/*
 *      Copyright (C) 2005-2013 Team XBMC
 *      http://xbmc.org
 *
 *  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, 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 XBMC; see the file COPYING.  If not, see
 *  <http://www.gnu.org/licenses/>.
 *
 */

#include <stdlib.h>
#include <string.h>
#include <algorithm> 
#include "RegExp.h"
#include "StdString.h"
#include "log.h"
#include "utils/StringUtils.h"
#include "utils/Utf8Utils.h"

using namespace PCRE;

#ifndef PCRE_UCP
#define PCRE_UCP 0
#endif // PCRE_UCP

#ifdef PCRE_CONFIG_JIT
#define PCRE_HAS_JIT_CODE 1
#endif

#ifndef PCRE_STUDY_JIT_COMPILE
#define PCRE_STUDY_JIT_COMPILE 0
#endif
#ifndef PCRE_INFO_JIT
// some unused number
#define PCRE_INFO_JIT 2048
#endif
#ifndef PCRE_HAS_JIT_CODE
#define pcre_free_study(x) pcre_free((x))
#endif

int CRegExp::m_Utf8Supported = -1;
int CRegExp::m_UcpSupported  = -1;
int CRegExp::m_JitSupported  = -1;


CRegExp::CRegExp(bool caseless /*= false*/, CRegExp::utf8Mode utf8 /*= asciiOnly*/)
{
  InitValues(caseless, utf8);
}

void CRegExp::InitValues(bool caseless /*= false*/, CRegExp::utf8Mode utf8 /*= asciiOnly*/)
{
  m_utf8Mode    = utf8;
  m_re          = NULL;
  m_sd          = NULL;
  m_iOptions    = PCRE_DOTALL | PCRE_NEWLINE_ANY;
  if(caseless)
    m_iOptions |= PCRE_CASELESS;
  if (m_utf8Mode == forceUtf8)
  {
    if (IsUtf8Supported())
      m_iOptions |= PCRE_UTF8;
    if (AreUnicodePropertiesSupported())
      m_iOptions |= PCRE_UCP;
  }

  m_offset      = 0;
  m_jitCompiled = false;
  m_bMatched    = false;
  m_iMatchCount = 0;
  m_jitStack    = NULL;

  memset(m_iOvector, 0, sizeof(m_iOvector));
}

CRegExp::CRegExp(bool caseless, CRegExp::utf8Mode utf8, const char *re, studyMode study /*= NoStudy*/)
{
  if (utf8 == autoUtf8)
    utf8 = requireUtf8(re) ? forceUtf8 : asciiOnly;

  InitValues(caseless, utf8);
  RegComp(re, study);
}

bool CRegExp::requireUtf8(const std::string& regexp)
{
  // enable UTF-8 mode if regexp string has UTF-8 multibyte sequences
  if (CUtf8Utils::checkStrForUtf8(regexp) == CUtf8Utils::utf8string)
    return true;

  // check for explicit Unicode Properties (\p, \P, \X) and for Unicode character codes (greater than 0xFF) in form \x{hhh..}
  // note: PCRE change meaning of \w, \s, \d (and \W, \S, \D) when Unicode Properties are enabled,
  //       but in auto mode we enable UNP for US-ASCII regexp only if regexp contains explicit \p, \P, \X or Unicode character code
  const char* const regexpC = regexp.c_str();
  const size_t len = regexp.length();
  size_t pos = 0;

  while (pos < len)
  {
    const char chr = regexpC[pos];
    if (chr == '\\')
    {
      const char nextChr = regexpC[pos + 1];

      if (nextChr == 'p' || nextChr == 'P' || nextChr == 'X')
        return true; // found Unicode Properties
      else if (nextChr == 'Q')
        pos = regexp.find("\\E", pos + 2); // skip all literals in "\Q...\E"
      else if (nextChr == 'x' && regexpC[pos + 2] == '{')
      { // Unicode character with hex code
        if (readCharXCode(regexp, pos) >= 0x100)
          return true; // found Unicode character code
      }
      else if (nextChr == '\\' || nextChr == '(' || nextChr == ')'
               || nextChr == '[' || nextChr == ']')
               pos++; // exclude next character from analyze

    } // chr != '\\'
    else if (chr == '(' && regexpC[pos + 1] == '?' && regexpC[pos + 2] == '#') // comment in regexp
      pos = regexp.find(')', pos); // skip comment
    else if (chr == '[')
    {
      if (isCharClassWithUnicode(regexp, pos))
        return true;
    }

    if (pos == std::string::npos) // check results of regexp.find() and isCharClassWithUnicode
      return false;

    pos++;
  }

  // no Unicode Properties was found
  return false;
}

inline int CRegExp::readCharXCode(const std::string& regexp, size_t& pos)
{
  // read hex character code in form "\x{hh..}"
  // 'pos' must point to '\'
  if (pos >= regexp.length())
    return -1;
  const char* const regexpC = regexp.c_str();
  if (regexpC[pos] != '\\' || regexpC[pos + 1] != 'x' || regexpC[pos + 2] != '{')
    return -1;

  pos++;
  const size_t startPos = pos; // 'startPos' points to 'x'
  const size_t closingBracketPos = regexp.find('}', startPos + 2);
  if (closingBracketPos == std::string::npos)
    return 0; // return character zero code, leave 'pos' at 'x'

  pos++; // 'pos' points to '{'
  int chCode = 0;
  while (++pos < closingBracketPos)
  {
    const int xdigitVal = StringUtils::asciixdigitvalue(regexpC[pos]);
    if (xdigitVal >= 0)
      chCode = chCode * 16 + xdigitVal;
    else
    { // found non-hexdigit
      pos = startPos; // reset 'pos' to 'startPos', process "{hh..}" as non-code
      return 0; // return character zero code
    }
  }

  return chCode;
}

bool CRegExp::isCharClassWithUnicode(const std::string& regexp, size_t& pos)
{
  const char* const regexpC = regexp.c_str();
  const size_t len = regexp.length();
  if (pos > len || regexpC[pos] != '[')
    return false;

  // look for Unicode character code "\x{hhh..}" and Unicode properties "\P", "\p" and "\X"
  // find end (terminating ']') of character class (like "[a-h45]")
  // detect nested POSIX classes like "[[:lower:]]" and escaped brackets like "[\]]"
  bool needUnicode = false;
  while (++pos < len)
  {
    if (regexpC[pos] == '[' && regexpC[pos + 1] == ':')
    { // possible POSIX character class, like "[:alpha:]"
      const size_t nextClosingBracketPos = regexp.find(']', pos + 2); // don't care about "\]", as it produce error if used inside POSIX char class

      if (nextClosingBracketPos == std::string::npos)
      { // error in regexp: no closing ']' for character class
        pos = std::string::npos;
        return needUnicode;
      }
      else if (regexpC[nextClosingBracketPos - 1] == ':')
        pos = nextClosingBracketPos; // skip POSIX character class
      // if ":]" is not found, process "[:..." as part of normal character class
    }
    else if (regexpC[pos] == ']')
      return needUnicode; // end of character class
    else if (regexpC[pos] == '\\')
    {
      const char nextChar = regexpC[pos + 1];
      if (nextChar == ']' || nextChar == '[')
        pos++; // skip next character
      else if (nextChar == 'Q')
      {
        pos = regexp.find("\\E", pos + 2);
        if (pos == std::string::npos)
          return needUnicode; // error in regexp: no closing "\E" after "\Q" in character class
        else
          pos++; // skip "\E"
      }
      else if (nextChar == 'p' || nextChar == 'P' || nextChar == 'X')
        needUnicode = true; // don't care about property name as it can contain only ASCII chars
      else if (nextChar == 'x')
      {
        if (readCharXCode(regexp, pos) >= 0x100)
          needUnicode = true;
      }
    }
  }
  pos = std::string::npos; // closing square bracket was not found

  return needUnicode;
}


CRegExp::CRegExp(const CRegExp& re)
{
  m_re = NULL;
  m_sd = NULL;
  m_jitStack = NULL;
  m_utf8Mode = re.m_utf8Mode;
  m_iOptions = re.m_iOptions;
  *this = re;
}

const CRegExp& CRegExp::operator=(const CRegExp& re)
{
  size_t size;
  Cleanup();
  m_jitCompiled = false;
  m_pattern = re.m_pattern;
  if (re.m_re)
  {
    if (pcre_fullinfo(re.m_re, NULL, PCRE_INFO_SIZE, &size) >= 0)
    {
      if ((m_re = (pcre*)malloc(size)))
      {
        memcpy(m_re, re.m_re, size);
        memcpy(m_iOvector, re.m_iOvector, OVECCOUNT*sizeof(int));
        m_offset = re.m_offset;
        m_iMatchCount = re.m_iMatchCount;
        m_bMatched = re.m_bMatched;
        m_subject = re.m_subject;
        m_iOptions = re.m_iOptions;
      }
      else
        CLog::Log(LOGSEVERE, "%s: Failed to allocate memory", __FUNCTION__);
    }
  }
  return *this;
}

CRegExp::~CRegExp()
{
  Cleanup();
}

bool CRegExp::RegComp(const char *re, studyMode study /*= NoStudy*/)
{
  if (!re)
    return false;

  m_offset           = 0;
  m_jitCompiled      = false;
  m_bMatched         = false;
  m_iMatchCount      = 0;
  const char *errMsg = NULL;
  int errOffset      = 0;
  int options        = m_iOptions;
  if (m_utf8Mode == autoUtf8 && requireUtf8(re))
    options |= (IsUtf8Supported() ? PCRE_UTF8 : 0) | (AreUnicodePropertiesSupported() ? PCRE_UCP : 0);

  Cleanup();

  m_re = pcre_compile(re, options, &errMsg, &errOffset, NULL);
  if (!m_re)
  {
    m_pattern.clear();
    CLog::Log(LOGERROR, "PCRE: %s. Compilation failed at offset %d in expression '%s'",
              errMsg, errOffset, re);
    return false;
  }

  m_pattern = re;

  if (study)
  {
    const bool jitCompile = (study == StudyWithJitComp) && IsJitSupported();
    const int studyOptions = jitCompile ? PCRE_STUDY_JIT_COMPILE : 0;

    m_sd = pcre_study(m_re, studyOptions, &errMsg);
    if (errMsg != NULL)
    {
      CLog::Log(LOGWARNING, "%s: PCRE error \"%s\" while studying expression", __FUNCTION__, errMsg);
      if (m_sd != NULL)
      {
        pcre_free_study(m_sd);
        m_sd = NULL;
      }
    }
    else if (jitCompile)
    {
      int jitPresent = 0;
      m_jitCompiled = (pcre_fullinfo(m_re, m_sd, PCRE_INFO_JIT, &jitPresent) == 0 && jitPresent == 1);
    }
  }

  return true;
}

int CRegExp::RegFind(const char *str, unsigned int startoffset /*= 0*/, int maxNumberOfCharsToTest /*= -1*/)
{
  return PrivateRegFind(strlen(str), str, startoffset, maxNumberOfCharsToTest);
}

int CRegExp::PrivateRegFind(size_t bufferLen, const char *str, unsigned int startoffset /* = 0*/, int maxNumberOfCharsToTest /*= -1*/)
{
  m_offset      = 0;
  m_bMatched    = false;
  m_iMatchCount = 0;

  if (!m_re)
  {
    CLog::Log(LOGERROR, "PCRE: Called before compilation");
    return -1;
  }

  if (!str)
  {
    CLog::Log(LOGERROR, "PCRE: Called without a string to match");
    return -1;
  } 

  if (startoffset > bufferLen)
  {
    CLog::Log(LOGERROR, "%s: startoffset is beyond end of string to match", __FUNCTION__);
    return -1;
  }

#ifdef PCRE_HAS_JIT_CODE
  if (m_jitCompiled && !m_jitStack)
  {
    m_jitStack = pcre_jit_stack_alloc(32*1024, 512*1024);
    if (m_jitStack == NULL)
      CLog::Log(LOGWARNING, "%s: can't allocate address space for JIT stack", __FUNCTION__);

    pcre_assign_jit_stack(m_sd, NULL, m_jitStack);
  }
#endif

  if (maxNumberOfCharsToTest >= 0)
    bufferLen = std::min<size_t>(bufferLen, startoffset + maxNumberOfCharsToTest);

  m_subject.assign(str + startoffset, bufferLen - startoffset);
  int rc = pcre_exec(m_re, NULL, m_subject.c_str(), m_subject.length(), 0, 0, m_iOvector, OVECCOUNT);

  if (rc<1)
  {
    static const int fragmentLen = 80; // length of excerpt before erroneous char for log
    switch(rc)
    {
    case PCRE_ERROR_NOMATCH:
      return -1;

    case PCRE_ERROR_MATCHLIMIT:
      CLog::Log(LOGERROR, "PCRE: Match limit reached");
      return -1;

#ifdef PCRE_ERROR_SHORTUTF8 
    case PCRE_ERROR_SHORTUTF8:
      {
        const size_t startPos = (m_subject.length() > fragmentLen) ? CUtf8Utils::RFindValidUtf8Char(m_subject, m_subject.length() - fragmentLen) : 0;
        if (startPos != std::string::npos)
          CLog::Log(LOGERROR, "PCRE: Bad UTF-8 character at the end of string. Text before bad character: \"%s\"", m_subject.substr(startPos).c_str());
        else
          CLog::Log(LOGERROR, "PCRE: Bad UTF-8 character at the end of string");
        return -1;
      }
#endif
    case PCRE_ERROR_BADUTF8:
      {
        const size_t startPos = (m_iOvector[0] > fragmentLen) ? CUtf8Utils::RFindValidUtf8Char(m_subject, m_iOvector[0] - fragmentLen) : 0;
        if (m_iOvector[0] >= 0 && startPos != std::string::npos)
          CLog::Log(LOGERROR, "PCRE: Bad UTF-8 character, error code: %d, position: %d. Text before bad char: \"%s\"", m_iOvector[1], m_iOvector[0], m_subject.substr(startPos, m_iOvector[0] - startPos + 1).c_str());
        else
          CLog::Log(LOGERROR, "PCRE: Bad UTF-8 character, error code: %d, position: %d", m_iOvector[1], m_iOvector[0]);
        return -1;
      }
    case PCRE_ERROR_BADUTF8_OFFSET:
      CLog::Log(LOGERROR, "PCRE: Offset is pointing to the middle of UTF-8 character");
      return -1;

    default:
      CLog::Log(LOGERROR, "PCRE: Unknown error: %d", rc);
      return -1;
    }
  }
  m_offset = startoffset;
  m_bMatched = true;
  m_iMatchCount = rc;
  return m_iOvector[0] + m_offset;
}

int CRegExp::GetCaptureTotal() const
{
  int c = -1;
  if (m_re)
    pcre_fullinfo(m_re, NULL, PCRE_INFO_CAPTURECOUNT, &c);
  return c;
}

std::string CRegExp::GetReplaceString(const std::string& sReplaceExp) const
{
  if (!m_bMatched || sReplaceExp.empty())
    return "";

  const char* const expr = sReplaceExp.c_str();

  size_t pos = sReplaceExp.find_first_of("\\&");
  std::string result(sReplaceExp, 0, pos);
  result.reserve(sReplaceExp.size()); // very rough estimate

  while(pos != std::string::npos)
  {
    if (expr[pos] == '\\')
    {
      // string is null-terminated and current char isn't null, so it's safe to advance to next char
      pos++; // advance to next char
      const char nextChar = expr[pos];
      if (nextChar == '&' || nextChar == '\\')
      { // this is "\&" or "\\" combination
        result.push_back(nextChar); // add '&' or '\' to result 
        pos++; 
      }
      else if (isdigit(nextChar))
      { // this is "\0" - "\9" combination
        int subNum = nextChar - '0';
        pos++; // advance to second next char
        const char secondNextChar = expr[pos];
        if (isdigit(secondNextChar))
        { // this is "\00" - "\99" combination
          subNum = subNum * 10 + (secondNextChar - '0');
          pos++;
        }
        result.append(GetMatch(subNum));
      }
    }
    else
    { // '&' char
      result.append(GetMatch(0));
      pos++;
    }

    const size_t nextPos = sReplaceExp.find_first_of("\\&", pos);
    result.append(sReplaceExp, pos, nextPos - pos);
    pos = nextPos;
  }

  return result;
}

int CRegExp::GetSubStart(int iSub) const
{
  if (!IsValidSubNumber(iSub))
    return -1;

  return m_iOvector[iSub*2] + m_offset;
}

int CRegExp::GetSubStart(const std::string& subName) const
{
  return GetSubStart(GetNamedSubPatternNumber(subName.c_str()));
}

int CRegExp::GetSubLength(int iSub) const
{
  if (!IsValidSubNumber(iSub))
    return -1;

  return m_iOvector[(iSub*2)+1] - m_iOvector[(iSub*2)];
}

int CRegExp::GetSubLength(const std::string& subName) const
{
  return GetSubLength(GetNamedSubPatternNumber(subName.c_str()));
}

std::string CRegExp::GetMatch(int iSub /* = 0 */) const
{
  if (!IsValidSubNumber(iSub))
    return "";

  int pos = m_iOvector[(iSub*2)];
  int len = m_iOvector[(iSub*2)+1] - pos;
  if (pos < 0 || len <= 0)
    return "";

  return m_subject.substr(pos, len);
}

std::string CRegExp::GetMatch(const std::string& subName) const
{
  return GetMatch(GetNamedSubPatternNumber(subName.c_str()));
}

bool CRegExp::GetNamedSubPattern(const char* strName, std::string& strMatch) const
{
  strMatch.clear();
  int iSub = pcre_get_stringnumber(m_re, strName);
  if (!IsValidSubNumber(iSub))
    return false;
  strMatch = GetMatch(iSub);
  return true;
}

int CRegExp::GetNamedSubPatternNumber(const char* strName) const
{
  return pcre_get_stringnumber(m_re, strName);
}

void CRegExp::DumpOvector(int iLog /* = LOGDEBUG */)
{
  if (iLog < LOGDEBUG || iLog > LOGNONE)
    return;

  CStdString str = "{";
  int size = GetSubCount(); // past the subpatterns is junk
  for (int i = 0; i <= size; i++)
  {
    CStdString t = StringUtils::Format("[%i,%i]", m_iOvector[(i*2)], m_iOvector[(i*2)+1]);
    if (i != size)
      t += ",";
    str += t;
  }
  str += "}";
  CLog::Log(iLog, "regexp ovector=%s", str.c_str());
}

void CRegExp::Cleanup()
{
  if (m_re)
  {
    pcre_free(m_re); 
    m_re = NULL; 
  }

  if (m_sd)
  {
    pcre_free_study(m_sd);
    m_sd = NULL;
  }

#ifdef PCRE_HAS_JIT_CODE
  if (m_jitStack)
  {
    pcre_jit_stack_free(m_jitStack);
    m_jitStack = NULL;
  }
#endif
}

inline bool CRegExp::IsValidSubNumber(int iSub) const
{
  return iSub >= 0 && iSub <= m_iMatchCount && iSub <= m_MaxNumOfBackrefrences;
}


bool CRegExp::IsUtf8Supported(void)
{
  if (m_Utf8Supported == -1)
  {
    if (pcre_config(PCRE_CONFIG_UTF8, &m_Utf8Supported) != 0)
      m_Utf8Supported = 0;
  }

  return m_Utf8Supported == 1;
}

bool CRegExp::AreUnicodePropertiesSupported(void)
{
#if defined(PCRE_CONFIG_UNICODE_PROPERTIES) && PCRE_UCP != 0
  if (m_UcpSupported == -1)
  {
    if (pcre_config(PCRE_CONFIG_UNICODE_PROPERTIES, &m_UcpSupported) != 0)
      m_UcpSupported = 0;
  }
#endif

  return m_UcpSupported == 1;
}

bool CRegExp::LogCheckUtf8Support(void)
{
  bool utf8FullSupport = true;

  if (!CRegExp::IsUtf8Supported())
  {
    utf8FullSupport = false;
    CLog::Log(LOGWARNING, "UTF-8 is not supported in PCRE lib, support for national symbols is limited!");
  }

  if (!CRegExp::AreUnicodePropertiesSupported())
  {
    utf8FullSupport = false;
    CLog::Log(LOGWARNING, "Unicode properties are not enabled in PCRE lib, support for national symbols may be limited!");
  }

  if (!utf8FullSupport)
  {
    CLog::Log(LOGNOTICE, "Consider installing PCRE lib version 8.10 or later with enabled Unicode properties and UTF-8 support. Your PCRE lib version: %s", PCRE::pcre_version());
#if PCRE_UCP == 0
    CLog::Log(LOGNOTICE, "You will need to rebuild XBMC after PCRE lib update.");
#endif
  }

  return utf8FullSupport;
}

bool CRegExp::IsJitSupported(void)
{
  if (m_JitSupported == -1)
  {
#ifdef PCRE_HAS_JIT_CODE
    if (pcre_config(PCRE_CONFIG_JIT, &m_JitSupported) != 0)
#endif
      m_JitSupported = 0;
  }

  return m_JitSupported == 1;
}
