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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@
 *
 * ---------------
 * RandomAccessFileBuffer.java
 * ---------------
 */
package org.jpedal.io;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.URL;

import org.jpedal.utils.LogWriter;
import org.jpedal.utils.repositories.FastByteArrayOutputStream;

public class RandomAccessFileBuffer implements RandomAccessBuffer {

    private final String fileName;
    private final RandomAccessFile ra;
    private final boolean isBig;

    private int bp;
    private int bl;
    byte[] temp;
    int tSize = 4096;
    int ts;
    int te;

    public RandomAccessFileBuffer(final String fileName, final String mode) throws IOException {
        this.fileName = fileName;
        final File file = new File(fileName);
        ra = new RandomAccessFile(file, mode);

        isBig = file.length() > Integer.MAX_VALUE;

        if (!isBig) {
            bl = (int) file.length();
            tSize = Math.min(tSize, bl);
            temp = new byte[tSize];
            te = tSize;
            ra.read(temp);
        }
    }

    @Override
    public byte[] getPdfBuffer() {

        final URL url;
        byte[] pdfByteArray = null;
        final InputStream is;
        final FastByteArrayOutputStream os;

        try {
            url = new URL("file:///" + fileName);

            is = url.openStream();
            os = new FastByteArrayOutputStream();

            // Download buffer
            final byte[] buffer = new byte[4096];

            // Download the PDF document
            int read;
            while ((read = is.read(buffer)) != -1) {
                os.write(buffer, 0, read);
            }

            // Close streams
            is.close();

            // Copy output stream to byte array
            pdfByteArray = os.toByteArray();

        } catch (final IOException e) {
            LogWriter.writeLog("[PDF] Exception " + e + " getting byte[] for " + fileName);
        }

        return pdfByteArray;
    }

    @Override
    public long getFilePointer() throws IOException {
        if (isBig) {
            return ra.getFilePointer();
        } else {
            return bp;
        }
    }

    @Override
    public void seek(final long pos) throws IOException {
        if (isBig) {
            ra.seek(pos);
        } else {
            bp = (int) pos;
        }
    }

    @Override
    public int read() throws IOException {
        if (isBig) {
            return ra.read();
        } else {
            if (bp < bl) {
                if (bp >= ts && bp < te) {
                    final int v = temp[(bp - ts)] & 0xff;
                    bp++;
                    return v;
                } else {
                    ts = bp;
                    te = ts + tSize;
                    ra.seek(bp);
                    final int max = Math.min(bl - bp, tSize);
                    ra.read(temp, 0, max);
                    bp++;
                    return temp[0] & 0xff;
                }
            }
            return -1;
        }
    }

    @Override
    public String readLine() throws IOException {
        final StringBuilder input = new StringBuilder();
        int c = -1;
        boolean eol = false;

        while (!eol) {
            switch (c = read()) {
                case -1:
                case '\n':
                    eol = true;
                    break;
                case '\r':
                    eol = true;
                    final long cur = getFilePointer();
                    if ((read()) != '\n') {
                        seek(cur);
                    }
                    break;
                default:
                    input.append((char) c);
                    break;
            }
        }

        if ((c == -1) && (input.length() == 0)) {
            return null;
        }
        return input.toString();
    }

    @Override
    public long length() throws IOException {
        return ra.length();
    }

    @Override
    public void close() throws IOException {
        if (ra != null) {
            ra.close();
        }
    }

    @Override
    public int read(final byte[] b) throws IOException {
        if (isBig) {
            return ra.read(b);
        } else {
            ra.seek(bp);
            final int maxRead = ra.read(b);
            bp += maxRead;
            return maxRead;
        }
    }
}