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/*
 * ===========================================
 * Java Pdf Extraction Decoding Access Library
 * ===========================================
 *
 * Project Info:  http://www.idrsolutions.com
 * Help section for developers at http://www.idrsolutions.com/support/
 *
 * (C) Copyright 1997-2017 IDRsolutions and Contributors.
 *
 * This file is part of JPedal/JPDF2HTML5
 *
 @LICENSE@
 *
 * ---------------
 * RandomAccessMemoryMapBuffer.java
 * ---------------
 */

package org.jpedal.io;

import java.io.*;

import org.jpedal.utils.LogWriter;

public class RandomAccessMemoryMapBuffer implements RandomAccessBuffer {

    //private byte[] data;
    private long pointer;

    private int length;

    private File file;
    private RandomAccessFile buf;

    public RandomAccessMemoryMapBuffer(final InputStream in) {

        this.pointer = -1;

        length = 0;

        FileOutputStream to = null;
        BufferedInputStream from = null;

        try {

            file = File.createTempFile("page", ".bin", new File(ObjectStore.temp_dir));

            to = new java.io.FileOutputStream(file);

            from = new BufferedInputStream(in);

            //write
            final byte[] buffer = new byte[65535];
            int bytes_read;
            while ((bytes_read = from.read(buffer)) != -1) {
                to.write(buffer, 0, bytes_read);
                length += bytes_read;
            }

        } catch (final Exception e) {
            LogWriter.writeLog("Exception: " + e.getMessage());
        }
        //close streams
        try {
            if (to != null) {
                to.close();
            }
            if (from != null) {
                from.close();
            }
        } catch (final Exception e) {
            LogWriter.writeLog("Exception " + e + " closing files");
        }

        try {
            init();
        } catch (final Exception e) {
            LogWriter.writeLog("Exception: " + e.getMessage());
        }


    }

    private void init() throws Exception {

        // Create a read-only memory-mapped file
        buf = new RandomAccessFile(file, "r");

    }

    @Override
    public long getFilePointer() throws IOException {
        return pointer;
    }

    @Override
    public void seek(final long pos) throws IOException {
        if (checkPos(pos)) {
            this.pointer = pos;
        } else {
            throw new IOException("Position out of bounds");
        }
    }

    @Override
    public void close() throws IOException {

        if (buf != null) {

            buf.close();
            buf = null;
        }


        this.pointer = -1;

        if (file != null && file.exists()) {
            file.delete();
        }
    }

    /**/
    @Override
    protected void finalize() {

        try {
            super.finalize();
        } catch (final Throwable e) {
            LogWriter.writeLog("Exception: " + e.getMessage());
        }

        //ensure removal actual file
        try {
            close();
        } catch (final IOException e) {
            LogWriter.writeLog("Exception: " + e.getMessage());
        }

    } /**/

    @Override
    public long length() throws IOException {

        if (buf != null) {
            return length;
        } else {
            throw new IOException("Data buffer not initialized.");
        }
    }

    @Override
    public int read() throws IOException {
        if (checkPos(this.pointer)) {
            buf.seek(pointer++);
            return b2i(buf.readByte());
        } else {
            return -1;
        }
    }

    private int peek() throws IOException {
        if (checkPos(this.pointer)) {
            buf.seek(pointer++);
            final int returnInt = b2i(buf.readByte());
            pointer--; //needs to roll bakc - peek should not increment as it stops readLine working
            return returnInt;
        } else {
            return -1;
        }
    }

    /**
     * return next line (returns null if no line)
     */
    @Override
    public String readLine() throws IOException {

        if (this.pointer >= this.length - 1) {
            return null;
        } else {

            final StringBuilder buf = new StringBuilder();
            int c;
            while ((c = read()) >= 0) {
                if ((c == 10) || (c == 13)) {
                    if (((peek() == 10) || (peek() == 13)) && (peek() != c)) {
                        read();
                    }
                    break;
                }
                buf.append((char) c);
            }
            return buf.toString();
        }
    }

    @Override
    public int read(final byte[] b) throws IOException {

        if (buf == null) {
            throw new IOException("Data buffer not initialized.");
        }

        if (pointer < 0 || pointer >= length) {
            return -1;
        }

        int length = this.length - (int) pointer;
        if (length > b.length) {
            length = b.length;
        }

        //replaced inefficient code with an improved performance version (up to ~60 %)
        //buf.seek(pointer);
        //buf.read(b);
        //pointer += b.length;

        for (int i = 0; i < length; i++) {
            buf.seek(pointer++);
            b[i] = buf.readByte();
        }
        return length;
    }

    private static int b2i(final byte b) {
        if (b >= 0) {
            return b;
        }
        return 256 + b;
    }

    private boolean checkPos(final long pos) throws IOException {
        return ((pos >= 0) && (pos < length()));
    }

    /* returns the byte data*/
    @Override
    public byte[] getPdfBuffer() {

        final byte[] bytes = new byte[length];
        try {
            buf.seek(0);
            buf.read(bytes);
        } catch (final IOException e) {
            LogWriter.writeLog("Exception: " + e.getMessage());
        }

        return bytes;
    }
}