/******************************************************************************
 * Top contributors (to current version):
 *   Christopher L. Conway, Francois Bobot, Mathias Preiner
 *
 * This file is part of the cvc5 project.
 *
 * Copyright (c) 2009-2021 by the authors listed in the file AUTHORS
 * in the top-level source directory and their institutional affiliations.
 * All rights reserved.  See the file COPYING in the top-level source
 * directory for licensing information.
 * ****************************************************************************
 *
 * [[ Add one-line brief description here ]]
 *
 * [[ Add lengthier description here ]]
 * \todo document this file
 */

/*
 * The functions in this file are based on implementations in libantlr3c,
 * with only minor CVC4-specific changes.
 */

// [The "BSD licence"]
// Copyright (c) 2005-2009 Jim Idle, Temporal Wave LLC
// http://www.temporal-wave.com
// http://www.linkedin.com/in/jimidle
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions 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.
// 3. The name of the author may not be used to endorse or promote products
//    derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
// OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
// IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
// NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include <antlr3.h>

#include <sstream>

#include "base/check.h"
#include "parser/antlr_input.h"
#include "parser/parser.h"
#include "parser/parser_exception.h"

using namespace std;

namespace cvc5 {
namespace parser {

/// Report a recognition problem.
///
/// This method sets errorRecovery to indicate the parser is recovering
/// not parsing.  Once in recovery mode, no errors are generated.
/// To get out of recovery mode, the parser must successfully match
/// a token (after a resync).  So it will go:
///
///             1. error occurs
///             2. enter recovery mode, report error
///             3. consume until token found in resynch set
///             4. try to resume parsing
///             5. next match() will reset errorRecovery mode
///
/// If you override, make sure to update errorCount if you care about that.
///
/* *** CVC4 NOTE ***
 * This function is has been modified in not-completely-trivial ways from its
 * libantlr3c implementation to support more informative error messages and to
 * invoke the error reporting mechanism of the Input class instead of the
 * default error printer.
 */
void AntlrInput::reportError(pANTLR3_BASE_RECOGNIZER recognizer) {
  pANTLR3_EXCEPTION ex = recognizer->state->exception;
  pANTLR3_UINT8 * tokenNames = recognizer->state->tokenNames;
  stringstream ss;

  // Dig the CVC4 objects out of the ANTLR3 mess
  pANTLR3_PARSER antlr3Parser = (pANTLR3_PARSER)(recognizer->super);
  Assert(antlr3Parser != NULL);
  Parser *parser = (Parser*)(antlr3Parser->super);
  Assert(parser != NULL);
  AntlrInput *input = (AntlrInput*) parser->getInput() ;
  Assert(input != NULL);

  // Signal we are in error recovery now
  recognizer->state->errorRecovery = ANTLR3_TRUE;

  // Indicate this recognizer had an error while processing.
  recognizer->state->errorCount++;

  // Call the builtin error formatter
  // recognizer->displayRecognitionError(recognizer, recognizer->state->tokenNames);

  /* TODO: Make error messages more useful, maybe by including more expected tokens and information
   * about the current token. */
  switch(ex->type) {
  case ANTLR3_UNWANTED_TOKEN_EXCEPTION:

    // Indicates that the recognizer was fed a token which seems to be
    // spurious input. We can detect this when the token that follows
    // this unwanted token would normally be part of the syntactically
    // correct stream. Then we can see that the token we are looking at
    // is just something that should not be there and throw this exception.
    //
    if(tokenNames == NULL) {
      ss << "Unexpected token." ;
    } else {
      if(ex->expecting == ANTLR3_TOKEN_EOF) {
        ss << "Expected end of file.";
      } else {
        ss << "Expected " << tokenNames[ex->expecting]
           << ", found '" << tokenText((pANTLR3_COMMON_TOKEN)ex->token) << "'.";
      }
    }
    break;

  case ANTLR3_MISSING_TOKEN_EXCEPTION:

    // Indicates that the recognizer detected that the token we just
    // hit would be valid syntactically if preceded by a particular
    // token. Perhaps a missing ';' at line end or a missing ',' in an
    // expression list, and such like.
    //
    if(tokenNames == NULL) {
      ss << "Missing token (" << ex->expecting << ").";
    } else {
      if(ex->expecting == ANTLR3_TOKEN_EOF) {
        ss << "Missing end of file marker.";
      } else if( ex->expecting == 0 ) {
        ss << "Unexpected token: '" << tokenText((pANTLR3_COMMON_TOKEN)ex->token) << "'.";
        if( std::string(tokenText((pANTLR3_COMMON_TOKEN)ex->token)) == std::string("IN") ) {
          ss << " Did you mean: `IS_IN'?";
        }
      } else {
        ss << "Missing " << tokenNames[ex->expecting] << ".";
      }
    }
    break;

  case ANTLR3_RECOGNITION_EXCEPTION:

    // Indicates that the recognizer received a token
    // in the input that was not predicted. This is the basic exception type
    // from which all others are derived. So we assume it was a syntax error.
    // You may get this if there are not more tokens and more are needed
    // to complete a parse for instance.
    //
    ss <<"Syntax error.";
    break;

  case ANTLR3_MISMATCHED_TOKEN_EXCEPTION:

    // We were expecting to see one thing and got another. This is the
    // most common error if we could not detect a missing or unwanted token.
    // Here you can spend your efforts to
    // derive more useful error messages based on the expected
    // token set and the last token and so on. The error following
    // bitmaps do a good job of reducing the set that we were looking
    // for down to something small. Knowing what you are parsing may be
    // able to allow you to be even more specific about an error.
    //
    if(tokenNames == NULL) {
      ss << "Syntax error.";
    } else {
      if(ex->expecting == ANTLR3_TOKEN_EOF) {
        ss << "Expected end of file.";
      } else if( ex->expecting == 0 ) {
        ss << "Unexpected token: '" << tokenText((pANTLR3_COMMON_TOKEN)ex->token) << "'.";
      } else {
        ss << "Expected " << tokenNames[ex->expecting] << ".";
      }
    }
    break;

  case ANTLR3_NO_VIABLE_ALT_EXCEPTION:
    // We could not pick any alt decision from the input given
    // so god knows what happened - however when you examine your grammar,
    // you should. It means that at the point where the current token occurred
    // that the DFA indicates nowhere to go from here.
    //
    ss << "Unexpected token: '" << tokenText((pANTLR3_COMMON_TOKEN)ex->token) << "'.";
    break;

  case ANTLR3_MISMATCHED_SET_EXCEPTION:

  {
    ANTLR3_UINT32 count;
    ANTLR3_UINT32 bit;
    ANTLR3_UINT32 size;
    ANTLR3_UINT32 numbits;
    pANTLR3_BITSET errBits;

    // This means we were able to deal with one of a set of
    // possible tokens at this point, but we did not see any
    // member of that set.
    //
    ss << "Unexpected input: '" << tokenText((pANTLR3_COMMON_TOKEN)ex->token)
       << "'. Expected one of: ";

    // What tokens could we have accepted at this point in the
    // parse?
    //
    count = 0;
    errBits = antlr3BitsetLoad(ex->expectingSet);
    numbits = errBits->numBits(errBits);
    size = errBits->size(errBits);

    if(size > 0) {
      // However many tokens we could have dealt with here, it is usually
      // not useful to print ALL of the set here. I arbitrarily chose 8
      // here, but you should do whatever makes sense for you of course.
      // No token number 0, so look for bit 1 and on.
      //
      for(bit = 1; bit < numbits && count < 8 && count < size; bit++) {
        // TODO: This doesn;t look right - should be asking if the bit is set!!
        //
        if(tokenNames[bit]) {
          if( count++ > 0 ) {
            ss << ", ";
          }
          ss << tokenNames[bit];
        }
      }
    } else {
      Assert(false);  //("Parse error with empty set of expected tokens.");
    }
  }
    break;

  case ANTLR3_EARLY_EXIT_EXCEPTION:

    // We entered a loop requiring a number of token sequences
    // but found a token that ended that sequence earlier than
    // we should have done.
    //
    ss << "Sequence terminated early by token: '"
       << tokenText((pANTLR3_COMMON_TOKEN)ex->token) << "'.";
    break;

  default:

    // We don't handle any other exceptions here, but you can
    // if you wish. If we get an exception that hits this point
    // then we are just going to report what we know about the
    // token.
    //
    Assert(false);  //("Unexpected exception in parser.");
    break;
  }

  // Call the error display routine
  input->parseError(ss.str(), ((pANTLR3_COMMON_TOKEN)ex->token)->type == ANTLR3_TOKEN_EOF);
}

///
/// \brief
/// Returns the next available token from the current input stream.
///
/// \param toksource
/// Points to the implementation of a token source. The lexer is
/// addressed by the super structure pointer.
///
/// \returns
/// The next token in the current input stream or the EOF token
/// if there are no more tokens.
///
/// \remarks
/// Write remarks for nextToken here.
///
/// \see nextToken
///
/* *** CVC4 NOTE ***
 * This is copied, largely unmodified, from antlr3lexer.c
 *
 */
pANTLR3_COMMON_TOKEN
AntlrInput::nextTokenStr (pANTLR3_TOKEN_SOURCE toksource)
{
  pANTLR3_LEXER lexer;

  lexer = (pANTLR3_LEXER)(toksource->super);

  /// Loop until we get a non skipped token or EOF
  ///
  for (;;)
  {
    // Get rid of any previous token (token factory takes care of
    // any de-allocation when this token is finally used up.
    //
    lexer->rec->state->token = NULL;
    lexer->rec->state->error = ANTLR3_FALSE; // Start out without an exception
    lexer->rec->state->failed = ANTLR3_FALSE;

    // Now call the matching rules and see if we can generate a new token
    //
    for (;;)
    {
      // Record the start of the token in our input stream.
      //
      lexer->rec->state->channel = ANTLR3_TOKEN_DEFAULT_CHANNEL;
      lexer->rec->state->tokenStartCharIndex = lexer->input->istream->index(lexer->input->istream);
      lexer->rec->state->tokenStartCharPositionInLine = lexer->input->getCharPositionInLine(lexer->input);
      lexer->rec->state->tokenStartLine = lexer->input->getLine(lexer->input);
      lexer->rec->state->text = NULL;

      if (lexer->input->istream->_LA(lexer->input->istream, 1) == ANTLR3_CHARSTREAM_EOF)
      {
        // Reached the end of the current stream, nothing more to do if this is
        // the last in the stack.
        //
        pANTLR3_COMMON_TOKEN teof = &(toksource->eofToken);

        teof->setStartIndex (teof, lexer->getCharIndex(lexer));
        teof->setStopIndex (teof, lexer->getCharIndex(lexer));
        teof->setLine (teof, lexer->getLine(lexer));
        teof->factoryMade = ANTLR3_TRUE; // This isn't really manufactured but it stops things from trying to free it
        return teof;
      }

      lexer->rec->state->token = NULL;
      lexer->rec->state->error = ANTLR3_FALSE; // Start out without an exception
      lexer->rec->state->failed = ANTLR3_FALSE;

      // Call the generated lexer, see if it can get a new token together.
      //
      lexer->mTokens(lexer->ctx);

      if (lexer->rec->state->error == ANTLR3_TRUE)
      {
        // Recognition exception, report it and try to recover.
        //
        lexer->rec->state->failed = ANTLR3_TRUE;
        // *** CVC4 EDIT: Just call the AntlrInput error routine
        lexerError(lexer->rec);
        lexer->recover(lexer);
      }
      else
      {
        if (lexer->rec->state->token == NULL)
        {
          // Emit the real token, which adds it in to the token stream basically
          //
          // *** CVC4 Edit: call emit on the lexer object
          lexer->emit(lexer);
        }
        else if (lexer->rec->state->token == &(toksource->skipToken))
        {
          // A real token could have been generated, but "Computer say's naaaaah" and it
          // it is just something we need to skip altogether.
          //
          continue;
        }

        // Good token, not skipped, not EOF token
        //
        return lexer->rec->state->token;
      }
    }
  }
}

/* *** CVC4 NOTE ***
 * This is copied, totaly unmodified, from antlr3lexer.c
 * in order to use nextTokenStr previously defined.
 *
 */
pANTLR3_COMMON_TOKEN
AntlrInput::nextToken	    (pANTLR3_TOKEN_SOURCE toksource)
{
	pANTLR3_COMMON_TOKEN tok;

	// Find the next token in the current stream
	//
	tok = nextTokenStr(toksource);

	// If we got to the EOF token then switch to the previous
	// input stream if there were any and just return the
	// EOF if there are none. We must check the next token
	// in any outstanding input stream we pop into the active
	// role to see if it was sitting at EOF after PUSHing the
	// stream we just consumed, otherwise we will return EOF
	// on the reinstalled input stream, when in actual fact
	// there might be more input streams to POP before the
	// real EOF of the whole logical inptu stream. Hence we
	// use a while loop here until we find somethign in the stream
	// that isn't EOF or we reach the actual end of the last input
	// stream on the stack.
	//
	while	(tok->type == ANTLR3_TOKEN_EOF)
	{
		pANTLR3_LEXER   lexer;

		lexer   = (pANTLR3_LEXER)(toksource->super);

		if  (lexer->rec->state->streams != NULL && lexer->rec->state->streams->size(lexer->rec->state->streams) > 0)
		{
			// We have another input stream in the stack so we
			// need to revert to it, then resume the loop to check
			// it wasn't sitting at EOF itself.
			//
			lexer->popCharStream(lexer);
			tok = nextTokenStr(toksource);
		}
		else
		{
			// There were no more streams on the input stack
			// so this EOF is the 'real' logical EOF for
			// the input stream. So we just exit the loop and 
			// return the EOF we have found.
			//
			break;
		}
		
	}

	// return whatever token we have, which may be EOF
	//
	return  tok;
}



} // namespace parser
}  // namespace cvc5