//
// System.Data.DataColumnCollection.cs
//
// Author:
//   Christopher Podurgiel (cpodurgiel@msn.com)
//   Stuart Caborn	<stuart.caborn@virgin.net>
//   Tim Coleman (tim@timcoleman.com)
//
// (C) Chris Podurgiel
// Copyright (C) Tim Coleman, 2002
// Copyright (C) Daniel Morgan, 2003
//

//
// Copyright (C) 2004 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

using System;
using System.Text;
using System.Collections;
using System.ComponentModel;

namespace System.Data {

	internal class Doublet
	{
		public Doublet (int count, string columnname)
		{
			this.count = count;
			this.columnNames.Add (columnname);
		}
		// Number of case insensitive column name
		public int count;
		// Array of exact column names
		public ArrayList columnNames = new ArrayList ();
	}

	[Editor ("Microsoft.VSDesigner.Data.Design.ColumnsCollectionEditor, " + Consts.AssemblyMicrosoft_VSDesigner,
		 "System.Drawing.Design.UITypeEditor, " + Consts.AssemblySystem_Drawing)]
#if !NET_2_0
	[Serializable]
#endif
	[DefaultEvent ("CollectionChanged")]
	public
#if NET_2_0
	sealed
#endif
	class DataColumnCollection : InternalDataCollectionBase	{
		//This hashtable maps between unique case insensetive column name to a doublet containing column ref and column count
#if NET_2_0
		private Hashtable columnNameCount = new Hashtable (StringComparer.OrdinalIgnoreCase);
#else
		private Hashtable columnNameCount = new Hashtable (CaseInsensitiveHashCodeProvider.Default, CaseInsensitiveComparer.Default);
#endif
		//This hashtable maps between column name to DataColumn object.
		private Hashtable columnFromName = new Hashtable ();
		//This ArrayList contains the auto-increment columns names
		private ArrayList autoIncrement = new ArrayList ();
		//This holds the next index to use for default column name.
		private int defaultColumnIndex = 1;
		//table should be the DataTable this DataColumnCollection belongs to.
		private DataTable parentTable = null;
		// Keep reference to most recent columns passed to AddRange()
		// so that they can be added when EndInit() is called.
		DataColumn [] _mostRecentColumns = null;

		static readonly string ColumnPrefix = "Column";

		// Internal Constructor.  This Class can only be created from other classes in this assembly.
		internal DataColumnCollection (DataTable table)
		{
			parentTable = table;
		}

		/// <summary>
		/// Gets the DataColumn from the collection at the specified index.
		/// </summary>
		public
#if !NET_2_0
		virtual
#endif
		DataColumn this [int index] {
			get {
				if (index < 0 || index >= base.List.Count)
					throw new IndexOutOfRangeException ("Cannot find column " + index + ".");
				return (DataColumn) base.List [index];
			}
		}

		/// <summary>
		/// Gets the DataColumn from the collection with the specified name.
		/// </summary>
		public
#if !NET_2_0
		virtual
#endif
		DataColumn this [string name] {
			get {
#if NET_2_0
				if (name == null)
					throw new ArgumentNullException ("name");
#endif

				DataColumn dc = columnFromName [name] as DataColumn;
				if (dc != null)
					return dc;

				int tmp = IndexOf (name, true);
				return tmp == -1 ? null : (DataColumn) base.List [tmp];
			}
		}

		/// <summary>
		/// Gets a list of the DataColumnCollection items.
		/// </summary>
		protected override ArrayList List {
			get { return base.List; }
		}

		internal ArrayList AutoIncrmentColumns {
			get { return autoIncrement; }
		}

		//Add Logic
		//
		//Changing Event
		//DefaultValue set and AutoInc set check
		//?Validate Expression??
		//Name check and creation
		//Set Table
		//Check Unique if true then add a unique constraint
		//?Notify Rows of new column ?
		//Add to collection
		//Changed Event

		/// <summary>
		/// Creates and adds a DataColumn object to the DataColumnCollection.
		/// </summary>
		/// <returns></returns>
		public
#if !NET_2_0
		virtual
#endif
		DataColumn Add ()
		{
			DataColumn column = new DataColumn (null);
			Add (column);
			return column;
		}

#if NET_2_0
		public void CopyTo (DataColumn [] array, int index)
		{
			CopyTo ((Array) array, index);
		}
#endif

		internal void RegisterName (string name, DataColumn column)
		{
			try {
				columnFromName.Add (name, column);
			} catch (ArgumentException) {
				throw new DuplicateNameException ("A DataColumn named '" + name + "' already belongs to this DataTable.");
			}

			// Get existing doublet
			Doublet d = (Doublet) columnNameCount [name];
			if (d != null) {
				// Add reference count
				d.count++;
				// Add a new name
				d.columnNames.Add (name);
			} else {
				// no existing doublet
				// create one
				d = new Doublet (1, name);
				columnNameCount [name] = d;
			}

#if NET_2_0
			if (name.Length <= ColumnPrefix.Length || !name.StartsWith (ColumnPrefix, StringComparison.Ordinal))
				return;
#else
			if (name.Length <= ColumnPrefix.Length || !name.StartsWith (ColumnPrefix))
				return;
#endif

			if (name == MakeName (defaultColumnIndex + 1)) {
				do {
					defaultColumnIndex++;
				} while (Contains (MakeName (defaultColumnIndex + 1)));
			}
		}

		internal void UnregisterName (string name)
		{
			if (columnFromName.Contains (name))
				columnFromName.Remove (name);

			// Get the existing doublet
			Doublet d = (Doublet) columnNameCount [name];
			if (d != null) {
				// decrease reference count
				d.count--;
				d.columnNames.Remove (name);
				// remove doublet if no more references
				if (d.count == 0)
					columnNameCount.Remove (name);
			}

			if (name.StartsWith(ColumnPrefix) && name == MakeName(defaultColumnIndex - 1)) {
				do {
					defaultColumnIndex--;
				} while (!Contains (MakeName (defaultColumnIndex - 1)) && defaultColumnIndex > 1);
			}
		}

		private string GetNextDefaultColumnName ()
		{
			string defColumnName = MakeName (defaultColumnIndex);
			for (int index = defaultColumnIndex + 1; Contains (defColumnName); ++index) {
				defColumnName = MakeName (index);
				defaultColumnIndex++;
			}
			defaultColumnIndex++;
			return defColumnName;
		}

		static readonly string[] TenColumns = { "Column0", "Column1", "Column2", "Column3", "Column4", "Column5", "Column6", "Column7", "Column8", "Column9" };

		static string MakeName (int index)
		{
			if (index < 10)
				return TenColumns [index];
			return String.Concat (ColumnPrefix, index.ToString());
		}

		/// <summary>
		/// Creates and adds the specified DataColumn object to the DataColumnCollection.
		/// </summary>
		/// <param name="column">The DataColumn to add.</param>
		public void Add (DataColumn column)
		{
			if (column == null)
				throw new ArgumentNullException ("column", "'column' argument cannot be null.");

#if !NET_2_0
			/* in 1.1, they must do this here, as the
			 * setting of ColumnName below causes an event
			 * to be raised */
			column.PropertyChanged += new PropertyChangedEventHandler (ColumnPropertyChanged);
#endif

			if (column.ColumnName.Length == 0) {
				column.ColumnName = GetNextDefaultColumnName ();
			}

//			if (Contains(column.ColumnName))
//				throw new DuplicateNameException("A DataColumn named '" + column.ColumnName + "' already belongs to this DataTable.");

			if (column.Table != null)
				throw new ArgumentException ("Column '" + column.ColumnName + "' already belongs to this or another DataTable.");

			column.SetTable (parentTable);
			RegisterName (column.ColumnName, column);
			int ordinal = base.List.Add (column);

#if NET_2_0
			column.Ordinal = ordinal;
#else
			column.SetOrdinal (ordinal);
#endif

			// Check if the Column Expression is ok
			if (column.CompiledExpression != null)
				if (parentTable.Rows.Count == 0)
					column.CompiledExpression.Eval (parentTable.NewRow());
				else
					column.CompiledExpression.Eval (parentTable.Rows[0]);

			// if table already has rows we need to allocate space
			// in the column data container
			if (parentTable.Rows.Count > 0)
				column.DataContainer.Capacity = parentTable.RecordCache.CurrentCapacity;

			if (column.AutoIncrement) {
				DataRowCollection rows = column.Table.Rows;
				for (int i = 0; i < rows.Count; i++)
					rows [i] [ordinal] = column.AutoIncrementValue ();
			}

			if (column.AutoIncrement)
				autoIncrement.Add (column);

#if NET_2_0
			column.PropertyChanged += new PropertyChangedEventHandler (ColumnPropertyChanged);
#endif

			OnCollectionChanged (new CollectionChangeEventArgs(CollectionChangeAction.Add, column));
		}

		/// <summary>
		/// Creates and adds a DataColumn object with the specified name to the DataColumnCollection.
		/// </summary>
		/// <param name="columnName">The name of the column.</param>
		/// <returns>The newly created DataColumn.</returns>
		public
#if !NET_2_0
		virtual
#endif
		DataColumn Add (string columnName)
		{
			DataColumn column = new DataColumn (columnName);
			Add (column);
			return column;
		}

		/// <summary>
		/// Creates and adds a DataColumn object with the specified name and type to the DataColumnCollection.
		/// </summary>
		/// <param name="columnName">The ColumnName to use when cretaing the column.</param>
		/// <param name="type">The DataType of the new column.</param>
		/// <returns>The newly created DataColumn.</returns>
		public
#if !NET_2_0
		virtual
#endif
		DataColumn Add (string columnName, Type type)
		{
			if (columnName == null || columnName == "")
				columnName = GetNextDefaultColumnName ();

			DataColumn column = new DataColumn (columnName, type);
			Add (column);
			return column;
		}

		/// <summary>
		/// Creates and adds a DataColumn object with the specified name, type, and expression to the DataColumnCollection.
		/// </summary>
		/// <param name="columnName">The name to use when creating the column.</param>
		/// <param name="type">The DataType of the new column.</param>
		/// <param name="expression">The expression to assign to the Expression property.</param>
		/// <returns>The newly created DataColumn.</returns>
		public
#if !NET_2_0
		virtual
#endif
		DataColumn Add (string columnName, Type type, string expression)
		{
			if (columnName == null || columnName == "")
				columnName = GetNextDefaultColumnName ();

			DataColumn column = new DataColumn (columnName, type, expression);
			Add (column);
			return column;
		}

		/// <summary>
		/// Copies the elements of the specified DataColumn array to the end of the collection.
		/// </summary>
		/// <param name="columns">The array of DataColumn objects to add to the collection.</param>
		public void AddRange (DataColumn [] columns)
		{
			if (parentTable.InitInProgress){
				_mostRecentColumns = columns;
				return;
			}

			if (columns == null)
				return;

			foreach (DataColumn column in columns){
				if (column == null)
					continue;
				Add(column);
			}
		}

		private string GetColumnDependency (DataColumn column)
		{

			foreach (DataRelation rel in parentTable.ParentRelations)
				if (Array.IndexOf (rel.ChildColumns, column) != -1)
					return String.Format (" child key for relationship {0}.", rel.RelationName);
			foreach (DataRelation rel in parentTable.ChildRelations)
				if (Array.IndexOf (rel.ParentColumns, column) != -1)
					return String.Format (" parent key for relationship {0}.", rel.RelationName);

			foreach (Constraint c in parentTable.Constraints)
				if (c.IsColumnContained (column))
					return String.Format (" constraint {0} on the table {1}.",
							c.ConstraintName, parentTable);


			// check if the foreign-key constraint on any table in the dataset refers to this column.
			// though a forignkeyconstraint automatically creates a uniquecontrainton the parent
			// table and would fail above, but we still need to check, as it is legal to manually remove
			// the constraint on the parent table.
			if (parentTable.DataSet != null)
				foreach (DataTable table in parentTable.DataSet.Tables)
					foreach (Constraint c in table.Constraints)
						if (c is ForeignKeyConstraint && c.IsColumnContained(column))
							return String.Format (
								" constraint {0} on the table {1}.", c.ConstraintName, table.TableName);

			foreach (DataColumn col in this)
				if (col.CompiledExpression != null && col.CompiledExpression.DependsOn (column))
					return  col.Expression;
			return String.Empty;
		}

		/// <summary>
		/// Checks whether a given column can be removed from the collection.
		/// </summary>
		/// <param name="column">A DataColumn in the collection.</param>
		/// <returns>true if the column can be removed; otherwise, false.</returns>
		public bool CanRemove (DataColumn column)
		{
			if (column == null || column.Table != parentTable || GetColumnDependency (column) != String.Empty)
				return false;
			return true;
		}

		/// <summary>
		/// Clears the collection of any columns.
		/// </summary>
		public void Clear ()
		{
			CollectionChangeEventArgs e = new CollectionChangeEventArgs(CollectionChangeAction.Refresh, this);

			// its not necessary to check if each column in the collection can removed.
			// Can simply check, if there are any constraints/relations related to the table,
			// in which case, throw an exception.
			// Also, shudnt check for expression columns since all the columns in the table
			// are being removed.
			if (parentTable.Constraints.Count != 0 ||
			    parentTable.ParentRelations.Count != 0 ||
			    parentTable.ChildRelations.Count != 0)
				foreach (DataColumn col in this) {
					string s = GetColumnDependency (col);
					if (s != String.Empty)
						throw new ArgumentException ("Cannot remove this column, because it is part of the" + s);
				}

			if (parentTable.DataSet != null)
				foreach (DataTable table in parentTable.DataSet.Tables)
					foreach (Constraint c in table.Constraints) {
						if (!(c is ForeignKeyConstraint) ||
						    ((ForeignKeyConstraint) c).RelatedTable != parentTable)
							continue;
						throw new ArgumentException (
							String.Format (
								"Cannot remove this column, because it is part of the constraint {0} on the table {1}",
								c.ConstraintName, table.TableName));
					}

			foreach (DataColumn col in this)
				col.ResetColumnInfo ();

			columnFromName.Clear ();
			autoIncrement.Clear ();
			columnNameCount.Clear ();
			base.List.Clear ();
			defaultColumnIndex = 1;
			OnCollectionChanged (e);
		}

		/// <summary>
		/// Checks whether the collection contains a column with the specified name.
		/// </summary>
		/// <param name="name">The ColumnName of the column to check for.</param>
		/// <returns>true if a column exists with this name; otherwise, false.</returns>
		public bool Contains (string name)
		{
			if (columnFromName.Contains (name))
				return true;

			return (IndexOf (name, false) != -1);
		}

		/// <summary>
		/// Gets the index of a column specified by name.
		/// </summary>
		/// <param name="column">The name of the column to return.</param>
		/// <returns>The index of the column specified by column if it is found; otherwise, -1.</returns>
		public
#if !NET_2_0
		virtual
#endif
		int IndexOf (DataColumn column)
		{
			if (column == null)
				return -1;
			return base.List.IndexOf (column);
		}

		/// <summary>
		/// Gets the index of the column with the given name (the name is not case sensitive).
		/// </summary>
		/// <param name="columnName">The name of the column to find.</param>
		/// <returns>The zero-based index of the column with the specified name, or -1 if the column doesn't exist in the collection.</returns>
		public int IndexOf (string columnName)
		{
			if (columnName == null)
				return -1;
			DataColumn dc = columnFromName [columnName] as DataColumn;

			if (dc != null)
				return IndexOf (dc);

			return IndexOf (columnName, false);
		}

		/// <summary>
		/// Raises the OnCollectionChanged event.
		/// </summary>
		/// <param name="ccevent">A CollectionChangeEventArgs that contains the event data.</param>
#if !NET_2_0
		protected virtual
#else
		internal
#endif
		void OnCollectionChanged (CollectionChangeEventArgs ccevent)
		{
			parentTable.ResetPropertyDescriptorsCache ();
			if (CollectionChanged != null)
				CollectionChanged (this, ccevent);
		}

		/// <summary>
		/// Raises the OnCollectionChanging event.
		/// </summary>
		/// <param name="ccevent">A CollectionChangeEventArgs that contains the event data.</param>
#if !NET_2_0
		protected internal virtual
#else
		internal
#endif
		void OnCollectionChanging (CollectionChangeEventArgs ccevent)
		{
			if (CollectionChanged != null) {
				//FIXME: this is not right
				//CollectionChanged(this, ccevent);
				throw new NotImplementedException();
			}
		}

		/// <summary>
		/// Removes the specified DataColumn object from the collection.
		/// </summary>
		/// <param name="column">The DataColumn to remove.</param>
		public void Remove (DataColumn column)
		{
			if (column == null)
				throw new ArgumentNullException ("column", "'column' argument cannot be null.");

			if (!Contains (column.ColumnName))
				throw new ArgumentException ("Cannot remove a column that doesn't belong to this table.");

			string dependency = GetColumnDependency (column);
			if (dependency != String.Empty)
				throw new ArgumentException ("Cannot remove this column, because it is part of " + dependency);

			CollectionChangeEventArgs e = new CollectionChangeEventArgs (CollectionChangeAction.Remove, column);

			int ordinal = column.Ordinal;
			UnregisterName (column.ColumnName);
			base.List.Remove (column);

			// Reset column info
			column.ResetColumnInfo ();

			//Update the ordinals
			for( int i = ordinal ; i < this.Count ; i ++ )
#if NET_2_0
				this[i].Ordinal = i;
#else
				this[i].SetOrdinal(i);
#endif

			if (parentTable != null)
				parentTable.OnRemoveColumn (column);

			if (column.AutoIncrement)
				autoIncrement.Remove (column);

			column.PropertyChanged -= new PropertyChangedEventHandler (ColumnPropertyChanged);

			OnCollectionChanged (e);
		}

		/// <summary>
		/// Removes the DataColumn object with the specified name from the collection.
		/// </summary>
		/// <param name="name">The name of the column to remove.</param>
		public void Remove (string name)
		{
			DataColumn column = this [name];

			if (column == null)
				throw new ArgumentException ("Column '" + name + "' does not belong to table " + ( parentTable == null ? "" : parentTable.TableName ) + ".");
			Remove (column);
		}

		/// <summary>
		/// Removes the column at the specified index from the collection.
		/// </summary>
		/// <param name="index">The index of the column to remove.</param>
		public void RemoveAt (int index)
		{
			if (Count <= index)
				throw new IndexOutOfRangeException ("Cannot find column " + index + ".");

			DataColumn column = this [index];
			Remove (column);
		}

		// Helper AddRange() - Call this function when EndInit is called
		internal void PostAddRange ()
		{
			if (_mostRecentColumns == null)
				return;

			foreach (DataColumn column in _mostRecentColumns){
				if (column == null)
					continue;
				Add (column);
			}
			_mostRecentColumns = null;
		}

		internal void UpdateAutoIncrement (DataColumn col,bool isAutoIncrement)
		{
			if (isAutoIncrement) {
				if (!autoIncrement.Contains (col))
					autoIncrement.Add (col);
			} else {
				if (autoIncrement.Contains (col))
					autoIncrement.Remove (col);
			}
		}

		private int IndexOf (string name, bool error)
		{
			// exact case matching has already be done by the caller
			// Get existing doublet
			Doublet d = (Doublet) columnNameCount [name];
			if (d != null) {
				if (d.count == 1) {
					// There's only one
					// return index of the column from the only column name of the doublet
					return base.List.IndexOf (columnFromName [d.columnNames [0]]);
				} else if (d.count > 1 && error) {
					// there's more than one, exception!
					throw new ArgumentException ("There is no match for '" + name + "' in the same case and there are multiple matches in different case.");
				} else {
					return -1;
				}
			}
			return -1;
		}

		#region Events

		/// <summary>
		/// Occurs when the columns collection changes, either by adding or removing a column.
		/// </summary>
		[ResDescriptionAttribute ("Occurs whenever this collection's membership changes.")]
		public event CollectionChangeEventHandler CollectionChanged;

		internal event CollectionChangeEventHandler CollectionMetaDataChanged;
		#endregion

		private void OnCollectionMetaDataChanged (CollectionChangeEventArgs ccevent)
		{
			parentTable.ResetPropertyDescriptorsCache ();
			if (CollectionMetaDataChanged != null)
				CollectionMetaDataChanged (this, ccevent);
		}

		private void ColumnPropertyChanged (object sender, PropertyChangedEventArgs args)
		{
			OnCollectionMetaDataChanged (new CollectionChangeEventArgs(CollectionChangeAction.Refresh, sender));
		}

#if NET_2_0
		internal void MoveColumn (int oldOrdinal, int newOrdinal)
		{
			if (newOrdinal == -1 || newOrdinal > this.Count)
				throw new ArgumentOutOfRangeException ("ordinal", "Ordinal '" + newOrdinal + "' exceeds the maximum number.");
			if (oldOrdinal == newOrdinal)
				return;

			int start = newOrdinal > oldOrdinal ? oldOrdinal : newOrdinal;
			int end = newOrdinal > oldOrdinal ?  newOrdinal : oldOrdinal;
			int direction = newOrdinal > oldOrdinal ? 1 : (-1);
			
			// swap ordinals as per direction of column movement
			if (direction < 0) {
				start = start + end;
				end = start - end;
				start -= end;
			}

			DataColumn currColumn = this [start];
			for (int i = start; (direction>0 ? i<end : i>end); i += direction) {
				List [i] = List [i+direction];
				((DataColumn) List [i]).Ordinal = i;
			}
			List [end] = currColumn;
			currColumn.Ordinal = end;
		}
#endif
	}
}