/*
 * StructureBackgroundHighlighter - a jEdit BSH script that replaces the
 * box-around structure highlighter by highlighting the background of the match
 * Copyright © 2011 Björn "Vampire" Kautler
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License 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 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/>.
 *
 * Version 1.0
 */

import org.gjt.sp.jedit.textarea.StructureMatcher.Highlight;
import org.gjt.sp.jedit.textarea.StructureMatcher.Match;

class StructureBackgroundHighlighter extends TextAreaExtension {
    private Point point = new Point();
    private TextArea textArea;

    StructureBackgroundHighlighter(TextArea textArea) {
        this.textArea = textArea;
    }

    public void paintValidLine(Graphics2D gfx, int screenLine, int physicalLine, int start, int end, int y) {
        if (!textArea.getPainter().isStructureHighlightEnabled()) {
            return;
        }

        Match match = textArea.getStructureMatch();
        if (match != null) {
            int caret = textArea.getCaretPosition();
            int from;
            int to;
            if (match.start < caret) {
                from = Math.max(match.start, start);
                to = Math.min(caret, end - 1);
            } else {
                from = Math.max(caret, start);
                to = Math.min(match.end, end - 1);
            }
            if ((from <= end) && (to >= start)) {
                highlight(textArea.getPainter().getStructureHighlightColor(), gfx, physicalLine, from - start, to - start, y);
            }
        }
    }

    private void highlight(Color highlightColor, Graphics2D gfx, int physicalLine, int startOffset, int endOffset, int y) {
        Point p = textArea.offsetToXY(physicalLine, startOffset, point);
        if (p == null) {
            // The start offset was not visible
            return;
        }
        int startX = p.x;

        p = textArea.offsetToXY(physicalLine, endOffset, point);
        if (p == null) {
            // The end offset was not visible
            return;
        }
        int endX = p.x;
        Color oldColor = gfx.getColor();
        gfx.setColor(highlightColor);
        gfx.fillRect(startX, y, endX - startX, textArea.getPainter().getFontMetrics().getHeight() - 1);

        gfx.setColor(oldColor);
    }
}

class Attacher implements EBComponent {
    public void handleMessage(EBMessage message) {
        if (message instanceof EditPaneUpdate) {
            JEditTextArea textArea = ((EditPaneUpdate) message).getEditPane().getTextArea();
            Object what = ((EditPaneUpdate) message).getWhat();

            if (what == EditPaneUpdate.CREATED) {
                StructureBackgroundHighlighter highlighter = new StructureBackgroundHighlighter(textArea);
                textArea.getPainter().addExtension(TextAreaPainter.BRACKET_HIGHLIGHT_LAYER, highlighter);
                textArea.putClientProperty(StructureBackgroundHighlighter.class, highlighter);
                Iterator iter = Arrays.asList(textArea.getPainter().getExtensions()).iterator();
                while (iter.hasNext()) {
                    TextAreaExtension extension = (TextAreaExtension) iter.next();
                    if (extension instanceof Highlight) {
                        textArea.getPainter().removeExtension(extension);
                    }
                }
                textArea.revalidate();
            } else if (what == EditPaneUpdate.DESTROYED) {
                StructureBackgroundHighlighter highlighter = (StructureBackgroundHighlighter) textArea.getClientProperty(StructureBackgroundHighlighter.class);
                if (highlighter != null) {
                    textArea.getPainter().removeExtension(highlighter);
                    textArea.putClientProperty(StructureBackgroundHighlighter.class, null);
                }
            }
        }
    }
}

EditBus.addToBus(new Attacher());