/*
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 
 * - Redistribution of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * 
 * - Redistribution in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * 
 * Neither the name of Sun Microsystems, Inc. or the names of
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
 * INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN
 * MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR
 * ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR
 * DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE
 * DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY,
 * ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF
 * SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 * 
 * You acknowledge that this software is not designed or intended for use
 * in the design, construction, operation or maintenance of any nuclear
 * facility.
 * 
 * Sun gratefully acknowledges that this software was originally authored
 * and developed by Kenneth Bradley Russell and Christopher John Kline.
 */

package com.sun.gluegen.pcpp;

import java.io.*;

/** A Reader implementation which finds lines ending in the backslash
    character ('\') and concatenates them with the next line. */

public class ConcatenatingReader extends FilterReader {
    // Any leftover characters go here
    private char[] curBuf;
    private int    curPos;
    private BufferedReader reader;
    private static String newline = System.getProperty("line.separator");

    /** This class requires that the input reader be a BufferedReader so
        it can do line-oriented operations. */
    public ConcatenatingReader(BufferedReader in) {
        super(in);
        this.reader = in;
    }

    @Override
    public int read() throws IOException {
        char[] tmp = new char[1];
        int num = read(tmp, 0, 1);
        if (num < 0)
            return -1;
        return tmp[0];
    }

    // It's easier not to support mark/reset since we don't need it
    @Override
    public boolean markSupported() {
        return false;
    }

    @Override
    public void mark(int readAheadLimit) throws IOException {
        throw new IOException("mark/reset not supported");
    }

    @Override
    public void reset() throws IOException {
        throw new IOException("mark/reset not supported");
    }

    @Override
    public boolean ready() throws IOException {
        if (curBuf != null || reader.ready())
            return true;
        return false;
    }

    @Override
    public int read(char[] cbuf, int off, int len) throws IOException {
        if (curBuf == null) {
            nextLine();
        }

        if (curBuf == null) {
            return -1;
        }

        int numRead = 0;

        while ((len > 0) && (curBuf != null) && (curPos < curBuf.length)) {
            cbuf[off] = curBuf[curPos];
            ++curPos;
            ++off;
            --len;
            ++numRead;
            if (curPos == curBuf.length) {
                nextLine();
            }
        }

        return numRead;
    }

    @Override
    public long skip(long n) throws IOException {
        long numSkipped = 0;

        while (n > 0) {
            int intN = (int) n;
            char[] tmp = new char[intN];
            int numRead = read(tmp, 0, intN);
            n -= numRead;
            numSkipped += numRead;
            if (numRead < intN)
                break;
        }
        return numSkipped;
    }

    private void nextLine() throws IOException {
        String cur = reader.readLine();
        if (cur == null) {
            curBuf = null;
            return;
        }
        // The trailing newline was trimmed by the readLine() method. See
        // whether we have to put it back or not, depending on whether the
        // last character of the line is the concatenation character.
        int numChars = cur.length();
        boolean needNewline = true;
        if ((numChars > 0) &&
            (cur.charAt(cur.length() - 1) == '\\')) {
            --numChars;
            needNewline = false;
        }
        char[] buf = new char[numChars + (needNewline ? newline.length() : 0)];
        cur.getChars(0, numChars, buf, 0);
        if (needNewline) {
            newline.getChars(0, newline.length(), buf, numChars);
        }
        curBuf = buf;
        curPos = 0;
    }

    // Test harness
    /*
      public static void main(String[] args) throws IOException {
      if (args.length != 1) {
      System.out.println("Usage: java ConcatenatingReader [file name]");
      System.exit(1);
      }

      ConcatenatingReader reader = new ConcatenatingReader(new BufferedReader(new FileReader(args[0])));
      OutputStreamWriter writer = new OutputStreamWriter(System.out);
      char[] buf = new char[8192];
      boolean done = false;
      while (!done && reader.ready()) {
      int numRead = reader.read(buf, 0, buf.length);
      writer.write(buf, 0, numRead);
      if (numRead < buf.length)
      done = true;
      }
      writer.flush();
      }
    */
}