Db.Model = new Class ().extend
({
	Status:
	{
		 CLEAN   : 1
		,LOADING : 2
		,READY   : 3
		,ERROR   : 4
	}
});

Db.Model.implement
({
	Extends: Vn.Object
	,Tag: 'db-model'
	,Child: 'query'
	,Properties:
	{
		/**
		 * The connection used to execute the statement.
		 **/
		conn:
		{
			type: Db.Conn
			,set: function (x)
			{
				this._conn = x;
				this.refresh ();
			}
			,get: function ()
			{
				return this._conn;
			}
		},
		/**
		 * The result index.
		 **/
		resultIndex:
		{
			type: Number
			,set: function (x)
			{
				this._resultIndex = x;
			}
			,get: function ()
			{
				return this._resultIndex;
			}
		},
		/**
		 * The batch used to execute the statement.
		 **/
		batch:
		{
			type: Sql.Batch
			,set: function (x)
			{
				this.link ({_batch: x}, {'changed': this.refresh});
				this.refresh ();
			}
			,get: function ()
			{
				return this._batch;
			}
		},
		/**
		 * The model select statement.
		 **/
		stmt:
		{
			type: Sql.Stmt
			,set: function (x)
			{
				this._stmt = x;
				this.refresh ();
			}
			,get: function ()
			{
				return this._stmt;
			}
		},
		/**
		 * The model query.
		 **/
		query:
		{
			type: String
			,set: function (x)
			{
				this._stmt = new Sql.String ({query: x});
			}
			,get: function ()
			{
				return this._stmt.render (null);
			}
		},
		/**
		 * The main table.
		 **/
		mainTable:
		{
			type: String
			,set: function (x)
			{
				this._mainTable = null;
				this.requestedMainTable = x;
				this.refreshMainTable ();
			}
			,get: function ()
			{
				return this._mainTable;
			}
		},
		/**
		 * Determines if the model is updatable.
		 **/
		updatable:
		{
			type: Boolean
			,set: function (x)
			{
				this._updatable = false;
				this.requestedUpdatable = x;
				this.refreshUpdatable ();
			}
			,get: function ()
			{
				return this._updatable;
			}
		},
		/**
		 * The number of rows in the model.
		 **/
		numRows:
		{
			type: Number
			,get: function ()
			{
				if (this.data)
					return this.data.length;
	
				return 0;
			}
		},
		/**
		 * The current status of the model.
		 **/
		status:
		{
			type: Number
			,get: function ()
			{
				return this._status;
			}
		},
		/**
		 * Checks if the model data is ready.
		 **/
		ready:
		{
			type: Boolean
			,get: function ()
			{
				return this._status == Db.Model.Status.READY;
			}
		}
	}

	,_resultIndex: 0
	,_batch: null
	,_stmt: null
	,_status: Db.Model.Status.CLEAN
	,requestedMainTable: null
	,requestedUpdatable: true
	,data: null
	,columns: null
	,columnMap: null
	,insertedRow: -1
	,defaults: []
	,columnDefaults: []
	,sortColumn: -1
	,requestedIndexes: {}
	,indexes: []

	,initialize: function (props)
	{
		this.parent (props);
		this.cleanData ();
		this.setStatus (Db.Model.Status.CLEAN);
	}

	,loadXml: function (builder, node)
	{
		this.parent (builder, node);

		var query = node.firstChild.nodeValue;
		
		if (query)
			this.query = query;
	}

	,refresh: function ()
	{
		if (this._stmt && this._batch)
			this._stmt.findHolders (this._batch);

		if (this._conn && this._stmt
		&& (!this._batch || this._batch.isReady ()))
		{
			this.setStatus (Db.Model.Status.LOADING);
			this._conn.execStmt (this._stmt, this.selectDone.bind (this), this._batch);
		}
		else
		{
			this.cleanData ();
			this.setStatus (Db.Model.Status.CLEAN);
		}
	}
	
	
	,cleanData: function (error)
	{
		this.data = null;
		this.columns = null;
		this.columnMap = null;
		this.indexes = [];
	}
	
	,refreshUpdatable: function ()
	{
		var oldValue = this._updatable;
		this._updatable = this._mainTable != null && this.requestedUpdatable;
		
		if (oldValue != this._updatable)
			this.signalEmit ('updatable-changed');
	}
	
	,refreshMainTable: function ()
	{
		var newMainTable = null;
		var newMainSchema = null;
		var x = this.columns;

		if (x)
		for (var i = 0; i < x.length; i++)
		if (x[i].flags & Db.Conn.Flag.PRI_KEY)
		if (!this.requestedMainTable
		|| x[i].table === this.requestedMainTable)
		{
			newMainTable = x[i].table;
			break;
		}

		this._mainTable = newMainTable;
		this.refreshUpdatable ();
	}

	/**
	 * Sets the default value for inserted fields.
	 *
	 * @param {String} field The destination field name
	 * @param {String} table The destination table name
	 * @param {Object} value The default value
	 **/
	,setDefaultFromValue: function (field, table, value)
	{
		this.defaults.push
		({
			 field: field
			,table: table
			,value: value
		});
	}

	/**
	 * Sets the default value for inserted fields from another column in the
	 * model.
	 *
	 * @param {String} field The destination field name
	 * @param {String} table The destination table name
	 * @param {String} srcColumn The source column
	 **/
	,setDefaultFromColumn: function (field, table, srcColumn)
	{
		this.columnDefaults.push
		({
			 field: field
			,table: table
			,srcColumn: srcColumn
		});
	}

	/**
	 * Checks if the column exists.
	 *
	 * @param {integer} column The column index
	 * @return {Boolean} %true if column exists, %false otherwise
	 **/
	,checkColExists: function (column)
	{
		return this.columns && column >= 0 && column < this.columns.length;
	}

	/**
	 * Checks if the row exists.
	 *
	 * @param {integer} row The row index
	 * @return {Boolean} %true if row exists, %false otherwise
	 **/
	,checkRowExists: function (row)
	{
		return this.data && row >= 0 && row < this.data.length;
	}

	,checkRowUpdatable: function (row)
	{
		return this.checkRowExists (row);
	}
	
	/**
	 * Get the index of the column from its name.
	 *
	 * @param {string} columnName The column name
	 * @return {number} The column index or -1 if column not exists
	 **/
	,getColumnIndex: function (columnName)
	{
		var index;

		if (this.columnMap
		&& (index = this.columnMap[columnName]) !== undefined)
			return index;

		return -1;
	}
	
	/**
	 * Gets a value from the model.
	 *
	 * @param {number} row The row index
	 * @param {string} columnName The column name
	 * @return {mixed} The value
	 **/
	,get: function (row, columnName)
	{
		var index = this.getColumnIndex (columnName);
	
		if (index != -1)
			return this.getByIndex (row, index);
			
		return undefined;
	}

	/**
	 * Updates a value on the model.
	 *
	 * @param {number} row The row index
	 * @param {string} columnName The column name
	 * @param {mixed} value The new value
	 **/
	,set: function (row, columnName, value)
	{
		var index = this.getColumnIndex (columnName);
		
		if (index != -1)
			this.setByIndex (row, index, value);
	}

	/**
	 * Gets a value from the model using the column index.
	 *
	 * @param {number} row The row index
	 * @param {number} column The column index
	 * @return {mixed} The value
	 **/
	,getByIndex: function (row, column)
	{
		if (this.checkRowExists (row) && this.checkColExists (column))
			return this.data[row][column];

		return undefined;
	}

	/**
	 * Updates a value on the model using the column index.
	 *
	 * @param {number} row The row index
	 * @param {number} col The column index
	 * @param {mixed} value The new value
	 **/
	,setByIndex: function (row, col, value)
	{
		if (!(this.checkRowUpdatable (row) && this.checkColExists (col)))
			return;

		if (row == this.insertedRow)
		{
			this.performUpdate (row, [col], [value]);
			return;
		}

		var column = this.columns[col];
		var where = this.getWhere (column.table, row, false);

		if (where)
		{
			var multiStmt = new Sql.MultiStmt ();

			var table = new Sql.Table
			({
				 name: column.orgtable
				,schema: column.db
			});

			var update = new Sql.Update ({where: where});
			update.addTarget (table);
			update.addSet (column.orgname, value);
			multiStmt.addStmt (update);
		
			var select = new Sql.Select ({where: where});
			select.addTarget (table);
			select.addField (column.orgname);
			multiStmt.addStmt (select);

			var updateData = {
				 row: row
				,columns: [col]
			};

			this._conn.execStmt (multiStmt,
				this.updateDone.bind (this, updateData));
		}
		else
			this.sendInsert (column.table, row, col, value);
	}

	/**
	 * Deletes a row from the model. 
	 *
	 * @param {number} row The row index
	 **/
	,deleteRow: function (row)
	{
		if (!this.checkRowUpdatable (row))
			return;
			
		if (row != this.insertedRow)
		{
			var where = this.getWhere (this._mainTable, row, false);

			if (where)
			{
				var deleteQuery = new Sql.Delete ({where: where});

				var table = this.getTarget (this._mainTable);
				deleteQuery.addTarget (table);

				this._conn.execStmt (deleteQuery,
					this.deleteDone.bind (this, row));
			}
		}
		else
		{
			this.performDelete (row);
			this.insertedRow = -1;
		}
	}

	/**
	 * Inserts a new row on the model.
	 *
	 * @return The index of the inserted row
	 **/
	,insertRow: function ()
	{
		if (!this._updatable || this.insertedRow != -1)
			return -1;
					
		var x = this.columns;
		var newRow = new Array (x.length);
		
		for (var i = 0; i < x.length; i++)
		if (x[i].table === this._mainTable)
			newRow[i] = x[i].def;
		else
			newRow[i] = null;
			
		this.insertedRow = this.data.push (newRow) - 1;
		this.signalEmit ('row-inserted', this.insertedRow);
	
		return this.insertedRow;
	}
	
	,performOperations: function ()
	{
		if (this.insertedRow == -1)
			return;
		
		this.sendInsert (this._mainTable, this.insertedRow, -1, null);
	}
	
	/*
	 * Function used to sort the model.
	 */
	,sortFunction: function (column, a, b)
	{
		if (a[column] < b[column])
			return -1;
		else if (a[column] > b[column])
			return 1;
			
		return 0;
	}

	/**
	 * Orders the model by the specified column.
	 *
	 * @param {integer} column the column index
	 **/
	,sort: function (column)
	{
		if (!this.checkColExists (column))
			return;
	
		this.setStatus (Db.Model.Status.LOADING);

		if (column != this.sortColumn)
		{
			this.data.sort (this.sortFunction.bind (this, column));
			this.sortColumn = column;
		}
		else
			this.data.reverse ();

		this.setStatus (Db.Model.Status.READY);
	}

	/**
	 * Builds an internal hash index for the specified column, this speeds
	 * significantly searches on that column.
	 * Not implemented yet.
	 *
	 * @param {String} column The column name
	 **/
	,indexColumn: function (column)
	{
		this.requestedIndexes[column] = true;

		if (this._status == Db.Model.Status.READY)
			this.buildIndex (column);
	}

	,buildIndex: function (column)
	{
		var columnIndex = this.getColumnIndex (column);

		if (columnIndex != -1)
		{
			var index = {};
			var data = this.data;

			switch (this.columns[columnIndex].type)
			{
				case Db.Conn.Type.TIMESTAMP:
				case Db.Conn.Type.DATE_TIME:
				case Db.Conn.Type.DATE:
					for (var i = 0; i < data.length; i++)
						index[data[i][columnIndex].toString ()] = i;
					break;
				default:
					for (var i = 0; i < data.length; i++)
						index[data[i][columnIndex]] = i;
			}

			this.indexes[columnIndex] = index;
		}
	}

	/**
	 * Searchs a value on the model and returns the row index of the first
	 * ocurrence.
	 *
	 * @param {String} column The column name
	 * @param {Object} value The value to search
	 * @return {integer} The column index
	 **/
	,search: function (column, value)
	{
		var index = this.getColumnIndex (column);
		return this.searchByIndex (index, value);
	}

	/**
	 * Searchs a value on the model and returns the row index of the first
	 * ocurrence.
	 *
	 * @param {integer} col The column index
	 * @param {Object} value The value to search
	 * @return {integer} The column index
	 **/
	,searchByIndex: function (col, value)
	{
		if (!this.checkColExists (col))
			return -1;
		
		if (value)
		switch (this.columns[col].type)
		{
			case Db.Conn.Type.BOOLEAN:
				value = !!value;
				break;
			case Db.Conn.Type.INTEGER:
				value = parseInt (value);
				break;
			case Db.Conn.Type.DOUBLE:
				value = parseFloat (value);
				break;
			default:
				value = value.toString ();
		}
		
		var index = this.indexes[col];
		
		if (index)
		{
			if (index[value])
				return index[value];
				
			return -1;
		}

		var data = this.data;
	
		switch (this.columns[col].type)
		{
			case Db.Conn.Type.TIMESTAMP:
			case Db.Conn.Type.DATE_TIME:
			case Db.Conn.Type.DATE:
			{
				for (var i = 0; i < data.length; i++)
				if (value === data[i][col].toString ());
					return i;

				break;
			}
			default:
				for (var i = 0; i < data.length; i++)
				if (value === data[i][col])
					return i;
		}
		
		return -1;
	}
	
// private:

	,setStatus: function (status)
	{
		this._status = status;
		this.signalEmit ('status-changed', status);
	}
	
	,getTarget: function (table)
	{
		var x = this.columns;
	
		for (var i = 0; i < x.length; i++)
		if (x[i].table == table)
			return new Sql.Table
			({
				 name: x[i].orgtable
				,schema: x[i].db
			});
			
		return null;
	}

	,getWhere: function (table, rowIndex, forInsert)
	{
		var keyFound = false;
		var row = this.data[rowIndex];
		var andOp = new Sql.Operation ({type: Sql.Operation.Type.AND});

		var x = this.columns;

		for (var i = 0; i < x.length; i++)
		if (x[i].flags & Db.Conn.Flag.PRI_KEY
		&& x[i].table === table)
		{
			var equalOp = new Sql.Operation ({type: Sql.Operation.Type.EQUAL});
			equalOp.exprs.add (new Sql.Field ({name: x[i].orgname}));
			andOp.exprs.add (equalOp);

			if (row[i])
				equalOp.exprs.add (new Sql.Value ({value: row[i]}));
			else if (x[i].flags & Db.Conn.Flag.AI && forInsert)
				equalOp.exprs.add (new Sql.Func ({name: 'LAST_INSERT_ID'}));
			else
				break;

			keyFound = true;
		}
		
		return (keyFound) ? andOp : null;
	}

	,sendInsert: function (table, rowIndex, singleColumn, newValue)
	{
		var where = this.getWhere (table, rowIndex, true);
		
		if (!where)
			return;

		var multiStmt = new Sql.MultiStmt ();
		var target = this.getTarget (table);

		var insert = new Sql.Insert ();
		insert.addTarget (target);
		multiStmt.addStmt (insert);

		var x = this.defaults;

		for (var i = 0; i < x.length; i++)
		if (x[i].table === table)
			insert.addSet (x[i].field, x[i].value);
			
		var x = this.columnDefaults;

		for (var i = 0; i < x.length; i++)
		if (x[i].table === table)
			insert.addSet (x[i].field, this.get (rowIndex, x[i].srcColumn));
		
		var select = new Sql.Select ({where: where});
		select.addTarget (target);
		multiStmt.addStmt (select);

		var columns = [];
		var row = this.data[rowIndex];
		var x = this.columns;

		for (var i = 0; i < x.length; i++)
		if (x[i].table === table)
		{
			var setValue = singleColumn != i ? row[i] : newValue;
		
			if (setValue)
				insert.addSet (x[i].orgname, setValue);

			select.addField (x[i].orgname);
			columns.push (i);
		}

		var updateData = {
			 row: rowIndex
			,columns: columns
		};

		this._conn.execStmt (multiStmt,
			this.updateDone.bind (this, updateData));
	}

	,selectDone: function (resultSet)
	{
		var result;
		var dataResult;
		
		this.cleanData ();

		for (var i = 0; result = resultSet.fetchResult (); i++)
			if (i == this._resultIndex)
				dataResult = result;

		if (dataResult && typeof dataResult === 'object')
		{
			this.sortColumn = -1;
			this.data = dataResult.data;
			this.columns = dataResult.columns;
			this.columnMap = dataResult.columnMap;
			this.repairColumns (this.columns);
			this.refreshMainTable ();
			
			for (column in this.requestedIndexes)
				this.buildIndex (column);
			
			this.setStatus (Db.Model.Status.READY);
		}
		else
			this.setStatus (Db.Model.Status.ERROR);
	}

	,updateDone: function (updateData, resultSet)
	{
		var newValues;

		if (resultSet.fetchResult () && (newValues = resultSet.fetchRow ()))
			this.performUpdate (updateData.row, updateData.columns, newValues);
	}

	,performUpdate: function (rowIndex, columns, newValues)
	{
		this.signalEmit ('row-updated-before', rowIndex);

		var row = this.data[rowIndex];

		for (var i = 0; i < columns.length; i++)
			row[columns[i]] = newValues[i];

		this.signalEmit ('row-updated', rowIndex, columns);
	}

	,deleteDone: function (rowIndex, resultSet)
	{
		if (resultSet.fetchResult())
			this.performDelete (rowIndex);
	}
	
	,performDelete: function (rowIndex)
	{
		var row = this.data[rowIndex];

		if (!this.requestedMainTable)
		{
			this.signalEmit ('row-deleted-before', rowIndex);
			this.data.splice (rowIndex, 1);
			this.signalEmit ('row-deleted', rowIndex);
		}
		else
		{
			this.signalEmit ('row-updated-before', rowIndex);

			var columns = [];

			for (var i = 0; i < this.columns.length; i++)
			if (this.columns[i].table == this._mainTable)
			{
				row[i] = null;
				columns.push (i);
			}

			this.signalEmit ('row-updated', rowIndex, columns);
		}
	}

// Delete when MySQL FLAG and view orgname "bugs" are repaired:
	
	,tableInfo: {}
	,fieldFlags: {}
	
	,setTableInfo: function (table, orgtable, db)
	{
		this.tableInfo[table] =
		({
			 orgtable: orgtable
			,db: db
		});
	}

	,setFieldFlags: function (field, flags)
	{
		this.fieldFlags[field] = flags;
	}

	,repairColumns: function (columns)
	{
		for (var i = 0; i < columns.length; i++)
		{
			var newFlags = this.fieldFlags[columns[i].name];
			
			if (newFlags)
				columns[i].flags |= newFlags;
				
			var tableInfo = this.tableInfo[columns[i].table];
			
			if (tableInfo)
			{
				columns[i].orgtable = tableInfo.orgtable;
				columns[i].db = tableInfo.db;
			}				
		}
	}
});