/*
  Copyright (c) 2012 Montel Laurent <montel@kde.org>

  based on code from qt-labs-graphics-dojo/htmleditor/highlighter.*

  This library is free software; you can redistribute it and/or modify it
  under the terms of the GNU Library General Public License as published by
  the Free Software Foundation; either version 2 of the License, or (at your
  option) any later version.

  This library is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
  License for more details.

  You should have received a copy of the GNU Library General Public License
  along with this library; see the file COPYING.LIB.  If not, write to the
  Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  02110-1301, USA.

*/

#include "htmlhighlighter.h"

namespace KPIMTextEdit {

class HtmlHighlighterPrivate
{
  public:
    enum Construct {
      DocType,
      Entity,
      Tag,
      Comment,
      AttributeName,
      AttributeValue
    };

    enum State {
      State_Text = -1,
      State_DocType,
      State_Comment,
      State_TagStart,
      State_TagName,
      State_InsideTag,
      State_AttributeName,
      State_SingleQuote,
      State_DoubleQuote,
      State_AttributeValue
    };

    HtmlHighlighterPrivate()
    {
      colors[DocType] = QColor( 192, 192, 192 );
      colors[Entity] = QColor( 128, 128, 128 );
      colors[Tag] = QColor( 136, 18, 128 );
      colors[Comment] = QColor( 35, 110, 37 );
      colors[AttributeName] = QColor( 153, 69, 0 );
      colors[AttributeValue] = QColor( 36, 36, 170 );
    }
    QHash<int, QColor> colors;
};

HtmlHighlighter::HtmlHighlighter( QTextDocument *document )
  : QSyntaxHighlighter( document ), d( new HtmlHighlighterPrivate )
{
}

HtmlHighlighter::~HtmlHighlighter()
{
  delete d;
}

void HtmlHighlighter::highlightBlock( const QString &text )
{
  int state = previousBlockState();
  int len = text.length();
  int start = 0;
  int pos = 0;

  while ( pos < len ) {
    switch ( state ) {
    case HtmlHighlighterPrivate::State_Text:
    default:
      while ( pos < len ) {
        QChar ch = text.at( pos );
        if ( ch == QLatin1Char( '<' ) ) {
          if ( text.mid( pos, 4 ) == QLatin1String( "<!--" ) ) {
            state = HtmlHighlighterPrivate::State_Comment;
          } else {
            if ( text.mid( pos, 9 ).toUpper() == QLatin1String( "<!DOCTYPE" ) ) {
              state = HtmlHighlighterPrivate::State_DocType;
            } else {
              state = HtmlHighlighterPrivate::State_TagStart;
            }
          }
          break;
        } else if ( ch == QLatin1Char( '&' ) ) {
          start = pos;
          while ( pos < len && text.at( pos++ ) != QLatin1Char( ';' ) )
            ;
          setFormat( start, pos - start, d->colors[HtmlHighlighterPrivate::Entity] );
        } else {
          ++pos;
        }
      }
      break;

    case HtmlHighlighterPrivate::State_Comment:
      start = pos;
      while ( pos < len ) {
        if ( text.mid( pos, 3 ) == QLatin1String( "-->" ) ) {
          pos += 3;
          state = HtmlHighlighterPrivate::State_Text;
          break;
        } else {
          ++pos;
        }
      }
      setFormat( start, pos - start, d->colors[HtmlHighlighterPrivate::Comment] );
      break;

    case HtmlHighlighterPrivate::State_DocType:
      start = pos;
      while ( pos < len ) {
        QChar ch = text.at( pos );
        ++pos;
        if ( ch == QLatin1Char( '>' ) ) {
          state = HtmlHighlighterPrivate::State_Text;
          break;
        }
      }
      setFormat( start, pos - start, d->colors[HtmlHighlighterPrivate::DocType] );
      break;

    // at '<' in e.g. "<span>foo</span>"
    case HtmlHighlighterPrivate::State_TagStart:
      start = pos + 1;
      while ( pos < len ) {
        QChar ch = text.at( pos );
        ++pos;
        if ( ch == QLatin1Char( '>' ) ) {
          state = HtmlHighlighterPrivate::State_Text;
          break;
        }
        if ( !ch.isSpace() ) {
          --pos;
          state = HtmlHighlighterPrivate::State_TagName;
          break;
        }
      }
      break;

    // at 'b' in e.g "<blockquote>foo</blockquote>"
    case HtmlHighlighterPrivate::State_TagName:
      start = pos;
      while ( pos < len ) {
        QChar ch = text.at( pos );
        ++pos;
        if ( ch.isSpace() ) {
          --pos;
          state = HtmlHighlighterPrivate::State_InsideTag;
          break;
        }
        if ( ch == QLatin1Char( '>' ) ) {
          state = HtmlHighlighterPrivate::State_Text;
          break;
        }
      }
      setFormat( start, pos - start, d->colors[HtmlHighlighterPrivate::Tag] );
      break;

    // anywhere after tag name and before tag closing ('>')
    case HtmlHighlighterPrivate::State_InsideTag:
      start = pos;

      while ( pos < len ) {
        QChar ch = text.at( pos );
        ++pos;

        if ( ch == QLatin1Char( '/' ) ) {
          continue;
        }

        if ( ch == QLatin1Char( '>' ) ) {
          state = HtmlHighlighterPrivate::State_Text;
          break;
        }

        if ( !ch.isSpace() ) {
          --pos;
          state = HtmlHighlighterPrivate::State_AttributeName;
          break;
        }

      }

      break;

    // at 's' in e.g. <img src=bla.png/>
    case HtmlHighlighterPrivate::State_AttributeName:
      start = pos;

      while ( pos < len ) {
        QChar ch = text.at( pos );
        ++pos;

        if ( ch == QLatin1Char( '=' ) ) {
          state = HtmlHighlighterPrivate::State_AttributeValue;
          break;
        }

        if ( ch == QLatin1Char( '>' ) || ch == QLatin1Char( '/' ) ) {
          state = HtmlHighlighterPrivate::State_InsideTag;
          break;
        }
      }

      setFormat( start, pos - start, d->colors[HtmlHighlighterPrivate::AttributeName] );
      break;

    // after '=' in e.g. <img src=bla.png/>
    case HtmlHighlighterPrivate::State_AttributeValue:
      start = pos;

      // find first non-space character
      while ( pos < len ) {
        QChar ch = text.at( pos );
        ++pos;

        // handle opening single quote
        if ( ch == QLatin1Char( '\'' ) ) {
          state = HtmlHighlighterPrivate::State_SingleQuote;
          break;
        }

        // handle opening double quote
        if ( ch == QLatin1Char( '"' ) ) {
          state = HtmlHighlighterPrivate::State_DoubleQuote;
          break;
        }

        if ( !ch.isSpace() ) {
          break;
        }
      }

      if ( state == HtmlHighlighterPrivate::State_AttributeValue ) {
        // attribute value without quote
        // just stop at non-space or tag delimiter
        start = pos;
        while ( pos < len ) {
          QChar ch = text.at( pos );
          if ( ch.isSpace() ) {
            break;
          }
          if ( ch == QLatin1Char( '>' ) || ch == QLatin1Char( '/' ) ) {
            break;
          }
          ++pos;
        }
        state = HtmlHighlighterPrivate::State_InsideTag;
        setFormat( start, pos - start, d->colors[HtmlHighlighterPrivate::AttributeValue] );
      }

      break;

    // after the opening single quote in an attribute value
    case HtmlHighlighterPrivate::State_SingleQuote:
      start = pos;

      while ( pos < len ) {
        QChar ch = text.at(pos);
        ++pos;
        if ( ch == QLatin1Char( '\'' ) ) {
          break;
        }
      }

      state = HtmlHighlighterPrivate::State_InsideTag;

      setFormat( start, pos - start, d->colors[HtmlHighlighterPrivate::AttributeValue] );
      break;

    // after the opening double quote in an attribute value
    case HtmlHighlighterPrivate::State_DoubleQuote:
      start = pos;

      while ( pos < len ) {
        QChar ch = text.at(pos);
        ++pos;
        if ( ch == QLatin1Char( '"' ) ) {
          break;
        }
      }

      state = HtmlHighlighterPrivate::State_InsideTag;

      setFormat( start, pos - start, d->colors[HtmlHighlighterPrivate::AttributeValue] );
      break;

    }
  }

  setCurrentBlockState( state );
}

}