#include "../config/pathan_config.h"
/*
 * Copyright (c) 2001, DecisionSoft Limited All rights reserved.
 * Please see LICENSE.TXT for more information.
 */

#include <pathan/functions/FunctionSubstring.hpp>
#include <pathan/ATStringOrDerived.hpp>
#include <pathan/ATDoubleOrDerived.hpp>
#include <pathan/exceptions/FunctionException.hpp>
#include <pathan/XPath2Utils.hpp>
#include <pathan/DynamicContext.hpp>
#include <pathan/internal/m_apm.h>
#include <pathan/internal/factory/DatatypeFactory.hpp>
#include <xercesc/util/XMLString.hpp>

const XMLCh FunctionSubstring::name[] = {
XERCES_CPP_NAMESPACE_QUALIFIER chLatin_s, XERCES_CPP_NAMESPACE_QUALIFIER chLatin_u, XERCES_CPP_NAMESPACE_QUALIFIER chLatin_b, XERCES_CPP_NAMESPACE_QUALIFIER chLatin_s, XERCES_CPP_NAMESPACE_QUALIFIER chLatin_t, XERCES_CPP_NAMESPACE_QUALIFIER chLatin_r, XERCES_CPP_NAMESPACE_QUALIFIER chLatin_i, XERCES_CPP_NAMESPACE_QUALIFIER chLatin_n, XERCES_CPP_NAMESPACE_QUALIFIER chLatin_g, XERCES_CPP_NAMESPACE_QUALIFIER chNull };

/**
 * fn:substring($sourceString as xs:string?, $startingLoc as xs:double) as xs:string
 * fn:substring($sourceString as xs:string?, $startingLoc as xs:double, $length as xs:double) as xs:string
**/

FunctionSubstring::FunctionSubstring(const VectorOfDataItems &args, XPath2MemoryManager* memMgr)
  : ConstantFoldingFunction(name,2, 3, "string?, double, double", args, memMgr)
{
}

Sequence FunctionSubstring::collapseTreeInternal(DynamicContext* context, int flags) const
{
	XPath2MemoryManager* memMgr = context->getMemoryManager();

	Sequence string=getParamNumber(1, context);
	if(string.isEmpty())
		return Sequence(DatatypeFactory::STR2AT::createString(memMgr, XERCES_CPP_NAMESPACE_QUALIFIER XMLUni::fgZeroLenString, context), memMgr);
	
  const ATStringOrDerived* str = (const ATStringOrDerived*)string.first();

	Sequence startingLoc=getParamNumber(2,context);
  const ATDoubleOrDerived* one = DatatypeFactory::POD2AT::createDouble(memMgr, 1, context);
	// The first character of a string is located at position 1 (not position 0).
	const ATDoubleOrDerived* index = (const ATDoubleOrDerived*)startingLoc.first();
  if (index->lessThan(one, context))
      index = one;

	const ATDoubleOrDerived* subStrLength;
	if(getNumArgs()>2)
	{
		Sequence length=getParamNumber(3,context);
		subStrLength=(const ATDoubleOrDerived*)length.first();
	}
	else {
		subStrLength=(const ATDoubleOrDerived*)DatatypeFactory::POD2AT::createDouble(memMgr, (long)str->getLength(), context)->subtract(index, context)->add(one, context);
  }
  
	return Sequence(str->substring(index, subStrLength, context), memMgr);
}