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

}  // namespace

CPDF_ToUnicodeMap::CPDF_ToUnicodeMap() : m_pBaseMap(nullptr) {}

CPDF_ToUnicodeMap::~CPDF_ToUnicodeMap() {}

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

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) {
  int len = str.GetLength();
  if (len == 0)
    return 0;

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

  for (int 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) {
  int len = str.GetLength();
  if (len == 0)
    return WideString();

  WideString result;
  if (str[0] == '<') {
    int byte_pos = 0;
    wchar_t ch = 0;
    for (int i = 1; i < len && std::isxdigit(str[i]); ++i) {
      ch = ch * 16 + FXSYS_HexCharToInt(str[i]);
      byte_pos++;
      if (byte_pos == 4) {
        result += ch;
        byte_pos = 0;
        ch = 0;
      }
    }
    return result;
  }
  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);
        int len = destcode.GetLength();
        if (len == 0) {
          continue;
        }
        if (len == 1) {
          m_Map[srccode] = destcode[0];
        } else {
          m_Map[srccode] = GetUnicode();
          m_MultiCharBuf.AppendChar(destcode.GetLength());
          m_MultiCharBuf << destcode;
        }
      }
    } else if (word == "beginbfrange") {
      while (1) {
        ByteString low, high;
        low = parser.GetWord();
        if (low.IsEmpty() || low == "endbfrange") {
          break;
        }
        high = parser.GetWord();
        uint32_t lowcode = StringToCode(low.AsStringView());
        uint32_t highcode =
            (lowcode & 0xffffff00) | (StringToCode(high.AsStringView()) & 0xff);
        if (highcode == (uint32_t)-1) {
          break;
        }
        ByteString start(parser.GetWord());
        if (start == "[") {
          for (uint32_t code = lowcode; code <= highcode; code++) {
            ByteString dest(parser.GetWord());
            WideString destcode = StringToWideString(dest.AsStringView());
            int len = destcode.GetLength();
            if (len == 0) {
              continue;
            }
            if (len == 1) {
              m_Map[code] = destcode[0];
            } else {
              m_Map[code] = GetUnicode();
              m_MultiCharBuf.AppendChar(destcode.GetLength());
              m_MultiCharBuf << destcode;
            }
          }
          parser.GetWord();
        } else {
          WideString destcode = StringToWideString(start.AsStringView());
          int len = destcode.GetLength();
          uint32_t value = 0;
          if (len == 1) {
            value = StringToCode(start.AsStringView());
            for (uint32_t code = lowcode; code <= highcode; code++) {
              m_Map[code] = value++;
            }
          } else {
            for (uint32_t code = lowcode; code <= highcode; code++) {
              WideString retcode;
              if (code == lowcode) {
                retcode = destcode;
              } else {
                retcode = 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) {
    m_pBaseMap =
        CPDF_FontGlobals::GetInstance()->GetCMapManager()->GetCID2UnicodeMap(
            cid_set);
  } else {
    m_pBaseMap = nullptr;
  }
}

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