/*
*******************************************************************************
* Copyright (C) 1996-1999, International Business Machines Corporation and    *
* others. All Rights Reserved.                                                *
*******************************************************************************
*/

/*
* File coleitr.cpp
*
* 
*
* Created by: Helena Shih
*
* Modification History:
*
*  Date         Name          Description
*
*  6/23/97     helena      Adding comments to make code more readable.
* 08/03/98     erm         Synched with 1.2 version of CollationElementIterator.java
* 12/10/99      aliu          Ported Thai collation support from Java.
* 01/25/01     swquek      Modified to a C++ wrapper calling C APIs (ucoliter.h)
*/

// #include "unicode/sortkey.h"
#include "unicode/coleitr.h"

// #include "unicode/chariter.h"
#include "tables.h"
// #include "unicode/normlzr.h"
// #include "unicode/unicode.h"
// #include "tcoldata.h"
// #include "ucmp32.h"

// Constants ------------------------------------------------------------------

int32_t const CollationElementIterator::NULLORDER = 0xffffffff;
int32_t const CollationElementIterator::UNMAPPEDCHARVALUE = 0x7fff0000;

// CollationElementIterator public constructor/destructor ---------------------

CollationElementIterator::CollationElementIterator(
                                          const CollationElementIterator& other)
                                          : text(0), 
                                          ownBuffer(new VectorOfInt(2)),
                                          reorderBuffer(0), 
                                          expIndex(other.expIndex)
{
  *this = other;
}

CollationElementIterator::~CollationElementIterator()
{
  delete text;
  text = NULL;
  bufferAlias = NULL;
  orderAlias = NULL;
  delete ownBuffer;
  delete reorderBuffer;
}

// CollationElementIterator public methods ------------------------------------

UTextOffset CollationElementIterator::getOffset() const
{
  // Since the DecompositionIterator is doing the work of iterating through
  // the text string, we can just ask it what its offset is.
  return (text != NULL) ? text->getIndex() : 0;
}

/**
* Get the ordering priority of the next character in the string.
* @return the next character's ordering. Returns NULLORDER if the end of string 
*         is reached.
*/
int32_t CollationElementIterator::next(UErrorCode& status)
{
  if (text == NULL || U_FAILURE(status))
    return NULLORDER;
    
  // Update the decomposition mode if necessary.
  text->setMode(orderAlias->getDecomposition());
    
  if (bufferAlias != NULL)
  {
    // bufferAlias needs a bit of an explanation.
    // When we hit an expanding character in the text, we call the order's
    // getExpandValues method to retrieve an array of the orderings for all of 
    // the characters in the expansion (see the end of this method).
    // The first ordering is returned, and an alias to the orderings array is 
    // saved so that the remaining orderings can be returned on subsequent calls 
    // to next. So, if the expanding buffer is not exhausted, all we have to do 
    // here is return the next ordering in the buffer.  
    if (expIndex < bufferAlias->size())
      return strengthOrder(bufferAlias->at(expIndex++));
    else
      bufferAlias = NULL;
  }

  // Gets the next character from the string using decomposition iterator.
  UChar32 ch = text->current();
  text->next();

  if (U_FAILURE(status))
    return NULLORDER;
    

  if (ch == Normalizer::DONE)
    return NULLORDER;
    
  // Ask the collator for this character's ordering.
  // Used to be RuleBasedCollator.getUnicodeOrder(). 
  // It can't be inlined in tblcoll.h file unfortunately.
  /*
  synwee : have to modify this part
  int32_t value = ucmp32_get(orderAlias->data->mapping, ch);

  if (value == RuleBasedCollator::UNMAPPED)
  {
    // Returned an "unmapped" flag and save the character so it can be 
    // returned next time this method is called.
    if (ch == 0x0000) 
      return ch;
    // \u0000 is not valid in C++'s UnicodeString
    ownBuffer->at(0) = UNMAPPEDCHARVALUE;
    ownBuffer->at(1) = ch << 16;
    bufferAlias = ownBuffer;
  }
  else 
  {
    if (value >= RuleBasedCollator::CONTRACTCHARINDEX)
      value = nextContractChar(ch, status);
    if (value >= RuleBasedCollator::EXPANDCHARINDEX)
      bufferAlias = orderAlias->getExpandValueList(value);
      
    if (isThaiPreVowel(ch))
    {
      UChar32 consonant = text->current();
      text->next();
      if (isThaiBaseConsonant(consonant))
        bufferAlias = makeReorderedBuffer((UChar)consonant, value, bufferAlias,
                                          TRUE, status);
      else
        text->previous();
    }
  }

  if (bufferAlias != NULL) 
  {
    expIndex = 1;
    value = bufferAlias->at(0);
  }

  return strengthOrder(value);
  */
  return 0;
}

UBool CollationElementIterator::operator!=(
                                   const CollationElementIterator& other) const
{
  return !(*this == other);
}

UBool CollationElementIterator::operator==(const CollationElementIterator& that) 
                                                                           const
{
  if (this == &that)
    return TRUE;
    
  if (*text != *(that.text))
    return FALSE;
    
  if (((bufferAlias == NULL) != (that.bufferAlias == NULL)) ||
      (bufferAlias != NULL && *bufferAlias != *(that.bufferAlias)))
    return FALSE;
    
  if (expIndex != that.expIndex)
    return FALSE;
    
  if (orderAlias != that.orderAlias)
    return FALSE;
    
  return TRUE;
}

/**
* Get the ordering priority of the previous collation element in the string.
* @param status the error code status.
* @return the previous element's ordering. Returns NULLORDER if the beginning of 
*         string is reached.
*/
int32_t CollationElementIterator::previous(UErrorCode& status)
{
  if (text == NULL || U_FAILURE(status))
    return NULLORDER;
    
  text->setMode(orderAlias->getDecomposition());

  if (bufferAlias != NULL)
  {
    if (expIndex > 0)
      return strengthOrder(bufferAlias->at(--expIndex));
      
    bufferAlias = NULL;
  }

  UChar32 ch = text->previous();

  if (ch == Normalizer::DONE)
    return NULLORDER;
    
  // Used to be RuleBasedCollator.getUnicodeOrder(). It can't be inlined in 
  // tblcoll.h file unfortunately.
  /*

  int32_t value = ucmp32_get(orderAlias->data->mapping, ch);

  if (value == RuleBasedCollator::UNMAPPED)
  {
    if (ch == 0x0000) 
      return ch;
    
    ownBuffer->at(0) = UNMAPPEDCHARVALUE;
    ownBuffer->at(1) = ch << 16;
    bufferAlias = ownBuffer;
  }
  else 
  {
    if (value >= RuleBasedCollator::CONTRACTCHARINDEX)
      value = prevContractChar(ch, status);
      
    if (value >= RuleBasedCollator::EXPANDCHARINDEX)
      bufferAlias = orderAlias->getExpandValueList(value);
      
    if (isThaiBaseConsonant(ch)) 
    {
      UChar32 vowel = text->previous();
      if (isThaiPreVowel(vowel))
        bufferAlias = makeReorderedBuffer((UChar)vowel, value, bufferAlias,
                                          FALSE, status);
      else
        text->next();
    }
  }

  if (bufferAlias != NULL) 
  {
    expIndex = bufferAlias->size()-1;
    value = bufferAlias->at(expIndex);
  }

  return strengthOrder(value);
  */
  return 0;
}

/**
* Resets the cursor to the beginning of the string.
*/
void CollationElementIterator::reset()
{
  if (text != NULL)
  {
    text->reset();
    text->setMode(orderAlias->getDecomposition());
  }

  bufferAlias = NULL;
  expIndex = 0;
}

void CollationElementIterator::setOffset(UTextOffset newOffset, 
                                         UErrorCode& status)
{
  if (U_FAILURE(status))
    return;
    
  if (text != NULL)
    text->setIndex(newOffset);
    
  bufferAlias = NULL;
}

/**
* Sets the source to the new source string.
*/
void CollationElementIterator::setText(const UnicodeString& source,
                                       UErrorCode& status)
{
  if (U_FAILURE(status))
    return;
    
  bufferAlias = 0;

  if (text == NULL)
    text = new Normalizer(source, orderAlias->getDecomposition());
  else
  {
    text->setText(source, status);
    text->setMode(orderAlias->getDecomposition());
  }
}

// Sets the source to the new character iterator.
void CollationElementIterator::setText(CharacterIterator& source, 
                                       UErrorCode& status)
{
  if (U_FAILURE(status)) 
    return;
    
  bufferAlias = 0;

  if (text == NULL)
    text = new Normalizer(source, orderAlias->getDecomposition());
  else
  {
    text->setMode(orderAlias->getDecomposition());
    text->setText(source, status);
  }
}

int32_t CollationElementIterator::strengthOrder(int32_t order) const
{
  Collator::ECollationStrength s = orderAlias->getStrength();
  // Mask off the unwanted differences.
  if (s == Collator::PRIMARY)
    order &= RuleBasedCollator::PRIMARYDIFFERENCEONLY;
  else 
    if (s == Collator::SECONDARY)
      order &= RuleBasedCollator::SECONDARYDIFFERENCEONLY;
    
  return order;
}

// CollationElementIterator private constructors/destructors ------------------

// This private method will never be called, but it makes the linker happy
CollationElementIterator::CollationElementIterator() : text(0), bufferAlias(0),
                                                  ownBuffer(new VectorOfInt(2)), 
                                                  reorderBuffer(0), expIndex(0),
                                                  orderAlias(0)
{
}

CollationElementIterator::CollationElementIterator(
                                                 const RuleBasedCollator* order)
                                               : text(0), bufferAlias(0),
                                                 ownBuffer(new VectorOfInt(2)),
                                                 reorderBuffer(0), expIndex(0),
                                                 orderAlias(order)
{
}

/** 
* This is the "real" constructor for this class; it constructs an iterator
* over the source text using the specified collator
*/
CollationElementIterator::CollationElementIterator(
                                                const UnicodeString& sourceText,
                                                const RuleBasedCollator* order,
                                                UErrorCode& status) 
                                                : text(NULL),
                                                  bufferAlias(NULL),
                                                  ownBuffer(new VectorOfInt(2)),
                                                  reorderBuffer(0),
                                                  expIndex(0), 
                                                  orderAlias(order)
{
  if (U_FAILURE(status))
    return;
    
  if ( sourceText.length() != 0 ) 
  {
    // A CollationElementIterator is really a two-layered beast.
    // Internally it uses a Normalizer to munge the source text into a form 
    // where all "composed" Unicode characters (such as ü) are split into a 
    // normal character and a combining accent character.  
    // Afterward, CollationElementIterator does its own processing to handle
    // expanding and contracting collation sequences, ignorables, and so on.
    
    Normalizer::EMode decomp = (order->getStrength() == Collator::IDENTICAL)
                               ? Normalizer::NO_OP : order->getDecomposition();
      
    text = new Normalizer(sourceText, decomp);
    if (text == NULL)
      status = U_MEMORY_ALLOCATION_ERROR;
  }
}

/** 
* This is the "real" constructor for this class; it constructs an iterator over 
* the source text using the specified collator
*/
CollationElementIterator::CollationElementIterator(
                                            const CharacterIterator& sourceText,
                                            const RuleBasedCollator* order,
                                            UErrorCode& status) 
                                            : text(NULL),
                                              bufferAlias(NULL),
                                              ownBuffer(new VectorOfInt(2)),
                                              reorderBuffer(0),
                                              expIndex(0), 
                                              orderAlias(order)
{
  if (U_FAILURE(status))
    return;
    
  // **** should I just drop this test? ****
  if ( sourceText.endIndex() != 0 )
  {
    // A CollationElementIterator is really a two-layered beast.
    // Internally it uses a Normalizer to munge the source text into a form 
    // where all "composed" Unicode characters (such as ü) are split into a 
    // normal character and a combining accent character.  
    // Afterward, CollationElementIterator does its own processing to handle
    // expanding and contracting collation sequences, ignorables, and so on.
    
    Normalizer::EMode decomp = order->getStrength() == Collator::IDENTICAL
                               ? Normalizer::NO_OP : order->getDecomposition();
      
    text = new Normalizer(sourceText, decomp);
    if (text == NULL)
      status = U_MEMORY_ALLOCATION_ERROR;    
  }
}

// CollationElementIterator private methods -----------------------------------

const CollationElementIterator& CollationElementIterator::operator=(
                                          const CollationElementIterator& other)
{
  if (this != &other)
  {
    expIndex = other.expIndex;
    delete text;
    text = (Normalizer*)other.text->clone();

    if (other.bufferAlias == other.ownBuffer) 
    {
      *ownBuffer = *other.ownBuffer;
      bufferAlias = ownBuffer;
    } 
    else 
      if (other.bufferAlias != NULL && other.bufferAlias == other.reorderBuffer) 
      {
        if (reorderBuffer == NULL)
          reorderBuffer = new VectorOfInt(*other.reorderBuffer);
        else 
          *reorderBuffer = *other.reorderBuffer;
          
        bufferAlias = reorderBuffer;
      } 
      else 
        bufferAlias = other.bufferAlias;
        
      orderAlias = other.orderAlias;
  }

  return *this;
}

/**
 * Get the ordering priority of the next contracting character in the
 * string.
 * @param ch the starting character of a contracting character token
 * @return the next contracting character's ordering.  Returns NULLORDER
 * if the end of string is reached.
 */
/*
synwee : removed 
int32_t
CollationElementIterator::nextContractChar(UChar32 ch,
                                           UErrorCode& status)
{
    // First get the ordering of this single character
    VectorOfPToContractElement *list = orderAlias->getContractValues((UChar)ch);
    EntryPair *pair = (EntryPair *)list->at(0);
    int32_t order = pair->value;

    // Now iterate through the chars following it and
    // look for the longest match
    key.remove();
    key += ch;

    while ((ch = text->current()) != Normalizer::DONE)
    {
        if (U_FAILURE(status))
        {
            return NULLORDER;
        }

        key += ch;

        int32_t n = RuleBasedCollator::getEntry(list, key, TRUE);

        if (n == RuleBasedCollator::UNMAPPED)
        {
            break;
        }
        text->next();

        pair = (EntryPair *)list->at(n);
        order = pair->value;
    }

    return order;
}
*/

/**
 * Get the ordering priority of the previous contracting character in the
 * string.
 * @param ch the starting character of a contracting character token
 * @return the next contracting character's ordering.  Returns NULLORDER
 * if the end of string is reached.
 */
/* synwee : removed
int32_t CollationElementIterator::prevContractChar(UChar32 ch,
                                                   UErrorCode &status)
{
    // First get the ordering of this single character
    VectorOfPToContractElement *list = orderAlias->getContractValues((UChar)ch);
    EntryPair *pair = (EntryPair *)list->at(0);
    int32_t order = pair->value;

    // Now iterate through the chars following it and
    // look for the longest match
    key.remove();
    key += ch;

    while ((ch = text->previous()) != Normalizer::DONE)
    {
        key += ch;

        int32_t n = RuleBasedCollator::getEntry(list, key, FALSE);

        if (n == RuleBasedCollator::UNMAPPED)
        {
            ch = text->next();

            if (U_FAILURE(status))
            {
                return NULLORDER;
            }

            break;
        }

        pair = (EntryPair *)list->at(n);
        order = pair->value;
    }

    return order;
}
*/

/**
 * This method produces a buffer which contains the collation
 * elements for the two characters, with colFirst's values preceding
 * another character's.  Presumably, the other character precedes colFirst
 * in logical
 * order (otherwise you wouldn't need this method would you?).
 * The assumption is that the other char's value(s) have already been
 * computed.  If this char has a single element it is passed to this
 * method as lastValue, and lastExpasion is null.  If it has an
 * expasion it is passed in lastExpansion, and colLastValue is ignored.
 * This method may return the ownBuffer array as its value so ownBuffer
 * had better not be in use anywhere else.
 */
/*
VectorOfInt* CollationElementIterator::makeReorderedBuffer(UChar colFirst,
                                                           int32_t lastValue,
                                                           VectorOfInt* lastExpansion,
                                                           UBool forward,
                                                           UErrorCode& status) {

    VectorOfInt* result;

    int32_t firstValue = ucmp32_get(orderAlias->data->mapping, colFirst);
    if (firstValue >= RuleBasedCollator::CONTRACTCHARINDEX) {
        firstValue = forward ? nextContractChar(colFirst, status)
                             : prevContractChar(colFirst, status);
    }

    VectorOfInt* firstExpansion = NULL;
    if (firstValue >= RuleBasedCollator::EXPANDCHARINDEX) {
        firstExpansion = orderAlias->getExpandValueList(firstValue);
    }

    if (!forward) {
        int32_t temp1 = firstValue;
        firstValue = lastValue;
        lastValue = temp1;
        VectorOfInt* temp2 = firstExpansion;
        firstExpansion = lastExpansion;
        lastExpansion = temp2;
    }

    if (firstExpansion == NULL && lastExpansion == NULL) {
        ownBuffer->at(0) = firstValue;
        ownBuffer->at(1) = lastValue;
        result = ownBuffer;
    }
    else {
        int32_t firstLength = firstExpansion==NULL? 1 : firstExpansion->size();
        int32_t lastLength = lastExpansion==NULL? 1 : lastExpansion->size();
        if (reorderBuffer == NULL) {
            reorderBuffer = new VectorOfInt(firstLength+lastLength);
        }
        // reorderdBuffer gets reused for the life of this object.
        // Since its internal buffer only grows, there is a danger
        // that it will get really, really big, and never shrink.  If
        // this is actually happening, insert code here to check for
        // the condition.  Something along the lines of:
        //! else if (reorderBuffer->size() >= 256 &&
        //!          (firstLength+lastLength) < 16) {
        //!     delete reorderBuffer;
        //!     reorderBuffer = new VectorOfInt(firstLength+lastLength);
        //! }
        // The specific numeric values need to be determined
        // empirically. [aliu]
        result = reorderBuffer;

        if (firstExpansion == NULL) {
            result->atPut(0, firstValue);
        }
        else {
            // System.arraycopy(firstExpansion, 0, result, 0, firstLength);
            *result = *firstExpansion;
        }

        if (lastExpansion == NULL) {
            result->atPut(firstLength, lastValue);
        }
        else {
            // System.arraycopy(lastExpansion, 0, result, firstLength, lastLength);
            for (int32_t i=0; i<lastLength; ++i) {
                result->atPut(firstLength + i, lastExpansion->at(i));
            }
        }
        result->setSize(firstLength+lastLength);
    }

    return result;
}
*/