/******************************************************************************

Copyright (c) 2009-2010, Terry Caton
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
    * Redistributions of source code must retain the above copyright 
      notice, this list of conditions and the following disclaimer.
    * 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.
    * Neither the name of the projecct nor the names of its contributors 
      may be used to endorse or promote products derived from this software 
      without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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(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 <cassert>
#include <set>
#include <sstream>

/*  

TODO:
* better documentation
* unicode character decoding

*/

namespace json
{

template<typename istream>
inline istream& operator >> (istream& istr, UnknownElement& elementRoot) {
   Reader<istream>::Read(elementRoot, istr);
   return istr;
}

//////////////////////
// Reader::InputStream
///////////////////
// Reader (finally)


template <typename istream>
template <typename ElementTypeT>   
void Reader<istream>::Read_i(ElementTypeT& element, istream& istr)
{
   Reader reader;

   Tokens tokens;
   InputStream inputStream(istr);
   reader.Scan(tokens, inputStream);

   TokenStream tokenStream(tokens);
   reader.Parse(element, tokenStream);

   if (tokenStream.EOS() == false)
   {
      const Token& token = tokenStream.Peek();
      std::string sMessage = std::string("Expected End of token stream; found ") + token.sValue;
      throw ParseException(sMessage, token.locBegin, token.locEnd);
   }
}

template <typename istream>
inline void Reader<istream>::Scan(Tokens& tokens, InputStream& inputStream)
{
   while (EatWhiteSpace(inputStream),              // ignore any leading white space...
          inputStream.EOS() == false) // ...before checking for EOS
   {
      // if all goes well, we'll create a token each pass
      Token token;
      token.locBegin = inputStream.GetLocation();

      // gives us null-terminated string
      char sChar = inputStream.Peek();
      switch (sChar)
      {
         case '{':
            token.sValue = MatchExpectedString(inputStream, "{");
            token.nType = Token::TOKEN_OBJECT_BEGIN;
            break;

         case '}':
            token.sValue = MatchExpectedString(inputStream, "}");
            token.nType = Token::TOKEN_OBJECT_END;
            break;

         case '[':
            token.sValue = MatchExpectedString(inputStream, "[");
            token.nType = Token::TOKEN_ARRAY_BEGIN;
            break;

         case ']':
            token.sValue = MatchExpectedString(inputStream, "]");
            token.nType = Token::TOKEN_ARRAY_END;
            break;

         case ',':
            token.sValue = MatchExpectedString(inputStream, ",");
            token.nType = Token::TOKEN_NEXT_ELEMENT;
            break;

         case ':':
            token.sValue = MatchExpectedString(inputStream, ":");
            token.nType = Token::TOKEN_MEMBER_ASSIGN;
            break;

         case '"':
            token.sValue = MatchString(inputStream);
            token.nType = Token::TOKEN_STRING;
            break;

         case '-':
         case '0':
         case '1':
         case '2':
         case '3':
         case '4':
         case '5':
         case '6':
         case '7':
         case '8':
         case '9':
            token.nValue = MatchNumber(inputStream);
            token.nType = Token::TOKEN_NUMBER;
            break;

         case 't':
            token.sValue = MatchExpectedString(inputStream, "true");
            token.nType = Token::TOKEN_BOOLEAN;
            break;

         case 'f':
            token.sValue = MatchExpectedString(inputStream, "false");
            token.nType = Token::TOKEN_BOOLEAN;
            break;

         case 'n':
            token.sValue = MatchExpectedString(inputStream, "null");
            token.nType = Token::TOKEN_NULL;
            break;

         default:
         {
            std::string sErrorMessage = std::string("Unexpected character in stream: ") + sChar;
            throw ScanException(sErrorMessage, inputStream.GetLocation());
         }
      }

      token.locEnd = inputStream.GetLocation();
      tokens.push_back(token);
   }
}


template <typename istream>
inline void Reader<istream>::EatWhiteSpace(InputStream& inputStream)
{
   while (inputStream.EOS() == false && 
          ::isspace(inputStream.Peek()))
      inputStream.Get();
}

template <typename istream>
inline const std::string &Reader<istream>::MatchExpectedString(InputStream& inputStream, const std::string& sExpected)
{
   std::string::const_iterator it(sExpected.begin()),
                               itEnd(sExpected.end());
   for ( ; it != itEnd; ++it) {
      if (inputStream.EOS() ||      // did we reach the end before finding what we're looking for...
          inputStream.Get() != *it) // ...or did we find something different?
      {
         std::string sMessage = std::string("Expected string: ") + sExpected;
         throw ScanException(sMessage, inputStream.GetLocation());
      }
   }

   // all's well if we made it here
   return sExpected;
}

inline unsigned int decodeUnicodeCodePoint (InputStream& inputStream)
{
	unsigned int v_[2];
	unsigned int &unicode = v_[0];
	unsigned int &surrogate = v_[1];

	for (int n=0; n<2; n++)
	{
		unsigned int &v = v_[x];
		v = 0;
		
		for (int i=3; i>=0 && !inputStream.EOS(); --i)
		{
			char c = inputStream.Get();
			unsigned int ord = 0;
			if ('0' <= c && c <= '9')
				ord = c - '0';
			else
			if ('A' <= c && c <= 'F')
				ord = 10 + (c - 'A');
			else
			if ('a' <= c && c <= 'f')
				ord = 10 + (c - 'a');
				
			v |= ord << (4 * i);
		}
		
		bool hasSurrogate = false;
		if (v >= 0xD800 && v <= 0xDBFF)
		{
			int pos = inputStream.TellG();
			
			if (!inputStream.Get() != '\\' || !inputStream.Get() != 'u')
				inputStream.SetG(pos);
			else
				hasSurrogate = true;
		}
		
		if (!hasSurrogate)
			break;
	}

	if (n == 2)
		unicode = 0x10000 + ((unicode & 0x3FF) << 10) + (surrogate & 0x3FF);
		
	return unicode;
}

inline std::string codePointToUTF8(unsigned int cp)
{
   std::string result;
   
   // based on description from http://en.wikipedia.org/wiki/UTF-8

   if (cp <= 0x7f) 
   {
      result.resize(1);
      result[0] = static_cast<char>(cp);
   } 
   else if (cp <= 0x7FF) 
   {
      result.resize(2);
      result[1] = static_cast<char>(0x80 | (0x3f & cp));
      result[0] = static_cast<char>(0xC0 | (0x1f & (cp >> 6)));
   } 
   else if (cp <= 0xFFFF) 
   {
      result.resize(3);
      result[2] = static_cast<char>(0x80 | (0x3f & cp));
      result[1] = 0x80 | static_cast<char>((0x3f & (cp >> 6)));
      result[0] = 0xE0 | static_cast<char>((0xf & (cp >> 12)));
   }
   else if (cp <= 0x10FFFF) 
   {
      result.resize(4);
      result[3] = static_cast<char>(0x80 | (0x3f & cp));
      result[2] = static_cast<char>(0x80 | (0x3f & (cp >> 6)));
      result[1] = static_cast<char>(0x80 | (0x3f & (cp >> 12)));
      result[0] = static_cast<char>(0xF0 | (0x7 & (cp >> 18)));
   }

   return result;
}

template <typename istream>
inline const std::string &Reader<istream>::MatchString(InputStream& inputStream)
{
   MatchExpectedString(inputStream, "\"");

   buffer.resize(0);
   std::string &string = buffer;
   
   while (inputStream.EOS() == false &&
          inputStream.Peek() != '"')
   {
      char c = inputStream.Get();

      // escape?
      if (c == '\\' &&
          inputStream.EOS() == false) // shouldn't have reached the end yet
      {
         c = inputStream.Get();
         switch (c) {
            case '/':      string.push_back('/');     break;
            case '"':      string.push_back('"');     break;
            case '\\':     string.push_back('\\');    break;
            case 'b':      string.push_back('\b');    break;
            case 'f':      string.push_back('\f');    break;
            case 'n':      string.push_back('\n');    break;
            case 'r':      string.push_back('\r');    break;
            case 't':      string.push_back('\t');    break;
            case 'u': 
			{
				string += codePointToUTF8(decodeUnicodeCodePoint(inputStream));
			}
			break;
            default: {
               std::string sMessage = std::string("Unrecognized escape sequence found in string: \\") + c;
               throw ScanException(sMessage, inputStream.GetLocation());
            }
         }
      }
      else {
         string.push_back(c);
      }
   }

   // eat the last '"' that we just peeked
   MatchExpectedString(inputStream, "\"");

   // all's well if we made it here
   return buffer;
}


template <typename istream>
inline Number::ValueType Reader<istream>::MatchNumber(InputStream& inputStream)
{
	const int MAX_BUF=255;
	char buffer[MAX_BUF+1];
	char p = 0;
	
   while (p<MAX_BUF && inputStream.EOS() == false &&
          numericChars.find(inputStream.Peek()) != numericChars.end())
   {
	buffer[p++] = inputStream.Get();
   }
   buffer[p] = 0;
   
#ifdef JSON_USE_STRING_AS_NUMBER
	return json::NumberString(buffer);
#else
   int base=0;
   char *end;
   return strtol(buffer,&end, base);
#endif
}

template <typename istream>
inline void Reader<istream>::Parse(UnknownElement& element, Reader::TokenStream& tokenStream) 
{
   const Token& token = tokenStream.Peek();
   switch (token.nType) {
      case Token::TOKEN_OBJECT_BEGIN:
      {
         // implicit non-const cast will perform conversion for us (if necessary)
         Object& object = element;
         Parse(object, tokenStream);
         break;
      }

      case Token::TOKEN_ARRAY_BEGIN:
      {
         Array& array = element;
         Parse(array, tokenStream);
         break;
      }

      case Token::TOKEN_STRING:
      {
         String& string = element;
         Parse(string, tokenStream);
         break;
      }

      case Token::TOKEN_NUMBER:
      {
         Number& number = element;
         Parse(number, tokenStream);
         break;
      }

      case Token::TOKEN_BOOLEAN:
      {
         Boolean& boolean = element;
         Parse(boolean, tokenStream);
         break;
      }

      case Token::TOKEN_NULL:
      {
         Null& null = element;
         Parse(null, tokenStream);
         break;
      }

      default:
      {
         std::string sMessage = std::string("Unexpected token: ") + token.sValue;
         throw ParseException(sMessage, token.locBegin, token.locEnd);
      }
   }
}


template <typename istream>
inline void Reader<istream>::Parse(Object& object, Reader::TokenStream& tokenStream)
{
   MatchExpectedToken(Token::TOKEN_OBJECT_BEGIN, tokenStream);

   bool bContinue = (tokenStream.EOS() == false &&
                     tokenStream.Peek().nType != Token::TOKEN_OBJECT_END);
   while (bContinue)
   {
      Object::Member member;

      // first the member name. save the token in case we have to throw an exception
      const Token& tokenName = tokenStream.Peek();
      member.name = MatchExpectedToken(Token::TOKEN_STRING, tokenStream);

      // ...then the key/value separator...
      MatchExpectedToken(Token::TOKEN_MEMBER_ASSIGN, tokenStream);

      // ...then the value itself (can be anything).
      Parse(member.element, tokenStream);

      // try adding it to the object (this could throw)
      try
      {
         object.Insert(member);
      }
      catch (Exception&)
      {
         // must be a duplicate name
         std::string sMessage = std::string("Duplicate object member token: ") + member.name; 
         throw ParseException(sMessage, tokenName.locBegin, tokenName.locEnd);
      }

      bContinue = (tokenStream.EOS() == false &&
                   tokenStream.Peek().nType == Token::TOKEN_NEXT_ELEMENT);
      if (bContinue)
         MatchExpectedToken(Token::TOKEN_NEXT_ELEMENT, tokenStream);
   }

   MatchExpectedToken(Token::TOKEN_OBJECT_END, tokenStream);
}

template <typename istream>
inline void Reader<istream>::Parse(Array& array, Reader::TokenStream& tokenStream)
{
   MatchExpectedToken(Token::TOKEN_ARRAY_BEGIN, tokenStream);

   bool bContinue = (tokenStream.EOS() == false &&
                     tokenStream.Peek().nType != Token::TOKEN_ARRAY_END);
   while (bContinue)
   {
      // ...what's next? could be anything
      Array::iterator itElement = array.Insert(UnknownElement());
      UnknownElement& element = *itElement;
      Parse(element, tokenStream);

      bContinue = (tokenStream.EOS() == false &&
                   tokenStream.Peek().nType == Token::TOKEN_NEXT_ELEMENT);
      if (bContinue)
         MatchExpectedToken(Token::TOKEN_NEXT_ELEMENT, tokenStream);
   }

   MatchExpectedToken(Token::TOKEN_ARRAY_END, tokenStream);
}

template <typename istream>
inline void Reader<istream>::Parse(String& string, Reader::TokenStream& tokenStream)
{
   string = MatchExpectedToken(Token::TOKEN_STRING, tokenStream);
}


template <typename istream>
inline void Reader<istream>::Parse(Number& number, Reader::TokenStream& tokenStream)
{
/*
#ifdef JSON_USE_STRING_AS_NUMBER
   const std::string& sValue = MatchExpectedToken(Token::TOKEN_NUMBER, tokenStream);
	
//   std::istringstream iStr(sValue);
   Number::ValueType dValue;
//   iStr >> dValue;

	int base=0;
	char *end;
	const char *s = sValue.c_str();
	dValue = strtol(s, &end, base);

   // did we consume all characters in the token?
   if (*end != '\0')
//   if (iStr.eof() == false)
   {
 //     char c = iStr.peek();
	char c = *end;
      std::string sMessage = std::string("Unexpected character in NUMBER token: ") + c;
      throw ParseException(sMessage, currentToken.locBegin, currentToken.locEnd);
   }

   number = dValue;
#else
*/
   const Token& currentToken = tokenStream.Get(); // might need this later for throwing exception
	number = currentToken.nValue;
//#endif
}


template <typename istream>
inline void Reader<istream>::Parse(Boolean& boolean, Reader::TokenStream& tokenStream)
{
   const std::string& sValue = MatchExpectedToken(Token::TOKEN_BOOLEAN, tokenStream);
   boolean = (sValue == "true" ? true : false);
}


template <typename istream>
inline void Reader<istream>::Parse(Null&, Reader::TokenStream& tokenStream)
{
   MatchExpectedToken(Token::TOKEN_NULL, tokenStream);
}


} // End namespace