// Copyright 2017 PDFium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com

#include "core/fpdfapi/font/cpdf_tounicodemap.h"

#include <utility>

#include "core/fpdfapi/font/cpdf_cid2unicodemap.h"
#include "core/fpdfapi/font/cpdf_fontglobals.h"
#include "core/fpdfapi/parser/cpdf_simple_parser.h"
#include "core/fpdfapi/parser/cpdf_stream.h"
#include "core/fxcrt/fx_extension.h"
#include "core/fxcrt/fx_safe_types.h"
#include "third_party/base/numerics/safe_conversions.h"

namespace {

WideString StringDataAdd(WideString str) {
  WideString ret;
  wchar_t value = 1;
  for (size_t i = str.GetLength(); i > 0; --i) {
    wchar_t ch = str[i - 1] + value;
    if (ch < str[i - 1]) {
      ret.InsertAtFront(0);
    } else {
      ret.InsertAtFront(ch);
      value = 0;
    }
  }
  if (value)
    ret.InsertAtFront(value);
  return ret;
}

}  // namespace

CPDF_ToUnicodeMap::CPDF_ToUnicodeMap(const CPDF_Stream* pStream) {
  Load(pStream);
}

CPDF_ToUnicodeMap::~CPDF_ToUnicodeMap() = default;

WideString CPDF_ToUnicodeMap::Lookup(uint32_t charcode) const {
  auto it = m_Map.find(charcode);
  if (it == m_Map.end()) {
    if (!m_pBaseMap)
      return WideString();
    return m_pBaseMap->UnicodeFromCID(static_cast<uint16_t>(charcode));
  }

  uint32_t value = it->second;
  wchar_t unicode = static_cast<wchar_t>(value & 0xffff);
  if (unicode != 0xffff)
    return unicode;

  const wchar_t* buf = m_MultiCharBuf.GetBuffer();
  uint32_t buf_len = m_MultiCharBuf.GetLength();
  if (!buf || buf_len == 0)
    return WideString();

  uint32_t index = value >> 16;
  if (index >= buf_len)
    return WideString();

  uint32_t len = buf[index];
  if (index + len < index || index + len >= buf_len)
    return WideString();

  return WideString(buf + index + 1, len);
}

uint32_t CPDF_ToUnicodeMap::ReverseLookup(wchar_t unicode) const {
  for (const auto& pair : m_Map) {
    if (pair.second == static_cast<uint32_t>(unicode))
      return pair.first;
  }
  return 0;
}

// static
uint32_t CPDF_ToUnicodeMap::StringToCode(ByteStringView str) {
  size_t len = str.GetLength();
  if (len == 0)
    return 0;

  uint32_t result = 0;
  if (str[0] == '<') {
    for (size_t i = 1; i < len && std::isxdigit(str[i]); ++i)
      result = result * 16 + FXSYS_HexCharToInt(str.CharAt(i));
    return result;
  }

  for (size_t i = 0; i < len && std::isdigit(str[i]); ++i)
    result = result * 10 + FXSYS_DecimalCharToInt(str.CharAt(i));

  return result;
}

// static
WideString CPDF_ToUnicodeMap::StringToWideString(ByteStringView str) {
  size_t len = str.GetLength();
  if (len == 0 || str[0] != '<')
    return WideString();

  WideString result;
  int byte_pos = 0;
  wchar_t ch = 0;
  for (size_t i = 1; i < len && std::isxdigit(str[i]); ++i) {
    ch = ch * 16 + FXSYS_HexCharToInt(str.CharAt(i));
    byte_pos++;
    if (byte_pos == 4) {
      result += ch;
      byte_pos = 0;
      ch = 0;
    }
  }
  return result;
}

void CPDF_ToUnicodeMap::Load(const CPDF_Stream* pStream) {
  CIDSet cid_set = CIDSET_UNKNOWN;
  auto pAcc = pdfium::MakeRetain<CPDF_StreamAcc>(pStream);
  pAcc->LoadAllDataFiltered();
  CPDF_SimpleParser parser(pAcc->GetSpan());
  while (1) {
    ByteStringView word = parser.GetWord();
    if (word.IsEmpty())
      break;

    if (word == "beginbfchar") {
      while (1) {
        word = parser.GetWord();
        if (word.IsEmpty() || word == "endbfchar")
          break;

        uint32_t srccode = StringToCode(word);
        word = parser.GetWord();
        WideString destcode = StringToWideString(word);
        size_t len = destcode.GetLength();
        if (len == 0)
          continue;

        if (len == 1) {
          m_Map[srccode] = destcode[0];
        } else {
          m_Map[srccode] = GetUnicode();
          m_MultiCharBuf.AppendChar(len);
          m_MultiCharBuf << destcode;
        }
      }
    } else if (word == "beginbfrange") {
      while (1) {
        ByteStringView low = parser.GetWord();
        if (low.IsEmpty() || low == "endbfrange")
          break;

        ByteStringView high = parser.GetWord();
        uint32_t lowcode = StringToCode(low);
        uint32_t highcode =
            (lowcode & 0xffffff00) | (StringToCode(high) & 0xff);
        if (highcode == 0xffffffff)
          break;

        ByteStringView start = parser.GetWord();
        if (start == "[") {
          for (uint32_t code = lowcode; code <= highcode; code++) {
            ByteStringView dest = parser.GetWord();
            WideString destcode = StringToWideString(dest);
            size_t len = destcode.GetLength();
            if (len == 0)
              continue;

            if (len == 1) {
              m_Map[code] = destcode[0];
            } else {
              m_Map[code] = GetUnicode();
              m_MultiCharBuf.AppendChar(len);
              m_MultiCharBuf << destcode;
            }
          }
          parser.GetWord();
          continue;
        }

        WideString destcode = StringToWideString(start);
        size_t len = destcode.GetLength();
        uint32_t value = 0;
        if (len == 1) {
          value = StringToCode(start);
          for (uint32_t code = lowcode; code <= highcode; code++)
            m_Map[code] = value++;
        } else {
          for (uint32_t code = lowcode; code <= highcode; code++) {
            WideString retcode =
                code == lowcode ? destcode : StringDataAdd(destcode);
            m_Map[code] = GetUnicode();
            m_MultiCharBuf.AppendChar(retcode.GetLength());
            m_MultiCharBuf << retcode;
            destcode = std::move(retcode);
          }
        }
      }
    } else if (word == "/Adobe-Korea1-UCS2") {
      cid_set = CIDSET_KOREA1;
    } else if (word == "/Adobe-Japan1-UCS2") {
      cid_set = CIDSET_JAPAN1;
    } else if (word == "/Adobe-CNS1-UCS2") {
      cid_set = CIDSET_CNS1;
    } else if (word == "/Adobe-GB1-UCS2") {
      cid_set = CIDSET_GB1;
    }
  }
  if (cid_set) {
    auto* manager = CPDF_FontGlobals::GetInstance()->GetCMapManager();
    m_pBaseMap = manager->GetCID2UnicodeMap(cid_set);
  }
}

uint32_t CPDF_ToUnicodeMap::GetUnicode() const {
  FX_SAFE_UINT32 uni = m_MultiCharBuf.GetLength();
  uni = uni * 0x10000 + 0xffff;
  return uni.ValueOrDefault(0);
}