/*
    Mosh: the mobile shell
    Copyright 2012 Keith Winstein

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <assert.h>
#include <typeinfo>
#include <langinfo.h>
#include <errno.h>

#include "parser.h"

static void append_or_delete( Parser::Action *act,
			      std::list<Parser::Action *>&vec )
{
  assert( act );

  if ( typeid( *act ) != typeid( Parser::Ignore ) ) {
    vec.push_back( act );
  } else {
    delete act;
  }
}

std::list<Parser::Action *> Parser::Parser::input( wchar_t ch )
{
  std::list<Action *> ret;

  Transition tx = state->input( ch );

  if ( tx.next_state != NULL ) {
    append_or_delete( state->exit(), ret );
  }

  append_or_delete( tx.action, ret );

  if ( tx.next_state != NULL ) {
    append_or_delete( tx.next_state->enter(), ret );
    state = tx.next_state;
  }

  return ret;
}

Parser::UTF8Parser::UTF8Parser()
  : parser(), buf_len( 0 )
{
  assert( BUF_SIZE >= (size_t)MB_CUR_MAX );
}

std::list<Parser::Action *> Parser::UTF8Parser::input( char c )
{
  assert( buf_len < BUF_SIZE );

  buf[ buf_len++ ] = c;

  /* This function will only work in a UTF-8 locale. */

  wchar_t pwc;
  mbstate_t ps;
  memset( &ps, 0, sizeof( ps ) );

  size_t total_bytes_parsed = 0;
  size_t orig_buf_len = buf_len;
  std::list<Action *> ret;

  /* this routine is somewhat complicated in order to comply with
     Unicode 6.0, section 3.9, "Best Practices for using U+FFFD" */

  while ( total_bytes_parsed != orig_buf_len ) {
    assert( total_bytes_parsed < orig_buf_len );
    assert( buf_len > 0 );
    size_t bytes_parsed = mbrtowc( &pwc, buf, buf_len, &ps );

    /* this returns 0 when n = 0! */

    /* This function annoying returns a size_t so we have to check
       the negative values first before the "> 0" branch */

    if ( bytes_parsed == 0 ) {
      /* character was NUL, accept and clear buffer */
      assert( buf_len == 1 );
      buf_len = 0;
      pwc = L'\0';
      bytes_parsed = 1;
    } else if ( bytes_parsed == (size_t) -1 ) {
      /* invalid sequence, use replacement character and try again with last char */
      assert( errno == EILSEQ );
      if ( buf_len > 1 ) {
	buf[ 0 ] = buf[ buf_len - 1 ];
	bytes_parsed = buf_len - 1;
	buf_len = 1;
      } else {
	buf_len = 0;
	bytes_parsed = 1;
      }
      pwc = (wchar_t) 0xFFFD;
    } else if ( bytes_parsed == (size_t) -2 ) {
      /* can't parse incomplete multibyte character */
      total_bytes_parsed += buf_len;
      continue;
    } else if ( bytes_parsed > 0 ) {
      /* parsed into pwc, accept */
      assert( bytes_parsed <= buf_len );
      memcpy( buf, buf + bytes_parsed, buf_len - bytes_parsed );
      buf_len = buf_len - bytes_parsed;
    } else {
      throw std::string( "Unknown return value from mbrtowc" );
    }

    if ( (pwc < 0) || (pwc > 0x10FFFF) ) { /* outside Unicode range */
      pwc = (wchar_t) 0xFFFD;
    }

    if ( (pwc >= 0xD800) && (pwc <= 0xDFFF) ) { /* surrogate code point */
      /*
	OS X unfortunately allows these sequences without EILSEQ, but
	they are ill-formed UTF-8 and we shouldn't repeat them to the
	user's terminal.
      */
      pwc = (wchar_t) 0xFFFD;
    }

    std::list<Action *> vec = parser.input( pwc );
    ret.insert( ret.end(), vec.begin(), vec.end() );

    total_bytes_parsed += bytes_parsed;
  }

  return ret;
}

Parser::Parser::Parser( const Parser &other )
  : state( other.state )
{}

Parser::Parser & Parser::Parser::operator=( const Parser &other )
{
  state = other.state;
  return *this;
}