/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* $Id$ */

package org.apache.fop.svg;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.awt.geom.AffineTransform;
import java.awt.geom.Ellipse2D;
import java.awt.geom.GeneralPath;
import java.awt.geom.Point2D;
import java.io.IOException;
import java.text.AttributedCharacterIterator;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.apache.batik.bridge.SVGGVTFont;
import org.apache.batik.gvt.font.FontFamilyResolver;
import org.apache.batik.gvt.font.GVTGlyphVector;
import org.apache.batik.gvt.renderer.StrokingTextPainter;
import org.apache.batik.gvt.text.TextPaintInfo;
import org.apache.batik.gvt.text.TextSpanLayout;

import org.apache.fop.fonts.Font;
import org.apache.fop.fonts.FontInfo;
import org.apache.fop.svg.font.FOPFontFamilyResolverImpl;
import org.apache.fop.svg.font.FOPGVTFont;
import org.apache.fop.util.CharUtilities;

/**
 * Abstract base class for text painters that use specialized text commands native to an output
 * format to render text.
 */
public abstract class NativeTextPainter extends StrokingTextPainter {

    /** the logger for this class */
    protected static final Log log = LogFactory.getLog(NativeTextPainter.class);

    private static final boolean DEBUG = false;

    /** the font collection */
    protected final FontInfo fontInfo;

    protected final FontFamilyResolver fontFamilyResolver;

    protected Font font;

    protected TextPaintInfo tpi;

    /**
     * Creates a new instance.
     * @param fontInfo the font collection
     */
    public NativeTextPainter(FontInfo fontInfo) {
        this.fontInfo = fontInfo;
        this.fontFamilyResolver = new FOPFontFamilyResolverImpl(fontInfo);
    }

    /**
     * Indicates whether the given {@link Graphics2D} instance if compatible with this text painter
     * implementation.
     * @param g2d the instance to check
     * @return true if the instance is compatible.
     */
    protected abstract boolean isSupported(Graphics2D g2d);

    /**
     * Paints a single text run.
     * @param textRun the text run
     * @param g2d the target Graphics2D instance
     * @throws IOException if an I/O error occurs while rendering the text
     */
    protected final void paintTextRun(TextRun textRun, Graphics2D g2d) throws IOException {
        AttributedCharacterIterator runaci = textRun.getACI();
        runaci.first();

        tpi = (TextPaintInfo) runaci.getAttribute(PAINT_INFO);
        if (tpi == null || !tpi.visible) {
            return;
        }
        if (tpi.composite != null) {
            g2d.setComposite(tpi.composite);
        }

        //------------------------------------
        TextSpanLayout layout = textRun.getLayout();
        logTextRun(runaci, layout);
        runaci.first(); //Reset ACI

        GeneralPath debugShapes = null;
        if (DEBUG) {
            debugShapes = new GeneralPath();
        }

        preparePainting(g2d);

        GVTGlyphVector gv = layout.getGlyphVector();
        if (!(gv.getFont() instanceof FOPGVTFont)) {
            assert gv.getFont() == null || gv.getFont() instanceof SVGGVTFont;
            //Draw using Java2D when no native fonts are available
            textRun.getLayout().draw(g2d);
            return;
        }
        font = ((FOPGVTFont) gv.getFont()).getFont();

        saveGraphicsState();
        setInitialTransform(g2d.getTransform());
        clip(g2d.getClip());
        beginTextObject();

        AffineTransform localTransform = new AffineTransform();
        Point2D prevPos = null;
        AffineTransform prevGlyphTransform = null;
        for (int index = 0, c = gv.getNumGlyphs(); index < c; index++) {
            if (!gv.isGlyphVisible(index)) {
                continue;
            }
            Point2D glyphPos = gv.getGlyphPosition(index);

            AffineTransform glyphTransform = gv.getGlyphTransform(index);
            if (log.isTraceEnabled()) {
                log.trace("pos " + glyphPos + ", transform " + glyphTransform);
            }
            if (DEBUG) {
                Shape sh = gv.getGlyphLogicalBounds(index);
                if (sh == null) {
                    sh = new Ellipse2D.Double(glyphPos.getX(), glyphPos.getY(), 2, 2);
                }
                debugShapes.append(sh, false);
            }

            //Exact position of the glyph
            localTransform.setToIdentity();
            localTransform.translate(glyphPos.getX(), glyphPos.getY());
            if (glyphTransform != null) {
                localTransform.concatenate(glyphTransform);
            }
            localTransform.scale(1, -1);

            positionGlyph(prevPos, glyphPos, glyphTransform != null || prevGlyphTransform != null);
            char glyph = (char) gv.getGlyphCode(index);
            //Update last position
            prevPos = glyphPos;
            prevGlyphTransform = glyphTransform;

            writeGlyph(glyph, localTransform);
        }
        endTextObject();
        restoreGraphicsState();
        if (DEBUG) {
            //Paint debug shapes
            g2d.setStroke(new BasicStroke(0));
            g2d.setColor(Color.LIGHT_GRAY);
            g2d.draw(debugShapes);
        }
    }

    @Override
    protected void paintTextRuns(@SuppressWarnings("rawtypes") List textRuns, Graphics2D g2d) {
        if (log.isTraceEnabled()) {
            log.trace("paintTextRuns: count = " + textRuns.size());
        }
        if (!isSupported(g2d)) {
            super.paintTextRuns(textRuns, g2d);
            return;
        }
        for (int i = 0; i < textRuns.size(); i++) {
            TextRun textRun = (TextRun) textRuns.get(i);
            try {
                paintTextRun(textRun, g2d);
            } catch (IOException ioe) {
                //No other possibility than to use a RuntimeException
                throw new RuntimeException(ioe);
            }
        }
    }

    /**
     * Collects all characters from an {@link AttributedCharacterIterator}.
     * @param runaci the character iterator
     * @return the characters
     */
    protected CharSequence collectCharacters(AttributedCharacterIterator runaci) {
        StringBuffer chars = new StringBuffer();
        for (runaci.first(); runaci.getIndex() < runaci.getEndIndex();) {
            chars.append(runaci.current());
            runaci.next();
        }
        return chars;
    }

    protected abstract void preparePainting(Graphics2D g2d);

    protected abstract void saveGraphicsState() throws IOException;

    protected abstract void restoreGraphicsState() throws IOException;

    protected abstract void setInitialTransform(AffineTransform transform) throws IOException;

    protected abstract void clip(Shape clip) throws IOException;

    protected abstract void beginTextObject() throws IOException;

    protected abstract void endTextObject() throws IOException;

    protected abstract void positionGlyph(Point2D prevPos, Point2D glyphPos, boolean reposition);

    protected abstract void writeGlyph(char glyph, AffineTransform transform) throws IOException;


    /**
     * @param runaci an attributed character iterator
     * @param layout a text span layout
     */
    protected final void logTextRun(AttributedCharacterIterator runaci, TextSpanLayout layout) {
        if (log.isTraceEnabled()) {
            int charCount = runaci.getEndIndex() - runaci.getBeginIndex();
            log.trace("================================================");
            log.trace("New text run:");
            log.trace("char count: " + charCount);
            log.trace("range: "
                    + runaci.getBeginIndex() + " - " + runaci.getEndIndex());
            log.trace("glyph count: " + layout.getGlyphCount()); //=getNumGlyphs()
        }
    }

    /**
     * @param ch a character
     * @param layout a text span layout
     * @param index an index
     * @param visibleChar visible character flag
     */
    protected final void logCharacter(char ch, TextSpanLayout layout, int index,
            boolean visibleChar) {
        if (log.isTraceEnabled()) {
            log.trace("glyph " + index
                    + " -> " + layout.getGlyphIndex(index) + " => " + ch);
            if (CharUtilities.isAnySpace(ch) && ch != 32) {
                log.trace("Space found: " + Integer.toHexString(ch));
            } else if (ch == CharUtilities.ZERO_WIDTH_JOINER) {
                log.trace("ZWJ found: " + Integer.toHexString(ch));
            } else if (ch == CharUtilities.SOFT_HYPHEN) {
                log.trace("Soft hyphen found: " + Integer.toHexString(ch));
            }
            if (!visibleChar) {
                log.trace("Invisible glyph found: " + Integer.toHexString(ch));
            }
        }
    }

    @Override
    protected FontFamilyResolver getFontFamilyResolver() {
        return this.fontFamilyResolver;
    }

}