//
// This software is now distributed according to
// the Lesser Gnu Public License.  Please see
// http://www.gnu.org/copyleft/lesser.txt for
// the details.
//    -- Happy Computing!
//
package com.stevesoft.pat;

import java.io.*;

import com.stevesoft.pat.wrap.*;

/** This class allows you to replace the text in strings
    as you read them in.  Be careful what you do with
    this freedom... using Regex.perlCode("s{.*}{x}s")
    as your pattern will result in loading the entire
    contents of the Reader into memory.
 */
public class RegexReader
    extends Reader
{
  RBuffer rb = new RBuffer(new StringBuffer());
  PartialBuffer wrap = new PartialBuffer(rb.sb);
  boolean moreToRead = true;
  Reader r;
  Replacer rp;

  // the buffer size
  int nmax = 2 * 1024;

  public RegexReader(Regex rex, Reader r)
  {
    this.r = r;
    rp = rex.getReplacer();
  }

  public RegexReader(Transformer tex, Reader r)
  {
    this.r = r;
    rp = tex.getReplacer();
  }

  public void reset()
      throws IOException
  {
    r.reset();
    rb = new RBuffer(new StringBuffer());
    wrap = new PartialBuffer(rb.sb);
    moreToRead = true;
  }

  void readData()
      throws IOException
  {
    int c;
    int n = 0;
    while ( (c = r.read()) != -1)
    {
      rb.sb.append( (char) c);
      if (n++ > nmax)
      {
        break;
      }
    }
    if (c == -1 && n == 0)
    {
      moreToRead = false;
      wrap.allowOverRun = false;
    }
  }

  void getMoreData()
      throws IOException
  {
    while (rb.pos >= rb.epos)
    {
      wrap.overRun = false;
      if (rb.next != null)
      {
        rb = rb.next;
      }
      else if (rb.done)
      {
        break;
      }
      else if (rb.epos >= rb.sb.length()
               && rb.epos > nmax)
      {
        rb.pos = 1;
        rb.epos = 1;
        rb.sb.setLength(1);
        readData();
      }
      else if (rb.epos >= rb.sb.length()
               && moreToRead)
      {
        readData();
      }
      else if (rp.getRegex().matchAt(wrap, rb.epos))
      {
        if (wrap.overRun)
        {
          readData();
        }
        else
        {
          StringBufferWrap sbw = new StringBufferWrap();
          StringBufferLike sbl = new StringBufferLike(sbw);
          /*
                 ReplaceRule rr = rex.getReplaceRule();
              while(rr != null) {
            rr.apply(sbl,rex);
            rr = rr.next;
              }
           */
          Regex rex = rp.getRegex();
          int npos = rex.matchedTo();
          rp.setBuffer(sbl);
          rp.setSource(wrap);
          rp.setPos(npos);
          rp.apply(rex, rex.getReplaceRule());
          int opos = rb.epos;
          RBuffer rb2 = new RBuffer( (StringBuffer) sbw.unwrap());
          rb2.epos = rb2.sb.length();
          RBuffer rb3 = new RBuffer(rb.sb);

          rb.next = rb2;
          rb2.next = rb3;

          if (npos == opos)
          {
            rb3.epos = npos + 1;
            if (rb3.epos > rb3.sb.length())
            {
              if (rb.pos >= rb.epos)
              {
                rb = rb.next;
              }
              rb3.pos = rb3.epos = 0;
              rb3.done = true;
              //break;
            }
            rb3.pos = npos;
          }
          else
          {
            rb3.pos = rb3.epos = npos;
          }

        }
      }
      else
      {
        if (wrap.overRun)
        {
          readData();
        }
        else if (rb.epos < rb.sb.length())
        {
          rb.epos++;
        }
        else
        {
          break;
        }
      }
    }
  }

  public int read()
      throws IOException
  {
    if (rb.pos >= rb.epos)
    {
      getMoreData();
      if (rb.pos >= rb.epos)
      {
        return -1;
      }
    }
    //System.out.println(rb);
    return rb.sb.charAt(rb.pos++);
  }

  public int read(char[] buf, int off, int len)
      throws IOException
  {
    int c = -1;
    int end = off + len;
    for (int i = off; i < end; i++)
    {
      c = read();
      if (c < 0)
      {
        if (i == off)
        {
          return -1;
        }
        return i - off;
      }
      buf[i] = (char) c;
    }
    return len;
  }

  public void close()
      throws IOException
  {
    r.close();
  }

  public boolean markSupported()
  {
    return false;
  }

  /** Get the size of the working buffer.
      The current buffer may be larger if
      the pattern demands it. */
  public int getBufferSize()
  {
    return nmax;
  }

  /** Set the size of the working buffer.
      The current buffer may be larger if
      the pattern demands it. */
  public void setBufferSize(int n)
  {
    nmax = n;
  }

  int max_lines = 2;
  /** This function no longer serves any purpose.
      @deprecated
   */
  public int getMaxLines()
  {
    return max_lines;
  }

  /** This function no longer serves any purpose.
      @deprecated
   */
  public void setMaxLines(int ml)
  {
    max_lines = ml;
  }

  char EOLchar = '\n';
  /** This function no longer serves any purpose.
      @deprecated
   */
  public char getEOLchar()
  {
    return EOLchar;
  }

  /** This function no longer serves any purpose.
      @deprecated
   */
  public void setEOLchar(char c)
  {
    EOLchar = c;
  }

  public long skip(long d)
      throws IOException
  {
    // This is probably inefficient, I just did it
    // this way to avoid possible bugs.
    long n = 0;
    while (n < d && read() != -1)
    {
      n++;
    }
    return n;
  }

  /*
     static void test(String re,String inp,int n) throws Exception {
    Reader r = new StringReader(inp);
    r = new BufferedReader(r);
    Regex rex = Regex.perlCode(re);
    String res1 = rex.replaceAll(inp);
    int c = -1;
    StringBuffer sb = new StringBuffer();
    RegexReader rr = new RegexReader(rex,r);
    rr.setBufferSize(n);
    while( (c = rr.read()) != -1)
      sb.append((char)c);
    String res2 = sb.toString();
    if(!res1.equals(res2)) {
      System.out.println("nmax="+n);
      System.out.println("re="+re);
      System.out.println("inp="+inp);
      System.out.println("res1="+res1);
      System.out.println("res2="+res2);
      System.exit(255);
    }
     }
     public static void main(String[] args) throws Exception {
    for(int n=6;n<15;n++) {
      test("s/x/y/","-----x123456789",n);
      test("s/x/y/","x123456789",n);
      test("s/x/y/","-----x",n);
      test("s/x.*?x/y/",".xx..x..x...x...x....x....x",n);
      test("s/x.*x/[$&]/","--x........x--xx",n);
      test("s/x.*x/[$&]/","--x........x------",n);
      test("s/.$/a/m","bb\nbbb\nbbbb\nbbbbb\nbbbbbb\nbbbbbbbbbbbb",n);
      test("s/.$/a/","123",n);
      test("s/.$/a/","bb\nbbb\nbbbb\nbbbbb\nbbbbbb\nbb",n);
      test("s/^./a/","bb\nbbb\nbbbb\nbbbbb\nbbbbbb\nbb",n);
      test("s/$/a/","bbb",n);
      test("s/^/a/","bbb",n);
      test("s/^/a/","",n);
      test("s{.*}{N}","xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",n);
      test("s/.{0,7}/y/","AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA",n);
      test("s/x/$&/","xxx",n);
    }
    System.out.println("Success!!!");
     }
   */
}