src/Apache.IoTDB.Data/IoTDBDataReader.cs

using Apache.IoTDB.DataStructure;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Data.Common;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
 

namespace Apache.IoTDB.Data
{
    /// <summary>
    ///     Provides methods for reading the result of a command executed against a IoTDB database.
    /// </summary>
    public class IoTDBDataReader : DbDataReader
    {
        private readonly SessionPool _IoTDB;
        private readonly IoTDBCommand _command;
        private bool _hasRows;
        private readonly int _recordsAffected;
        private bool _closed;
        private readonly  List<string> _metas;
        private bool _closeConnection;
 
        private int _fieldCount;
      
        RowRecord rowdata= null;


        SessionDataSet _dataSet;
        internal IoTDBDataReader(IoTDBCommand IoTDBCommand, SessionDataSet dataSet, bool closeConnection)
        {
            _IoTDB = IoTDBCommand.Connection._IoTDB;
            _command = IoTDBCommand;
            _closeConnection = closeConnection;
            _fieldCount = dataSet.ColumnNames.Count;
            _hasRows = dataSet.RowCount > 0;
            _recordsAffected =dataSet.RowCount;
            _closed = _closeConnection;
            _metas = dataSet.ColumnNames;
            _dataSet = dataSet;
        }

        /// <summary>
        ///     Gets the depth of nesting for the current row. Always zero.
        /// </summary>
        /// <value>The depth of nesting for the current row.</value>
        public override int Depth => 0;

        /// <summary>
        ///     Gets the number of columns in the current row.
        /// </summary>
        /// <value>The number of columns in the current row.</value>
        public override int FieldCount => _fieldCount+1;

        /// <summary>
        ///     Gets a value indicating whether the data reader contains any rows.
        /// </summary>
        /// <value>A value indicating whether the data reader contains any rows.</value>
        public override bool HasRows
            => _hasRows;
 
 
        /// <summary>
        ///     Gets a value indicating whether the data reader is closed.
        /// </summary>
        /// <value>A value indicating whether the data reader is closed.</value>
        public override bool IsClosed
            => _closed;

        /// <summary>
        ///     Gets the number of rows inserted, updated, or deleted. -1 for SELECT statements.
        /// </summary>
        /// <value>The number of rows inserted, updated, or deleted.</value>
        public override int RecordsAffected
        {
            get
            {
                return _recordsAffected; 
            }
        }

        /// <summary>
        ///     Gets the value of the specified column.
        /// </summary>
        /// <param name="name">The name of the column. The value is case-sensitive.</param>
        /// <returns>The value.</returns>
        public override object this[string name]
            => this[GetOrdinal(name)];

        /// <summary>
        ///     Gets the value of the specified column.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value.</returns>
        public override object this[int ordinal]
            => GetValue(ordinal);

        /// <summary>
        ///     Gets an enumerator that can be used to iterate through the rows in the data reader.
        /// </summary>
        /// <returns>The enumerator.</returns>
        public override IEnumerator GetEnumerator()
            => new DbEnumerator(this, closeReader: false);


        /// <summary>
        ///     Advances to the next row in the result set.
        /// </summary>
        /// <returns>true if there are more rows; otherwise, false.</returns>
        public override bool Read()
        {
            if (_closed)
            {
                throw new InvalidOperationException($"DataReaderClosed{nameof(Read)}");
            }
            if (_dataSet.HasNext())
            {
                rowdata = _dataSet.Next();
            }
            else
            {
                rowdata = null;
            }
            return rowdata != null;

        }

        /// <summary>
        ///     Advances to the next result set for batched statements.
        /// </summary>
        /// <returns>true if there are more result sets; otherwise, false.</returns>
        public override bool NextResult()
        {
            return Read();
        }

        /// <summary>
        ///     Closes the data reader.
        /// </summary>
        public override void Close()
            => Dispose(true);

        /// <summary>
        ///     Releases any resources used by the data reader and closes it.
        /// </summary>
        /// <param name="disposing">
        ///     true to release managed and unmanaged resources; false to release only unmanaged resources.
        /// </param>
        protected override void Dispose(bool disposing)
        {
            if (!disposing)
            {
                return;
            }
            _dataSet.Close().GetAwaiter().GetResult();
            _command.DataReader = null;

            if (_closeConnection  )
            {
                _command.Connection.Close();
                _closed = true;
            }
            rowdata = null;
        
        }

        /// <summary>
        ///     Gets the name of the specified column.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The name of the column.</returns>
        public override string GetName(int ordinal)
        {
            return ordinal==0? "timestamp" : rowdata.Measurements[ordinal-1];
        }

        /// <summary>
        ///     Gets the ordinal of the specified column.
        /// </summary>
        /// <param name="name">The name of the column.</param>
        /// <returns>The zero-based column ordinal.</returns>
        public override int GetOrdinal(string name)
            => "timestamp"==name?0: rowdata.Measurements.IndexOf(  name)+1;

        public override string GetDataTypeName(int ordinal)
        {
            return GetFieldType(ordinal).Name;
        }

        /// <summary>
        ///     Gets the data type of the specified column.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The data type of the column.</returns>
        public override Type GetFieldType(int ordinal)
        {
        
            return ordinal==0?typeof(DateTime): rowdata.GetCrlType(ordinal-1);
        }

        /// <summary>
        ///     Gets a value indicating whether the specified column is <see cref="DBNull" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>true if the specified column is <see cref="DBNull" />; otherwise, false.</returns>
        public override bool IsDBNull(int ordinal)
                => GetValue(ordinal) == DBNull.Value;

        /// <summary>
        ///     Gets the value of the specified column as a <see cref="bool" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public override bool GetBoolean(int ordinal) => GetFieldValue<bool>(ordinal);

        /// <summary>
        ///     Gets the value of the specified column as a <see cref="byte" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public override byte GetByte(int ordinal) => GetFieldValue<byte>(ordinal);

        /// <summary>
        ///     Gets the value of the specified column as a <see cref="char" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public override char GetChar(int ordinal) => GetFieldValue<char>(ordinal);

        /// <summary>
        ///     Gets the value of the specified column as a <see cref="DateTime" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public override DateTime GetDateTime(int ordinal)
        {
            return GetFieldValue<DateTime>(ordinal);
        }

        /// <summary>
        ///     Gets the value of the specified column as a <see cref="DateTimeOffset" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public virtual DateTimeOffset GetDateTimeOffset(int ordinal)
        {
            return GetDateTime(ordinal);
        }

        /// <summary>
        ///     Gets the value of the specified column as a <see cref="TimeSpan" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public virtual TimeSpan GetTimeSpan(int ordinal)
        {
            var val = GetInt64(ordinal);
            return TimeSpan.FromMilliseconds(val);
        }

        /// <summary>
        ///     Gets the value of the specified column as a <see cref="decimal" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public override decimal GetDecimal(int ordinal) => (decimal)GetValue(ordinal);

        /// <summary>
        ///     Gets the value of the specified column as a <see cref="double" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public override double GetDouble(int ordinal) => (double)GetValue(ordinal);

        /// <summary>
        ///     Gets the value of the specified column as a <see cref="float" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public override float GetFloat(int ordinal) => (float)GetValue(ordinal);

        /// <summary>
        ///     Gets the value of the specified column as a <see cref="Guid" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public override Guid GetGuid(int ordinal) => GetFieldValue<Guid>(ordinal);

        /// <summary>
        ///     Gets the value of the specified column as a <see cref="short" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public override short GetInt16(int ordinal) => (short)GetValue(ordinal);

        /// <summary>
        ///     Gets the value of the specified column as a <see cref="ushort" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public ushort GetUInt16(int ordinal) => (ushort)GetValue(ordinal);

        /// <summary>
        ///     Gets the value of the specified column as a <see cref="int" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public override int GetInt32(int ordinal) => (int)GetValue(ordinal);

        /// <summary>
        ///     Gets the value of the specified column as a <see cref="uint" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public uint GetUInt32(int ordinal) => (uint)GetValue(ordinal);

        /// <summary>
        ///     Gets the value of the specified column as a <see cref="long" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public override long GetInt64(int ordinal) => (long)GetValue(ordinal);

        /// <summary>
        ///     Gets the value of the specified column as a <see cref="ulong" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public ulong GetUInt64(int ordinal) => (ulong)GetValue(ordinal);

        /// <summary>
        ///     Gets the value of the specified column as a <see cref="string" />.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public override string GetString(int ordinal) => (string)GetValue(ordinal);
 
  
        /// <summary>
        ///     Reads a stream of bytes from the specified column. Not supported.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <param name="dataOffset">The index from which to begin the read operation.</param>
        /// <param name="buffer">The buffer into which the data is copied.</param>
        /// <param name="bufferOffset">The index to which the data will be copied.</param>
        /// <param name="length">The maximum number of bytes to read.</param>
        /// <returns>The actual number of bytes read.</returns>
        public override long GetBytes(int ordinal, long dataOffset, byte[] buffer, int bufferOffset, int length)
        {
            throw new NotSupportedException();
        }

        /// <summary>
        ///     Reads a stream of characters from the specified column. Not supported.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <param name="dataOffset">The index from which to begin the read operation.</param>
        /// <param name="buffer">The buffer into which the data is copied.</param>
        /// <param name="bufferOffset">The index to which the data will be copied.</param>
        /// <param name="length">The maximum number of characters to read.</param>
        /// <returns>The actual number of characters read.</returns>
        public override long GetChars(int ordinal, long dataOffset, char[] buffer, int bufferOffset, int length)
           => throw new NotSupportedException();

        /// <summary>
        /// Retrieves data as a Stream.  Not supported.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The returned object.</returns>
        public override Stream GetStream(int ordinal)
         => throw new NotSupportedException();
        /// <summary>
        ///     Gets the value of the specified column.
        /// </summary>
        /// <typeparam name="T">The type of the value.</typeparam>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public override T GetFieldValue<T>(int ordinal) => (T)Convert.ChangeType(GetValue(ordinal), typeof(T));

        /// <summary>
        ///     Gets the value of the specified column.
        /// </summary>
        /// <param name="ordinal">The zero-based column ordinal.</param>
        /// <returns>The value of the column.</returns>
        public override object GetValue(int ordinal)
        {
            object result;
            if (ordinal == 0)
            {
                result = rowdata.GetDateTime();
            }
            else
            {
                result = rowdata.Values[ordinal - 1];
            }
            if (result == null)

            {
                result = DBNull.Value;
            }
            return result;
        }

       

        /// <summary>
        ///     Gets the column values of the current row.
        /// </summary>
        /// <param name="values">An array into which the values are copied.</param>
        /// <returns>The number of values copied into the array.</returns>
        public override int GetValues(object[] values)
        {
            int count = 0;
            values[0] = rowdata.GetDateTime();
            for (int i = 0; i < _fieldCount; i++)
            {
                var obj = rowdata.Values[i];
                if (obj != null  )
                {
                    values[i+1] = obj;
                    count++;
                }
            }
            return count;
        }


        /// <summary>
        ///     Returns a System.Data.DataTable that describes the column metadata of the System.Data.Common.DbDataReader.
        /// </summary>
        /// <returns>A System.Data.DataTable that describes the column metadata.</returns>
        public override DataTable GetSchemaTable()
        {
            if (_dataSet.HasNext())
            {
                rowdata = _dataSet.GetRow();
            }
                   var schemaTable = new DataTable("SchemaTable");
            if (_metas != null && rowdata !=null)
            {
                var ColumnName = new DataColumn(SchemaTableColumn.ColumnName, typeof(string));
                var ColumnOrdinal = new DataColumn(SchemaTableColumn.ColumnOrdinal, typeof(int));
                var ColumnSize = new DataColumn(SchemaTableColumn.ColumnSize, typeof(int));
                var NumericPrecision = new DataColumn(SchemaTableColumn.NumericPrecision, typeof(short));
                var NumericScale = new DataColumn(SchemaTableColumn.NumericScale, typeof(short));

                var DataType = new DataColumn(SchemaTableColumn.DataType, typeof(Type));
                var DataTypeName = new DataColumn("DataTypeName", typeof(string));

                var IsLong = new DataColumn(SchemaTableColumn.IsLong, typeof(bool));
                var AllowDBNull = new DataColumn(SchemaTableColumn.AllowDBNull, typeof(bool));

                var IsUnique = new DataColumn(SchemaTableColumn.IsUnique, typeof(bool));
                var IsKey = new DataColumn(SchemaTableColumn.IsKey, typeof(bool));
                var IsAutoIncrement = new DataColumn(SchemaTableOptionalColumn.IsAutoIncrement, typeof(bool));

                var BaseCatalogName = new DataColumn(SchemaTableOptionalColumn.BaseCatalogName, typeof(string));
                var BaseSchemaName = new DataColumn(SchemaTableColumn.BaseSchemaName, typeof(string));
                var BaseTableName = new DataColumn(SchemaTableColumn.BaseTableName, typeof(string));
                var BaseColumnName = new DataColumn(SchemaTableColumn.BaseColumnName, typeof(string));

                var BaseServerName = new DataColumn(SchemaTableOptionalColumn.BaseServerName, typeof(string));
                var IsAliased = new DataColumn(SchemaTableColumn.IsAliased, typeof(bool));
                var IsExpression = new DataColumn(SchemaTableColumn.IsExpression, typeof(bool));

                var columns = schemaTable.Columns;

                columns.Add(ColumnName);
                columns.Add(ColumnOrdinal);
                columns.Add(ColumnSize);
                columns.Add(NumericPrecision);
                columns.Add(NumericScale);
                columns.Add(IsUnique);
                columns.Add(IsKey);
                columns.Add(BaseServerName);
                columns.Add(BaseCatalogName);
                columns.Add(BaseColumnName);
                columns.Add(BaseSchemaName);
                columns.Add(BaseTableName);
                columns.Add(DataType);
                columns.Add(DataTypeName);
                columns.Add(AllowDBNull);
                columns.Add(IsAliased);
                columns.Add(IsExpression);
                columns.Add(IsAutoIncrement);
                columns.Add(IsLong);



                var schemaRow1 = schemaTable.NewRow();

                var columnName1 = "timestamp";
                schemaRow1[ColumnName] = columnName1;
                schemaRow1[ColumnOrdinal] = 0;

                schemaRow1[NumericPrecision] = DBNull.Value;
                schemaRow1[NumericScale] = DBNull.Value;
                schemaRow1[BaseServerName] = _command.Connection.DataSource;

                schemaRow1[BaseColumnName] = columnName1;
                schemaRow1[BaseSchemaName] = DBNull.Value;
                var tableName1 = string.Empty;
                schemaRow1[BaseTableName] = tableName1;
                schemaRow1[DataType] = typeof(DateTime);
                schemaRow1[DataTypeName] = typeof(DateTime).Name;
                schemaRow1[IsExpression] = columnName1 == null;
                schemaRow1[IsLong] = DBNull.Value;
                schemaRow1[IsKey] = true;
        
 
                schemaTable.Rows.Add(schemaRow1);


                for (var i = 1; i < rowdata.Measurements.Count+1; i++)
                {
                    var schemaRow = schemaTable.NewRow();

                    var columnName = rowdata.Measurements[i-1] ;
                    schemaRow[ColumnName] = columnName;
                    schemaRow[ColumnOrdinal] = i;
               
                    schemaRow[NumericPrecision] = DBNull.Value;
                    schemaRow[NumericScale] = DBNull.Value;
                    schemaRow[BaseServerName] = _command.Connection.DataSource;
              
                    schemaRow[BaseColumnName] = columnName;
                    schemaRow[BaseSchemaName] = DBNull.Value;
                    var tableName = string.Empty;
                    schemaRow[BaseTableName] = tableName;
                    schemaRow[DataType] = GetFieldType(i);
                    schemaRow[DataTypeName] = GetDataTypeName(i);
                    schemaRow[IsExpression] = columnName == null;
                    schemaRow[IsLong] = DBNull.Value;
                    schemaRow[IsKey]= false;
                    schemaRow[AllowDBNull] = true;
                    schemaTable.Rows.Add(schemaRow);
                }

            }

            return schemaTable;
        }
    }
}