package org.expeditee.core;

import org.expeditee.core.bounds.AxisAlignedBoxBounds;

/**
 * Class for anchoring the position of items within the frame. Anchoring is when
 * the position of the item is defined relative to the edge of the frame instead
 * of being defined in absolute coordinates. Can't be anchored to the left and
 * right edge at the same time, nor the top and bottom edge at the same time.
 * 
 * @author cts16
 */
public class Anchoring {
	
	private enum VerticalDirection { left, center, right }
	private enum HorizontalDirection { top, center, bottom }

	/**
	 * The relative distance from the left, center or right edge (null means unanchored).
	 */
	private Integer _xAnchor = null;
	/**
	 * The relative distance from the top, center or bottom edge (null means unanchored).
	 */
	private Integer _yAnchor = null;

	/** Whether the x-anchor is relative to the left or right edge. */
	private VerticalDirection verticalDirection = VerticalDirection.left;
	/** Whether the y-anchor is relative to the top or bottom edge. */
	private HorizontalDirection horizonalDirection = HorizontalDirection.top;

	public Anchoring() {
	}
	
	public void setXAnchor(Anchoring other) {
		if (other == null) {
			return;
		}
		
		setXAnchor(other._xAnchor, other.verticalDirection);
	}

	public void setYAnchor(Anchoring other) {
		if (other == null)
			return;

		setYAnchor(other._yAnchor, other.horizonalDirection);
	}

	public void setLeftAnchor(Integer offset) {
		setXAnchor(offset, VerticalDirection.left);
	}
	
	public void setCenterXAnchor(Integer offset) {
		setXAnchor(offset, VerticalDirection.center);
	}

	public void setRightAnchor(Integer offset) {
		setXAnchor(offset, VerticalDirection.right);
	}

	public void setTopAnchor(Integer offset) {
		setYAnchor(offset, HorizontalDirection.top);
	}
	
	public void setCenterYAnchor(Integer offset) {
		setYAnchor(offset, HorizontalDirection.center);
	}

	public void setBottomAnchor(Integer offset) {
		setYAnchor(offset, HorizontalDirection.bottom);
	}
	
	public void removeXAnchor() {
		setXAnchor(null, verticalDirection);
	}

	public void removeYAnchor() {
		setYAnchor(null, horizonalDirection);
	}

	public void removeAllAnchors() {
		removeXAnchor();
		removeYAnchor();
	}

	public Point getPositionInBox(AxisAlignedBoxBounds box) {
		Integer x = getXPositionInBox(box);
		Integer y = getYPositionInBox(box);

		if (x == null || y == null)
			return null;

		return new Point(x, y);
	}

	public boolean isXAnchored() {
		return _xAnchor != null;
	}

	public boolean isYAnchored() {
		return _yAnchor != null;
	}

	public boolean isAnchored() {
		return isXAnchored() || isYAnchored();
	}
	
	public Integer getLeftAnchor() {
		return verticalDirection.equals(VerticalDirection.left) ? _xAnchor : null;
	}
	
	public Integer getCenterXAnchor() {
		return verticalDirection.equals(VerticalDirection.center) ? _xAnchor : null;
	}

	public Integer getRightAnchor() {
		return verticalDirection.equals(VerticalDirection.right) ? _xAnchor : null;
	}

	public Integer getTopAnchor() {
		return horizonalDirection.equals(HorizontalDirection.top) ? _yAnchor : null;
	}
	
	public Integer getCenterYAnchor() {
		return horizonalDirection.equals(HorizontalDirection.center) ? _yAnchor : null;
	}
	
	public Integer getBottomAnchor() {
		return horizonalDirection.equals(HorizontalDirection.bottom) ? _yAnchor : null;
	}
			
	private void setXAnchor(Integer offset, VerticalDirection left) {
		_xAnchor = offset;
		verticalDirection = left;
	}

	private void setYAnchor(Integer offset, HorizontalDirection top) {
		_yAnchor = offset;
		horizonalDirection = top;
	}
	
	private Integer getXPositionInBox(AxisAlignedBoxBounds box) {
		if (box == null || _xAnchor == null)
			return null;
		
		switch (verticalDirection) {
		case left:
			return box.getMinX() + _xAnchor;
		case center:
			return box.getCentreX() + _xAnchor;
		case right:
			return box.getMaxX() - _xAnchor;
		default:
			System.err.println("Anchoring::getXPositionInBox::VerticalDirection does not match available options.  Has the enum been updated without this function being updated?");
			return null;
		}
	}
	
	private Integer getYPositionInBox(AxisAlignedBoxBounds box) {
		if (box == null || _yAnchor == null) {
			return null;
		}
		
		switch (horizonalDirection) {
		case top:
			return box.getMinY() + _yAnchor;
		case center:
			return box.getCentreY() + _yAnchor;
		case bottom:
			return box.getMaxY() - _yAnchor;
		default:
			System.err.println("Anchoring::getYPositionInBox::HorizonalDirection does not match available options.  Has the enum been updated without this function being updated?");
			return null;
		}
	}
}