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package javax.swing.text;

import java.util.Vector;

import java.awt.*;

import javax.swing.event.*;

import javax.swing.SwingConstants;

/**

 * <code>CompositeView</code> is an abstract <code>View</code>

 * implementation which manages one or more child views.

 * (Note that <code>CompositeView</code> is intended

 * for managing relatively small numbers of child views.)

 * <code>CompositeView</code> is intended to be used as

 * a starting point for <code>View</code> implementations,

 * such as <code>BoxView</code>, that will contain child

 * <code>View</code>s. Subclasses that wish to manage the

 * collection of child <code>View</code>s should use the

 * {@link #replace} method.  As <code>View</code> invokes

 * <code>replace</code> during <code>DocumentListener</code>

 * notification, you normally won't need to directly

 * invoke <code>replace</code>.

 *

 * <p>While <code>CompositeView</code>

 * does not impose a layout policy on its child <code>View</code>s,

 * it does allow for inseting the child <code>View</code>s

 * it will contain.  The insets can be set by either

 * {@link #setInsets} or {@link #setParagraphInsets}.

 *

 * <p>In addition to the abstract methods of

 * {@link javax.swing.text.View},

 * subclasses of <code>CompositeView</code> will need to

 * override:

 * <ul>

 * <li>{@link #isBefore} - Used to test if a given

 *     <code>View</code> location is before the visual space

 *     of the <code>CompositeView</code>.

 * <li>{@link #isAfter} - Used to test if a given

 *     <code>View</code> location is after the visual space

 *     of the <code>CompositeView</code>.

 * <li>{@link #getViewAtPoint} - Returns the view at

 *     a given visual location.

 * <li>{@link #childAllocation} - Returns the bounds of

 *     a particular child <code>View</code>.

 *     <code>getChildAllocation</code> will invoke

 *     <code>childAllocation</code> after offseting

 *     the bounds by the <code>Inset</code>s of the

 *     <code>CompositeView</code>.

 * </ul>

 *

 * @author  Timothy Prinzing

 */

public abstract class CompositeView extends View {

    /**

     * Constructs a <code>CompositeView</code> for the given element.

     *

     * @param elem  the element this view is responsible for

     */

    public CompositeView(Element elem) {

        super(elem);

        children = new View[1];

        nchildren = 0;

        childAlloc = new Rectangle();

    }

    /**

     * Loads all of the children to initialize the view.

     * This is called by the {@link #setParent}

     * method.  Subclasses can reimplement this to initialize

     * their child views in a different manner.  The default

     * implementation creates a child view for each

     * child element.

     *

     * @param f the view factory

     * @see #setParent

     */

    protected void loadChildren(ViewFactory f) {

        if (f == null) {

            // No factory. This most likely indicates the parent view

            // has changed out from under us, bail!

            return;

        }

        Element e = getElement();

        int n = e.getElementCount();

        if (n > 0) {

            View[] added = new View[n];

            for (int i = 0; i < n; i++) {

                added[i] = f.create(e.getElement(i));

            }

            replace(0, 0, added);

        }

    }

    // --- View methods ---------------------------------------------

    /**

     * Sets the parent of the view.

     * This is reimplemented to provide the superclass

     * behavior as well as calling the <code>loadChildren</code>

     * method if this view does not already have children.

     * The children should not be loaded in the

     * constructor because the act of setting the parent

     * may cause them to try to search up the hierarchy

     * (to get the hosting <code>Container</code> for example).

     * If this view has children (the view is being moved

     * from one place in the view hierarchy to another),

     * the <code>loadChildren</code> method will not be called.

     *

     * @param parent the parent of the view, <code>null</code> if none

     */

    public void setParent(View parent) {

        super.setParent(parent);

        if ((parent != null) && (nchildren == 0)) {

            ViewFactory f = getViewFactory();

            loadChildren(f);

        }

    }

    /**

     * Returns the number of child views of this view.

     *

     * @return the number of views >= 0

     * @see #getView

     */

    public int getViewCount() {

        return nchildren;

    }

    /**

     * Returns the n-th view in this container.

     *

     * @param n the number of the desired view, >= 0 && < getViewCount()

     * @return the view at index <code>n</code>

     */

    public View getView(int n) {

        return children[n];

    }

    /**

     * Replaces child views.  If there are no views to remove

     * this acts as an insert.  If there are no views to

     * add this acts as a remove.  Views being removed will

     * have the parent set to <code>null</code>,

     * and the internal reference to them removed so that they

     * may be garbage collected.

     *

     * @param offset the starting index into the child views to insert

     *   the new views; >= 0 and <= getViewCount

     * @param length the number of existing child views to remove;

     *   this should be a value >= 0 and <= (getViewCount() - offset)

     * @param views the child views to add; this value can be

     *  <code>null</code>

     *   to indicate no children are being added (useful to remove)

     */

    public void replace(int offset, int length, View[] views) {

        // make sure an array exists

        if (views == null) {

            views = ZERO;

        }

        // update parent reference on removed views

        for (int i = offset; i < offset + length; i++) {

            if (children[i].getParent() == this) {

                // in FlowView.java view might be referenced

                // from two super-views as a child. see logicalView

                children[i].setParent(null);

            }

            children[i] = null;

        }

        // update the array

        int delta = views.length - length;

        int src = offset + length;

        int nmove = nchildren - src;

        int dest = src + delta;

        if ((nchildren + delta) >= children.length) {

            // need to grow the array

            int newLength = Math.max(2*children.length, nchildren + delta);

            View[] newChildren = new View[newLength];

            System.arraycopy(children, 0, newChildren, 0, offset);

            System.arraycopy(views, 0, newChildren, offset, views.length);

            System.arraycopy(children, src, newChildren, dest, nmove);

            children = newChildren;

        } else {

            // patch the existing array

            System.arraycopy(children, src, children, dest, nmove);

            System.arraycopy(views, 0, children, offset, views.length);

        }

        nchildren = nchildren + delta;

        // update parent reference on added views

        for (int i = 0; i < views.length; i++) {

            views[i].setParent(this);

        }

    }

    /**

     * Fetches the allocation for the given child view to

     * render into. This enables finding out where various views

     * are located.

     *

     * @param index the index of the child, >= 0 && < getViewCount()

     * @param a  the allocation to this view

     * @return the allocation to the child

     */

    public Shape getChildAllocation(int index, Shape a) {

        Rectangle alloc = getInsideAllocation(a);

        childAllocation(index, alloc);

        return alloc;

    }

    /**

     * Provides a mapping from the document model coordinate space

     * to the coordinate space of the view mapped to it.

     *

     * @param pos the position to convert >= 0

     * @param a the allocated region to render into

     * @param b a bias value of either <code>Position.Bias.Forward</code>

     *  or <code>Position.Bias.Backward</code>

     * @return the bounding box of the given position

     * @exception BadLocationException  if the given position does

     *   not represent a valid location in the associated document

     * @see View#modelToView

     */

    public Shape modelToView(int pos, Shape a, Position.Bias b) throws BadLocationException {

        boolean isBackward = (b == Position.Bias.Backward);

        int testPos = (isBackward) ? Math.max(0, pos - 1) : pos;

        if(isBackward && testPos < getStartOffset()) {

            return null;

        }

        int vIndex = getViewIndexAtPosition(testPos);

        if ((vIndex != -1) && (vIndex < getViewCount())) {

            View v = getView(vIndex);

            if(v != null && testPos >= v.getStartOffset() &&

               testPos < v.getEndOffset()) {

                Shape childShape = getChildAllocation(vIndex, a);

                if (childShape == null) {

                    // We are likely invalid, fail.

                    return null;

                }

                Shape retShape = v.modelToView(pos, childShape, b);

                if(retShape == null && v.getEndOffset() == pos) {

                    if(++vIndex < getViewCount()) {

                        v = getView(vIndex);

                        retShape = v.modelToView(pos, getChildAllocation(vIndex, a), b);

                    }

                }

                return retShape;

            }

        }

        throw new BadLocationException("Position not represented by view",

                                       pos);

    }

    /**

     * Provides a mapping from the document model coordinate space

     * to the coordinate space of the view mapped to it.

     *

     * @param p0 the position to convert >= 0

     * @param b0 the bias toward the previous character or the

     *  next character represented by p0, in case the

     *  position is a boundary of two views; either

     *  <code>Position.Bias.Forward</code> or

     *  <code>Position.Bias.Backward</code>

     * @param p1 the position to convert >= 0

     * @param b1 the bias toward the previous character or the

     *  next character represented by p1, in case the

     *  position is a boundary of two views

     * @param a the allocated region to render into

     * @return the bounding box of the given position is returned

     * @exception BadLocationException  if the given position does

     *   not represent a valid location in the associated document

     * @exception IllegalArgumentException for an invalid bias argument

     * @see View#viewToModel

     */

    public Shape modelToView(int p0, Position.Bias b0, int p1, Position.Bias b1, Shape a) throws BadLocationException {

        if (p0 == getStartOffset() && p1 == getEndOffset()) {

            return a;

        }

        Rectangle alloc = getInsideAllocation(a);

        Rectangle r0 = new Rectangle(alloc);

        View v0 = getViewAtPosition((b0 == Position.Bias.Backward) ?

                                    Math.max(0, p0 - 1) : p0, r0);

        Rectangle r1 = new Rectangle(alloc);

        View v1 = getViewAtPosition((b1 == Position.Bias.Backward) ?

                                    Math.max(0, p1 - 1) : p1, r1);

        if (v0 == v1) {

            if (v0 == null) {

                return a;

            }

            // Range contained in one view

            return v0.modelToView(p0, b0, p1, b1, r0);

        }

        // Straddles some views.

        int viewCount = getViewCount();

        int counter = 0;

        while (counter < viewCount) {

            View v;

            // Views may not be in same order as model.

            // v0 or v1 may be null if there is a gap in the range this

            // view contains.

            if ((v = getView(counter)) == v0 || v == v1) {

                View endView;

                Rectangle retRect;

                Rectangle tempRect = new Rectangle();

                if (v == v0) {

                    retRect = v0.modelToView(p0, b0, v0.getEndOffset(),

                                             Position.Bias.Backward, r0).

                              getBounds();

                    endView = v1;

                }

                else {

                    retRect = v1.modelToView(v1.getStartOffset(),

                                             Position.Bias.Forward,

                                             p1, b1, r1).getBounds();

                    endView = v0;

                }

                // Views entirely covered by range.

                while (++counter < viewCount &&

                       (v = getView(counter)) != endView) {

                    tempRect.setBounds(alloc);

                    childAllocation(counter, tempRect);

                    retRect.add(tempRect);

                }

                // End view.

                if (endView != null) {

                    Shape endShape;

                    if (endView == v1) {

                        endShape = v1.modelToView(v1.getStartOffset(),

                                                  Position.Bias.Forward,

                                                  p1, b1, r1);

                    }

                    else {

                        endShape = v0.modelToView(p0, b0, v0.getEndOffset(),

                                                  Position.Bias.Backward, r0);

                    }

                    if (endShape instanceof Rectangle) {

                        retRect.add((Rectangle)endShape);

                    }

                    else {

                        retRect.add(endShape.getBounds());

                    }

                }

                return retRect;

            }

            counter++;

        }

        throw new BadLocationException("Position not represented by view", p0);

    }

    /**

     * Provides a mapping from the view coordinate space to the logical

     * coordinate space of the model.

     *

     * @param x   x coordinate of the view location to convert >= 0

     * @param y   y coordinate of the view location to convert >= 0

     * @param a the allocated region to render into

     * @param bias either <code>Position.Bias.Forward</code> or

     *  <code>Position.Bias.Backward</code>

     * @return the location within the model that best represents the

     *  given point in the view >= 0

     * @see View#viewToModel

     */

    public int viewToModel(float x, float y, Shape a, Position.Bias[] bias) {

        Rectangle alloc = getInsideAllocation(a);

        if (isBefore((int) x, (int) y, alloc)) {

            // point is before the range represented

            int retValue = -1;

            try {

                retValue = getNextVisualPositionFrom(-1, Position.Bias.Forward,

                                                     a, EAST, bias);

            } catch (BadLocationException ble) { }

            catch (IllegalArgumentException iae) { }

            if(retValue == -1) {

                retValue = getStartOffset();

                bias[0] = Position.Bias.Forward;

            }

            return retValue;

        } else if (isAfter((int) x, (int) y, alloc)) {

            // point is after the range represented.

            int retValue = -1;

            try {

                retValue = getNextVisualPositionFrom(-1, Position.Bias.Forward,

                                                     a, WEST, bias);

            } catch (BadLocationException ble) { }

            catch (IllegalArgumentException iae) { }

            if(retValue == -1) {

                // NOTE: this could actually use end offset with backward.

                retValue = getEndOffset() - 1;

                bias[0] = Position.Bias.Forward;

            }

            return retValue;

        } else {

            // locate the child and pass along the request

            View v = getViewAtPoint((int) x, (int) y, alloc);

            if (v != null) {

              return v.viewToModel(x, y, alloc, bias);

            }

        }

        return -1;

    }

    /**

     * Provides a way to determine the next visually represented model

     * location that one might place a caret.  Some views may not be visible,

     * they might not be in the same order found in the model, or they just

     * might not allow access to some of the locations in the model.

     * This is a convenience method for {@link #getNextNorthSouthVisualPositionFrom}

     * and {@link #getNextEastWestVisualPositionFrom}.

     * This method enables specifying a position to convert

     * within the range of >=0.  If the value is -1, a position

     * will be calculated automatically.  If the value < -1,

     * the {@code BadLocationException} will be thrown.

     *

     * @param pos the position to convert

     * @param b a bias value of either <code>Position.Bias.Forward</code>

     *  or <code>Position.Bias.Backward</code>

     * @param a the allocated region to render into

     * @param direction the direction from the current position that can

     *  be thought of as the arrow keys typically found on a keyboard;

     *  this may be one of the following:

     *  <ul>

     *  <li><code>SwingConstants.WEST</code>

     *  <li><code>SwingConstants.EAST</code>

     *  <li><code>SwingConstants.NORTH</code>

     *  <li><code>SwingConstants.SOUTH</code>

     *  </ul>

     * @param biasRet an array containing the bias that was checked

     * @return the location within the model that best represents the next

     *  location visual position

     * @exception BadLocationException the given position is not a valid

     *                                 position within the document

     * @exception IllegalArgumentException if <code>direction</code> is invalid

     */

    public int getNextVisualPositionFrom(int pos, Position.Bias b, Shape a,

                                         int direction, Position.Bias[] biasRet)

      throws BadLocationException {

        if (pos < -1) {

            throw new BadLocationException("invalid position", pos);

        }

        Rectangle alloc = getInsideAllocation(a);

        switch (direction) {

        case NORTH:

            return getNextNorthSouthVisualPositionFrom(pos, b, a, direction,

                                                       biasRet);

        case SOUTH:

            return getNextNorthSouthVisualPositionFrom(pos, b, a, direction,

                                                       biasRet);

        case EAST:

            return getNextEastWestVisualPositionFrom(pos, b, a, direction,

                                                     biasRet);

        case WEST:

            return getNextEastWestVisualPositionFrom(pos, b, a, direction,

                                                     biasRet);

        default:

            throw new IllegalArgumentException("Bad direction: " + direction);

        }

    }

    /**

     * Returns the child view index representing the given

     * position in the model.  This is implemented to call the

     * <code>getViewIndexByPosition</code>

     * method for backward compatibility.

     *

     * @param pos the position >= 0

     * @return  index of the view representing the given position, or

     *   -1 if no view represents that position

     * @since 1.3

     */

    public int getViewIndex(int pos, Position.Bias b) {

        if(b == Position.Bias.Backward) {

            pos -= 1;

        }

        if ((pos >= getStartOffset()) && (pos < getEndOffset())) {

            return getViewIndexAtPosition(pos);

        }

        return -1;

    }

    // --- local methods ----------------------------------------------------

    /**

     * Tests whether a point lies before the rectangle range.

     *

     * @param x the X coordinate >= 0

     * @param y the Y coordinate >= 0

     * @param alloc the rectangle

     * @return true if the point is before the specified range

     */

    protected abstract boolean isBefore(int x, int y, Rectangle alloc);

    /**

     * Tests whether a point lies after the rectangle range.