/*
 * Copyright (C) 2004, 2006, 2008 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/351564777): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif

#include "third_party/blink/renderer/platform/wtf/text/text_codec_latin1.h"

#include <unicode/utf16.h>
#include <memory>

#include "third_party/blink/renderer/platform/wtf/text/string_buffer.h"
#include "third_party/blink/renderer/platform/wtf/text/text_codec_ascii_fast_path.h"
#include "third_party/blink/renderer/platform/wtf/text/wtf_string.h"

namespace WTF {

static const UChar kTable[256] = {
    0x0000, 0x0001, 0x0002, 0x0003, 0x0004, 0x0005, 0x0006, 0x0007,  // 00-07
    0x0008, 0x0009, 0x000A, 0x000B, 0x000C, 0x000D, 0x000E, 0x000F,  // 08-0F
    0x0010, 0x0011, 0x0012, 0x0013, 0x0014, 0x0015, 0x0016, 0x0017,  // 10-17
    0x0018, 0x0019, 0x001A, 0x001B, 0x001C, 0x001D, 0x001E, 0x001F,  // 18-1F
    0x0020, 0x0021, 0x0022, 0x0023, 0x0024, 0x0025, 0x0026, 0x0027,  // 20-27
    0x0028, 0x0029, 0x002A, 0x002B, 0x002C, 0x002D, 0x002E, 0x002F,  // 28-2F
    0x0030, 0x0031, 0x0032, 0x0033, 0x0034, 0x0035, 0x0036, 0x0037,  // 30-37
    0x0038, 0x0039, 0x003A, 0x003B, 0x003C, 0x003D, 0x003E, 0x003F,  // 38-3F
    0x0040, 0x0041, 0x0042, 0x0043, 0x0044, 0x0045, 0x0046, 0x0047,  // 40-47
    0x0048, 0x0049, 0x004A, 0x004B, 0x004C, 0x004D, 0x004E, 0x004F,  // 48-4F
    0x0050, 0x0051, 0x0052, 0x0053, 0x0054, 0x0055, 0x0056, 0x0057,  // 50-57
    0x0058, 0x0059, 0x005A, 0x005B, 0x005C, 0x005D, 0x005E, 0x005F,  // 58-5F
    0x0060, 0x0061, 0x0062, 0x0063, 0x0064, 0x0065, 0x0066, 0x0067,  // 60-67
    0x0068, 0x0069, 0x006A, 0x006B, 0x006C, 0x006D, 0x006E, 0x006F,  // 68-6F
    0x0070, 0x0071, 0x0072, 0x0073, 0x0074, 0x0075, 0x0076, 0x0077,  // 70-77
    0x0078, 0x0079, 0x007A, 0x007B, 0x007C, 0x007D, 0x007E, 0x007F,  // 78-7F
    0x20AC, 0x0081, 0x201A, 0x0192, 0x201E, 0x2026, 0x2020, 0x2021,  // 80-87
    0x02C6, 0x2030, 0x0160, 0x2039, 0x0152, 0x008D, 0x017D, 0x008F,  // 88-8F
    0x0090, 0x2018, 0x2019, 0x201C, 0x201D, 0x2022, 0x2013, 0x2014,  // 90-97
    0x02DC, 0x2122, 0x0161, 0x203A, 0x0153, 0x009D, 0x017E, 0x0178,  // 98-9F
    0x00A0, 0x00A1, 0x00A2, 0x00A3, 0x00A4, 0x00A5, 0x00A6, 0x00A7,  // A0-A7
    0x00A8, 0x00A9, 0x00AA, 0x00AB, 0x00AC, 0x00AD, 0x00AE, 0x00AF,  // A8-AF
    0x00B0, 0x00B1, 0x00B2, 0x00B3, 0x00B4, 0x00B5, 0x00B6, 0x00B7,  // B0-B7
    0x00B8, 0x00B9, 0x00BA, 0x00BB, 0x00BC, 0x00BD, 0x00BE, 0x00BF,  // B8-BF
    0x00C0, 0x00C1, 0x00C2, 0x00C3, 0x00C4, 0x00C5, 0x00C6, 0x00C7,  // C0-C7
    0x00C8, 0x00C9, 0x00CA, 0x00CB, 0x00CC, 0x00CD, 0x00CE, 0x00CF,  // C8-CF
    0x00D0, 0x00D1, 0x00D2, 0x00D3, 0x00D4, 0x00D5, 0x00D6, 0x00D7,  // D0-D7
    0x00D8, 0x00D9, 0x00DA, 0x00DB, 0x00DC, 0x00DD, 0x00DE, 0x00DF,  // D8-DF
    0x00E0, 0x00E1, 0x00E2, 0x00E3, 0x00E4, 0x00E5, 0x00E6, 0x00E7,  // E0-E7
    0x00E8, 0x00E9, 0x00EA, 0x00EB, 0x00EC, 0x00ED, 0x00EE, 0x00EF,  // E8-EF
    0x00F0, 0x00F1, 0x00F2, 0x00F3, 0x00F4, 0x00F5, 0x00F6, 0x00F7,  // F0-F7
    0x00F8, 0x00F9, 0x00FA, 0x00FB, 0x00FC, 0x00FD, 0x00FE, 0x00FF   // F8-FF
};

void TextCodecLatin1::RegisterEncodingNames(EncodingNameRegistrar registrar) {
  // Taken from the alias table at https://encoding.spec.whatwg.org/
  registrar("windows-1252", "windows-1252");
  registrar("ANSI_X3.4-1968", "windows-1252");
  registrar("ASCII", "windows-1252");
  registrar("cp1252", "windows-1252");
  registrar("cp819", "windows-1252");
  registrar("csISOLatin1", "windows-1252");
  registrar("IBM819", "windows-1252");
  registrar("ISO-8859-1", "windows-1252");
  registrar("iso-ir-100", "windows-1252");
  registrar("iso8859-1", "windows-1252");
  registrar("iso88591", "windows-1252");
  registrar("iso_8859-1", "windows-1252");
  registrar("iso_8859-1:1987", "windows-1252");
  registrar("l1", "windows-1252");
  registrar("latin1", "windows-1252");
  registrar("US-ASCII", "windows-1252");
  registrar("x-cp1252", "windows-1252");
}

static std::unique_ptr<TextCodec> NewStreamingTextDecoderWindowsLatin1(
    const TextEncoding&,
    const void*) {
  return std::make_unique<TextCodecLatin1>();
}

void TextCodecLatin1::RegisterCodecs(TextCodecRegistrar registrar) {
  registrar("windows-1252", NewStreamingTextDecoderWindowsLatin1, nullptr);

  // ASCII and Latin-1 both decode as Windows Latin-1 although they retain
  // unique identities.
  registrar("ISO-8859-1", NewStreamingTextDecoderWindowsLatin1, nullptr);
  registrar("US-ASCII", NewStreamingTextDecoderWindowsLatin1, nullptr);
}

String TextCodecLatin1::Decode(base::span<const uint8_t> bytes,
                               FlushBehavior,
                               bool,
                               bool&) {
  if (bytes.empty()) {
    return g_empty_string;
  }
  base::span<LChar> characters;
  String result = String::CreateUninitialized(
      base::checked_cast<wtf_size_t>(bytes.size()), characters);

  const uint8_t* source = bytes.data();
  const uint8_t* end = source + bytes.size();
  const uint8_t* aligned_end = AlignToMachineWord(end);
  LChar* destination = characters.data();

  while (source < end) {
    if (IsASCII(*source)) {
      // Fast path for ASCII. Most Latin-1 text will be ASCII.
      if (IsAlignedToMachineWord(source)) {
        while (source < aligned_end) {
          MachineWord chunk = *reinterpret_cast_ptr<const MachineWord*>(source);

          if (!IsAllASCII<LChar>(chunk))
            goto useLookupTable;

          CopyASCIIMachineWord(destination, source);
          source += sizeof(MachineWord);
          destination += sizeof(MachineWord);
        }

        if (source == end)
          break;
      }
      *destination = *source;
    } else {
    useLookupTable:
      if (kTable[*source] > 0xff)
        goto upConvertTo16Bit;

      *destination = static_cast<LChar>(kTable[*source]);
    }

    ++source;
    ++destination;
  }

  return result;

upConvertTo16Bit:
  base::span<UChar> characters16;
  String result16 = String::CreateUninitialized(
      base::checked_cast<wtf_size_t>(bytes.size()), characters16);

  UChar* destination16 = characters16.data();

  // Zero extend and copy already processed 8 bit data
  LChar* ptr8 = characters.data();
  LChar* end_ptr8 = destination;

  while (ptr8 < end_ptr8)
    *destination16++ = *ptr8++;

  // Handle the character that triggered the 16 bit path
  *destination16 = kTable[*source];
  ++source;
  ++destination16;

  while (source < end) {
    if (IsASCII(*source)) {
      // Fast path for ASCII. Most Latin-1 text will be ASCII.
      if (IsAlignedToMachineWord(source)) {
        while (source < aligned_end) {
          MachineWord chunk = *reinterpret_cast_ptr<const MachineWord*>(source);

          if (!IsAllASCII<LChar>(chunk))
            goto useLookupTable16;

          CopyASCIIMachineWord(destination16, source);
          source += sizeof(MachineWord);
          destination16 += sizeof(MachineWord);
        }

        if (source == end)
          break;
      }
      *destination16 = *source;
    } else {
    useLookupTable16:
      *destination16 = kTable[*source];
    }

    ++source;
    ++destination16;
  }

  return result16;
}

template <typename CharType>
static std::string EncodeComplexWindowsLatin1(
    base::span<const CharType> char_data,
    UnencodableHandling handling) {
  DCHECK_NE(handling, kNoUnencodables);
  const auto* characters = char_data.data();
  const wtf_size_t length = base::checked_cast<wtf_size_t>(char_data.size());
  wtf_size_t target_length = length;
  std::string result;
  result.reserve(target_length);

  for (wtf_size_t i = 0; i < length;) {
    UChar32 c;
    // If CharType is LChar the U16_NEXT call reads a byte and increments;
    // since the convention is that LChar is already latin1 this is safe.
    U16_NEXT(characters, i, length, c);
    // If input was a surrogate pair (non-BMP character) then we overestimated
    // the length.
    if (c > 0xffff)
      --target_length;
    unsigned char b = static_cast<unsigned char>(c);
    // Do an efficient check to detect characters other than 00-7F and A0-FF.
    if (b != c || (c & 0xE0) == 0x80) {
      // Look for a way to encode this with Windows Latin-1.
      for (b = 0x80; b < 0xA0; ++b) {
        if (kTable[b] == c)
          goto gotByte;
      }
      // No way to encode this character with Windows Latin-1.
      std::string replacement =
          TextCodec::GetUnencodableReplacement(c, handling);
      DCHECK_GT(replacement.length(), 0UL);
      // Only one char was initially reserved per input character, so grow if
      // necessary.
      target_length += replacement.length() - 1;
      if (target_length > result.size()) {
        result.reserve(target_length);
      }
      result.append(replacement);
      continue;
    }
  gotByte:
    result.push_back(b);
  }

  return result;
}

template <typename CharType>
std::string TextCodecLatin1::EncodeCommon(base::span<const CharType> characters,
                                          UnencodableHandling handling) {
  std::string string(characters.size(), '\0');

  // Convert the string a fast way and simultaneously do an efficient check to
  // see if it's all ASCII.
  UChar ored = 0;
  for (size_t i = 0; i < characters.size(); ++i) {
    UChar c = characters[i];
    string[i] = static_cast<char>(c);
    ored |= c;
  }

  if (!(ored & 0xFF80))
    return string;

  // If it wasn't all ASCII, call the function that handles more-complex cases.
  return EncodeComplexWindowsLatin1(characters, handling);
}

std::string TextCodecLatin1::Encode(base::span<const UChar> characters,
                                    UnencodableHandling handling) {
  return EncodeCommon(characters, handling);
}

std::string TextCodecLatin1::Encode(base::span<const LChar> characters,
                                    UnencodableHandling handling) {
  return EncodeCommon(characters, handling);
}

}  // namespace WTF