//========================================================================
//
// Parser.cc
//
// Copyright 1996 Derek B. Noonburg
//
//========================================================================

#ifdef __GNUC__
#pragma implementation
#endif

#include <stddef.h>
#include "Object.h"
#include "Array.h"
#include "Dict.h"
#include "Parser.h"
#include "Error.h"
#include "md5.h"
#include "XRef.h"

Parser::Parser(Lexer *lexer1) {
  lexer = lexer1;
  inlineImg = 0;
  lexer->getObj(&buf1);
  lexer->getObj(&buf2);
}

Parser::~Parser() {
  buf1.free();
  buf2.free();
  delete lexer;
}

Object *Parser::getObj(Object *obj) {
  char *key;
  Stream *str;
  Object obj2;
  int num;

  // refill buffer after inline image data
  if (inlineImg == 2) {
    buf1.free();
    buf2.free();
    lexer->getObj(&buf1);
    lexer->getObj(&buf2);
    inlineImg = 0;
  }

  // array
  if (buf1.isCmd("[")) {
    shift();
    obj->initArray();
    while (!buf1.isCmd("]") && !buf1.isEOF())
      obj->arrayAdd(getObj(&obj2));
    if (buf1.isEOF())
      error(getPos(), "End of file inside array");
    shift();

  // dictionary or stream
  } else if (buf1.isCmd("<<")) {
    shift();
    obj->initDict();
    while (!buf1.isCmd(">>") && !buf1.isEOF()) {
      if (!buf1.isName()) {
	error(getPos(), "Dictionary key must be a name object");
	shift();
      } else {
	key = copyString(buf1.getName());
	shift();
	if (buf1.isEOF() || buf1.isError())
	  break;
	obj->dictAdd(key, getObj(&obj2));
      }
    }
    if (buf1.isEOF())
      error(getPos(), "End of file inside dictionary");
    if (buf2.isCmd("stream")) {
      if ((str = makeStream(obj))) {
	obj->initStream(str);
      } else {
	obj->free();
	obj->initError();
      }
    } else {
      shift();
    }

  // indirect reference or integer
  } else if (buf1.isInt()) {
    num = buf1.getInt();
    shift();
    if (buf1.isInt() && buf2.isCmd("R")) {
      obj->initRef(num, buf1.getInt());
      shift();
      shift();
    } else {
      obj->initInt(num);
    }

  // simple object
  } else {
    buf1.copy(obj);
    shift();
  }

  return obj;
}

Stream *Parser::makeStream(Object *dict) {
  Object obj;
  Stream *str;
  int pos, length;

  // get stream start position
  lexer->skipToNextLine();
  pos = lexer->getPos();

  // get length
  dict->dictLookup("Length", &obj);
  if (obj.isInt()) {
    length = obj.getInt();
    obj.free();
  } else {
    error(getPos(), "Bad 'Length' attribute in stream");
    obj.free();
    return NULL;
  }

  // make base stream
  str = new FileStream(lexer->getStream()->getFile(), pos, length, dict);

  // get filters
  str = str->addFilters(dict);

  // skip over stream data
  lexer->setPos(pos + length);

  // refill token buffers and check for 'endstream'
  shift();  // kill '>>'
  shift();  // kill 'stream'
  if (buf1.isCmd("endstream"))
    shift();
  else
    error(getPos(), "Missing 'endstream'");

  return str;
}

void Parser::shift() {
  if (inlineImg > 0) {
    ++inlineImg;
  } else if (buf2.isCmd("ID")) {
    lexer->skipChar();          // skip char after 'ID' command
    inlineImg = 1;
  }
  buf1.free();
  buf1 = buf2;
  if (inlineImg > 0)            // don't buffer inline image data
    buf2.initNull();
  else
    lexer->getObj(&buf2);
}

Object *Parser::getEncryptedObj(Object *obj, int num, int gen) {
  char *key;
  Stream *str;
  Object obj2;
  MD5 context;
  RC4KEY rc4Key;
  GString MD5Key;
  GString Key;

  // refill buffer after inline image data
  if (inlineImg == 2) {
    buf1.free();
    buf2.free();
    lexer->getObj(&buf1);
    lexer->getObj(&buf2);
    inlineImg = 0;
  }

  // array
  if (buf1.isCmd("[")) {
    shift();
    obj->initArray();
    while (!buf1.isCmd("]") && !buf1.isEOF())
      obj->arrayAdd(getEncryptedObj(&obj2, num, gen));
    if (buf1.isEOF())
      error(getPos(), "End of file inside array");
    shift();

  // dictionary or stream
  } else if (buf1.isCmd("<<")) {
    shift();
    obj->initDict();
    while (!buf1.isCmd(">>") && !buf1.isEOF()) {
      if (!buf1.isName()) {
      error(getPos(), "Dictionary key must be a name object");
      shift();
      } else {
      key = copyString(buf1.getName());
      shift();
      if (buf1.isEOF() || buf1.isError())
	break;
      obj->dictAdd(key, getEncryptedObj(&obj2, num, gen));
      }
    }
    if (buf1.isEOF())
      error(getPos(), "End of file inside dictionary");
    if (buf2.isCmd("stream")) {
      if ((str = makeStream(obj))) {
      obj->initStream(str);
	// enable Decryption on base File Stream
	str = obj->getStream()->getBaseStream();
	Key.append(xref->getEncryptionKey());
	Key.append((char)( num       & 0xff));
	Key.append((char)((num >> 8) & 0xff));
	Key.append((char)((num >>16) & 0xff));
	Key.append((char)( gen       & 0xff));
	Key.append((char)((gen >> 8) & 0xff));
	context.update((unsigned char *)Key.getCString(), 10);
	context.finalize();
	MD5Key.clear();
	char *p = (char *)context.raw_digest();
	MD5Key.append(p,10);
	delete p;
	// determine rc4Key
	rc4ExpandKey(&rc4Key, (unsigned char *)MD5Key.getCString(), 10);
	str->enableEncryption(&rc4Key);
      } else {
      obj->free();
      obj->initError();
      }
    } else {
      shift();
    }

  // indirect reference or integer
  } else if (buf1.isInt()) {
    num = buf1.getInt();
    shift();
    if (buf1.isInt() && buf2.isCmd("R")) {
      obj->initRef(num, buf1.getInt());
      shift();
      shift();
    } else {
      obj->initInt(num);
    }

  // decrypt strings
  } else if (buf1.isString()) {
    buf1.copy(obj);
    GString *s;
    s = obj->getString();
    Key.append(xref->getEncryptionKey());
    Key.append((char)( num       & 0xff));
    Key.append((char)((num >> 8) & 0xff));
    Key.append((char)((num >>16) & 0xff));
    Key.append((char)( gen       & 0xff));
    Key.append((char)((gen >> 8) & 0xff));
    context.update((unsigned char *)Key.getCString(),10);
    context.finalize();
    MD5Key.clear();
    char *p = (char *)context.raw_digest();
    MD5Key.append(p,10);
    delete p;
    // determine rc4Key
    rc4ExpandKey(&rc4Key, (unsigned char *)MD5Key.getCString(),10);
    rc4Crypt (&rc4Key,
      (unsigned char *) obj->getString()->getCString(),
      obj->getString()->getLength());
    shift();

  } else {
    buf1.copy(obj);
    shift();
  }

  return obj;
}