//
// System.Data.OleDb.OleDbDataReader
//
// Author:
//   Rodrigo Moya (rodrigo@ximian.com)
//   Tim Coleman (tim@timcoleman.com)
//
// Copyright (C) Rodrigo Moya, 2002
// Copyright (C) Tim Coleman, 2002
//

using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Data.Common;
using System.Runtime.InteropServices;

namespace System.Data.OleDb
{
	public sealed class OleDbDataReader : MarshalByRefObject, IDataReader, IDisposable, IDataRecord, IEnumerable
	{
		#region Fields
		
		private OleDbCommand command;
		private bool open;
		private ArrayList gdaResults;
		private int currentResult;
		private int currentRow;

		#endregion

		#region Constructors

		internal OleDbDataReader (OleDbCommand command, ArrayList results) 
		{
			this.command = command;
			this.command.Connection.DataReader = this;
			open = true;
			if (results != null)
				gdaResults = results;
			else
				gdaResults = new ArrayList ();
			currentResult = -1;
			currentRow = -1;
		}

		#endregion

		#region Properties

		public int Depth {
			get {
				return 0; // no nested selects supported
			}
		}

		public int FieldCount {
			get {
				if (currentResult < 0 ||
				    currentResult >= gdaResults.Count)
					return 0;

				return libgda.gda_data_model_get_n_columns (
					(IntPtr) gdaResults[currentResult]);
			}
		}

		public bool IsClosed {
			get {
				return !open;
			}
		}

		public object this[string name] {
			get {
				int pos;

				if (currentResult == -1)
					throw new InvalidOperationException ();

				pos = libgda.gda_data_model_get_column_position (
					(IntPtr) gdaResults[currentResult],
					name);
				if (pos == -1)
					throw new IndexOutOfRangeException ();

				return this[pos];
			}
		}

		public object this[int index] {
			get {
				return (object) GetValue (index);
			}
		}

		public int RecordsAffected {
			get {
				int total_rows;
				
				if (currentResult < 0 ||
				    currentResult >= gdaResults.Count)
					return 0;

				total_rows = libgda.gda_data_model_get_n_rows (
					(IntPtr) gdaResults[currentResult]);
				if (total_rows > 0) {
					if (FieldCount > 0) {
						// It's a SELECT statement
						return -1;
					}
				}

				return FieldCount > 0 ? -1 : total_rows;
			}
		}

		#endregion

		#region Methods

		public void Close ()
		{
			for (int i = 0; i < gdaResults.Count; i++) {
				IntPtr obj = (IntPtr) gdaResults[i];
				libgda.FreeObject (obj);
			}

			gdaResults.Clear ();
			gdaResults = null;
			
			open = false;
			currentResult = -1;
			currentRow = -1;

			this.command.Connection.DataReader = null;
		}

		~OleDbDataReader ()
		{
			if (open)
				Close ();
		}

		public bool GetBoolean (int ordinal)
		{
			IntPtr value;

			if (currentResult == -1)
				throw new InvalidCastException ();

			value = libgda.gda_data_model_get_value_at ((IntPtr) gdaResults[currentResult],
								    ordinal, currentRow);
			if (value == IntPtr.Zero)
				throw new InvalidCastException ();
			
			if (libgda.gda_value_get_vtype (value) != GdaValueType.Boolean)
				throw new InvalidCastException ();
			return libgda.gda_value_get_boolean (value);
		}

		public byte GetByte (int ordinal)
		{
			IntPtr value;

			if (currentResult == -1)
				throw new InvalidCastException ();

			value = libgda.gda_data_model_get_value_at ((IntPtr) gdaResults[currentResult],
								    ordinal, currentRow);
			if (value == IntPtr.Zero)
				throw new InvalidCastException ();
			
			if (libgda.gda_value_get_vtype (value) != GdaValueType.Tinyint)
				throw new InvalidCastException ();
			return libgda.gda_value_get_tinyint (value);
		}

		[MonoTODO]
		public long GetBytes (int ordinal, long dataIndex, byte[] buffer, int bufferIndex, int length)
		{
			throw new NotImplementedException ();
		}
		
		public char GetChar (int ordinal)
		{
			IntPtr value;

			if (currentResult == -1)
				throw new InvalidCastException ();

			value = libgda.gda_data_model_get_value_at ((IntPtr) gdaResults[currentResult],
								    ordinal, currentRow);
			if (value == IntPtr.Zero)
				throw new InvalidCastException ();
			
			if (libgda.gda_value_get_vtype (value) != GdaValueType.Tinyint)
				throw new InvalidCastException ();
			return (char) libgda.gda_value_get_tinyint (value);
		}

		[MonoTODO]
		public long GetChars (int ordinal, long dataIndex, char[] buffer, int bufferIndex, int length)
		{
			throw new NotImplementedException ();
		}

		[MonoTODO]
		public OleDbDataReader GetData (int ordinal)
		{
			throw new NotImplementedException ();
		}

		public string GetDataTypeName (int index)
		{
			IntPtr attrs;
			GdaValueType type;

			if (currentResult == -1)
				return "unknown";

			
			attrs = libgda.gda_data_model_describe_column ((IntPtr) gdaResults[currentResult],
								       index);
			if (attrs == IntPtr.Zero)
				return "unknown";

			type = libgda.gda_field_attributes_get_gdatype (attrs);
			libgda.gda_field_attributes_free (attrs);
			
			return libgda.gda_type_to_string (type);
		}

		public DateTime GetDateTime (int ordinal)
		{
			IntPtr value;
			DateTime dt;

			if (currentResult == -1)
				throw new InvalidCastException ();

			value = libgda.gda_data_model_get_value_at ((IntPtr) gdaResults[currentResult],
								    ordinal, currentRow);
			if (value == IntPtr.Zero)
				throw new InvalidCastException ();
			
			if (libgda.gda_value_get_vtype (value) == GdaValueType.Date) {
				GdaDate gdt;

				gdt = (GdaDate) Marshal.PtrToStructure (libgda.gda_value_get_date (value),
									typeof (GdaDate));
				return new DateTime ((int) gdt.year, (int) gdt.month, (int) gdt.day);
			} else if (libgda.gda_value_get_vtype (value) == GdaValueType.Time) {
				GdaTime gdt;

				gdt = (GdaTime) Marshal.PtrToStructure (libgda.gda_value_get_time (value),
									typeof (GdaTime));
				return new DateTime (0, 0, 0, (int) gdt.hour, (int) gdt.minute, (int) gdt.second, 0);
			} else if (libgda.gda_value_get_vtype (value) == GdaValueType.Timestamp) {
				GdaTimestamp gdt;
				
				gdt = (GdaTimestamp) Marshal.PtrToStructure (libgda.gda_value_get_timestamp (value),
									     typeof (GdaTimestamp));

				return new DateTime ((int) gdt.year, (int) gdt.month, (int) gdt.day,
						     (int) gdt.hour, (int) gdt.minute, (int) gdt.second,
						     (int) gdt.fraction);
			}

			throw new InvalidCastException ();
		}

		[MonoTODO]
		public decimal GetDecimal (int ordinal)
		{
			throw new NotImplementedException ();
		}

		public double GetDouble (int ordinal)
		{
			IntPtr value;

			if (currentResult == -1)
				throw new InvalidCastException ();

			value = libgda.gda_data_model_get_value_at ((IntPtr) gdaResults[currentResult],
								    ordinal, currentRow);
			if (value == IntPtr.Zero)
				throw new InvalidCastException ();
			
			if (libgda.gda_value_get_vtype (value) != GdaValueType.Double)
				throw new InvalidCastException ();
			return libgda.gda_value_get_double (value);
		}

		[MonoTODO]
		public Type GetFieldType (int index)
		{
			throw new NotImplementedException ();
		}

		public float GetFloat (int ordinal)
		{
			IntPtr value;

			if (currentResult == -1)
				throw new InvalidCastException ();

			value = libgda.gda_data_model_get_value_at ((IntPtr) gdaResults[currentResult],
								    ordinal, currentRow);
			if (value == IntPtr.Zero)
				throw new InvalidCastException ();
			
			if (libgda.gda_value_get_vtype (value) != GdaValueType.Single)
				throw new InvalidCastException ();
			return libgda.gda_value_get_single (value);
		}

		[MonoTODO]
		public Guid GetGuid (int ordinal)
		{
			throw new NotImplementedException ();
		}

		public short GetInt16 (int ordinal)
		{
			IntPtr value;

			if (currentResult == -1)
				throw new InvalidCastException ();

			value = libgda.gda_data_model_get_value_at ((IntPtr) gdaResults[currentResult],
								    ordinal, currentRow);
			if (value == IntPtr.Zero)
				throw new InvalidCastException ();
			
			if (libgda.gda_value_get_vtype (value) != GdaValueType.Smallint)
				throw new InvalidCastException ();
			return (short) libgda.gda_value_get_smallint (value);
		}

		public int GetInt32 (int ordinal)
		{
			IntPtr value;

			if (currentResult == -1)
				throw new InvalidCastException ();

			value = libgda.gda_data_model_get_value_at ((IntPtr) gdaResults[currentResult],
								    ordinal, currentRow);
			if (value == IntPtr.Zero)
				throw new InvalidCastException ();
			
			if (libgda.gda_value_get_vtype (value) != GdaValueType.Integer)
				throw new InvalidCastException ();
			return libgda.gda_value_get_integer (value);
		}

		public long GetInt64 (int ordinal)
		{
			IntPtr value;

			if (currentResult == -1)
				throw new InvalidCastException ();

			value = libgda.gda_data_model_get_value_at ((IntPtr) gdaResults[currentResult],
								    ordinal, currentRow);
			if (value == IntPtr.Zero)
				throw new InvalidCastException ();
			
			if (libgda.gda_value_get_vtype (value) != GdaValueType.Bigint)
				throw new InvalidCastException ();
			return libgda.gda_value_get_bigint (value);
		}

		public string GetName (int index)
		{
			if (currentResult == -1)
				return null;

			return libgda.gda_data_model_get_column_title (
				(IntPtr) gdaResults[currentResult], index);
		}

		public int GetOrdinal (string name)
		{
			if (currentResult == -1)
				throw new IndexOutOfRangeException ();

			for (int i = 0; i < FieldCount; i++) {
				if (GetName (i) == name)
					return i;
			}

			throw new IndexOutOfRangeException ();
		}

		public DataTable GetSchemaTable ()
		{
			DataTable table = new DataTable ();

			// FIXME: implement
			return table;
		}

		public string GetString (int ordinal)
		{
			IntPtr value;

			if (currentResult == -1)
				throw new InvalidCastException ();

			value = libgda.gda_data_model_get_value_at ((IntPtr) gdaResults[currentResult],
								    ordinal, currentRow);
			if (value == IntPtr.Zero)
				throw new InvalidCastException ();
			
			if (libgda.gda_value_get_vtype (value) != GdaValueType.String)
				throw new InvalidCastException ();
			return libgda.gda_value_get_string (value);
		}

		[MonoTODO]
		public TimeSpan GetTimeSpan (int ordinal)
		{
			throw new NotImplementedException ();
		}

		public object GetValue (int ordinal)
		{
			IntPtr value;
			GdaValueType type;

			if (currentResult == -1)
				throw new IndexOutOfRangeException ();

			value = libgda.gda_data_model_get_value_at ((IntPtr) gdaResults[currentResult],
								    ordinal, currentRow);
			if (value == IntPtr.Zero)
				throw new IndexOutOfRangeException ();

			type = libgda.gda_value_get_vtype (value);
			switch (type) {
			case GdaValueType.Bigint : return GetInt64 (ordinal);
			case GdaValueType.Boolean : return GetBoolean (ordinal);
			case GdaValueType.Date : return GetDateTime (ordinal);
			case GdaValueType.Double : return GetDouble (ordinal);
			case GdaValueType.Integer : return GetInt32 (ordinal);
			case GdaValueType.Single : return GetFloat (ordinal);
			case GdaValueType.Smallint : return GetByte (ordinal);
			case GdaValueType.String : return GetString (ordinal);
			case GdaValueType.Time : return GetDateTime (ordinal);
			case GdaValueType.Timestamp : return GetDateTime (ordinal);
			case GdaValueType.Tinyint : return GetByte (ordinal);
			}

			return (object) libgda.gda_value_stringify (value);
		}

		[MonoTODO]
		public int GetValues (object[] values)
		{
			throw new NotImplementedException ();
		}

		[MonoTODO]
		IDataReader IDataRecord.GetData (int ordinal)
		{
			throw new NotImplementedException ();
		}

		[MonoTODO]
		void IDisposable.Dispose ()
		{
			throw new NotImplementedException ();
		}

		[MonoTODO]
		IEnumerator IEnumerable.GetEnumerator ()
		{
			throw new NotImplementedException ();
		}

		public bool IsDBNull (int ordinal)
		{
			IntPtr value;

			if (currentResult == -1)
				throw new IndexOutOfRangeException ();

			value = libgda.gda_data_model_get_value_at ((IntPtr) gdaResults[currentResult],
								    ordinal, currentRow);
			if (value == IntPtr.Zero)
				throw new IndexOutOfRangeException ();

			return libgda.gda_value_is_null (value);
		}

		public bool NextResult ()
		{
			int i = currentResult + 1;
			if (i >= 0 && i < gdaResults.Count) {
				currentResult++;
				return true;
			}

			return false;
		}

		public bool Read ()
		{
			if (currentResult < 0 ||
			    currentResult >= gdaResults.Count)
				return false;

			currentRow++;
			if (currentRow <
			    libgda.gda_data_model_get_n_rows ((IntPtr) gdaResults[currentResult]))
				return true;

			return false;
		}

		#endregion
	}
}