/*
  Copyright (c) 2002 Dave Corrie <kde@davecorrie.com>

  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.
*/
/**
  @file
  This file is part of the KDEPIM Utilities library and provides the
  LinkLocator class.

  @brief
  Identifies URLs and email addresses embedded in plaintext.

  @author Dave Corrie \<kde@davecorrie.com\>
*/

#include "linklocator.h"

#include <kglobal.h>
#include <kstandarddirs.h>
#include <kcodecs.h>
#include <kdebug.h>
#include <kdeversion.h>
#if KDE_IS_VERSION( 4, 0, 95 )
#include <kemoticons.h>
#endif

#include <QtCore/QCoreApplication>
#include <QtCore/QFile>
#include <QtCore/QRegExp>
#include <QtGui/QTextDocument>

#include <limits.h>

using namespace KPIMUtils;

/**
  Private class that helps to provide binary compatibility between releases.
  @internal
*/
//@cond PRIVATE
class KPIMUtils::LinkLocator::Private
{
  public:
    int mMaxUrlLen;
    int mMaxAddressLen;
};
//@endcond

#if KDE_IS_VERSION( 4, 0, 95 )
// Use a static for this as calls to the KEmoticons constructor are expensive.
K_GLOBAL_STATIC( KEmoticons, sEmoticons )
#endif

LinkLocator::LinkLocator( const QString &text, int pos )
  : mText( text ), mPos( pos ), d( new KPIMUtils::LinkLocator::Private )
{
  d->mMaxUrlLen = 4096;
  d->mMaxAddressLen = 255;

  // If you change either of the above values for maxUrlLen or
  // maxAddressLen, then please also update the documentation for
  // setMaxUrlLen()/setMaxAddressLen() in the header file AND the
  // default values used for the maxUrlLen/maxAddressLen parameters
  // of convertToHtml().
}

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

void LinkLocator::setMaxUrlLen( int length )
{
  d->mMaxUrlLen = length;
}

int LinkLocator::maxUrlLen() const
{
  return d->mMaxUrlLen;
}

void LinkLocator::setMaxAddressLen( int length )
{
  d->mMaxAddressLen = length;
}

int LinkLocator::maxAddressLen() const
{
  return d->mMaxAddressLen;
}

QString LinkLocator::getUrl()
{
  QString url;
  if ( atUrl() ) {
    // handle cases like this: <link>http://foobar.org/</link>
    int start = mPos;
    while ( mPos < (int)mText.length() &&
            mText[mPos] > ' ' && mText[mPos] != '"' &&
            QString( "<>()[]" ).indexOf( mText[mPos] ) == -1 ) {
      ++mPos;
    }

    /* some URLs really end with:  # / & - _    */
    const QString allowedSpecialChars = QString( "#/&-_" );
    while ( mPos > start && mText[mPos-1].isPunct() &&
            allowedSpecialChars.indexOf( mText[mPos-1] ) == -1 ) {
      --mPos;
    }

    url = mText.mid( start, mPos - start );
    if ( isEmptyUrl(url) || mPos - start > maxUrlLen() ) {
      mPos = start;
      url = "";
    } else {
      --mPos;
    }
  }
  return url;
}

// keep this in sync with KMMainWin::slotUrlClicked()
bool LinkLocator::atUrl() const
{
  // the following characters are allowed in a dot-atom (RFC 2822):
  // a-z A-Z 0-9 . ! # $ % & ' * + - / = ? ^ _ ` { | } ~
  const QString allowedSpecialChars = QString( ".!#$%&'*+-/=?^_`{|}~" );

  // the character directly before the URL must not be a letter, a number or
  // any other character allowed in a dot-atom (RFC 2822).
  if ( ( mPos > 0 ) &&
       ( mText[mPos-1].isLetterOrNumber() ||
         ( allowedSpecialChars.indexOf( mText[mPos-1] ) != -1 ) ) ) {
    return false;
  }

  QChar ch = mText[mPos];
  return
    ( ch == 'h' && ( mText.mid( mPos, 7 ) == "http://" ||
                     mText.mid( mPos, 8 ) == "https://" ) ) ||
    ( ch == 'v' && mText.mid( mPos, 6 ) == "vnc://" ) ||
    ( ch == 'f' && ( mText.mid( mPos, 7 ) == "fish://" ||
                     mText.mid( mPos, 6 ) == "ftp://" ||
                     mText.mid( mPos, 7 ) == "ftps://" ) ) ||
    ( ch == 's' && ( mText.mid( mPos, 7 ) == "sftp://" ||
                     mText.mid( mPos, 6 ) == "smb://" ) ) ||
    ( ch == 'm' && mText.mid( mPos, 7 ) == "mailto:" ) ||
    ( ch == 'w' && mText.mid( mPos, 4 ) == "www." ) ||
    ( ch == 'f' && ( mText.mid( mPos, 4 ) == "ftp." ||
                     mText.mid( mPos, 7 ) == "file://" ) ) ||
    ( ch == 'n' && mText.mid( mPos, 5 ) == "news:" );
}

bool LinkLocator::isEmptyUrl( const QString &url ) const
{
  return url.isEmpty() ||
    url == "http://" ||
    url == "https://" ||
    url == "fish://" ||
    url == "ftp://" ||
    url == "ftps://" ||
    url == "sftp://" ||
    url == "smb://" ||
    url == "vnc://" ||
    url == "mailto" ||
    url == "www" ||
    url == "ftp" ||
    url == "news" ||
    url == "news://";
}

QString LinkLocator::getEmailAddress()
{
  QString address;

  if ( mText[mPos] == '@' ) {
    // the following characters are allowed in a dot-atom (RFC 2822):
    // a-z A-Z 0-9 . ! # $ % & ' * + - / = ? ^ _ ` { | } ~
    const QString allowedSpecialChars = QString( ".!#$%&'*+-/=?^_`{|}~" );

    // determine the local part of the email address
    int start = mPos - 1;
    while ( start >= 0 && mText[start].unicode() < 128 &&
            ( mText[start].isLetterOrNumber() ||
              mText[start] == '@' || // allow @ to find invalid email addresses
              allowedSpecialChars.indexOf( mText[start] ) != -1 ) ) {
      if ( mText[start] == '@' ) {
        return QString(); // local part contains '@' -> no email address
      }
      --start;
    }
    ++start;
    // we assume that an email address starts with a letter or a digit
    while ( ( start < mPos ) && !mText[start].isLetterOrNumber() ) {
      ++start;
    }
    if ( start == mPos ) {
      return QString(); // local part is empty -> no email address
    }

    // determine the domain part of the email address
    int dotPos = INT_MAX;
    int end = mPos + 1;
    while ( end < (int)mText.length() &&
            ( mText[end].isLetterOrNumber() ||
              mText[end] == '@' || // allow @ to find invalid email addresses
              mText[end] == '.' ||
              mText[end] == '-' ) ) {
      if ( mText[end] == '@' ) {
        return QString(); // domain part contains '@' -> no email address
      }
      if ( mText[end] == '.' ) {
        dotPos = qMin( dotPos, end ); // remember index of first dot in domain
      }
      ++end;
    }
    // we assume that an email address ends with a letter or a digit
    while ( ( end > mPos ) && !mText[end - 1].isLetterOrNumber() ) {
      --end;
    }
    if ( end == mPos ) {
      return QString(); // domain part is empty -> no email address
    }
    if ( dotPos >= end ) {
      return QString(); // domain part doesn't contain a dot
    }

    if ( end - start > maxAddressLen() ) {
      return QString(); // too long -> most likely no email address
    }
    address = mText.mid( start, end - start );

    mPos = end - 1;
  }
  return address;
}

QString LinkLocator::convertToHtml( const QString &plainText, int flags,
                                    int maxUrlLen, int maxAddressLen )
{
  LinkLocator locator( plainText );
  locator.setMaxUrlLen( maxUrlLen );
  locator.setMaxAddressLen( maxAddressLen );

  QString str;
  QString result( (QChar*)0, (int)locator.mText.length() * 2 );
  QChar ch;
  int x;
  bool startOfLine = true;
  QString emoticon;

  for ( locator.mPos = 0, x = 0; locator.mPos < (int)locator.mText.length();
        locator.mPos++, x++ ) {
    ch = locator.mText[locator.mPos];
    if ( flags & PreserveSpaces ) {
      if ( ch == ' ' ) {
        if ( startOfLine ) {
          result += "&nbsp;";
          locator.mPos++, x++;
          startOfLine = false;
        }
        while ( locator.mText[locator.mPos] == ' ' ) {
          result += ' ';
          locator.mPos++, x++;
          if ( locator.mText[locator.mPos] == ' ' ) {
            result += "&nbsp;";
            locator.mPos++, x++;
          }
        }
        locator.mPos--, x--;
        continue;
      } else if ( ch == '\t' ) {
        do
        {
          result += "&nbsp;";
          x++;
        }
        while ( ( x & 7 ) != 0 );
        x--;
        startOfLine = false;
        continue;
      }
    }
    if ( ch == '\n' ) {
      result += "<br />\n"; // Keep the \n, so apps can figure out the quoting levels correctly.
      startOfLine = true;
      x = -1;
      continue;
    }

    startOfLine = false;
    if ( ch == '&' ) {
      result += "&amp;";
    } else if ( ch == '"' ) {
      result += "&quot;";
    } else if ( ch == '<' ) {
      result += "&lt;";
    } else if ( ch == '>' ) {
      result += "&gt;";
    } else {
      const int start = locator.mPos;
      if ( !( flags & IgnoreUrls ) ) {
        str = locator.getUrl();
        if ( !str.isEmpty() ) {
          QString hyperlink;
          if ( str.left( 4 ) == "www." ) {
            hyperlink = "http://" + str;
          } else if ( str.left( 4 ) == "ftp." ) {
            hyperlink = "ftp://" + str;
          } else {
            hyperlink = str;
          }

          str = str.replace( '&', "&amp;" );
          result += "<a href=\"" + hyperlink + "\">" + str + "</a>";
          x += locator.mPos - start;
          continue;
        }
        str = locator.getEmailAddress();
        if ( !str.isEmpty() ) {
          // len is the length of the local part
          int len = str.indexOf( '@' );
          QString localPart = str.left( len );

          // remove the local part from the result (as '&'s have been expanded to
          // &amp; we have to take care of the 4 additional characters per '&')
          result.truncate( result.length() -
                           len - ( localPart.count( '&' ) * 4 ) );
          x -= len;

          result += "<a href=\"mailto:" + str + "\">" + str + "</a>";
          x += str.length() - 1;
          continue;
        }
      }
      if ( flags & HighlightText ) {
        str = locator.highlightedText();
        if ( !str.isEmpty() ) {
          result += str;
          x += locator.mPos - start;
          continue;
        }
      }
      result += ch;
    }
  }

#if KDE_IS_VERSION( 4, 0, 95 )
  if ( flags & ReplaceSmileys ) {
    QStringList exclude;
    exclude << "(c)" << "(C)" << "&gt;:-(" << "&gt;:(" << "(B)" << "(b)" << "(P)" << "(p)";
    exclude << "(O)" << "(o)" << "(D)" << "(d)" << "(E)" << "(e)" << "(K)" << "(k)";
    exclude << "(I)" << "(i)" << "(L)" << "(l)" << "(8)" << "(T)" << "(t)" << "(G)";
    exclude << "(g)" << "(F)" << "(f)" << "(H)";
    exclude << "8)" << "(N)" << "(n)" << "(Y)" << "(y)" << "(U)" << "(u)" << "(W)" << "(w)";
    static QString cachedEmoticonsThemeName;
    if ( cachedEmoticonsThemeName.isEmpty() ) {
      cachedEmoticonsThemeName = KEmoticons::currentThemeName();
    }
    result =
      sEmoticons->theme( cachedEmoticonsThemeName ).parseEmoticons(
        result, KEmoticonsTheme::StrictParse | KEmoticonsTheme::SkipHTML, exclude );
  }
#endif

  return result;
}

QString LinkLocator::pngToDataUrl( const QString &iconPath )
{
  if ( iconPath.isEmpty() ) {
    return QString();
  }

  QFile pngFile( iconPath );
  if ( !pngFile.open( QIODevice::ReadOnly | QIODevice::Unbuffered ) ) {
    return QString();
  }

  QByteArray ba = pngFile.readAll();
  pngFile.close();
  return QString::fromLatin1( "data:image/png;base64,%1" ).arg( ba.toBase64().constData() );
}

QString LinkLocator::highlightedText()
{
  // formating symbols must be prepended with a whitespace
  if ( ( mPos > 0 ) && !mText[mPos-1].isSpace() ) {
    return QString();
  }

  const QChar ch = mText[mPos];
  if ( ch != '/' && ch != '*' && ch != '_' ) {
    return QString();
  }

  QRegExp re =
    QRegExp( QString( "\\%1([0-9A-Za-z]+)\\%2" ).arg( ch ).arg( ch ) );
  if ( re.indexIn( mText, mPos ) == mPos ) {
    int length = re.matchedLength();
    // there must be a whitespace after the closing formating symbol
    if ( mPos + length < mText.length() && !mText[mPos + length].isSpace() ) {
      return QString();
    }
    mPos += length - 1;
    switch ( ch.toLatin1() ) {
    case '*':
      return "<b>" + re.cap( 1 ) + "</b>";
    case '_':
      return "<u>" + re.cap( 1 ) + "</u>";
    case '/':
      return "<i>" + re.cap( 1 ) + "</i>";
    }
  }
  return QString();
}
