package org.eclipse.jface.layout;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.layout.FormAttachment;
import org.eclipse.swt.layout.FormData;
import org.eclipse.swt.widgets.Control;

/**
 * The FormDataBuilder creates and initializes FormData for a particular control. Instances are
 * created using one of the static method in this class.
 * 
 * @since 3.4
 */
public final class FormDataBuilder {
    private final FormData data;
    private final Control control;
    private boolean centerVertically = false;
    private int vertical;
    private boolean centerHorizontally = false;
    private int horizontal;

    private FormDataBuilder(Control control) {
        this.control = control;
        this.data = new FormData();
        control.setLayoutData(data);
    }

    /**
     * Creates a new FormDataBuilder to attach the given control to points within the layout.
     * 
     * @param control the control
     * 
     * @return this
     */
    public static FormDataBuilder position(Control control) {
        if (control == null) {
            throw new IllegalArgumentException("Control cannot be null");
        }
        return new FormDataBuilder(control);
    }

    /**
     * Sets the minimum size of the control. If SWT.DEFAULT is used for the width or height, the
     * preferred size will be used for that parameter.
     * 
     * @param width the minimum width
     * @param height the minimum height
     * @return this
     */
    public FormDataBuilder size(int width, int height) {
        if ((width != SWT.DEFAULT && width < 0) || (height != SWT.DEFAULT && height < 0)) {
            throw new IllegalArgumentException();
        }
        checkData();
        data.width = width;
        data.height = height;
        applyCentering();
        return this;
    }

    /**
     * Sets the minimum size of the control. If SWT.DEFAULT is used for the width or height, the
     * preferred size will be used for that parameter.
     * 
     * @param size the minimum size
     * @return this
     */
    public FormDataBuilder size(Point size) {
        return size(size.x, size.y);
    }

    /**
     * Sets the minimum width of the control. If SWT.DEFAULT is given, preferred size will be used.
     * 
     * @param width the minimum width
     * @return this
     */
    public FormDataBuilder width(int width) {
        if (width != SWT.DEFAULT && width < 0) {
            throw new IllegalArgumentException();
        }
        checkData();
        data.width = width;
        applyCentering();
        return this;
    }

    /**
     * Sets the minimum height of the control. If SWT.DEFAULT is given, preferred size will be used.
     * 
     * @param height the minimum height
     * @return this
     */
    public FormDataBuilder height(int height) {
        if (height != SWT.DEFAULT && height < 0) {
            throw new IllegalArgumentException();
        }
        checkData();
        data.height = height;
        applyCentering();
        return this;
    }

    /**
     * Horizontally centers the control given its current computed size.
     * 
     * @return this
     */
    public FormDataBuilder centerHorizontally() {
        return centerHorizontally(50);
    }

    /**
     * Horizontally centers the control to the position of the given percentage given its current
     * computed size.
     * 
     * @param percentage the percentage
     * @return this
     */
    public FormDataBuilder centerHorizontally(int percentage) {
        checkData();
        centerHorizontally = true;
        horizontal = percentage;
        applyCentering();
        return this;
    }

    /**
     * Vertically centers the control given its current computed size.
     * 
     * @return this
     */
    public FormDataBuilder centerVertically() {
        return centerVertically(50);
    }

    /**
     * Vertically centers the control to the position of the given percentage given its current
     * computed size.
     * 
     * @param percentage the percentage
     * @return this
     */
    public FormDataBuilder centerVertically(int percentage) {
        checkData();
        centerVertically = true;
        vertical = percentage;
        applyCentering();
        return this;
    }

    /**
     * Connects the left side of the control to the left side of the parent composite.
     * 
     * @return this
     */
    public FormDataBuilder left() {
        return left(0);
    }

    /**
     * Connects the left side of the control to the position of the given percentage. Thus a value
     * of 75 would attach the side to an invisible line 75% of the way across the parent composite.
     * 
     * @param percentage the percentage
     * @return this
     */
    public FormDataBuilder left(int percentage) {
        checkData();
        clearHorizontalCentering();
        data.left = new FormAttachment(percentage);
        return this;
    }

    /**
     * Attaches the left side of this control to the right side of the given control, with no
     * padding between them.
     * 
     * @param control the control to which to attach
     * @return this
     */
    public FormDataBuilder left(Control control) {
        return left(control, 0, SWT.RIGHT);
    }

    /**
     * Attaches the left side of this control to the right side of the given control, with the given
     * amount of padding between them.
     * 
     * @param control the control to which to attach
     * @param padding the padding between the controls
     * @return this
     */
    public FormDataBuilder left(Control control, int padding) {
        return left(control, padding, SWT.RIGHT);
    }

    /**
     * Attaches the left side of this control to the side of the given control, with the given
     * amount of padding between them. The side of the given control that we are attaching to is
     * given by the alignment, which will be one of SWT.LEFT, SWT.CENTER, or SWT.RIGHT.
     * 
     * @param control the control to which to attach
     * @param padding the padding between the controls
     * @param alignment the side of the control to which to attach
     * @return this
     * 
     * @throws IllegalArgumentException if the alignment is not one of the specified values.
     */
    public FormDataBuilder left(Control control, int padding, int alignment) {
        if (alignment != SWT.LEFT && alignment != SWT.RIGHT && alignment != SWT.CENTER) {
            throw new IllegalArgumentException();
        }
        checkData();
        clearHorizontalCentering();
        data.left = new FormAttachment(control, padding, alignment);
        return this;
    }

    /**
     * Connects the right side of the control to the right side of the parent composite.
     * 
     * @return this
     */
    public FormDataBuilder right() {
        return right(100);
    }

    /**
     * Connects the right side of the control to the position of the given percentage. Thus a value
     * of 75 would attach the side to an invisible line 75% of the way across the parent composite.
     * 
     * @param percentage the percentage
     * @return this
     */
    public FormDataBuilder right(int percentage) {
        checkData();
        clearHorizontalCentering();
        data.right = new FormAttachment(percentage);
        return this;
    }

    /**
     * Attaches the right side of this control to the left side of the given control, with no
     * padding between them.
     * 
     * @param control the control to which to attach
     * @return this
     */
    public FormDataBuilder right(Control control) {
        return right(control, 0, SWT.LEFT);
    }

    /**
     * Attaches the right side of this control to the left side of the given control, with the given
     * amount of padding between them.
     * 
     * @param control the control to which to attach
     * @param padding the padding between the controls
     * @return this
     */
    public FormDataBuilder right(Control control, int padding) {
        return right(control, padding, SWT.LEFT);
    }

    /**
     * Attaches the right side of this control to the side of the given control, with the given
     * amount of padding between them. The side of the given control that we are attaching to is
     * given by the alignment, which will be one of SWT.RIGHT, SWT.CENTER, or SWT.LEFT.
     * 
     * @param control the control to which to attach
     * @param padding the padding between the controls
     * @param alignment the side of the control to which to attach
     * @return this
     * 
     * @throws IllegalArgumentException if the alignment is not one of the specified values.
     */
    public FormDataBuilder right(Control control, int padding, int alignment) {
        if (alignment != SWT.RIGHT && alignment != SWT.LEFT && alignment != SWT.CENTER) {
            throw new IllegalArgumentException();
        }
        checkData();
        clearHorizontalCentering();
        data.right = new FormAttachment(control, -1 * padding, alignment);
        return this;
    }

    /**
     * Connects the top side of the control to the top of the parent composite.
     * 
     * @return this
     */
    public FormDataBuilder top() {
        return top(0);
    }

    /**
     * Connects the top side of the control to the position of the given percentage. Thus a value of
     * 75 would attach the side to an invisible line 75% of the way across the parent composite.
     * 
     * @param percentage the percentage
     * @return this
     */
    public FormDataBuilder top(int percentage) {
        checkData();
        clearVerticalCentering();
        data.top = new FormAttachment(percentage);
        return this;
    }

    /**
     * Attaches the top side of this control to the bottom side of the given control, with no
     * padding between them.
     * 
     * @param control the control to which to attach
     * @return this
     */
    public FormDataBuilder top(Control control) {
        return top(control, 0, SWT.BOTTOM);
    }

    /**
     * Attaches the top side of this control to the bottom side of the given control, with the given
     * amount of padding between them.
     * 
     * @param control the control to which to attach
     * @param padding the padding between the controls
     * @return this
     */
    public FormDataBuilder top(Control control, int padding) {
        return top(control, padding, SWT.BOTTOM);
    }

    /**
     * Attaches the top side of this control to the side of the given control, with the given amount
     * of padding between them. The side of the given control that we are attaching to is given by
     * the alignment, which will be one of SWT.TOP, SWT.CENTER, or SWT.BOTTOM.
     * 
     * @param control the control to which to attach
     * @param padding the padding between the controls
     * @param alignment the side of the control to which to attach
     * @return this
     * 
     * @throws IllegalArgumentException if the alignment is not one of the specified values.
     */
    public FormDataBuilder top(Control control, int padding, int alignment) {
        if (alignment != SWT.TOP && alignment != SWT.BOTTOM && alignment != SWT.CENTER) {
            throw new IllegalArgumentException();
        }
        checkData();
        clearVerticalCentering();
        data.top = new FormAttachment(control, padding, alignment);
        return this;
    }

    /**
     * Connects the bottom side of the control to the bottom of the parent composite.
     * 
     * @return this
     */
    public FormDataBuilder bottom() {
        return bottom(100);
    }

    /**
     * Connects the bottom side of the control to the position of the given percentage. Thus a value
     * of 75 would attach the side to an invisible line 75% of the way across the parent composite.
     * 
     * @param percentage the percentage
     * @return this
     */
    public FormDataBuilder bottom(int percentage) {
        checkData();
        clearVerticalCentering();
        data.bottom = new FormAttachment(percentage);
        return this;
    }

    /**
     * Attaches the bottom side of this control to the top side of the given control, with no
     * padding between them.
     * 
     * @param control the control to which to attach
     * @return this
     */
    public FormDataBuilder bottom(Control control) {
        return bottom(control, 0, SWT.TOP);
    }

    /**
     * Attaches the bottom side of this control to the top side of the given control, with the given
     * amount of padding between them.
     * 
     * @param control the control to which to attach
     * @param padding the padding between the controls
     * @return this
     */
    public FormDataBuilder bottom(Control control, int padding) {
        return bottom(control, padding, SWT.TOP);
    }

    /**
     * Attaches the bottom side of this control to the side of the given control, with the given
     * amount of padding between them. The side of the given control that we are attaching to is
     * given by the alignment, which will be one of SWT.TOP, SWT.CENTER, or SWT.BOTTOM.
     * 
     * @param control the control to which to attach
     * @param padding the padding between the controls
     * @param alignment the side of the control to which to attach
     * @return this
     * 
     * @throws IllegalArgumentException if the alignment is not one of the specified values.
     */
    public FormDataBuilder bottom(Control control, int padding, int alignment) {
        if (alignment != SWT.TOP && alignment != SWT.BOTTOM && alignment != SWT.CENTER) {
            throw new IllegalArgumentException();
        }
        checkData();
        clearVerticalCentering();
        data.bottom = new FormAttachment(control, -1 * padding, alignment);
        return this;
    }

    private final void applyCentering() {
        Point size = control.computeSize(data.width, data.height);
        if (centerHorizontally) {
            data.left = new FormAttachment(horizontal, -size.x / 2);
            data.right = new FormAttachment(horizontal, size.x / 2);
        }
        if (centerVertically) {
            data.top = new FormAttachment(vertical, -size.y / 2);
            data.bottom = new FormAttachment(vertical, size.y / 2);
        }
        control.setLayoutData(data);
    }

    private final void clearVerticalCentering() {
        if (centerVertically) {
            centerVertically = false;
            data.top = null;
            data.bottom = null;
        }
    }

    private final void clearHorizontalCentering() {
        if (centerHorizontally) {
            centerHorizontally = false;
            data.left = null;
            data.right = null;
        }
    }

    private final void checkData() {
        if (control.getLayoutData() != data) {
            throw new IllegalStateException(
                "The data associated to the control is not the data created by the builder.");
        }
    }
}