// Copyright 2014 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/fxcrt/css/cfx_csssyntaxparser.h"

#include <algorithm>

#include "core/fxcrt/css/cfx_cssdata.h"
#include "core/fxcrt/css/cfx_cssdeclaration.h"
#include "core/fxcrt/fx_codepage.h"
#include "core/fxcrt/fx_extension.h"
#include "third_party/base/compiler_specific.h"
#include "third_party/base/logging.h"

namespace {

bool IsSelectorStart(wchar_t wch) {
  return wch == '.' || wch == '#' || wch == '*' ||
         (isascii(wch) && isalpha(wch));
}

}  // namespace

CFX_CSSSyntaxParser::CFX_CSSSyntaxParser(const wchar_t* pBuffer,
                                         int32_t iBufferSize) {
  ASSERT(pBuffer);
  m_Output.InitWithSize(32);
  m_Input.AttachBuffer(pBuffer, iBufferSize);
}

CFX_CSSSyntaxParser::~CFX_CSSSyntaxParser() = default;

void CFX_CSSSyntaxParser::SetParseOnlyDeclarations() {
  m_eMode = SyntaxMode::kPropertyName;
}

CFX_CSSSyntaxStatus CFX_CSSSyntaxParser::DoSyntaxParse() {
  while (m_eStatus >= CFX_CSSSyntaxStatus::kNone) {
    if (m_Input.IsEOF()) {
      if (m_eMode == SyntaxMode::kPropertyValue && m_Output.GetLength() > 0) {
        SaveTextData();
        m_eStatus = CFX_CSSSyntaxStatus::kPropertyValue;
        return m_eStatus;
      }
      m_eStatus = CFX_CSSSyntaxStatus::kEOS;
      return m_eStatus;
    }
    wchar_t wch;
    while (!m_Input.IsEOF()) {
      wch = m_Input.GetChar();
      switch (m_eMode) {
        case SyntaxMode::kRuleSet:
          switch (wch) {
            case '}':
              m_Input.MoveNext();
              if (RestoreMode())
                return CFX_CSSSyntaxStatus::kDeclClose;

              m_eStatus = CFX_CSSSyntaxStatus::kError;
              return m_eStatus;
            case '/':
              if (m_Input.GetNextChar() == '*') {
                m_ModeStack.push(m_eMode);
                SwitchMode(SyntaxMode::kComment);
                break;
              }
              FALLTHROUGH;
            default:
              if (wch <= ' ') {
                m_Input.MoveNext();
              } else if (IsSelectorStart(wch)) {
                SwitchMode(SyntaxMode::kSelector);
                return CFX_CSSSyntaxStatus::kStyleRule;
              } else {
                m_eStatus = CFX_CSSSyntaxStatus::kError;
                return m_eStatus;
              }
              break;
          }
          break;
        case SyntaxMode::kSelector:
          switch (wch) {
            case ',':
              m_Input.MoveNext();
              SwitchMode(SyntaxMode::kSelector);
              if (m_iTextDataLen > 0)
                return CFX_CSSSyntaxStatus::kSelector;
              break;
            case '{':
              if (m_Output.GetLength() > 0) {
                SaveTextData();
                return CFX_CSSSyntaxStatus::kSelector;
              }
              m_Input.MoveNext();
              m_ModeStack.push(SyntaxMode::kRuleSet);
              SwitchMode(SyntaxMode::kPropertyName);
              return CFX_CSSSyntaxStatus::kDeclOpen;
            case '/':
              if (m_Input.GetNextChar() == '*') {
                if (SwitchToComment() > 0)
                  return CFX_CSSSyntaxStatus::kSelector;
                break;
              }
              FALLTHROUGH;
            default:
              AppendCharIfNotLeadingBlank(wch);
              m_Input.MoveNext();
              break;
          }
          break;
        case SyntaxMode::kPropertyName:
          switch (wch) {
            case ':':
              m_Input.MoveNext();
              SwitchMode(SyntaxMode::kPropertyValue);
              return CFX_CSSSyntaxStatus::kPropertyName;
            case '}':
              m_Input.MoveNext();
              if (RestoreMode())
                return CFX_CSSSyntaxStatus::kDeclClose;

              m_eStatus = CFX_CSSSyntaxStatus::kError;
              return m_eStatus;
            case '/':
              if (m_Input.GetNextChar() == '*') {
                if (SwitchToComment() > 0)
                  return CFX_CSSSyntaxStatus::kPropertyName;
                break;
              }
              FALLTHROUGH;
            default:
              AppendCharIfNotLeadingBlank(wch);
              m_Input.MoveNext();
              break;
          }
          break;
        case SyntaxMode::kPropertyValue:
          switch (wch) {
            case ';':
              m_Input.MoveNext();
              FALLTHROUGH;
            case '}':
              SwitchMode(SyntaxMode::kPropertyName);
              return CFX_CSSSyntaxStatus::kPropertyValue;
            case '/':
              if (m_Input.GetNextChar() == '*') {
                if (SwitchToComment() > 0)
                  return CFX_CSSSyntaxStatus::kPropertyValue;
                break;
              }
              FALLTHROUGH;
            default:
              AppendCharIfNotLeadingBlank(wch);
              m_Input.MoveNext();
              break;
          }
          break;
        case SyntaxMode::kComment:
          if (wch == '*' && m_Input.GetNextChar() == '/') {
            RestoreMode();
            m_Input.MoveNext();
          }
          m_Input.MoveNext();
          break;
        case SyntaxMode::kUnknownRule:
          if (wch == ';')
            SwitchMode(SyntaxMode::kRuleSet);
          m_Input.MoveNext();
          break;
        default:
          NOTREACHED();
          break;
      }
    }
  }
  return m_eStatus;
}

void CFX_CSSSyntaxParser::AppendCharIfNotLeadingBlank(wchar_t wch) {
  if (m_Output.GetLength() > 0 || wch > ' ')
    m_Output.AppendChar(wch);
}

void CFX_CSSSyntaxParser::SaveTextData() {
  m_iTextDataLen = m_Output.TrimEnd();
  m_Output.Clear();
}

void CFX_CSSSyntaxParser::SwitchMode(SyntaxMode eMode) {
  m_eMode = eMode;
  SaveTextData();
}

int32_t CFX_CSSSyntaxParser::SwitchToComment() {
  int32_t iLength = m_Output.GetLength();
  m_ModeStack.push(m_eMode);
  SwitchMode(SyntaxMode::kComment);
  return iLength;
}

bool CFX_CSSSyntaxParser::RestoreMode() {
  if (m_ModeStack.empty())
    return false;

  SwitchMode(m_ModeStack.top());
  m_ModeStack.pop();
  return true;
}

WideStringView CFX_CSSSyntaxParser::GetCurrentString() const {
  return WideStringView(m_Output.GetBuffer(), m_iTextDataLen);
}