/**********************************************************************
 *
 * cgiutils.cpp -- general cgi utilities
 * Copyright (C) 1999  The New Zealand Digital Library Project
 *
 * A component of the Greenstone digital library software
 * from the New Zealand Digital Library Project at the
 * University of Waikato, New Zealand.
 *
 * 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 2 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, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *********************************************************************/

#include "cgiutils.h"
#include "gsdlunicode.h"
#include "unitool.h" // in mg, for output_utf8_char

static unsigned short hexdigit (unsigned short c) {
  if (c >= '0' && c <= '9') return (c-'0');
  if (c >= 'a' && c <= 'f') return (c-'a'+10);
  if (c >= 'A' && c <= 'F') return (c-'A'+10);
  return c;
}


static void c2hex (unsigned short c, text_t &t) {
  t.clear();
  
  if (c >= 256) {
    t = "20"; // ' '
    return;
  }
  
  unsigned short o1, o2;
  
  o1 = (c/16) % 16;
  o2 = c % 16;
  if (o1 >= 10) o1 += 'a' - 10;
  else o1 += '0';
  if (o2 >= 10) o2 += 'a' - 10;
  else o2 += '0';
  
  t.push_back(o1);
  t.push_back(o2);
}

// convert %xx and + to their appropriate equivalents
// IE 6.0 and later use "%u" followed by 4 hex digits... MS IIS extension!
void decode_cgi_arg (text_t &argstr) {
  text_t::iterator in = argstr.begin();
  text_t::iterator out = in;
  text_t::iterator end = argstr.end();
  
  while (in != end) {
    if (*in == '+') *out = ' ';
    
    else if (*in == '%') {
      unsigned short c = '%';
      ++in;
      if (in != end) { // this is an encoding...
	if (*in == 'u') { // convert %uHHHH to unicode then current encoding
	  // this assumes a short int is at least 16 bits...
	  ++in;  
	  if (in != end)
	    c=hexdigit(*in++) << 12;
	  if (in != end)
	    c+=hexdigit(*in++) << 8;
	  if (in != end)
	    c+=hexdigit(*in++) << 4;
	  if (in != end)
	    c+=hexdigit(*in);
	  /* BAD!! The following assumes the interface is using utf-8. But
	     at this point we don't know what encoding we are using, unless
	     we can parse it out of the string we are currently decoding... */
	  text_t uni=" ";
	  uni[0]=c;
	  text_t utf8=to_utf8(uni);
	  int last_byte=utf8.size()-1;
	  for (int i=0;i<last_byte;++i)
	    *out++ = utf8[i];
	  c=utf8[last_byte];
	} else {  // convert %HH to hex value
	  c = hexdigit (*in);
	  ++in;
	  if (in != end && c < 16) { // sanity check on the previous character
	    c = c*16 + hexdigit (*in);
	  }
	}
      }
      *out = c;
    } else *out = *in;
    
    if (in != end) ++in;
    ++out;
  }
  
  // remove the excess characters
  argstr.erase (out, end);
}


// split up the cgi arguments
void split_cgi_args (const cgiargsinfoclass &argsinfo, text_t argstr, 
		     cgiargsclass &args) {
  args.clear();
  
  text_t::const_iterator here = argstr.begin();
  text_t::const_iterator end = argstr.end();
  text_t key, value;
  
  // extract out the key=value pairs
  while (here != end) {
    // get the next key and value pair
    here = getdelimitstr (here, end, '=', key);
    here = getdelimitstr (here, end, '&', value);
    
    // convert %xx and + to their appropriate equivalents
    decode_cgi_arg (value);

    value.setencoding(1); // other encoding
    // store this key=value pair
    if (!key.empty()) {

      // if arg occurs multiple times (as is the case with multiple
      // checkboxes using the same name) we'll create a comma separated
      // list of all the values (this uses a hack that encodes naturally
      // occurring commas as %2C - values will therefore need to be decoded
      // again before use) - it should use an array instead
      const cgiarginfo *info = argsinfo.getarginfo (key);
      if (info != NULL && info->multiplevalue) {
	text_t newvalue = args[key];
	if (args.lookupcgiarg(key).source == cgiarg_t::cgi_arg) newvalue += ",";
	newvalue += encode_commas(value);
	args.setarg (key, newvalue, cgiarg_t::cgi_arg);

      } else {
	args.setarg (key, value, cgiarg_t::cgi_arg);
      }
    }
  }
}

text_t encode_commas (const text_t &intext) {

  text_t outtext;

  text_t::const_iterator here = intext.begin ();
  text_t::const_iterator end = intext.end ();

  while (here != end) {
    if (*here == ',') outtext += "%2C";
    else outtext.push_back (*here);
    ++here;
  }
  return outtext;
}

text_t decode_commas (const text_t &intext) {

  text_t outtext;
  
  text_t::const_iterator here = intext.begin ();
  text_t::const_iterator end = intext.end ();
  
  while (here != end) {
    if ((here+2<end) && *here == '%' && *(here+1) == '2' &&
	(*(here+2) == 'C' || *(here+2) == 'c')) {
      here += 2;
      outtext.push_back(',');
      
    }else outtext.push_back (*here);
    ++here;
  }
  return outtext;
}

text_t minus_safe (const text_t &intext) {

  text_t outtext;

  text_t::const_iterator here = intext.begin ();
  text_t::const_iterator end = intext.end ();

  while (here != end) {
    if (*here == '-') outtext += "Zz-";
    else outtext.push_back (*here);
    ++here;
  }
  outtext = cgi_safe (outtext);
  return outtext;
}

text_t cgi_safe (const text_t &intext) {
  text_t outtext;
  
  text_t::const_iterator here = intext.begin ();
  text_t::const_iterator end = intext.end ();
  unsigned short c;
  text_t ttmp;
  
  while (here != end) {
    c = *here;
    if (((c >= 'a') && (c <= 'z')) ||
	((c >= 'A') && (c <= 'Z')) ||
	((c >= '0') && (c <= '9')) ||
	(c == '+') || (c == '%') || (c == '-')) {
      // alphanumeric character
      outtext.push_back(c);
    } else if (c == ' ') {
      // space
      outtext.push_back('+');
    } else if (c > 255) { // unicode character
      unsigned char buf[3]; // up to 3 bytes
      buf[0]='\0';buf[1]='\0';buf[2]='\0';
      output_utf8_char(c,buf, buf+2);
      outtext.push_back('%');
      c2hex(buf[0], ttmp);
      outtext += ttmp;
      outtext.push_back('%');
      c2hex(buf[1], ttmp);
      outtext += ttmp;
      if (buf[2]) {
      outtext.push_back('%');
      c2hex(buf[2], ttmp);
      outtext += ttmp;
      }
    } else {
      // everything else
      outtext.push_back('%');
      c2hex(c, ttmp);
      outtext += ttmp;
    }
    
    ++here;
  }
  
  return outtext;
}




static text_t::const_iterator get_next_save_arg (text_t::const_iterator first, 
					   text_t::const_iterator last,
					   text_t &argname) {
  first = getdelimitstr (first, last, '-', argname);
  return first;
}


// check_save_conf_str checks the configuration string for
// the saved args and makes sure it does not conflict with
// the information about the arguments. If an error is encountered
// it will return false and the program should not produce any
// output.
bool check_save_conf_str (const text_t &saveconf, 
			  const cgiargsinfoclass &argsinfo,
			  ostream &logout) {
  outconvertclass text_t2ascii;

  text_tset argsset;
  text_t::const_iterator saveconfhere = saveconf.begin ();
  text_t::const_iterator saveconfend = saveconf.end ();
  text_t argname;
  const cgiarginfo *info;

  // first check to make sure all saved arguments can be saved
  
  while (saveconfhere != saveconfend) {
    saveconfhere = get_next_save_arg (saveconfhere, saveconfend, argname);

    if (!argname.empty()) {
      // save the argument name for later
      argsset.insert (argname);

      // check the argument
      info =  argsinfo.getarginfo (argname);
      if (info == NULL) {
	logout << text_t2ascii << "Error: the cgi argument \"" << argname 
	       << "\" is used in the configuration string for the\n"
	       << "saved arguments but does not exist as a valid argument.\n\n";
	return false;
      }
      if (info->savedarginfo == cgiarginfo::mustnot) {
	logout << text_t2ascii << "Error: the cgi argument \"" << argname
	       << "\" is used in the configuration string for the\n"
	       << "saved arguments but has been specified as an argument whose\n"
	       << "state must not be saved.\n\n";
	return false;
      }
    }
  }


  // next check that all saved arguments that should be saved
  // are saved
  cgiargsinfoclass::const_iterator argsinfohere = argsinfo.begin ();
  cgiargsinfoclass::const_iterator argsinfoend = argsinfo.end ();

  while (argsinfohere != argsinfoend) {
    if (((*argsinfohere).second.savedarginfo == cgiarginfo::must) &&
	(argsset.find((*argsinfohere).second.shortname) == argsset.end())) {
      logout << text_t2ascii << "Error: the cgi argument \"" 
	     << (*argsinfohere).second.shortname << "\" was specified as needing to\n"
	     << "be save but was not listed in the saved arguments.\n\n";
      return false;
    }

    ++argsinfohere;
  }
  
  return true; // made it, no clashes
}


// create_save_conf_str will create a configuration string
// based on the information in argsinfo. This method of configuration
// is not recomended as small changes can produce large changes in
// the resulting configuration string (for instance a totally different
// ordering). Only arguments which "must" be saved are included in
// the resulting string.
text_t create_save_conf_str (const cgiargsinfoclass &argsinfo,
			     ostream &/*logout*/) {
  cgiargsinfoclass::const_iterator argsinfohere = argsinfo.begin ();
  cgiargsinfoclass::const_iterator argsinfoend = argsinfo.end ();
  text_t saveconf;
  bool first = true;

  while (argsinfohere != argsinfoend) {
    // save this argument if it must be saved
    if ((*argsinfohere).second.savedarginfo == cgiarginfo::must) {
      if (!first) saveconf.push_back ('-');
      else first = false;
      saveconf += (*argsinfohere).second.shortname;
    }

    ++argsinfohere;
  }
  
  return saveconf;
}


// expand_save_args will expand the saved arguments based
// on saveconf placing the results in args if they are not
// already defined. If it encounters an error it will return false
// and output more information to logout.
bool expand_save_args (const cgiargsinfoclass &argsinfo,
		       const text_t &saveconf, 
		       cgiargsclass &args,
		       ostream &logout) {
  outconvertclass text_t2ascii;

  text_t *arg_e = args.getarg("e");
  if (arg_e == NULL) return true; // no compressed arguments
  if (arg_e->empty()) return true; // no compressed arguments

  text_t argname, argvalue;
  const cgiarginfo *argnameinfo;
  
  text_t::const_iterator saveconfhere = saveconf.begin();
  text_t::const_iterator saveconfend = saveconf.end();
  
  text_t::iterator arg_ehere = arg_e->begin();
  text_t::iterator arg_eend = arg_e->end();
  while (saveconfhere != saveconfend && arg_ehere != arg_eend) {
    saveconfhere = get_next_save_arg (saveconfhere, saveconfend, argname);

    if (!argname.empty()) {
      // found another entry
      argnameinfo = argsinfo.getarginfo (argname);

      if (argnameinfo == NULL) {
	// no information about the argument could be found
	// we can't keep going because we don't know whether
	// this argument is a single or multiple character value
	logout << text_t2ascii << "Error: the cgi argument \"" << argname
	       << "\" was specified as being a compressed argument\n"
	       << "but no information about it could be found within the "
	       << "cgiargsinfoclass.\n";
	return false;

      } else {

	// found the argument information
	if (argnameinfo->multiplechar) {
	  text_t::const_iterator sav = arg_ehere;
	  arg_ehere = getdelimitstr (arg_ehere, arg_eend, '-', argvalue);
	  // replace any '-' chars escaped with 'Zz'
	  bool first = true;
	  while ((*(arg_ehere-3) == 'Z') && (*(arg_ehere-2) == 'z')) {
	    if (first) argvalue.clear();
	    arg_ehere = (findchar (arg_ehere, arg_eend, '-')) + 1;
	    while (sav != (arg_ehere-1)) {
	      if (!((*sav == 'Z') && (*(sav+1) == 'z') && (*(sav+2) == '-')) &&
		  !((*(sav-1) == 'Z') && (*sav == 'z') && (*(sav+1) == '-'))) argvalue.push_back (*sav);
	      ++sav;
	    }
	    first = false;
	  }

	  argvalue.setencoding(1); // other encoding
	  if (!argvalue.empty()) args.setdefaultarg (argname, argvalue, cgiarg_t::compressed_arg);
	} else {
	  args.setdefaultcarg (argname,*arg_ehere, cgiarg_t::compressed_arg);
	  ++arg_ehere;
	}
      }
    }
  }

  return true;
}


// adds the default values for those arguments which have not
// been specified
void add_default_args (const cgiargsinfoclass &argsinfo,
		       cgiargsclass &args,
		       ostream &/*logout*/) {
  cgiargsinfoclass::const_iterator argsinfohere = argsinfo.begin ();
  cgiargsinfoclass::const_iterator argsinfoend = argsinfo.end ();

  while (argsinfohere != argsinfoend) {
    if ((*argsinfohere).second.defaultstatus != cgiarginfo::none) {
      args.setdefaultarg ((*argsinfohere).second.shortname,
			  (*argsinfohere).second.argdefault, cgiarg_t::default_arg);
    }
    ++argsinfohere;
  }
}


// compress_save_args will compress the arguments and return
// them in compressed_args. If an error was encountered
// compressed_args will be set to to "", an error will be
// written to logout, and the function will return false.
bool compress_save_args (const cgiargsinfoclass &argsinfo,
			 const text_t &saveconf,
			 cgiargsclass &args,
			 text_t &compressed_args,
			 outconvertclass &outconvert,
			 ostream &logout) {
  outconvertclass text_t2ascii;

  compressed_args.clear();

  text_t argname, argvalue;
  const cgiarginfo *argnameinfo;
  
  text_t::const_iterator saveconfhere = saveconf.begin();
  text_t::const_iterator saveconfend = saveconf.end();
  
  while (saveconfhere != saveconfend) {
    saveconfhere = get_next_save_arg (saveconfhere, saveconfend, argname);

    if (!argname.empty()) {
      // found another entry
      argnameinfo = argsinfo.getarginfo (argname);

      if (argnameinfo == NULL) {
	// no information about the argument could be found
	// we can't keep going because we don't know whether
	// this argument is a single or multiple character value
	logout << text_t2ascii << "Error: the cgi argument \"" << argname
	       << "\" was specified as being a compressed argument\n"
	       << "but no information about it could be found within the "
	       << "cgiargsinfoclass.\n";
	compressed_args.clear();
	return false;

      } else {
	// found the argument information
	if (argnameinfo->multiplechar) {
	  // multiple character argument -- sort out any '-' chars
	  if (args["w"]=="utf-16be") // browsers don't like \0 in urls...
	    compressed_args += minus_safe (args[argname]);
	  else
	    compressed_args += minus_safe (outconvert.convert(args[argname]));

	  if (saveconfhere != saveconfend) compressed_args.push_back ('-');

	} else {
	  // single character argument
	  if (args[argname].size() == 0) {
	    logout << text_t2ascii << "Error: the cgi argument \"" << argname
		   << "\" was specified as being a compressed argument which\n"
		   << "should have a one character value but it was empty.\n\n";
	    compressed_args.clear ();
	    return false;

	  } else if (args[argname].size() > 1) {
	    logout << text_t2ascii << "Error: the cgi argument \"" << argname
		   << "\" was specified as being a compressed argument which\n"
		   << "should have a one character value but it had multiple characters.\n\n";
	    compressed_args.clear ();
	    return false;
	  }

	  // everything is ok
	  compressed_args += args[argname];
	}
      }
    }
  }

  return true;
}


// args_tounicode converts any arguments which are not in unicode
// to unicode using inconvert
void args_tounicode (cgiargsclass &args, inconvertclass &inconvert) {
  cgiargsclass::iterator here = args.begin();
  cgiargsclass::iterator end = args.end();

  while (here != end) {
    if ((*here).second.value.getencoding() > 0) {
      (*here).second.value = inconvert.convert((*here).second.value);
    }
    
    ++here;
  }
}

// fcgienv will be loaded with environment name-value pairs
// if using fastcgi (had to do this as getenv doesn't work
// with our implementation of fastcgi). if fcgienv is empty
// we'll simply use getenv
text_t gsdl_getenv (const text_t &name, text_tmap &fcgienv) {
  if (fcgienv.empty()) {
    char *n = name.getcstr();
    char *v = getenv(n);
    delete []n;
    if (v != NULL) return v;
    return g_EmptyText;

  } else return fcgienv[name];
}