/*
 * JSON.cpp
 * Copyright (C) 2010 Mike Anchor <mikea@mjpa.co.uk>
 *
 * Part of the MJPA JSON Library - http://mjpa.co.uk/blog/view/A-simple-C-JSON-library/
 *
 * License: http://mjpa.co.uk/licenses/GPLv2/
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "JSON.h"

/** 
 * Blocks off the public constructor
 *
 * @access private
 *
 */
JSON::JSON()
{
}

/**
 * Parses a complete JSON encoded string
 * This is just a wrapper around the UNICODE Parse().
 *
 * @access public
 *
 * @param char* data The JSON text
 *
 * @return JSONValue* Returns a JSON Value representing the root, or NULL on error
 */
JSONValue *JSON::Parse(const char *data)
{
	size_t length = strlen(data) + 1;
	wchar_t *w_data = (wchar_t*)malloc(length * sizeof(wchar_t));
	
	#ifdef WIN32
		size_t ret_value = 0;
		if (mbstowcs_s(&ret_value, w_data, length, data, length) != 0)
		{
			free(w_data);
			return NULL;
		}
	#else
		if (mbstowcs(w_data, data, length) == (size_t)-1)
		{
			free(w_data);
			return NULL;
		}
	#endif
	
	JSONValue *value = JSON::Parse(w_data);
	free(w_data);
	return value;
}

/**
 * Parses a complete JSON encoded string (UNICODE input version)
 *
 * @access public
 *
 * @param wchar_t* data The JSON text
 *
 * @return JSONValue* Returns a JSON Value representing the root, or NULL on error
 */
JSONValue *JSON::Parse(const wchar_t *data)
{
	// Skip any preceding whitespace, end of data = no JSON = fail
	if (!SkipWhitespace(&data))
		return NULL;

	// We need the start of a value here now...
	JSONValue *value = JSONValue::Parse(&data);
	if (value == NULL)
		return NULL;
	
	// Can be white space now and should be at the end of the string then...
	if (SkipWhitespace(&data))
	{
		delete value;
		return NULL;
	}
	
	// We're now at the end of the string
	return value;
}

/**
 * Turns the passed in JSONValue into a JSON encode string
 *
 * @access public
 *
 * @param JSONValue* value The root value
 *
 * @return std::wstring Returns a JSON encoded string representation of the given value
 */
std::wstring JSON::Stringify(JSONValue *value)
{
	if (value != NULL)
		return value->Stringify();
	else
		return L"";
}

/** 
 * Skips over any whitespace characters (space, tab, \r or \n) defined by the JSON spec
 *
 * @access protected
 *
 * @param wchar_t** data Pointer to a wchar_t* that contains the JSON text
 *
 * @return bool Returns true if there is more data, or false if the end of the text was reached
 */
bool JSON::SkipWhitespace(const wchar_t **data)
{
	while (**data != 0 && (**data == L' ' || **data == L'\t' || **data == L'\r' || **data == L'\n'))
		(*data)++;
	
	return **data != 0;
}

/** 
 * Extracts a JSON String as defined by the spec - "<some chars>"
 * Any escaped characters are swapped out for their unescaped values
 *
 * @access protected
 *
 * @param wchar_t** data Pointer to a wchar_t* that contains the JSON text
 * @param std::wstring& str Reference to a std::wstring to receive the extracted string
 *
 * @return bool Returns true on success, false on failure
 */
bool JSON::ExtractString(const wchar_t **data, std::wstring &str)
{
	size_t str_length = 0;
	str = L"";
	
	while (**data != 0)
	{
		// Save the char so we can change it if need be
		wchar_t next_char = **data;
		
		// Escaping something?
		if (next_char == L'\\')
		{
			// Move over the escape char
			(*data)++;
			
			// Deal with the escaped char
			switch (**data)
			{
				case L'"': next_char = L'"'; break;
				case L'\\': next_char = L'\\'; break;
				case L'/': next_char = L'/'; break;
				case L'b': next_char = L'\b'; break;
				case L'f': next_char = L'\f'; break;
				case L'n': next_char = L'\n'; break;
				case L'r': next_char = L'\r'; break;
				case L't': next_char = L'\t'; break;
				case L'u':
				{
					// We need 5 chars (4 hex + the 'u') or its not valid
					if (wcslen(*data) < 5)
						return false;
					
					// Deal with the chars
					next_char = 0;
					for (int i = 0; i < 4; i++)
					{
						// Do it first to move off the 'u' and leave us on the 
						// final hex digit as we move on by one later on
						(*data)++;
						
						next_char <<= 4;
						
						// Parse the hex digit
						if (**data >= '0' && **data <= '9')
							next_char |= (**data - '0');
						else if (**data >= 'A' && **data <= 'F')
							next_char |= (10 + (**data - 'A'));
						else if (**data >= 'a' && **data <= 'f')
							next_char |= (10 + (**data - 'a'));
						else
						{
							// Invalid hex digit = invalid JSON
							return false;
						}
					}
					break;
				}
				
				// By the spec, only the above cases are allowed
				default:
					return false;
			}
		}
		
		// End of the string?
		else if (next_char == L'"')
		{
			(*data)++;
			str.reserve(); // Remove unused capacity
			return true;
		}
		
		// Disallowed char?
		else if (next_char < L' ' && next_char != L'\t')
		{
			// SPEC Violation: Allow tabs due to real world cases
			return false;
		}
		
		// String will be one longer - do it before memory size check
		str_length++;
		
		// Need more memory?
		if (str_length > str.capacity())
		{
			str_length += 256;
			str.reserve(str_length);
		}
		
		// Add the next char
		str += next_char;
		
		// Move on
		(*data)++;
	}
	
	// If we're here, the string ended incorrectly
	return false;
}

/** 
 * Parses some text as though it is an integer
 *
 * @access protected
 *
 * @param wchar_t** data Pointer to a wchar_t* that contains the JSON text
 *
 * @return int Returns the int value of the number found
 */
int JSON::ParseInt(const wchar_t **data)
{
	int integer = 0;
	while (**data != 0 && **data >= '0' && **data <= '9')
		integer = integer * 10 + (*(*data)++ - '0');
	return integer;
}