// Copyright 2006 by Basil Vandegriend.  All rights reserved.

package com.basilv.core.richui;

import java.awt.Component;
import java.awt.Container;

import javax.swing.Spring;
import javax.swing.SpringLayout;

import com.basilv.core.Assert;

/**
 * Provides utility methods for creating form or grid-style layouts with SpringLayout.
 * 
 * From http://java.sun.com/docs/books/tutorial/uiswing/layout/example-1dot4/SpringUtilities.java
 */
public class SpringLayoutUtilities
{

	/**
	 * Aligns the first <code>rows</code> * <code>cols</code>
	 * components of <code>parent</code> in
	 * a grid. Each component is as big as the maximum
	 * preferred width and height of the components.
	 * The parent is made just big enough to fit them all.
	 *
	 * @param parent  Cannot be null. Must have a layout that is an instance of SpringLayout.
	 * @param rows  number of rows
	 * @param cols  number of columns
	 * @param initialX  x location to start the grid at
	 * @param initialY  y location to start the grid at
	 * @param xPad  x padding between cells
	 * @param yPad  y padding between cells
	 */
	public static void makeGrid(Container parent, int rows, int cols, int initialX, int initialY, int xPad, int yPad) {
		Assert.notNull("parent", parent);
		Assert.isTrue("parent's layout must be a Spring Layout", parent.getLayout() instanceof SpringLayout);

		SpringLayout layout = (SpringLayout) parent.getLayout();

		Spring xPadSpring = Spring.constant(xPad);
		Spring yPadSpring = Spring.constant(yPad);
		Spring initialXSpring = Spring.constant(initialX);
		Spring initialYSpring = Spring.constant(initialY);
		int max = rows * cols;

		// Calculate Springs that are the max of the width/height so that all
		// cells have the same size.
		Spring maxWidthSpring = layout.getConstraints(parent.getComponent(0)).getWidth();
		Spring maxHeightSpring = layout.getConstraints(parent.getComponent(0)).getWidth();
		for (int i = 1; i < max; i++) {
			SpringLayout.Constraints cons = layout.getConstraints(parent.getComponent(i));

			maxWidthSpring = Spring.max(maxWidthSpring, cons.getWidth());
			maxHeightSpring = Spring.max(maxHeightSpring, cons.getHeight());
		}

		// Apply the new width/height Spring. This forces all the
		// components to have the same size.
		for (int i = 0; i < max; i++) {
			SpringLayout.Constraints cons = layout.getConstraints(parent.getComponent(i));

			cons.setWidth(maxWidthSpring);
			cons.setHeight(maxHeightSpring);
		}

		// Then adjust the x/y constraints of all the cells so that they
		// are aligned in a grid.
		SpringLayout.Constraints lastCons = null;
		SpringLayout.Constraints lastRowCons = null;
		for (int i = 0; i < max; i++) {
			SpringLayout.Constraints cons = layout.getConstraints(parent.getComponent(i));
			if (i % cols == 0) { //start of new row
				lastRowCons = lastCons;
				cons.setX(initialXSpring);
			} else { //x position depends on previous component
				cons.setX(Spring.sum(lastCons.getConstraint(SpringLayout.EAST), xPadSpring));
			}

			if (i / cols == 0) { //first row
				cons.setY(initialYSpring);
			} else { //y position depends on previous row
				cons.setY(Spring.sum(lastRowCons.getConstraint(SpringLayout.SOUTH), yPadSpring));
			}
			lastCons = cons;
		}

		// Set the parent's size.
		SpringLayout.Constraints pCons = layout.getConstraints(parent);
		pCons.setConstraint(SpringLayout.SOUTH, Spring.sum(Spring.constant(yPad), lastCons
			.getConstraint(SpringLayout.SOUTH)));
		pCons.setConstraint(SpringLayout.EAST, Spring.sum(Spring.constant(xPad), lastCons
			.getConstraint(SpringLayout.EAST)));
	}

	/**
	 * Aligns the first <code>rows</code> * <code>cols</code>
	 * components of <code>parent</code> in
	 * a grid. Each component in a column is as wide as the maximum
	 * preferred width of the components in that column;
	 * height is similarly determined for each row.
	 * The parent is made just big enough to fit them all.
	 *
	 * @param parent  Cannot be null. Must have a layout that is an instance of SpringLayout.
	 * @param rows  number of rows
	 * @param cols  number of columns
	 * @param initialX  x location to start the grid at
	 * @param initialY  y location to start the grid at
	 * @param xPad  x padding between cells
	 * @param yPad  y padding between cells
	 */
	public static void makeCompactGrid(Container parent, int rows, int cols, int initialX, int initialY, int xPad,
		int yPad) {
		Assert.notNull("parent", parent);
		Assert.isTrue("parent's layout must be a Spring Layout", parent.getLayout() instanceof SpringLayout);

		SpringLayout layout = (SpringLayout) parent.getLayout();

		// Align all cells in each column and make them the same width.
		Spring x = Spring.constant(initialX);
		for (int c = 0; c < cols; c++) {
			Spring width = Spring.constant(0);
			for (int r = 0; r < rows; r++) {
				width = Spring.max(width, getConstraintsForCell(r, c, parent, cols).getWidth());
			}
			for (int r = 0; r < rows; r++) {
				SpringLayout.Constraints constraints = getConstraintsForCell(r, c, parent, cols);
				constraints.setX(x);
				constraints.setWidth(width);
			}
			x = Spring.sum(x, Spring.sum(width, Spring.constant(xPad)));
		}

		// Align all cells in each row and make them the same height.
		Spring y = Spring.constant(initialY);
		for (int r = 0; r < rows; r++) {
			Spring height = Spring.constant(0);
			for (int c = 0; c < cols; c++) {
				height = Spring.max(height, getConstraintsForCell(r, c, parent, cols).getHeight());
			}
			for (int c = 0; c < cols; c++) {
				SpringLayout.Constraints constraints = getConstraintsForCell(r, c, parent, cols);
				constraints.setY(y);
				constraints.setHeight(height);
			}
			y = Spring.sum(y, Spring.sum(height, Spring.constant(yPad)));
		}

		// Set the parent's size.
		SpringLayout.Constraints pCons = layout.getConstraints(parent);
		pCons.setConstraint(SpringLayout.SOUTH, y);
		pCons.setConstraint(SpringLayout.EAST, x);
	}

	/* Used by makeCompactGrid. */
	private static SpringLayout.Constraints getConstraintsForCell(int row, int col, Container parent, int cols) {
		SpringLayout layout = (SpringLayout) parent.getLayout();
		Component c = parent.getComponent(row * cols + col);
		return layout.getConstraints(c);
	}
	
}
