// Copyright 2016 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/parser/cpdf_simple_parser.h"

#include <vector>

#include "core/fpdfapi/parser/fpdf_parser_utility.h"

CPDF_SimpleParser::CPDF_SimpleParser(const uint8_t* pData, uint32_t dwSize)
    : m_pData(pData), m_dwSize(dwSize), m_dwCurPos(0) {}

CPDF_SimpleParser::CPDF_SimpleParser(const ByteStringView& str)
    : m_pData(str.raw_str()), m_dwSize(str.GetLength()), m_dwCurPos(0) {}

std::pair<const uint8_t*, uint32_t> CPDF_SimpleParser::ParseWord() {
  const uint8_t* pStart = nullptr;
  uint8_t dwSize = 0;
  uint8_t ch;

  // Skip whitespace and comment lines.
  while (1) {
    if (m_dwSize <= m_dwCurPos)
      return std::make_pair(pStart, dwSize);

    ch = m_pData[m_dwCurPos++];
    while (PDFCharIsWhitespace(ch)) {
      if (m_dwSize <= m_dwCurPos)
        return std::make_pair(pStart, dwSize);
      ch = m_pData[m_dwCurPos++];
    }

    if (ch != '%')
      break;

    while (1) {
      if (m_dwSize <= m_dwCurPos)
        return std::make_pair(pStart, dwSize);

      ch = m_pData[m_dwCurPos++];
      if (PDFCharIsLineEnding(ch))
        break;
    }
  }

  uint32_t start_pos = m_dwCurPos - 1;
  pStart = m_pData + start_pos;
  if (PDFCharIsDelimiter(ch)) {
    // Find names
    if (ch == '/') {
      while (1) {
        if (m_dwSize <= m_dwCurPos)
          break;

        ch = m_pData[m_dwCurPos++];
        if (!PDFCharIsOther(ch) && !PDFCharIsNumeric(ch)) {
          m_dwCurPos--;
          dwSize = m_dwCurPos - start_pos;
          break;
        }
      }
      return std::make_pair(pStart, dwSize);
    }

    dwSize = 1;
    if (ch == '<') {
      if (m_dwSize <= m_dwCurPos)
        return std::make_pair(pStart, dwSize);

      ch = m_pData[m_dwCurPos++];
      if (ch == '<')
        dwSize = 2;
      else
        m_dwCurPos--;
    } else if (ch == '>') {
      if (m_dwSize <= m_dwCurPos)
        return std::make_pair(pStart, dwSize);

      ch = m_pData[m_dwCurPos++];
      if (ch == '>')
        dwSize = 2;
      else
        m_dwCurPos--;
    }
    return std::make_pair(pStart, dwSize);
  }

  dwSize = 1;
  while (1) {
    if (m_dwSize <= m_dwCurPos)
      return std::make_pair(pStart, dwSize);
    ch = m_pData[m_dwCurPos++];

    if (PDFCharIsDelimiter(ch) || PDFCharIsWhitespace(ch)) {
      m_dwCurPos--;
      break;
    }
    dwSize++;
  }
  return std::make_pair(pStart, dwSize);
}

ByteStringView CPDF_SimpleParser::GetWord() {
  const uint8_t* pStart;
  uint32_t dwSize;
  std::tie(pStart, dwSize) = ParseWord();

  if (dwSize != 1)
    return ByteStringView(pStart, dwSize);

  if (pStart[0] == '<') {
    while (m_dwCurPos < m_dwSize && m_pData[m_dwCurPos] != '>')
      m_dwCurPos++;

    if (m_dwCurPos < m_dwSize)
      m_dwCurPos++;

    return ByteStringView(pStart,
                          static_cast<size_t>(m_dwCurPos - (pStart - m_pData)));
  }

  if (pStart[0] == '(') {
    int level = 1;
    while (m_dwCurPos < m_dwSize) {
      if (m_pData[m_dwCurPos] == ')') {
        level--;
        if (level == 0)
          break;
      }

      if (m_pData[m_dwCurPos] == '\\') {
        if (m_dwSize <= m_dwCurPos)
          break;

        m_dwCurPos++;
      } else if (m_pData[m_dwCurPos] == '(') {
        level++;
      }
      if (m_dwSize <= m_dwCurPos)
        break;

      m_dwCurPos++;
    }
    if (m_dwCurPos < m_dwSize)
      m_dwCurPos++;

    return ByteStringView(pStart,
                          static_cast<size_t>(m_dwCurPos - (pStart - m_pData)));
  }
  return ByteStringView(pStart, dwSize);
}

bool CPDF_SimpleParser::FindTagParamFromStart(const ByteStringView& token,
                                              int nParams) {
  nParams++;

  std::vector<uint32_t> pBuf(nParams);
  int buf_index = 0;
  int buf_count = 0;
  m_dwCurPos = 0;
  while (1) {
    pBuf[buf_index++] = m_dwCurPos;
    if (buf_index == nParams)
      buf_index = 0;

    buf_count++;
    if (buf_count > nParams)
      buf_count = nParams;

    ByteStringView word = GetWord();
    if (word.IsEmpty())
      return false;

    if (word == token) {
      if (buf_count < nParams)
        continue;

      m_dwCurPos = pBuf[buf_index];
      return true;
    }
  }
  return false;
}