/*
* SCAN Name Abstraction
* (C) 2008-2009 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/

#include <botan/scan_name.h>
#include <botan/parsing.h>
#include <botan/exceptn.h>
#include <stdexcept>

namespace Botan {

namespace {

std::string make_arg(
   const std::vector<std::pair<size_t, std::string> >& name, size_t start)
   {
   std::string output = name[start].second;
   size_t level = name[start].first;

   size_t paren_depth = 0;

   for(size_t i = start + 1; i != name.size(); ++i)
      {
      if(name[i].first <= name[start].first)
         break;

      if(name[i].first > level)
         {
         output += '(' + name[i].second;
         ++paren_depth;
         }
      else if(name[i].first < level)
         {
         output += ")," + name[i].second;
         --paren_depth;
         }
      else
         {
         if(output[output.size() - 1] != '(')
            output += ",";
         output += name[i].second;
         }

      level = name[i].first;
      }

   for(size_t i = 0; i != paren_depth; ++i)
      output += ')';

   return output;
   }

std::pair<size_t, std::string>
deref_aliases(const std::pair<size_t, std::string>& in)
   {
   return std::make_pair(in.first,
                         SCAN_Name::deref_alias(in.second));
   }

}

std::mutex SCAN_Name::s_alias_map_mutex;
std::map<std::string, std::string> SCAN_Name::s_alias_map;

SCAN_Name::SCAN_Name(std::string algo_spec)
   {
   orig_algo_spec = algo_spec;

   std::vector<std::pair<size_t, std::string> > name;
   size_t level = 0;
   std::pair<size_t, std::string> accum = std::make_pair(level, "");

   std::string decoding_error = "Bad SCAN name '" + algo_spec + "': ";

   algo_spec = SCAN_Name::deref_alias(algo_spec);

   for(size_t i = 0; i != algo_spec.size(); ++i)
      {
      char c = algo_spec[i];

      if(c == '/' || c == ',' || c == '(' || c == ')')
         {
         if(c == '(')
            ++level;
         else if(c == ')')
            {
            if(level == 0)
               throw Decoding_Error(decoding_error + "Mismatched parens");
            --level;
            }

         if(c == '/' && level > 0)
            accum.second.push_back(c);
         else
            {
            if(accum.second != "")
               name.push_back(deref_aliases(accum));
            accum = std::make_pair(level, "");
            }
         }
      else
         accum.second.push_back(c);
      }

   if(accum.second != "")
      name.push_back(deref_aliases(accum));

   if(level != 0)
      throw Decoding_Error(decoding_error + "Missing close paren");

   if(name.size() == 0)
      throw Decoding_Error(decoding_error + "Empty name");

   alg_name = name[0].second;

   bool in_modes = false;

   for(size_t i = 1; i != name.size(); ++i)
      {
      if(name[i].first == 0)
         {
         mode_info.push_back(make_arg(name, i));
         in_modes = true;
         }
      else if(name[i].first == 1 && !in_modes)
         args.push_back(make_arg(name, i));
      }
   }

std::string SCAN_Name::algo_name_and_args() const
   {
   std::string out;

   out = algo_name();

   if(arg_count())
      {
      out += '(';
      for(size_t i = 0; i != arg_count(); ++i)
         {
         out += arg(i);
         if(i != arg_count() - 1)
            out += ',';
         }
      out += ')';

      }

   return out;
   }

std::string SCAN_Name::arg(size_t i) const
   {
   if(i >= arg_count())
      throw std::range_error("SCAN_Name::argument - i out of range");
   return args[i];
   }

std::string SCAN_Name::arg(size_t i, const std::string& def_value) const
   {
   if(i >= arg_count())
      return def_value;
   return args[i];
   }

size_t SCAN_Name::arg_as_integer(size_t i, size_t def_value) const
   {
   if(i >= arg_count())
      return def_value;
   return to_u32bit(args[i]);
   }

void SCAN_Name::add_alias(const std::string& alias, const std::string& basename)
   {
   std::lock_guard<std::mutex> lock(s_alias_map_mutex);

   if(s_alias_map.find(alias) == s_alias_map.end())
      s_alias_map[alias] = basename;
   }

std::string SCAN_Name::deref_alias(const std::string& alias)
   {
   std::lock_guard<std::mutex> lock(s_alias_map_mutex);

   std::string name = alias;

   for(auto i = s_alias_map.find(name); i != s_alias_map.end(); i = s_alias_map.find(name))
      name = i->second;

   return name;
   }

void SCAN_Name::set_default_aliases()
   {
   // common variations worth supporting
   SCAN_Name::add_alias("EME-PKCS1-v1_5",  "PKCS1v15");
   SCAN_Name::add_alias("3DES",     "TripleDES");
   SCAN_Name::add_alias("DES-EDE",  "TripleDES");
   SCAN_Name::add_alias("CAST5",    "CAST-128");
   SCAN_Name::add_alias("SHA1",     "SHA-160");
   SCAN_Name::add_alias("SHA-1",    "SHA-160");
   SCAN_Name::add_alias("MARK-4",   "RC4(256)");
   SCAN_Name::add_alias("ARC4",     "RC4");
   SCAN_Name::add_alias("OMAC",     "CMAC");

   SCAN_Name::add_alias("EMSA-PSS",        "PSSR");
   SCAN_Name::add_alias("PSS-MGF1",        "PSSR");
   SCAN_Name::add_alias("EME-OAEP",        "OAEP");

   SCAN_Name::add_alias("EMSA2",           "EMSA_X931");
   SCAN_Name::add_alias("EMSA3",           "EMSA_PKCS1");
   SCAN_Name::add_alias("EMSA-PKCS1-v1_5", "EMSA_PKCS1");

   // should be renamed in sources
   SCAN_Name::add_alias("X9.31",           "EMSA2");

   // kept for compatability with old library versions
   SCAN_Name::add_alias("EMSA4",           "PSSR");
   SCAN_Name::add_alias("EME1",            "OAEP");

   // probably can be removed
   SCAN_Name::add_alias("GOST",     "GOST-28147-89");
   SCAN_Name::add_alias("GOST-34.11", "GOST-R-34.11-94");
   }

}