/*

 * lftp - file transfer program

 *

 * Copyright (c) 1996-2015 by Alexander V. Lukyanov (lav@yars.free.net)

 *

 * 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 <config.h>

#include <fcntl.h>

#include "CmdExec.h"

#include "alias.h"

#include "xstring.h"

bool CmdExec::quotable(char ch,char in_quotes)

{

   if(!ch)

      return false;

   if(ch=='\\' || ch=='!' || ch==in_quotes)

      return true;

   if(in_quotes)

      return false;

   if(strchr("\"' \t>|;&",ch))

      return true;

   return false;

}

CmdExec::parse_result CmdExec::parse_one_cmd()

{

   char	 in_quotes;

   const char *line=cmd_buf.Get();

   const char *line_begin=line;

   static xstring nextarg;

   const char *alias=0;

   if(args)

      args->Empty();

   else

      args=new ArgV;

   output=0;

   char redir_type=0;

   background=0;

   if(!*line)

   {

      // empty command

      return PARSE_OK;

   }

   if(line[0]=='&' && line[1]=='&')

   {

      condition=COND_AND;

      line+=2;

   }

   else if(line[0]=='|' && line[1]=='|')

   {

      condition=COND_OR;

      line+=2;

   }

   else

   {

      condition=COND_ANY;

   }

   // loop for all arguments

   for(;;)

   {

      // skip leading whitespace

      while(is_space(*line))

	 line++;

      if(line[0]=='\\' && line[1]=='\n')

      {

	 line+=2;

	 continue;   // and continue skipping space

      }

      if(line[0]=='\r' && line[1]=='\n')

	 line++;

      if(*line==0)

	 return PARSE_AGAIN;

      if(*line=='\n'

      || *line=='|' || *line=='>' || *line==';' || *line=='&')

	 break;

      nextarg.truncate(0);

      if(args->count()==0 && *line=='#')

      {

	 // comment -- skip and return

	 while(*line!='\n' && *line)

	    line++;

	 if(*line=='\n')

	    line++;

	 else

	    return PARSE_AGAIN;

	 skip_cmd(line-line_begin);

	 return PARSE_OK;

      }

      if(args->count()==0 && *line=='!')

      {

	 // shell command -- it ends only with '\n'

	 args->Append("!");

	 line++;

	 while(is_space(*line))

	    line++;

	 while(*line!='\n' && *line)

	 {

	    if(*line=='\\' && line[1]=='\n')

	    {

	       line+=2;

	       continue;

	    }

	    nextarg.append(*line++);

	 }

	 if(*line==0)

	    return PARSE_AGAIN;

	 if(*line=='\n')

	    line++;

	 skip_cmd(line-line_begin);

	 if(nextarg.length()>0)

	    args->Append(nextarg);

	 return PARSE_OK;

      }

      if(args->count()==0 && *line=='(')

      {

	 line++;

	 args->Append("(");

	 int level=1;

	 in_quotes=0;

	 for(;;)

	 {

	    if(*line==0)

	       return PARSE_AGAIN;

	    if(*line=='\\' && line[1] && (strchr("\"\\",line[1])

			         || (level==1 && line[1]==')')))

	    {

	       nextarg.append(*line++);

	    }

	    else

	    {

	       if(!in_quotes)

	       {

		  if(*line==')')

		  {

		     if(--level==0)

			break;

		  }

		  else if(*line=='(')

		     level++;

	       }

	       if(in_quotes && *line==in_quotes)

		  in_quotes=0;

	       else if(!in_quotes && is_quote(*line))

		  in_quotes=*line;

	    }

	    nextarg.append(*line++);

	 }

	 args->Append(nextarg);

	 line++;  // skip )

	 while(is_space(*line))

	    line++;

	 goto cmd_end;

      }

      if(args->count()==0 && *line=='?')

      {

	 line++;

	 args->Append("?");

	 continue;

      }

      // loop for one argument

      in_quotes=0;

      for(;;)

      {

	 if(*line=='\\' && line[1]=='\n')

	 {

	    line+=2;

	    continue;

	 }

	 if(line[0]=='\r' && line[1]=='\n')

	    line++;

	 if(*line=='\\' && quotable(line[1],in_quotes))

	 {

	    line++;

	 }

	 else

	 {

	    if(*line==0)

	       return PARSE_AGAIN;

	    if(*line=='\n'

	    || (!in_quotes && (is_space(*line)

		     || *line=='>' || *line=='|' || *line==';' || *line=='&')))

	       break;

	    if(!in_quotes && is_quote(*line))

	    {

	       in_quotes=*line;

	       line++;

	       continue;

	    }

	    if(in_quotes && *line==in_quotes)

	    {

	       in_quotes=0;

	       line++;

	       continue;

	    }

	 }

	 nextarg.append(*line++);

      }

      if(*line==0)

	 return PARSE_AGAIN;  // normal commands finish with \n or ;

      // check if the first arg is an alias, expand it accordingly.

      if(args->count()==0)

      {

	 alias=Alias::Find(nextarg);

      	 if(alias)

	 {

	    int alias_len=strlen(alias);

	    /* Check if the previous alias ends before the end of new one.

	     * So the new alias does not expand entirely from previous

	     * aliases and we can repeat the expansion from the very beginning. */

	    if(alias_field<(int)(line-line_begin))

	       free_used_aliases();

	    if(!TouchedAlias::IsTouched(alias,used_aliases))

	    {

	       skip_cmd(line-line_begin);

	       used_aliases=new TouchedAlias(alias,used_aliases);

	       cmd_buf.Prepend(alias);

	       alias_field+=alias_len;

	       line=line_begin=cmd_buf.Get();

	       continue;

	    }

	 }

      }

      args->Append(nextarg);

   }

   if(*line==0)

      return PARSE_AGAIN;

   if((line[0]=='&' && line[1]=='&')

   || (line[0]=='|' && line[1]=='|'))

   {

      skip_cmd(line-line_begin);

      return PARSE_OK;

   }

   if(*line=='>' || *line=='|')

   {

      redir_type=*line;

      line++;

      if(*line=='>')

      {

	 // '>>' means append

	 redir_type='+';

	 line++;

      }

      // skip leading whitespace

      while(is_space(*line))

	 line++;

      if(*line==0)

	 return PARSE_AGAIN;

      if(*line=='\n' || *line==';' || *line=='&')

      {

	 if(redir_type=='|')

	    eprintf(_("parse: missing filter command\n"));

	 else

	    eprintf(_("parse: missing redirection filename\n"));

	 if(*line==';' || *line=='&' || *line=='\n')

	    line++;

	 skip_cmd(line-line_begin);

	 return PARSE_ERR;

      }

      nextarg.truncate(0);

      in_quotes=0;

      for(;;)

      {

	 if(*line=='\\' && line[1]=='\n')

	 {

	    line+=2;

	    continue;

	 }

	 if(*line=='\\' && quotable(line[1],in_quotes))

	    line++;

	 else

	 {

	    if(*line==0)

	       return PARSE_AGAIN;

	    // filename can end with a space, filter command can't.

	    if(*line=='\n' || (!in_quotes

		  && ((redir_type!='|' && is_space(*line))

		      || *line==';' || *line=='&')))

	       break;

	    if(!in_quotes && is_quote(*line))

	    {

	       in_quotes=*line;

	       line++;

	       continue;

	    }

	    if(in_quotes && *line==in_quotes)

	    {

	       in_quotes=0;

	       line++;

	       continue;

	    }

	 }

	 nextarg.append(*line++);

      }

      // skip spaces

      while(is_space(*line))

	 line++;

   }

cmd_end:

   if((line[0]=='&' && line[1]=='&')

   || (line[0]=='|' && line[1]=='|'))

      ;

   else if(*line==';' || *line=='&' || *line=='\n')

   {

      if(*line=='&')

	 background=1;

      line++;

   }

   skip_cmd(line-line_begin);

   switch(redir_type)

   {

   case('|'):

      output=new OutputFilter(nextarg);

      break;

   case('>'):

      output=new FileStream(nextarg,O_WRONLY|O_TRUNC|O_CREAT);

      break;

   case('+'):

      output=new FileStream(nextarg,O_WRONLY|O_APPEND|O_CREAT);

      break;

   }

   return PARSE_OK;

}