        #endregion

        #region 方法
        private DbType ToDbType(object o)
        {
            Type t = o.GetType();
            DbType dbt = DbType.Object;
            try
            {
                dbt = (DbType)Enum.Parse(typeof(DbType), t.Name);
            }
            catch
            {
            }
            return dbt;
        }
        public void ClearParameter()
        {
            this.dbSession.Command.Parameters.Clear();
        }
        public DbParameter CreateParameter(string key, object value)
        {
            DbParameter Result = this.dbSession.ProviderFactory.CreateParameter();
            Result.ParameterName = key;
            if (value == null || value == System.DBNull.Value)
            {
                Result.Value = System.DBNull.Value;
            }
            else
            {
                Result.DbType = ToDbType(value);
                Result.Value = value;
            }
            return Result;
        }

        public DbParameter CreateParameter(string key)
        {
            DbParameter Result = this.dbSession.ProviderFactory.CreateParameter();
            Result.ParameterName = key;
            return Result;
        }

        public void AddParameter(string key, object value)
        {
            this.dbSession.Command.Parameters.Add(CreateParameter(key, value));
        }

        public void AddParameter(DbParameter para)
        {
            this.dbSession.Command.Parameters.Add(para);
        }

        public void OpenConnection(bool closeByHandle)
        {
            this.closeByHandle = closeByHandle;
            try
            {
                if (this.dbSession.Connection.State != ConnectionState.Open)
                {
                    this.dbSession.Connection.Open();
                }
            }
            catch (Exception ex)
            {
                //ICSharpCode.Core.LoggingService.Error("打开数据连接失败!");
                ICSharpCode.Core.LoggingService.Error(ex.Message);
                //ICSharpCode.Core.LoggingService.Error(ex.StackTrace);
            }
        }
        public void OpenConnection()
        {
            this.OpenConnection(false);
        }
        public void CloseConnection()
        {
            try
            {
                this.dbSession.Connection.Close();
                this.dbSession.Connection.Dispose();
                this.dbSession.Command.Dispose();
                this.dbSession.Close();
            }
            catch { }
        }

        private void AutoCloseConnection()
        {
            ClearParameter();
            if (this.closeByHandle) { return; }
            if (this.transaction != null) { return; }
            if (this.dbSession.Command.Transaction != null) { return; }
            CloseConnection();
        }
        public void ExecuteNonQuery()
        {
            try
            {
                this.OpenConnection();
                this.dbSession.Command.ExecuteNonQuery();
            }
            finally
            {
                this.AutoCloseConnection();
            }
        }
        public object ToDataSet()
        {
            try
            {
                this.OpenConnection();
                DataSet Result = new DataSet();
                DbDataAdapter dataAdapter = this.dbSession.ProviderFactory.CreateDataAdapter();
                dataAdapter.SelectCommand = this.dbSession.Command;
                dataAdapter.Fill(Result);
                return Result;
            }
            finally
            {
                this.AutoCloseConnection();
            }
        }
        public DataTable ToDataTable()
        {
            try
            {
                this.OpenConnection();
                DataTable Result = new DataTable();
                DbDataReader myReader = this.ToDbDataReader();
                if (myReader == null)
                {
                    return new DataTable();
                }
                Result.Load(myReader, LoadOption.Upsert);
                return Result;
            }
            finally
            {
                this.AutoCloseConnection();
            }
        }
        public object ToScalar()
        {
            try
            {
                this.OpenConnection();
                return this.dbSession.Command.ExecuteScalar();
            }
            finally
            {
                this.AutoCloseConnection();
            }
        }


        public DbDataReader ToDbDataReader()
        {
            try
            {
                this.OpenConnection();
                return this.dbSession.Command.ExecuteReader();
            }
            catch (Exception ex)
            {
                ICSharpCode.Core.LoggingService.Error("获取DataReader失败!");
                ICSharpCode.Core.LoggingService.Error(ex.Message);
                //ICSharpCode.Core.LoggingService.Error(ex.StackTrace);
                this.AutoCloseConnection();
                return null;
            }
            finally
            {
                this.ClearParameter();
            }
        }

        public DbTransaction BeginTransaction()
        {
            try
            {
                this.OpenConnection();
                if (this.transaction == null)
                {
                    this.transaction = this.dbSession.Connection.BeginTransaction();
                }
                this.dbSession.Command.Transaction = this.transaction;
                return this.transaction;
            }
            finally
            {
                this.AutoCloseConnection();
            }
        }
        public void RollbackTransaction()
        {
            try
            {
                if (this.transaction != null)
                {
                    this.transaction.Rollback();
                }
            }
            finally
            {
                this.transaction = null;
                this.AutoCloseConnection();
            }
        }
        public void CommitTransaction()
        {
            try
            {
                if (this.transaction != null)
                {
                    this.transaction.Commit();
                }
            }
            finally
            {
                this.transaction = null;
                this.AutoCloseConnection();
            }
        }
        #endregion
    }
}