/*
 * 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.
 */
package org.apache.fontbox.ttf;

import java.io.IOException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * This class is based on code from Apache Batik a subproject of Apache XMLGraphics. see
 * http://xmlgraphics.apache.org/batik/ for further details.
 */
public class GlyfSimpleDescript extends GlyfDescript
{

    /**
     * Log instance.
     */
    private static final Log LOG = LogFactory.getLog(GlyfSimpleDescript.class);

    private int[] endPtsOfContours;
    private byte[] flags;
    private short[] xCoordinates;
    private short[] yCoordinates;
    private final int pointCount;

    /**
     * Constructor for an empty description.
     */
    GlyfSimpleDescript()
    {
        super((short) 0);
        pointCount = 0;
    }

    /**
     * Constructor.
     * 
     * @param numberOfContours number of contours
     * @param bais the stream to be read
     * @param x0 the initial X-position
     * @throws IOException is thrown if something went wrong
     */
    GlyfSimpleDescript(short numberOfContours, TTFDataStream bais, short x0) throws IOException
    {
        super(numberOfContours);

        /*
         * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6glyf.html
         * "If a glyph has zero contours, it need not have any glyph data." set the pointCount to zero to initialize
         * attributes and avoid nullpointer but maybe there shouldn't have GlyphDescript in the GlyphData?
         */
        if (numberOfContours == 0)
        {
            pointCount = 0;
            return;
        }

        // Simple glyph description
        endPtsOfContours = bais.readUnsignedShortArray(numberOfContours);

        int lastEndPt = endPtsOfContours[numberOfContours - 1];
        if (numberOfContours == 1 && lastEndPt == 65535)
        {
            // PDFBOX-2939: assume an empty glyph
            pointCount = 0;
            return;
        }
        // The last end point index reveals the total number of points
        pointCount = lastEndPt + 1;

        flags = new byte[pointCount];
        xCoordinates = new short[pointCount];
        yCoordinates = new short[pointCount];

        int instructionCount = bais.readUnsignedShort();
        readInstructions(bais, instructionCount);
        readFlags(pointCount, bais);
        readCoords(pointCount, bais, x0);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public int getEndPtOfContours(int i)
    {
        return endPtsOfContours[i];
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public byte getFlags(int i)
    {
        return flags[i];
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public short getXCoordinate(int i)
    {
        return xCoordinates[i];
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public short getYCoordinate(int i)
    {
        return yCoordinates[i];
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean isComposite()
    {
        return false;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public int getPointCount()
    {
        return pointCount;
    }

    /**
     * The table is stored as relative values, but we'll store them as absolutes.
     */
    private void readCoords(int count, TTFDataStream bais, short x0) throws IOException
    {
        short x = x0;
        short y = 0;
        for (int i = 0; i < count; i++)
        {
            if ((flags[i] & X_DUAL) != 0)
            {
                if ((flags[i] & X_SHORT_VECTOR) != 0)
                {
                    x += (short) bais.readUnsignedByte();
                }
            }
            else
            {
                if ((flags[i] & X_SHORT_VECTOR) != 0)
                {
                    x -= (short) bais.readUnsignedByte();
                }
                else
                {
                    x += bais.readSignedShort();
                }
            }
            xCoordinates[i] = x;
        }

        for (int i = 0; i < count; i++)
        {
            if ((flags[i] & Y_DUAL) != 0)
            {
                if ((flags[i] & Y_SHORT_VECTOR) != 0)
                {
                    y += (short) bais.readUnsignedByte();
                }
            }
            else
            {
                if ((flags[i] & Y_SHORT_VECTOR) != 0)
                {
                    y -= (short) bais.readUnsignedByte();
                }
                else
                {
                    y += bais.readSignedShort();
                }
            }
            yCoordinates[i] = y;
        }
    }

    /**
     * The flags are run-length encoded.
     */
    private void readFlags(int flagCount, TTFDataStream bais) throws IOException
    {
        for (int index = 0; index < flagCount; index++)
        {
            flags[index] = (byte) bais.readUnsignedByte();
            if ((flags[index] & REPEAT) != 0)
            {
                int repeats = bais.readUnsignedByte();
                for (int i = 1; i <= repeats; i++)
                {
                    if (index + i >= flags.length)
                    {
                        throw new IOException(
                                "repeat count (" + repeats + ") higher than remaining space");
                    }
                    flags[index + i] = flags[index];
                }
                index += repeats;
            }
        }
    }
}
