////////////////////////////////////////////////////////////////////////////////
/// @brief Utf8/Utf16 Helper class
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 2014 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
///     http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Frank Celler
/// @author Achim Brandt
/// @author Copyright 2014, ArangoDB GmbH, Cologne, Germany
/// @author Copyright 2010-2013, triAGENS GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////

#include "Utf8Helper.h"
#include "Basics/logging.h"
#include "Basics/tri-strings.h"
#include "unicode/normalizer2.h"
#include "unicode/brkiter.h"
#include "unicode/ucasemap.h"
#include "unicode/uclean.h"
#include "unicode/unorm2.h"
#include "unicode/ustdio.h"

#ifdef _WIN32
#include "Basics/win-utils.h"
#endif

using namespace triagens::basics;
using namespace std;

Utf8Helper Utf8Helper::DefaultUtf8Helper;

// -----------------------------------------------------------------------------
// --SECTION--                                      constructors and destructors
// -----------------------------------------------------------------------------

Utf8Helper::Utf8Helper (std::string const& lang) : 
  _coll(nullptr) {

  setCollatorLanguage(lang);
}

Utf8Helper::Utf8Helper () : 
  Utf8Helper("") {
}

Utf8Helper::~Utf8Helper () {
  if (_coll) {
    delete _coll;
    if (this == &DefaultUtf8Helper) {
      u_cleanup();
    }
  }
}

int Utf8Helper::compareUtf8 (char const* left, 
                             char const* right) const {
  if (! _coll) {
    LOG_ERROR("no Collator in Utf8Helper::compareUtf8()!");
    return (strcmp(left, right));
  }

  UErrorCode status = U_ZERO_ERROR;
  int result = _coll->compareUTF8(StringPiece(left), StringPiece(right), status);
  if (U_FAILURE(status)) {
    LOG_ERROR("error in Collator::compareUTF8(...): %s", u_errorName(status));
    return (strcmp(left, right));
  }

  return result;
}

int Utf8Helper::compareUtf8 (char const* left, 
                             size_t leftLength,
                             char const* right,
                             size_t rightLength) const {
  if (! _coll) {
    LOG_ERROR("no Collator in Utf8Helper::compareUtf8()!");
    return (strcmp(left, right));
  }

  UErrorCode status = U_ZERO_ERROR;
  int result = _coll->compareUTF8(StringPiece(left, (int32_t) leftLength), StringPiece(right, (int32_t) rightLength), status);
  if (U_FAILURE(status)) {
    LOG_ERROR("error in Collator::compareUTF8(...): %s", u_errorName(status));
    return (strcmp(left, right));
  }

  return result;
}

int Utf8Helper::compareUtf16 (const uint16_t* left, size_t leftLength, const uint16_t* right, size_t rightLength) const {
  if (! _coll) {
    LOG_ERROR("no Collator in Utf8Helper::compareUtf16()!");

    if (leftLength == rightLength) {
      return memcmp((const void*)left, (const void*)right, leftLength * 2);
    }

    int result = memcmp((const void*)left, (const void*)right, leftLength < rightLength ? leftLength * 2 : rightLength * 2);

    if (result == 0) {
      if (leftLength < rightLength) {
        return -1;
      }
      return 1;
    }

    return result;
  }
  // ..........................................................................
  // Take note here: we are assuming that the ICU type UChar is two bytes.
  // There is no guarantee that this will be the case on all platforms and
  // compilers.
  // ..........................................................................
  return _coll->compare((const UChar*) left, (int32_t) leftLength, (const UChar*) right, (int32_t) rightLength);
}

bool Utf8Helper::setCollatorLanguage (std::string const& lang) {
#ifdef _WIN32
  TRI_FixIcuDataEnv();
#endif

  UErrorCode status = U_ZERO_ERROR;

  if (_coll) {
    ULocDataLocaleType type = ULOC_ACTUAL_LOCALE;
    const Locale& locale = _coll->getLocale(type, status);

    if(U_FAILURE(status)) {
      LOG_ERROR("error in Collator::getLocale(...): %s", u_errorName(status));
      return false;
    }
    if (lang == locale.getName()) {
      return true;
    }
  }

  Collator* coll;
  if (lang == "") {
    // get default collator for empty language
    coll = Collator::createInstance(status);
  }
  else {
    Locale locale(lang.c_str());
    coll = Collator::createInstance(locale, status);
  }

  if(U_FAILURE(status)) {
    LOG_ERROR("error in Collator::createInstance(): %s", u_errorName(status));
    if (coll) {
      delete coll;
    }
    return false;
  }

  // set the default attributes for sorting:
  coll->setAttribute(UCOL_CASE_FIRST, UCOL_UPPER_FIRST, status);  // A < a
  coll->setAttribute(UCOL_NORMALIZATION_MODE, UCOL_OFF, status);  // no normalization
  coll->setAttribute(UCOL_STRENGTH, UCOL_IDENTICAL, status);      // UCOL_IDENTICAL, UCOL_PRIMARY, UCOL_SECONDARY, UCOL_TERTIARY

  if(U_FAILURE(status)) {
    LOG_ERROR("error in Collator::setAttribute(...): %s", u_errorName(status));
    delete coll;
    return false;
  }

  if (_coll) {
    delete _coll;
  }

  _coll = coll;
  return true;
}

std::string Utf8Helper::getCollatorLanguage () {
  if (_coll) {
    UErrorCode status = U_ZERO_ERROR;
    ULocDataLocaleType type = ULOC_VALID_LOCALE;
    const Locale& locale = _coll->getLocale(type, status);

    if(U_FAILURE(status)) {
      LOG_ERROR("error in Collator::getLocale(...): %s", u_errorName(status));
      return "";
    }
    return locale.getLanguage();
  }
  return "";
}

std::string Utf8Helper::getCollatorCountry () {
  if (_coll) {
    UErrorCode status = U_ZERO_ERROR;
    ULocDataLocaleType type = ULOC_VALID_LOCALE;
    const Locale& locale = _coll->getLocale(type, status);

    if(U_FAILURE(status)) {
      LOG_ERROR("error in Collator::getLocale(...): %s", u_errorName(status));
      return "";
    }
    return locale.getCountry();
  }
  return "";
}

////////////////////////////////////////////////////////////////////////////////
/// @brief Lowercase the characters in a UTF-8 string.
////////////////////////////////////////////////////////////////////////////////

std::string Utf8Helper::toLowerCase (std::string const& src) {
  int32_t utf8len = 0;
  char* utf8 = tolower(TRI_UNKNOWN_MEM_ZONE, src.c_str(), (int32_t) src.length(), utf8len);

  if (utf8 == nullptr) {
    return string("");
  }

  string result(utf8, utf8len);
  TRI_Free(TRI_UNKNOWN_MEM_ZONE, utf8);
  return result;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief Lowercase the characters in a UTF-8 string.
////////////////////////////////////////////////////////////////////////////////

char* Utf8Helper::tolower (TRI_memory_zone_t* zone, 
                           char const* src, 
                           int32_t srcLength, 
                           int32_t& dstLength) {
  char* utf8_dest = nullptr;

  if (src == nullptr || srcLength == 0) {
    utf8_dest = (char*) TRI_Allocate(zone, sizeof(char), false);
    if (utf8_dest != nullptr) {
      utf8_dest[0] = '\0';
    }
    dstLength = 0;
    return utf8_dest;
  }

  uint32_t options = U_FOLD_CASE_DEFAULT;
  UErrorCode status = U_ZERO_ERROR;

  string locale = getCollatorLanguage();
  LocalUCaseMapPointer csm(ucasemap_open(locale.c_str(), options, &status));

  if (U_FAILURE(status)) {
    LOG_ERROR("error in ucasemap_open(...): %s", u_errorName(status));
  }
  else {
    utf8_dest = (char*) TRI_Allocate(zone, (srcLength + 1) * sizeof(char), false);
    if (utf8_dest == nullptr) {
      return nullptr;
    }

    dstLength = ucasemap_utf8ToLower(csm.getAlias(),
                    utf8_dest,
                    srcLength + 1,
                    src,
                    srcLength,
                    &status);

    if (status == U_BUFFER_OVERFLOW_ERROR) {
      status = U_ZERO_ERROR;
      TRI_Free(zone, utf8_dest);
      utf8_dest = (char*) TRI_Allocate(zone, (dstLength + 1) * sizeof(char), false);
      if (utf8_dest == nullptr) {
        return nullptr;
      }

      dstLength = ucasemap_utf8ToLower(csm.getAlias(),
                    utf8_dest,
                    dstLength + 1,
                    src,
                    srcLength,
                    &status);
    }

    if (U_FAILURE(status)) {
      LOG_ERROR("error in ucasemap_utf8ToLower(...): %s", u_errorName(status));
      TRI_Free(zone, utf8_dest);
    }
    else {
      return utf8_dest;
    }
  }

  utf8_dest = TRI_LowerAsciiString(zone, src);

  if (utf8_dest != nullptr) {
    dstLength = (int32_t) strlen(utf8_dest);
  }
  return utf8_dest;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief Uppercase the characters in a UTF-8 string.
////////////////////////////////////////////////////////////////////////////////

std::string Utf8Helper::toUpperCase (std::string const& src) {
  int32_t utf8len = 0;
  char* utf8 = toupper(TRI_UNKNOWN_MEM_ZONE, src.c_str(), (int32_t) src.length(), utf8len);
  if (utf8 == nullptr) {
    return string("");
  }

  string result(utf8, utf8len);
  TRI_Free(TRI_UNKNOWN_MEM_ZONE, utf8);
  return result;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief Lowercase the characters in a UTF-8 string.
////////////////////////////////////////////////////////////////////////////////

char* Utf8Helper::toupper (TRI_memory_zone_t* zone, 
                           char const* src, 
                           int32_t srcLength, 
                           int32_t& dstLength) {
  char* utf8_dest = nullptr;

  if (src == nullptr || srcLength == 0) {
    utf8_dest = (char*) TRI_Allocate(zone, sizeof(char), false);
    if (utf8_dest != nullptr) {
      utf8_dest[0] = '\0';
    }
    dstLength = 0;
    return utf8_dest;
  }

  uint32_t options = U_FOLD_CASE_DEFAULT;
  UErrorCode status = U_ZERO_ERROR;

  string locale = getCollatorLanguage();
  LocalUCaseMapPointer csm(ucasemap_open(locale.c_str(), options, &status));

  if (U_FAILURE(status)) {
    LOG_ERROR("error in ucasemap_open(...): %s", u_errorName(status));
  }
  else {
    utf8_dest = (char*) TRI_Allocate(zone, (srcLength+1) * sizeof(char), false);
    if (utf8_dest == nullptr) {
      return nullptr;
    }

    dstLength = ucasemap_utf8ToUpper(csm.getAlias(),
                    utf8_dest,
                    srcLength,
                    src,
                    srcLength,
                    &status);

    if (status == U_BUFFER_OVERFLOW_ERROR) {
      status = U_ZERO_ERROR;
      TRI_Free(zone, utf8_dest);
      utf8_dest = (char*) TRI_Allocate(zone, (dstLength + 1) * sizeof(char), false);
      if (utf8_dest == nullptr) {
        return nullptr;
      }

      dstLength = ucasemap_utf8ToUpper(csm.getAlias(),
                    utf8_dest,
                    dstLength + 1,
                    src,
                    srcLength,
                    &status);
    }

    if (U_FAILURE(status)) {
      LOG_ERROR("error in ucasemap_utf8ToUpper(...): %s", u_errorName(status));
      TRI_Free(zone, utf8_dest);
    }
    else {
      return utf8_dest;
    }
  }

  utf8_dest = TRI_UpperAsciiString(zone, src);

  if (utf8_dest != nullptr) {
    dstLength = (int32_t) strlen(utf8_dest);
  }
  return utf8_dest;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief Extract the words from a UTF-8 string.
////////////////////////////////////////////////////////////////////////////////

TRI_vector_string_t* Utf8Helper::getWords (char const* text,
                                           size_t textLength,
                                           size_t minimalLength,
                                           size_t maximalLength,
                                           bool lowerCase) {
  TRI_vector_string_t* words;
  UErrorCode status = U_ZERO_ERROR;
  UnicodeString word;

  if (textLength == 0) {
    // input text is empty
    return nullptr;
  }

  if (textLength < minimalLength) {
    // input text is shorter than required minimum length
    return nullptr;
  }

  size_t textUtf16Length = 0;
  UChar* textUtf16 = nullptr;

  if (lowerCase) {
    // lower case string
    int32_t lowerLength = 0;
    char* lower = tolower(TRI_UNKNOWN_MEM_ZONE, text, (int32_t) textLength, lowerLength);

    if (lower == nullptr) {
      // out of memory
      return nullptr;
    }

    if (lowerLength == 0) {
      TRI_Free(TRI_UNKNOWN_MEM_ZONE, lower);
      return nullptr;
    }

    textUtf16 = TRI_Utf8ToUChar(TRI_UNKNOWN_MEM_ZONE, lower, lowerLength, &textUtf16Length);
    TRI_Free(TRI_UNKNOWN_MEM_ZONE, lower);
  }
  else {
    textUtf16 = TRI_Utf8ToUChar(TRI_UNKNOWN_MEM_ZONE, text, (int32_t) textLength, &textUtf16Length);
  }

  if (textUtf16 == nullptr) {
    return nullptr;
  }

  ULocDataLocaleType type = ULOC_VALID_LOCALE;
  const Locale& locale = _coll->getLocale(type, status);

  if (U_FAILURE(status)) {
    TRI_Free(TRI_UNKNOWN_MEM_ZONE, textUtf16);
    LOG_ERROR("error in Collator::getLocale(...): %s", u_errorName(status));
    return nullptr;
  }

  UChar* tempUtf16 = (UChar *) TRI_Allocate(TRI_UNKNOWN_MEM_ZONE, (textUtf16Length + 1) * sizeof(UChar), false);

  if (tempUtf16 == nullptr) {
    TRI_Free(TRI_UNKNOWN_MEM_ZONE, textUtf16);
    return nullptr;
  }

  words = (TRI_vector_string_t*) TRI_Allocate(TRI_UNKNOWN_MEM_ZONE, sizeof(TRI_vector_string_t), false);

  if (words == nullptr) {
    TRI_Free(TRI_UNKNOWN_MEM_ZONE, textUtf16);
    TRI_Free(TRI_UNKNOWN_MEM_ZONE, tempUtf16);
    return nullptr;
  }

  // estimate an initial vector size. this is not accurate, but setting the initial size to some
  // value in the correct order of magnitude will save a lot of vector reallocations later
  size_t initialWordCount = textLength / (2 * (minimalLength + 1));
  if (initialWordCount < 32) {
    // alloc at least 32 pointers (= 256b)
    initialWordCount = 32;
  }
  else if (initialWordCount > 8192) {
    // alloc at most 8192 pointers (= 64kb)
    initialWordCount = 8192;
  }

  TRI_InitVectorString2(words, TRI_UNKNOWN_MEM_ZONE, initialWordCount);

  BreakIterator* wordIterator = BreakIterator::createWordInstance(locale, status);
  UnicodeString utext(textUtf16);

  wordIterator->setText(utext);
  int32_t start = wordIterator->first();
  for(int32_t end = wordIterator->next(); end != BreakIterator::DONE;
    start = end, end = wordIterator->next()) {

    size_t tempUtf16Length = (size_t) (end - start);
    // end - start = word length
    if (tempUtf16Length >= minimalLength) {
      size_t chunkLength = tempUtf16Length;
      if (chunkLength > maximalLength) {
        chunkLength = maximalLength;
      }
      utext.extractBetween(start, (int32_t) (start + chunkLength), tempUtf16, 0);

      size_t utf8WordLength;
      char* utf8Word = TRI_UCharToUtf8(TRI_UNKNOWN_MEM_ZONE, tempUtf16, chunkLength, &utf8WordLength);
      if (utf8Word != nullptr) {
        TRI_PushBackVectorString(words, utf8Word);
      }
    }
  }

  delete wordIterator;

  TRI_Free(TRI_UNKNOWN_MEM_ZONE, textUtf16);
  TRI_Free(TRI_UNKNOWN_MEM_ZONE, tempUtf16);

  if (words->_length == 0) {
    // no words found
    TRI_FreeVectorString(TRI_UNKNOWN_MEM_ZONE, words);
    return nullptr;
  }

  return words;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief Extract the words from a UTF-8 string.
////////////////////////////////////////////////////////////////////////////////

bool Utf8Helper::getWords (TRI_vector_string_t*& words,
                           char const* text,
                           size_t textLength,
                           size_t minimalLength,
                           size_t maximalLength,
                           bool lowerCase) {
  UErrorCode status = U_ZERO_ERROR;
  UnicodeString word;

  if (textLength == 0) {
    // input text is empty
    return true;
  }

  if (textLength < minimalLength) {
    // input text is shorter than required minimum length
    return true;
  }

  size_t textUtf16Length = 0;
  UChar* textUtf16 = nullptr;

  if (lowerCase) {
    // lower case string
    int32_t lowerLength = 0;
    char* lower = tolower(TRI_UNKNOWN_MEM_ZONE, text, (int32_t) textLength, lowerLength);

    if (lower == nullptr) {
      // out of memory
      return false;
    }

    if (lowerLength == 0) {
      TRI_Free(TRI_UNKNOWN_MEM_ZONE, lower);
      return false;
    }

    textUtf16 = TRI_Utf8ToUChar(TRI_UNKNOWN_MEM_ZONE, lower, lowerLength, &textUtf16Length);
    TRI_Free(TRI_UNKNOWN_MEM_ZONE, lower);
  }
  else {
    textUtf16 = TRI_Utf8ToUChar(TRI_UNKNOWN_MEM_ZONE, text, (int32_t) textLength, &textUtf16Length);
  }

  if (textUtf16 == nullptr) {
    return false;
  }

  ULocDataLocaleType type = ULOC_VALID_LOCALE;
  const Locale& locale = _coll->getLocale(type, status);

  if (U_FAILURE(status)) {
    TRI_Free(TRI_UNKNOWN_MEM_ZONE, textUtf16);
    LOG_ERROR("error in Collator::getLocale(...): %s", u_errorName(status));
    return false;
  }

  UChar* tempUtf16 = (UChar *) TRI_Allocate(TRI_UNKNOWN_MEM_ZONE, (textUtf16Length + 1) * sizeof(UChar), false);

  if (tempUtf16 == nullptr) {
    TRI_Free(TRI_UNKNOWN_MEM_ZONE, textUtf16);
    return false;
  }

  bool created = false;

  if (words == nullptr) {
    words = (TRI_vector_string_t*) TRI_Allocate(TRI_UNKNOWN_MEM_ZONE, sizeof(TRI_vector_string_t), false);
    created = true;
  }

  if (words == nullptr) {
    TRI_Free(TRI_UNKNOWN_MEM_ZONE, textUtf16);
    TRI_Free(TRI_UNKNOWN_MEM_ZONE, tempUtf16);
    return false;
  }


  if (created) {
    // estimate an initial vector size. this is not accurate, but setting the initial size to some
    // value in the correct order of magnitude will save a lot of vector reallocations later
    size_t initialWordCount = textLength / (2 * (minimalLength + 1));
    if (initialWordCount < 32) {
      // alloc at least 32 pointers (= 256b)
      initialWordCount = 32;
    }
    else if (initialWordCount > 8192) {
      // alloc at most 8192 pointers (= 64kb)
      initialWordCount = 8192;
    }
    TRI_InitVectorString2(words, TRI_UNKNOWN_MEM_ZONE, initialWordCount);
  }

  BreakIterator* wordIterator = BreakIterator::createWordInstance(locale, status);
  UnicodeString utext(textUtf16);

  wordIterator->setText(utext);
  int32_t start = wordIterator->first();
  for(int32_t end = wordIterator->next(); end != BreakIterator::DONE;
    start = end, end = wordIterator->next()) {

    size_t tempUtf16Length = (size_t) (end - start);
    // end - start = word length
    if (tempUtf16Length >= minimalLength) {
      size_t chunkLength = tempUtf16Length;
      if (chunkLength > maximalLength) {
        chunkLength = maximalLength;
      }
      utext.extractBetween(start, (int32_t) (start + chunkLength), tempUtf16, 0);

      size_t utf8WordLength;
      char* utf8Word = TRI_UCharToUtf8(TRI_UNKNOWN_MEM_ZONE, tempUtf16, chunkLength, &utf8WordLength);
      if (utf8Word != nullptr) {
        TRI_PushBackVectorString(words, utf8Word);
      }
    }
  }

  delete wordIterator;

  TRI_Free(TRI_UNKNOWN_MEM_ZONE, textUtf16);
  TRI_Free(TRI_UNKNOWN_MEM_ZONE, tempUtf16);

  return true;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief builds a regex matcher for the specified pattern
////////////////////////////////////////////////////////////////////////////////

RegexMatcher* Utf8Helper::buildMatcher (std::string const& pattern) {
  UErrorCode status = U_ZERO_ERROR;

  std::unique_ptr<RegexMatcher> matcher(new RegexMatcher(UnicodeString::fromUTF8(pattern), 0, status));
  if (U_FAILURE(status)) {
    return nullptr;
  }

  return matcher.release();
}

////////////////////////////////////////////////////////////////////////////////
/// @brief whether or not value matches a regex
////////////////////////////////////////////////////////////////////////////////

bool Utf8Helper::matches (RegexMatcher* matcher,
                          std::string const& value,
                          bool& error) {
  return matches(matcher, value.c_str(), value.size(), error);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief whether or not value matches a regex
////////////////////////////////////////////////////////////////////////////////

bool Utf8Helper::matches (RegexMatcher* matcher,
                          char const* value,
                          size_t valueLength,
                          bool& error) {

  TRI_ASSERT(value != nullptr);
  UnicodeString v = UnicodeString::fromUTF8(value);

  matcher->reset(v);

  UErrorCode status = U_ZERO_ERROR;
  error = false;

  TRI_ASSERT(matcher != nullptr);
  UBool result = matcher->matches(status);
  if (U_FAILURE(status)) {
    error = true;
  }

  return (result ? true : false);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief compare two utf16 strings
////////////////////////////////////////////////////////////////////////////////

int TRI_compare_utf16 (uint16_t const* left, 
                       size_t leftLength, 
                       uint16_t const* right, 
                       size_t rightLength) {
  return Utf8Helper::DefaultUtf8Helper.compareUtf16(left, leftLength, right, rightLength);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief compare two utf8 strings
////////////////////////////////////////////////////////////////////////////////

int TRI_compare_utf8 (char const* left, 
                      char const* right) {
  return Utf8Helper::DefaultUtf8Helper.compareUtf8(left, right);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief compare two utf8 strings
////////////////////////////////////////////////////////////////////////////////

int TRI_compare_utf8 (char const* left, 
                      size_t leftLength,
                      char const* right,
                      size_t rightLength) {
  return Utf8Helper::DefaultUtf8Helper.compareUtf8(left, leftLength, right, rightLength);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief Lowercase the characters in a UTF-8 string (implemented in Basic/Utf8Helper.cpp)
////////////////////////////////////////////////////////////////////////////////

char* TRI_tolower_utf8 (TRI_memory_zone_t* zone, 
                        char const* src, 
                        int32_t srcLength, 
                        int32_t* dstLength) {
  return Utf8Helper::DefaultUtf8Helper.tolower(zone, src, srcLength, *dstLength);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief Uppercase the characters in a UTF-8 string (implemented in Basic/Utf8Helper.cpp)
////////////////////////////////////////////////////////////////////////////////

char* TRI_toupper_utf8 (TRI_memory_zone_t* zone, 
                        char const* src, 
                        int32_t srcLength, 
                        int32_t* dstLength) {
  return Utf8Helper::DefaultUtf8Helper.toupper(zone, src, srcLength, *dstLength);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief Get words of an UTF-8 string (implemented in Basic/Utf8Helper.cpp)
////////////////////////////////////////////////////////////////////////////////

TRI_vector_string_t* TRI_get_words (char const* text,
                                    size_t textLength,
                                    size_t minimalWordLength,
                                    size_t maximalWordLength,
                                    bool lowerCase) {
  return Utf8Helper::DefaultUtf8Helper.getWords(text, textLength, minimalWordLength, maximalWordLength, lowerCase);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief Get words of an UTF-8 string (implemented in Basic/Utf8Helper.cpp)
////////////////////////////////////////////////////////////////////////////////

bool TRI_get_words (TRI_vector_string_t*& words,
                    char const* text,
                    size_t textLength,
                    size_t minimalWordLength,
                    size_t maximalWordLength,
                    bool lowerCase) {
  return Utf8Helper::DefaultUtf8Helper.getWords(words, text, textLength, minimalWordLength, maximalWordLength, lowerCase);
}

// -----------------------------------------------------------------------------
// --SECTION--                                                 private functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @brief convert a utf-8 string to a uchar (utf-16)
////////////////////////////////////////////////////////////////////////////////

UChar* TRI_Utf8ToUChar (TRI_memory_zone_t* zone,
                        char const* utf8,
                        size_t inLength,
                        size_t* outLength) {
  int32_t utf16Length;

  // 1. convert utf8 string to utf16
  // calculate utf16 string length
  UErrorCode status = U_ZERO_ERROR;
  u_strFromUTF8(nullptr, 0, &utf16Length, utf8, (int32_t) inLength, &status);
  if (status != U_BUFFER_OVERFLOW_ERROR) {
    return nullptr;
  }

  UChar* utf16 = (UChar *) TRI_Allocate(zone, (utf16Length + 1) * sizeof(UChar), false);
  if (utf16 == nullptr) {
    return nullptr;
  }

  // now convert
  status = U_ZERO_ERROR;
  // the +1 will append a 0 byte at the end
  u_strFromUTF8(utf16, utf16Length + 1, nullptr, utf8, (int32_t) inLength, &status);
  if (status != U_ZERO_ERROR) {
    TRI_Free(zone, utf16);
    return nullptr;
  }

  *outLength = (size_t) utf16Length;

  return utf16;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief convert a uchar (utf-16) to a utf-8 string
////////////////////////////////////////////////////////////////////////////////

char* TRI_UCharToUtf8 (TRI_memory_zone_t* zone,
                       UChar const* uchar,
                       size_t inLength,
                       size_t* outLength) {
  int32_t utf8Length;

  // calculate utf8 string length
  UErrorCode status = U_ZERO_ERROR;
  u_strToUTF8(nullptr, 0, &utf8Length, uchar, (int32_t) inLength, &status);
  if (status != U_BUFFER_OVERFLOW_ERROR) {
    return nullptr;
  }

  char* utf8 = static_cast<char*>(TRI_Allocate(zone, (utf8Length + 1) * sizeof(char), false));

  if (utf8 == nullptr) {
    return nullptr;
  }

  // convert to utf8
  status = U_ZERO_ERROR;
  // the +1 will append a 0 byte at the end
  u_strToUTF8(utf8, utf8Length + 1, nullptr, uchar, (int32_t) inLength, &status);
  if (status != U_ZERO_ERROR) {
    TRI_Free(zone, utf8);
    return nullptr;
  }

  *outLength = ((size_t) utf8Length);

  return utf8;
}

// -----------------------------------------------------------------------------
// --SECTION--                                                  public functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @brief normalize an utf8 string (NFC)
////////////////////////////////////////////////////////////////////////////////

char* TRI_normalize_utf8_to_NFC (TRI_memory_zone_t* zone,
                                 char const* utf8,
                                 size_t inLength,
                                 size_t* outLength) {
  size_t utf16Length;

  *outLength = 0;
  char* utf8Dest;

  if (inLength == 0) {
    utf8Dest = static_cast<char*>(TRI_Allocate(zone, sizeof(char), false));

    if (utf8Dest != nullptr) {
      utf8Dest[0] = '\0';
    }
    return utf8Dest;
  }

  UChar* utf16 = TRI_Utf8ToUChar(zone, utf8, inLength, &utf16Length);

  if (utf16 == nullptr) {
    return nullptr;
  }

  // continue in TR_normalize_utf16_to_NFC
  utf8Dest = TRI_normalize_utf16_to_NFC(zone, (const uint16_t*) utf16, (int32_t) utf16Length, outLength);
  TRI_Free(zone, utf16);

  return utf8Dest;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief normalize an utf8 string (NFC)
////////////////////////////////////////////////////////////////////////////////

char* TRI_normalize_utf16_to_NFC (TRI_memory_zone_t* zone,
                                  uint16_t const* utf16,
                                  size_t inLength,
                                  size_t* outLength) {
  *outLength = 0;
  char* utf8Dest;

  if (inLength == 0) {
    utf8Dest = static_cast<char*>(TRI_Allocate(zone, sizeof(char), false));
    if (utf8Dest != nullptr) {
      utf8Dest[0] = '\0';
    }
    return utf8Dest;
  }

  UErrorCode status = U_ZERO_ERROR;
  UNormalizer2 const* norm2 = unorm2_getInstance(nullptr, "nfc", UNORM2_COMPOSE, &status);

  if (status != U_ZERO_ERROR) {
    return nullptr;
  }

  // normalize UChar (UTF-16)
  UChar* utf16Dest;
  bool mustFree;
  char buffer[64];

  if (inLength < sizeof(buffer) / sizeof(UChar)) {
    // use a static buffer
    utf16Dest = (UChar *) &buffer[0];
    mustFree = false;
  }
  else {
    // use dynamic memory
    utf16Dest = (UChar *) TRI_Allocate(zone, (inLength + 1) * sizeof(UChar), false);
    if (utf16Dest == nullptr) {
      return nullptr;
    }
    mustFree = true;
  }

  size_t overhead = 0;
  int32_t utf16DestLength;
 
  while (true) {
    status = U_ZERO_ERROR;
    utf16DestLength = unorm2_normalize(norm2, (UChar*) utf16, (int32_t) inLength, utf16Dest, (int32_t) (inLength + overhead + 1), &status);

    if (status == U_ZERO_ERROR) {
      break;
    }

    if (status == U_BUFFER_OVERFLOW_ERROR ||
        status == U_STRING_NOT_TERMINATED_WARNING) {
      // output buffer was too small. now re-try with a bigger buffer (inLength + overhead size)
      if (mustFree) {
        // free original buffer first so we don't leak
        TRI_Free(zone, utf16Dest);
        mustFree = false;
      }
      
      if (overhead == 0) {
        // set initial overhead size
        if (inLength < 256) {
          overhead = 16;
        }
        else if (inLength < 4096) {
          overhead = 128;
        }
        else {
          overhead = 256;
        }
      }
      else {
        // use double buffer size
        overhead += overhead;

        if (overhead >= 1024 * 1024) {
          // enough is enough
          return nullptr;
        }
      }

      utf16Dest = (UChar *) TRI_Allocate(zone, (inLength + overhead + 1) * sizeof(UChar), false);

      if (utf16Dest != nullptr) {
        // got new memory. now try again with the adjusted, bigger buffer
        mustFree = true;
        continue;
      }
      // fall-through intentional
    }

    if (mustFree) {
      TRI_Free(zone, utf16Dest);
    }

    return nullptr;
  }

  // Convert data back from UChar (UTF-16) to UTF-8
  utf8Dest = TRI_UCharToUtf8(zone, utf16Dest, (size_t) utf16DestLength, outLength);

  if (mustFree) {
    TRI_Free(zone, utf16Dest);
  }

  return utf8Dest;
}

// -----------------------------------------------------------------------------
// --SECTION--                                                       END-OF-FILE
// -----------------------------------------------------------------------------

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