// Copyright 2014 The PDFium Authors
// 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/fxcrt/bytestring.h"

#include <ctype.h>
#include <stddef.h>

#include <algorithm>
#include <sstream>
#include <string>
#include <utility>

#include "core/fxcrt/fx_codepage.h"
#include "core/fxcrt/fx_extension.h"
#include "core/fxcrt/fx_memcpy_wrappers.h"
#include "core/fxcrt/fx_safe_types.h"
#include "core/fxcrt/fx_system.h"
#include "core/fxcrt/span_util.h"
#include "core/fxcrt/string_pool_template.h"
#include "third_party/base/check.h"
#include "third_party/base/check_op.h"
#include "third_party/base/containers/span.h"

template class fxcrt::StringDataTemplate<char>;
template class fxcrt::StringViewTemplate<char>;
template class fxcrt::StringPoolTemplate<ByteString>;
template struct std::hash<ByteString>;

namespace {

constexpr char kTrimChars[] = "\x09\x0a\x0b\x0c\x0d\x20";

std::optional<size_t> FX_strpos(pdfium::span<const char> haystack,
                                pdfium::span<const char> needle) {
  if (needle.empty() || needle.size() > haystack.size()) {
    return std::nullopt;
  }
  // After `end_pos`, not enough characters remain in `haystack` for
  // a full match to occur.
  size_t end_pos = haystack.size() - needle.size();
  for (size_t haystack_pos = 0; haystack_pos <= end_pos; ++haystack_pos) {
    auto candidate = haystack.subspan(haystack_pos, needle.size());
    if (fxcrt::span_equals(candidate, needle)) {
      return haystack_pos;
    }
  }
  return std::nullopt;
}

}  // namespace

namespace fxcrt {

static_assert(sizeof(ByteString) <= sizeof(char*),
              "Strings must not require more space than pointers");

// static
ByteString ByteString::FormatInteger(int i) {
  char buf[32];
  FXSYS_snprintf(buf, sizeof(buf), "%d", i);
  return ByteString(buf);
}

// static
ByteString ByteString::FormatFloat(float f) {
  char buf[32];
  return ByteString(buf, FloatToString(f, buf));
}

// static
ByteString ByteString::FormatV(const char* pFormat, va_list argList) {
  va_list argListCopy;
  va_copy(argListCopy, argList);
  int nMaxLen = vsnprintf(nullptr, 0, pFormat, argListCopy);
  va_end(argListCopy);

  if (nMaxLen <= 0)
    return ByteString();

  ByteString ret;
  {
    // Span's lifetime must end before ReleaseBuffer() below.
    pdfium::span<char> buf = ret.GetBuffer(nMaxLen);

    // In the following two calls, there's always space in the buffer for
    // a terminating NUL that's not included in nMaxLen.
    memset(buf.data(), 0, nMaxLen + 1);
    va_copy(argListCopy, argList);
    vsnprintf(buf.data(), nMaxLen + 1, pFormat, argListCopy);
    va_end(argListCopy);
  }
  ret.ReleaseBuffer(ret.GetStringLength());
  return ret;
}

// static
ByteString ByteString::Format(const char* pFormat, ...) {
  va_list argList;
  va_start(argList, pFormat);
  ByteString ret = FormatV(pFormat, argList);
  va_end(argList);

  return ret;
}

ByteString::ByteString(const char* pStr, size_t nLen) {
  if (nLen)
    m_pData.Reset(StringData::Create(pStr, nLen));
}

ByteString::ByteString(const uint8_t* pStr, size_t nLen) {
  if (nLen)
    m_pData.Reset(
        StringData::Create(reinterpret_cast<const char*>(pStr), nLen));
}

ByteString::ByteString() = default;

ByteString::ByteString(const ByteString& other) = default;

ByteString::ByteString(ByteString&& other) noexcept {
  m_pData.Swap(other.m_pData);
}

ByteString::ByteString(char ch) {
  m_pData.Reset(StringData::Create(1));
  m_pData->m_String[0] = ch;
}

ByteString::ByteString(const char* ptr)
    : ByteString(ptr, ptr ? strlen(ptr) : 0) {}

ByteString::ByteString(ByteStringView bstrc) {
  if (!bstrc.IsEmpty()) {
    m_pData.Reset(
        StringData::Create(bstrc.unterminated_c_str(), bstrc.GetLength()));
  }
}

ByteString::ByteString(ByteStringView str1, ByteStringView str2) {
  FX_SAFE_SIZE_T nSafeLen = str1.GetLength();
  nSafeLen += str2.GetLength();

  size_t nNewLen = nSafeLen.ValueOrDie();
  if (nNewLen == 0)
    return;

  m_pData.Reset(StringData::Create(nNewLen));
  m_pData->CopyContents(str1.unterminated_c_str(), str1.GetLength());
  m_pData->CopyContentsAt(str1.GetLength(), str2.unterminated_c_str(),
                          str2.GetLength());
}

ByteString::ByteString(const std::initializer_list<ByteStringView>& list) {
  FX_SAFE_SIZE_T nSafeLen = 0;
  for (const auto& item : list)
    nSafeLen += item.GetLength();

  size_t nNewLen = nSafeLen.ValueOrDie();
  if (nNewLen == 0)
    return;

  m_pData.Reset(StringData::Create(nNewLen));

  size_t nOffset = 0;
  for (const auto& item : list) {
    m_pData->CopyContentsAt(nOffset, item.unterminated_c_str(),
                            item.GetLength());
    nOffset += item.GetLength();
  }
}

ByteString::ByteString(const fxcrt::ostringstream& outStream) {
  auto str = outStream.str();
  if (!str.empty())
    m_pData.Reset(StringData::Create(str.c_str(), str.size()));
}

ByteString::~ByteString() = default;

void ByteString::clear() {
  if (m_pData && m_pData->CanOperateInPlace(0)) {
    m_pData->m_nDataLength = 0;
    return;
  }
  m_pData.Reset();
}

ByteString& ByteString::operator=(const char* str) {
  if (!str || !str[0])
    clear();
  else
    AssignCopy(str, strlen(str));

  return *this;
}

ByteString& ByteString::operator=(ByteStringView str) {
  if (str.IsEmpty())
    clear();
  else
    AssignCopy(str.unterminated_c_str(), str.GetLength());

  return *this;
}

ByteString& ByteString::operator=(const ByteString& that) {
  if (m_pData != that.m_pData)
    m_pData = that.m_pData;

  return *this;
}

ByteString& ByteString::operator=(ByteString&& that) noexcept {
  if (m_pData != that.m_pData)
    m_pData = std::move(that.m_pData);

  return *this;
}

ByteString& ByteString::operator+=(const char* str) {
  if (str)
    Concat(str, strlen(str));

  return *this;
}

ByteString& ByteString::operator+=(char ch) {
  Concat(&ch, 1);
  return *this;
}

ByteString& ByteString::operator+=(const ByteString& str) {
  if (str.m_pData)
    Concat(str.m_pData->m_String, str.m_pData->m_nDataLength);

  return *this;
}

ByteString& ByteString::operator+=(ByteStringView str) {
  if (!str.IsEmpty())
    Concat(str.unterminated_c_str(), str.GetLength());

  return *this;
}

bool ByteString::operator==(const char* ptr) const {
  if (!m_pData)
    return !ptr || !ptr[0];

  if (!ptr)
    return m_pData->m_nDataLength == 0;

  return strlen(ptr) == m_pData->m_nDataLength &&
         FXSYS_memcmp(ptr, m_pData->m_String, m_pData->m_nDataLength) == 0;
}

bool ByteString::operator==(ByteStringView str) const {
  if (!m_pData)
    return str.IsEmpty();

  return m_pData->m_nDataLength == str.GetLength() &&
         FXSYS_memcmp(m_pData->m_String, str.unterminated_c_str(),
                      str.GetLength()) == 0;
}

bool ByteString::operator==(const ByteString& other) const {
  if (m_pData == other.m_pData)
    return true;

  if (IsEmpty())
    return other.IsEmpty();

  if (other.IsEmpty())
    return false;

  return other.m_pData->m_nDataLength == m_pData->m_nDataLength &&
         memcmp(other.m_pData->m_String, m_pData->m_String,
                m_pData->m_nDataLength) == 0;
}

bool ByteString::operator<(const char* ptr) const {
  if (!m_pData && !ptr)
    return false;
  if (c_str() == ptr)
    return false;

  size_t len = GetLength();
  size_t other_len = ptr ? strlen(ptr) : 0;
  int result = FXSYS_memcmp(c_str(), ptr, std::min(len, other_len));
  return result < 0 || (result == 0 && len < other_len);
}

bool ByteString::operator<(ByteStringView str) const {
  return Compare(str) < 0;
}

bool ByteString::operator<(const ByteString& other) const {
  if (m_pData == other.m_pData)
    return false;

  size_t len = GetLength();
  size_t other_len = other.GetLength();
  int result = FXSYS_memcmp(c_str(), other.c_str(), std::min(len, other_len));
  return result < 0 || (result == 0 && len < other_len);
}

bool ByteString::EqualNoCase(ByteStringView str) const {
  if (!m_pData)
    return str.IsEmpty();

  size_t len = str.GetLength();
  if (m_pData->m_nDataLength != len)
    return false;

  const uint8_t* pThis = (const uint8_t*)m_pData->m_String;
  const uint8_t* pThat = str.raw_str();
  for (size_t i = 0; i < len; i++) {
    if ((*pThis) != (*pThat)) {
      uint8_t this_char = tolower(*pThis);
      uint8_t that_char = tolower(*pThat);
      if (this_char != that_char) {
        return false;
      }
    }
    pThis++;
    pThat++;
  }
  return true;
}

void ByteString::AssignCopy(const char* pSrcData, size_t nSrcLen) {
  AllocBeforeWrite(nSrcLen);
  m_pData->CopyContents(pSrcData, nSrcLen);
  m_pData->m_nDataLength = nSrcLen;
}

void ByteString::ReallocBeforeWrite(size_t nNewLength) {
  if (m_pData && m_pData->CanOperateInPlace(nNewLength))
    return;

  if (nNewLength == 0) {
    clear();
    return;
  }

  RetainPtr<StringData> pNewData(StringData::Create(nNewLength));
  if (m_pData) {
    size_t nCopyLength = std::min(m_pData->m_nDataLength, nNewLength);
    pNewData->CopyContents(m_pData->m_String, nCopyLength);
    pNewData->m_nDataLength = nCopyLength;
  } else {
    pNewData->m_nDataLength = 0;
  }
  pNewData->m_String[pNewData->m_nDataLength] = 0;
  m_pData.Swap(pNewData);
}

void ByteString::AllocBeforeWrite(size_t nNewLength) {
  if (m_pData && m_pData->CanOperateInPlace(nNewLength))
    return;

  if (nNewLength == 0) {
    clear();
    return;
  }

  m_pData.Reset(StringData::Create(nNewLength));
}

void ByteString::ReleaseBuffer(size_t nNewLength) {
  if (!m_pData)
    return;

  nNewLength = std::min(nNewLength, m_pData->m_nAllocLength);
  if (nNewLength == 0) {
    clear();
    return;
  }

  DCHECK_EQ(m_pData->m_nRefs, 1);
  m_pData->m_nDataLength = nNewLength;
  m_pData->m_String[nNewLength] = 0;
  if (m_pData->m_nAllocLength - nNewLength >= 32) {
    // Over arbitrary threshold, so pay the price to relocate.  Force copy to
    // always occur by holding a second reference to the string.
    ByteString preserve(*this);
    ReallocBeforeWrite(nNewLength);
  }
}

void ByteString::Reserve(size_t len) {
  GetBuffer(len);
}

pdfium::span<char> ByteString::GetBuffer(size_t nMinBufLength) {
  if (!m_pData) {
    if (nMinBufLength == 0)
      return pdfium::span<char>();

    m_pData.Reset(StringData::Create(nMinBufLength));
    m_pData->m_nDataLength = 0;
    m_pData->m_String[0] = 0;
    return pdfium::span<char>(m_pData->m_String, m_pData->m_nAllocLength);
  }

  if (m_pData->CanOperateInPlace(nMinBufLength))
    return pdfium::span<char>(m_pData->m_String, m_pData->m_nAllocLength);

  nMinBufLength = std::max(nMinBufLength, m_pData->m_nDataLength);
  if (nMinBufLength == 0)
    return pdfium::span<char>();

  RetainPtr<StringData> pNewData(StringData::Create(nMinBufLength));
  pNewData->CopyContents(*m_pData);
  pNewData->m_nDataLength = m_pData->m_nDataLength;
  m_pData.Swap(pNewData);
  return pdfium::span<char>(m_pData->m_String, m_pData->m_nAllocLength);
}

size_t ByteString::Delete(size_t index, size_t count) {
  if (!m_pData)
    return 0;

  size_t old_length = m_pData->m_nDataLength;
  if (count == 0 || index != std::clamp<size_t>(index, 0, old_length)) {
    return old_length;
  }

  size_t removal_length = index + count;
  if (removal_length > old_length)
    return old_length;

  ReallocBeforeWrite(old_length);
  size_t chars_to_copy = old_length - removal_length + 1;
  FXSYS_memmove(m_pData->m_String + index, m_pData->m_String + removal_length,
                chars_to_copy);
  m_pData->m_nDataLength = old_length - count;
  return m_pData->m_nDataLength;
}

void ByteString::Concat(const char* pSrcData, size_t nSrcLen) {
  if (!pSrcData || nSrcLen == 0)
    return;

  if (!m_pData) {
    m_pData.Reset(StringData::Create(pSrcData, nSrcLen));
    return;
  }

  if (m_pData->CanOperateInPlace(m_pData->m_nDataLength + nSrcLen)) {
    m_pData->CopyContentsAt(m_pData->m_nDataLength, pSrcData, nSrcLen);
    m_pData->m_nDataLength += nSrcLen;
    return;
  }

  size_t nConcatLen = std::max(m_pData->m_nDataLength / 2, nSrcLen);
  RetainPtr<StringData> pNewData(
      StringData::Create(m_pData->m_nDataLength + nConcatLen));
  pNewData->CopyContents(*m_pData);
  pNewData->CopyContentsAt(m_pData->m_nDataLength, pSrcData, nSrcLen);
  pNewData->m_nDataLength = m_pData->m_nDataLength + nSrcLen;
  m_pData.Swap(pNewData);
}

intptr_t ByteString::ReferenceCountForTesting() const {
  return m_pData ? m_pData->m_nRefs : 0;
}

ByteString ByteString::Substr(size_t offset) const {
  // Unsigned underflow is well-defined and out-of-range is handled by Substr().
  return Substr(offset, GetLength() - offset);
}

ByteString ByteString::Substr(size_t first, size_t count) const {
  if (!m_pData) {
    return ByteString();
  }
  if (first == 0 && count == m_pData->m_nDataLength) {
    return *this;
  }
  return ByteString(AsStringView().Substr(first, count));
}

ByteString ByteString::First(size_t count) const {
  return Substr(0, count);
}

ByteString ByteString::Last(size_t count) const {
  // Unsigned underflow is well-defined and out-of-range is handled by Substr().
  return Substr(GetLength() - count, count);
}

void ByteString::SetAt(size_t index, char c) {
  DCHECK(IsValidIndex(index));
  ReallocBeforeWrite(m_pData->m_nDataLength);
  m_pData->m_String[index] = c;
}

size_t ByteString::Insert(size_t index, char ch) {
  const size_t cur_length = GetLength();
  if (!IsValidLength(index))
    return cur_length;

  const size_t new_length = cur_length + 1;
  ReallocBeforeWrite(new_length);
  FXSYS_memmove(m_pData->m_String + index + 1, m_pData->m_String + index,
                new_length - index);
  m_pData->m_String[index] = ch;
  m_pData->m_nDataLength = new_length;
  return new_length;
}

std::optional<size_t> ByteString::Find(char ch, size_t start) const {
  if (!m_pData)
    return std::nullopt;

  if (!IsValidIndex(start))
    return std::nullopt;

  const char* pStr = static_cast<const char*>(FXSYS_memchr(
      m_pData->m_String + start, ch, m_pData->m_nDataLength - start));
  return pStr ? std::optional<size_t>(
                    static_cast<size_t>(pStr - m_pData->m_String))
              : std::nullopt;
}

std::optional<size_t> ByteString::Find(ByteStringView subStr,
                                       size_t start) const {
  if (!m_pData) {
    return std::nullopt;
  }
  if (!IsValidIndex(start)) {
    return std::nullopt;
  }
  std::optional<size_t> result =
      FX_strpos(m_pData->span().subspan(start), subStr.span());
  if (!result.has_value()) {
    return std::nullopt;
  }
  return start + result.value();
}

std::optional<size_t> ByteString::ReverseFind(char ch) const {
  if (!m_pData)
    return std::nullopt;

  size_t nLength = m_pData->m_nDataLength;
  while (nLength--) {
    if (m_pData->m_String[nLength] == ch)
      return nLength;
  }
  return std::nullopt;
}

void ByteString::MakeLower() {
  if (IsEmpty())
    return;

  ReallocBeforeWrite(m_pData->m_nDataLength);
  FXSYS_strlwr(m_pData->m_String);
}

void ByteString::MakeUpper() {
  if (IsEmpty())
    return;

  ReallocBeforeWrite(m_pData->m_nDataLength);
  FXSYS_strupr(m_pData->m_String);
}

size_t ByteString::Remove(char chRemove) {
  if (IsEmpty())
    return 0;

  char* pstrSource = m_pData->m_String;
  char* pstrEnd = m_pData->m_String + m_pData->m_nDataLength;
  while (pstrSource < pstrEnd) {
    if (*pstrSource == chRemove)
      break;
    pstrSource++;
  }
  if (pstrSource == pstrEnd)
    return 0;

  ptrdiff_t copied = pstrSource - m_pData->m_String;
  ReallocBeforeWrite(m_pData->m_nDataLength);
  pstrSource = m_pData->m_String + copied;
  pstrEnd = m_pData->m_String + m_pData->m_nDataLength;

  char* pstrDest = pstrSource;
  while (pstrSource < pstrEnd) {
    if (*pstrSource != chRemove) {
      *pstrDest = *pstrSource;
      pstrDest++;
    }
    pstrSource++;
  }

  *pstrDest = 0;
  size_t nCount = static_cast<size_t>(pstrSource - pstrDest);
  m_pData->m_nDataLength -= nCount;
  return nCount;
}

size_t ByteString::Replace(ByteStringView pOld, ByteStringView pNew) {
  if (!m_pData || pOld.IsEmpty())
    return 0;

  size_t nCount = 0;
  {
    // Limit span lifetime.
    pdfium::span<char> search_span = m_pData->span();
    while (true) {
      std::optional<size_t> found = FX_strpos(search_span, pOld.span());
      if (!found.has_value()) {
        break;
      }
      nCount++;
      search_span = search_span.subspan(found.value() + pOld.GetLength());
    }
  }
  if (nCount == 0)
    return 0;

  size_t nNewLength =
      m_pData->m_nDataLength + nCount * (pNew.GetLength() - pOld.GetLength());

  if (nNewLength == 0) {
    clear();
    return nCount;
  }

  RetainPtr<StringData> pNewData(StringData::Create(nNewLength));
  {
    // Spans can't outlive the StringData buffers.
    pdfium::span<const char> search_span = m_pData->span();
    pdfium::span<char> dest_span = pNewData->span();
    for (size_t i = 0; i < nCount; i++) {
      size_t found = FX_strpos(search_span, pOld.span()).value();
      dest_span = fxcrt::spancpy(dest_span, search_span.first(found));
      dest_span = fxcrt::spancpy(dest_span, pNew.span());
      search_span = search_span.subspan(found + pOld.GetLength());
    }
    dest_span = fxcrt::spancpy(dest_span, search_span);
    CHECK(dest_span.empty());
  }
  m_pData = std::move(pNewData);
  return nCount;
}

int ByteString::Compare(ByteStringView str) const {
  if (!m_pData)
    return str.IsEmpty() ? 0 : -1;

  size_t this_len = m_pData->m_nDataLength;
  size_t that_len = str.GetLength();
  size_t min_len = std::min(this_len, that_len);
  int result =
      FXSYS_memcmp(m_pData->m_String, str.unterminated_c_str(), min_len);
  if (result != 0)
    return result;
  if (this_len == that_len)
    return 0;
  return this_len < that_len ? -1 : 1;
}

void ByteString::Trim() {
  TrimRight(kTrimChars);
  TrimLeft(kTrimChars);
}

void ByteString::Trim(char target) {
  ByteStringView targets(target);
  TrimRight(targets);
  TrimLeft(targets);
}

void ByteString::Trim(ByteStringView targets) {
  TrimRight(targets);
  TrimLeft(targets);
}

void ByteString::TrimLeft() {
  TrimLeft(kTrimChars);
}

void ByteString::TrimLeft(char target) {
  TrimLeft(ByteStringView(target));
}

void ByteString::TrimLeft(ByteStringView targets) {
  if (!m_pData || targets.IsEmpty())
    return;

  size_t len = GetLength();
  if (len == 0)
    return;

  size_t pos = 0;
  while (pos < len) {
    size_t i = 0;
    while (i < targets.GetLength() && targets[i] != m_pData->m_String[pos])
      i++;
    if (i == targets.GetLength())
      break;
    pos++;
  }
  if (pos) {
    ReallocBeforeWrite(len);
    size_t nDataLength = len - pos;
    FXSYS_memmove(m_pData->m_String, m_pData->m_String + pos,
                  (nDataLength + 1) * sizeof(char));
    m_pData->m_nDataLength = nDataLength;
  }
}

void ByteString::TrimRight() {
  TrimRight(kTrimChars);
}

void ByteString::TrimRight(char target) {
  TrimRight(ByteStringView(target));
}

void ByteString::TrimRight(ByteStringView targets) {
  if (!m_pData || targets.IsEmpty())
    return;

  size_t pos = GetLength();
  if (pos == 0)
    return;

  while (pos) {
    size_t i = 0;
    while (i < targets.GetLength() && targets[i] != m_pData->m_String[pos - 1])
      i++;
    if (i == targets.GetLength())
      break;
    pos--;
  }
  if (pos < m_pData->m_nDataLength) {
    ReallocBeforeWrite(m_pData->m_nDataLength);
    m_pData->m_String[pos] = 0;
    m_pData->m_nDataLength = pos;
  }
}

std::ostream& operator<<(std::ostream& os, const ByteString& str) {
  return os.write(str.c_str(), str.GetLength());
}

std::ostream& operator<<(std::ostream& os, ByteStringView str) {
  return os.write(str.unterminated_c_str(), str.GetLength());
}

}  // namespace fxcrt

uint32_t FX_HashCode_GetA(ByteStringView str) {
  uint32_t dwHashCode = 0;
  for (ByteStringView::UnsignedType c : str)
    dwHashCode = 31 * dwHashCode + c;
  return dwHashCode;
}

uint32_t FX_HashCode_GetLoweredA(ByteStringView str) {
  uint32_t dwHashCode = 0;
  for (ByteStringView::UnsignedType c : str)
    dwHashCode = 31 * dwHashCode + tolower(c);
  return dwHashCode;
}

uint32_t FX_HashCode_GetAsIfW(ByteStringView str) {
  uint32_t dwHashCode = 0;
  for (ByteStringView::UnsignedType c : str)
    dwHashCode = 1313 * dwHashCode + c;
  return dwHashCode;
}

uint32_t FX_HashCode_GetLoweredAsIfW(ByteStringView str) {
  uint32_t dwHashCode = 0;
  for (ByteStringView::UnsignedType c : str)
    dwHashCode = 1313 * dwHashCode + FXSYS_towlower(c);
  return dwHashCode;
}