/**
 * linklocator.cpp
 *
 * Copyright (c) 2002 Dave Corrie <kde@davecorrie.com>
 *
 *  This file is part of KMail.
 *
 *  KMail is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "linklocator.h"

	LinkLocator::LinkLocator(const QString& text, int pos)
: mText(text), mPos(pos), mMaxUrlLen(4096), 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().
}

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

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

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

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

QString LinkLocator::getUrl()
{
	if ( !atUrl() )
		return QString::null;

	int start = mPos;
	QString delimiters = QString::fromLatin1( "\"<>()[]" );
	while ( mPos < static_cast<int>( mText.length() ) &&
	        mText[ mPos ] > ' ' &&
	        !delimiters.contains( mText[ mPos ] ) )
		++mPos;

	delimiters = QString::fromLatin1( "#/&" );
	while ( mPos > start && mText[ mPos - 1 ].isPunct() &&
	        !delimiters.contains( mText[ mPos - 1 ] ) )
		--mPos;
	
	QString url = mText.mid( start, mPos - start );
	if ( isEmptyUrl( url ) || mPos - start > maxUrlLen() ) {
		mPos = start;
		url = QString::fromLatin1( "" );	
	} else
		--mPos;

	return url;
}

bool LinkLocator::atUrl() const
{
	QChar ch = mText[mPos];
	return
		(ch=='h' && mText.mid(mPos, 7) == QString::fromLatin1( "http://")) ||
		(ch=='h' && mText.mid(mPos, 8) == QString::fromLatin1( "https://")) ||
		(ch=='f' && mText.mid(mPos, 6) == QString::fromLatin1( "ftp://")) ||
		(ch=='f' && mText.mid(mPos, 6) == QString::fromLatin1( "ftps://")) ||
		(ch=='f' && mText.mid(mPos, 4) == QString::fromLatin1( "ftp." )) ||
		(ch=='s' && mText.mid(mPos, 7) == QString::fromLatin1( "sftp://")) ||
		(ch=='m' && mText.mid(mPos, 7) == QString::fromLatin1( "mailto:" )) ||
		(ch=='w' && mText.mid(mPos, 4) == QString::fromLatin1( "www." ));
}

bool LinkLocator::isEmptyUrl(const QString& url)
{
	return url.isEmpty() ||
		url == QString::fromLatin1( "http://") ||
		url == QString::fromLatin1( "https://") ||
		url == QString::fromLatin1( "ftp://") ||
		url == QString::fromLatin1( "ftps://") ||
		url == QString::fromLatin1( "sftp://") ||
		url == QString::fromLatin1( "mailto" ) ||
		url == QString::fromLatin1( "www" ) ||
		url == QString::fromLatin1( "ftp" );
}

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(QString::fromLatin1( ".!#$%&'*+-/=?^_`{|}~") );

		// 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.find(mText[start]) != -1))
		{
			--start;
		}
		++start;
		// we assume that an email address starts with a letter or a digit
		while (allowedSpecialChars.find(mText[start]) != -1)
			++start;

		// determine the domain part of the email address
		int end = mPos + 1;
		while (end < (int)mText.length() && mText[end].unicode() < 128 &&
				(mText[end].isLetterOrNumber() ||
				 mText[end] == '@' || // allow @ to find invalid email addresses
				 allowedSpecialChars.find(mText[end]) != -1))
		{
			++end;
		}
		// we assume that an email address ends with a letter or a digit
		while (allowedSpecialChars.find(mText[end - 1]) != -1)
			--end;

		address = mText.mid(start, end - start);
		if(isEmptyAddress(address) || end - start > maxAddressLen() || address.contains('@') != 1)
			address = "";

		if(!address.isEmpty())
			mPos = end - 1;
	}
	return address;
}

bool LinkLocator::isEmptyAddress(const QString& address)
{
	return address.isEmpty() ||
		address[0] == '@' ||
		address[address.length() - 1] == '@';
}

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

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

	for (locator.mPos = 0, x = 0; locator.mPos < (int)locator.mText.length(); locator.mPos++, x++)
	{
		ch = locator.mText[locator.mPos];
		if (preserveBlanks)
		{
			if (ch==' ')
			{
				if (startOfLine) {
					result += QString::fromLatin1( "&nbsp;" );
					locator.mPos++, x++;
					startOfLine = false;
				}
				while (locator.mText[locator.mPos] == ' ')
				{
					result += QString::fromLatin1( " " );
					locator.mPos++, x++;
					if (locator.mText[locator.mPos] == ' ') {
						result += QString::fromLatin1( "&nbsp;" );
						locator.mPos++, x++;
					}
				}
				locator.mPos--, x--;
				continue;
			}
			else if (ch=='\t')
			{
				do
				{
					result += QString::fromLatin1( "&nbsp;" );
					x++;
				}
				while((x&7) != 0);
				x--;
				startOfLine = false;
				continue;
			}
		}
		if (ch=='\n')
		{
			result += QString::fromLatin1( "<br />" );
			startOfLine = true;
			x = -1;
			continue;
		}

		startOfLine = false;
		if (ch=='&')
			result += QString::fromLatin1( "&amp;" );
		else if (ch=='"')
			result += QString::fromLatin1( "&quot;" );
		else if (ch=='<')
			result += QString::fromLatin1( "&lt;" );
		else if (ch=='>')
			result += QString::fromLatin1( "&gt;" );
		else
		{
			int start = locator.mPos;
			str = locator.getUrl();
			if(!str.isEmpty())
			{
				QString hyperlink;
				if(str.left(4) == QString::fromLatin1( "www." ))
					hyperlink = QString::fromLatin1( "http://") + str;
				else if(str.left(4) == QString::fromLatin1( "ftp." ))
					hyperlink = QString::fromLatin1( "ftp://") + str;
				else
					hyperlink = str;

				result += QString::fromLatin1( "<a href=\"" ) + hyperlink +
					QString::fromLatin1( "\">" ) + str + QString::fromLatin1( "</a>" );
				x += locator.mPos - start;
			}
			else
			{
				str = locator.getEmailAddress();
				if(!str.isEmpty())
				{
					// len is the length of the local part
					int len = str.find('@');
					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.contains('&')*4));
					x -= len;

					result += QString::fromLatin1( "<a href=\"mailto:" ) + str +
						QString::fromLatin1( "\">" ) + str + QString::fromLatin1( "</a>" );
					x += str.length() - 1;
				}
				else
				{
					result += ch;
				}
			}
		}
	}

	return result;
}