/**
 * GridFieldManager.java
 * Version 1.1
 * 
 * Copyright 2008 by Anthony Rizk
 * http://www.thinkingblackberry.com
 * 
 * Changes:
 * V1.1 - added constructor with column widths
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License (LGPL) as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.thinkingblackberry;

import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.Manager;

public class GridFieldManager extends Manager {
	private int[] columnWidths;
	private int columns;
	private int allRowHeight = -1;
	
	/**
	 * Constructs a new GridFieldManager with the specified number of columns.
	 * Rows will be added as needed to display fields.
	 * Fields will be added to the grid in the order they are added to this manager,
	 * filling up each row left-to-right:
	 * 
	 * For example a 2 column manager:
	 * 
	 * [Field1][Field2]
	 * [Field3][Field4]
	 * [Field5]
	 * 
	 * Column widths are all equal, and the manager will attempt to use all available width.
	 * The height of each row will be equal to the height of the tallest Field in that row.
	 * Field positional styles are respected, so fields that are smaller than the row/column
	 * they are in can be positioned left, right, top bottom, or centered.  They default to top left.
	 * 
	 * @param columns Number of columns in the grid
	 * @param style
	 */
	public GridFieldManager(int columns, long style) {
		super(style);
		this.columns = columns;
	}
	
	
	public GridFieldManager(int[] columnWidths, long style) {
		super(style);
		this.columnWidths = columnWidths;
		this.columns = columnWidths.length;
	}
	
	public GridFieldManager(int[] columnWidths, int rowHeight, long style) {
		this(columnWidths, style);
		this.allRowHeight  = rowHeight;
	}
	
	protected boolean navigationMovement(int dx, int dy, int status, int time) {
		
		int focusIndex = getFieldWithFocusIndex();
		while(dy > 0) {
			focusIndex += columns;
			if (focusIndex >= getFieldCount()) {
				return false; // Focus moves out of this manager
			}
			else {
				Field f = getField(focusIndex);
				if (f.isFocusable()) { // Only move the focus onto focusable fields
					f.setFocus();
					dy--;
				}
			}
		}
		while(dy < 0) {
			focusIndex -= columns;
			if (focusIndex < 0) {
				return false;
			}
			else {
				Field f = getField(focusIndex);
				if (f.isFocusable()) {
					f.setFocus();
					dy++;
				}
			}
		}
		
		while(dx > 0) {
			focusIndex ++;
			if (focusIndex >= getFieldCount()) {
				return false;
			}
			else {
				Field f = getField(focusIndex);
				if (f.isFocusable()) {
					f.setFocus();
					dx--;
				}
			}
		}
		while(dx < 0) {
			focusIndex --;
			if (focusIndex < 0) {
				return false;
			}
			else {
				Field f = getField(focusIndex);
				if (f.isFocusable()) {
					f.setFocus();
					dx++;
				}
			}
		}
		return true;
	}

	
	protected void sublayout(int width, int height) {
		int y = 0;
		if (columnWidths == null) {
			columnWidths = new int[columns];
			for(int i = 0; i < columns; i++) {
				columnWidths[i] = width/columns;
			}
		}
		Field[] fields = new Field[columnWidths.length];
		int currentColumn = 0;
		int rowHeight = 0;
		for(int i = 0; i < getFieldCount(); i++) {
			fields[currentColumn] = getField(i);
			layoutChild(fields[currentColumn], columnWidths[currentColumn], height-y);
			if (fields[currentColumn].getHeight() > rowHeight) {
				rowHeight = fields[currentColumn].getHeight();
			}
			currentColumn++;
			if (currentColumn == columnWidths.length || i == getFieldCount()-1) {
				int x = 0;
				if (this.allRowHeight >= 0) {
					rowHeight = this.allRowHeight;
				}
				for(int c = 0; c < currentColumn; c++) {
					long fieldStyle = fields[c].getStyle();
					int fieldXOffset = 0;
					long fieldHalign = fieldStyle & Field.FIELD_HALIGN_MASK;
					if (fieldHalign == Field.FIELD_RIGHT) {
						fieldXOffset = columnWidths[c] - fields[c].getWidth();
					}
					else if (fieldHalign == Field.FIELD_HCENTER) {
						fieldXOffset = (columnWidths[c]-fields[c].getWidth())/2;
					}
					
					int fieldYOffset = 0;
					long fieldValign = fieldStyle & Field.FIELD_VALIGN_MASK;
					if (fieldValign == Field.FIELD_BOTTOM) {
						fieldYOffset = rowHeight - fields[c].getHeight();
					}
					else if (fieldValign == Field.FIELD_VCENTER) {
						fieldYOffset = (rowHeight-fields[c].getHeight())/2;
					}
					
					setPositionChild(fields[c], x+fieldXOffset, y + fieldYOffset);
					x += columnWidths[c];
				}
				currentColumn = 0;
				y += rowHeight;
			}
			if (y >= height) {
				break;
			}
		}
		int totalWidth = 0;
		for(int i = 0; i < columnWidths.length; i++) {
			totalWidth += columnWidths[i];
		}
		setExtent(totalWidth, Math.min(y, height));
	}
}