/*
 *  This file is part of the KDE libraries
 *  Copyright (C) 2000 Yves Arrouye <yves@realnames.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., 59 Temple Place - Suite 330,
 *  Boston, MA 02111-1307, USA.
 **/

#ifndef __kurifilter_h__
#define __kurifilter_h__ "$Id: kurifilter.h,v 1.27 2002/10/30 09:37:39 neil Exp $"

#include <qptrlist.h>
#include <qobject.h>

#include <kurl.h>

class KURIFilterPrivate;
class KURIFilterDataPrivate;

class QStringList;
class KCModule;

/**
* This is a basic message object used for exchanging filtering
* information between the filter plugins and the application
* whenever the application requires more information about the
* URI than just a filtered version of it.  Any application can
* create an instance of this class and send it to @ref KURIFilter
* to have the filter plugins fill the necessary information.
*
* @sect Example
* <pre>
*   QString text = "kde.org";
*   KURIFilterData d = text;
*   bool filtered = KURIFilter::self()->filter( d );
*   if( filtered )
*     print ( "URI: %s\n"Filtered URI: %s\n URI Type: %i\n"Was Filtered: %i"
*             text.latin1(), d.uri().url().latin1(), d.uriType(), filtered );
* </pre>
*
* The above code should yield the following output:
* <pre>
*   URI: kde.org
*   Filtered URI: http://kde.org
*   URI Type: 0            <== means NET_PROTOCOL
*   Was Filtered: 1        <== means the URL was successfully filtered
* </pre>
*
* @short A message object for exchanging filtering URI info.
*/

class KURIFilterData
{
friend class KURIFilterPlugin;

public:
    /**
     * Describes the type of URI to be filtered.
     *
     * This enumerator prvoides the return value for
     * @ref uriType.  A brief description for each value:
     *
     * @li NET_PROTOCOL - Any network protocol: http, ftp, nttp, pop3, etc...
     * @li LOCAL_FILE   - A local file whose executable flag is not set
     * @li LOCAL_DIR    - A local directory
     * @li EXECUTABLE   - A local file whose executable flag is set
     * @li HELP         - A man or info page
     * @li SHELL        - A shell executable (ex: echo "Test..." >> ~/testfile)
     * @li BLOCKED      - A URI that should be blocked/filtered (ex: ad filtering)
     * @li ERROR        - An incorrect URI (ex: "~johndoe" when user johndoe
     *                    does not exist in that system )
     * @li UNKNOWN      - A URI that is not identified. Default value when
     *                    a KURIFilterData is first created.
     */
    enum URITypes { NET_PROTOCOL=0, LOCAL_FILE, LOCAL_DIR, EXECUTABLE, HELP, SHELL, BLOCKED, ERROR, UNKNOWN };

    /**
     * Default constructor.
     *
     * Creates a URIFilterData object.
     */
    KURIFilterData() { init(); }

    /**
     * Creates a URIFilterData object from the given URL.
     *
     * @param url is the URL to be filtered.
     */
    KURIFilterData( const KURL& url ) { init( url); }

    /**
     * Creates a URIFilterData object from the given string.
     *
     * @param url is the string to be filtered.
     */
    KURIFilterData( const QString& url ) { init( url ); }

    /**
     * Copy constructor.
     *
     * Creates a URIFilterData object from another
     * URI filter data object.
     *
     * @param data the uri filter data to be copied.
     */
    KURIFilterData( const KURIFilterData& /*data*/);

    /**
     * Destructor.
     */
    ~KURIFilterData();

    /**
     * This method has been deprecated and will always return
     * TRUE.  You should instead use the result from the
     * @ref KURIFilter::filterURI() calls.
     *
     * @deprecated
     */
    bool hasBeenFiltered() const { return m_bFiltered; }

    /**
     * Returns the filtered or the original URL.
     *
     * This function returns the filtered url if one
     * of the plugins sucessfully filtered the original
     * URL.  Otherwise, it returns the original URL.
     * See @ref #hasBeenFiltered() and
     *
     * @return the filtered or original url.
     */
    KURL uri() const { return m_pURI; }

    /**
     * Returns an error message.
     *
     * This functions returns the error message set
     * by the plugin whenever the uri type is set to
     * KURIFilterData::ERROR.  Otherwise, it returns
     * a QString::null.
     *
     * @return the error message or a NULL when there is none.
     */
    QString errorMsg() const { return m_strErrMsg; }

    /**
     * Returns the URI type.
     *
     * This method always returns KURIFilterData::UNKNOWN
     * if the given URL was not filtered.
     */
    URITypes uriType() const { return m_iType; }
    
    /**
     * Sets the URL to be filtered.
     *
     * Use this function to set the string to be
     * filtered when you construct an empty filter
     * object.
     *
     * @param url the string to be filtered.     
     */    
    void setData( const QString& url ) { init( url ); }
    
    /**
     * Same as above except the argument is a URL.
     *
     * Use this function to set the string to be
     * filtered when you construct an empty filter
     * object.
     *
     * @param url the URL to be filtered.     
     */        
    void setData( const KURL& url ) { init( url ); }

    /**
     * Sets the absolute path to be used whenever the supplied
     * data is a relative local URL.
     *
     * NOTE: This function works only for a local resource and
     * expects the absolute path to the relative URL set in this
     * meta object.  If you are extracting the absolute path from
     * a KURL object, make sure you always set the argument below
     * using KURL::path() instead of KURL::url() so that "file:/"
     * would not be appended! Otherwise, the filter might not be
     * able to make correct determination whether the relative URL
     * locally exists!
     *
     * @param abs_path  the abolute path to the local resource.
     * @return true if absolute path is successfully set. Otherwise, false.
     */
    bool setAbsolutePath( const QString& /* abs_path */ );

    /**
     * Returns the absolute path if one has already been set.
     */
    QString absolutePath() const;

    /**
     * Returns true if the supplied data has an absolute path.
     */
    bool hasAbsolutePath() const;

    /**
     * Returns the command line options and arguments for a
     * local resource when present.
     *
     * @return options and arguments when present, otherwise QString::null
     */
    QString argsAndOptions() const;

    /**
     * Returns true if the current data is a local resource with
     * command line options and arguments.
     */
    bool hasArgsAndOptions() const;

    /**
     * Returns the name of the icon that matches
     * the current filtered URL.
     *
     * NOTE that this function will return a NULL
     * string by default and when no associated icon
     * is found.
     *
     * @return the name of the icon associated with the resource
     */    
    QString iconName();
    
    /**
     * Overloaded assigenment operator.
     *
     * This function allows you to easily assign a KURL
     * to a KURIFilterData object.
     *
     * @return an instance of a KURIFilterData object.
     */
    KURIFilterData& operator=( const KURL& url ) { init( url ); return *this; }

    /**
     * Overloaded assigenment operator.
     *
     * This function allows you to easily assign a QString
     * to a KURIFilterData object.
     *
     * @return an instance of a KURIFilterData object.
     */
    KURIFilterData& operator=( const QString& url ) { init( url ); return *this; }

protected:

    /**
     * Initializes the KURIFilterData on construction.
     */
    void init( const KURL& url = QString::null );

private:
    bool m_bFiltered;
    bool m_bChanged;
    
    QString m_strErrMsg;
    QString m_strIconName;
    
    KURL m_pURI; 
    URITypes m_iType;
    KURIFilterDataPrivate *d;
};


/**
 * Base class for URI filter plugins.
 *
 * This class applies a single filter to a URI.  All
 * plugins designed to provide URI filtering functionalities
 * should inherit from this abstract class and provide a
 * specific filtering implementation.
 *
 * All inheriting classes need to implement the pure
 * virtual function @ref filterURI.  Otherwise, they
 * would also become abstract.
 *
 * @short Abstract class for URI filter plugins.
 */
class KURIFilterPlugin : public QObject
{
    Q_OBJECT

public:

    /**
     * Constructs a filter plugin with a given name and
     * priority.
     *
     * @param parent the parent object.
     * @param name the name of the plugin.
     * @param pri the priority of the plugin.
     */
    KURIFilterPlugin( QObject *parent = 0, const char *name = 0, double pri = 1.0 );

    /**
     * Returns the filter's name.
     *
     * @return A string naming the filter.
     */
    virtual QString name() const { return m_strName; }

    /**
     * Returns the filter's priority.
     *
     * Each filter has an assigned priority, a float from 0 to 1. Filters
     * with the lowest priority are first given a chance to filter a URI.
     *
     * @return The priority of the filter.
     */
    virtual double priority() const { return m_dblPriority; }

    /**
     * Filters a URI.
     *
     * @param data the URI data to be filtered.
     * @return A boolean indicating whether the URI has been changed.
     */
    virtual bool filterURI( KURIFilterData& data ) const = 0;

    /**
     * Creates a configuration module for the filter.
     *
     * It is the responsability of the caller to delete the module
     * once it is not needed anymore.
     *
     * @return A configuration module, @p null if the filter isn't configurable.
     */
    virtual KCModule *configModule( QWidget*, const char* ) const { return 0; }

    /**
     * Returns the name of the configuration module for the filter.
     *
     * @return the name of a configuration module or @p null if none.
     */
    virtual QString configName() const { return name(); }

protected:

    /**
     * Sets the the URL in @p data to @p uri.
     */
    void setFilteredURI ( KURIFilterData& data, const KURL& uri ) const;

    /**
     * Sets the error message in @p data to @p errormsg.
     */
    void setErrorMsg ( KURIFilterData& data, const QString& errmsg ) const {
        data.m_strErrMsg = errmsg;
    }

    /**
     * Sets the URI type in @p data to @p type.
     */
    void setURIType ( KURIFilterData& data, KURIFilterData::URITypes type) const {
        data.m_iType = type;
        data.m_bChanged = true;
    }

    /**
     * Sets the arguments and options string in @p data
     * to @p args if any were found during filterting.
     */
    void setArguments( KURIFilterData& data, const QString& args ) const;

    QString m_strName;
    double m_dblPriority;

protected:
    virtual void virtual_hook( int id, void* data );
private:
    class KURIFilterPluginPrivate *d;
};


class KURIFilterPluginList : public QPtrList<KURIFilterPlugin>
{
public:
    virtual int compareItems(Item a, Item b)
    {
	    double diff = ((KURIFilterPlugin *) a)->priority() - ((KURIFilterPlugin *) b)->priority();
    	return diff < 0 ? -1 : (diff > 0 ? 1 : 0);
    }

private:
    KURIFilterPrivate *d;

};

/**
 * Manages the filtering of a URI.
 *
 * The intention of this plugin class is to allow people to extend
 * the functionality of KURL without modifying it directly.  This
 * way KURL will remain a generic parser capable of parsing any
 * generic URL that adheres to specifications.
 *
 * The KURIFilter class applies a number of filters to a URI,
 * and returns the filtered version whenever possible. The filters
 * are implemented using plugins to provide easy extensibility
 * of the filtering mechanism.  That is, new filters can be added in
 * the future by simply inheriting from @ref KURIFilterPlugin and
 * implementing the @ref KURIFilterPlugin::filterURI method.
 *
 * Use of this plugin-manager class is straight forward.  Since
 * it is a singleton object, all you have to do is obtain an instance
 * by doing @p KURIFilter::self() and use any of the public member
 * functions to preform the filtering.
 * 
 * @sect Example
 *
 * To simply filter a given string:
 * <pre>
 * bool filtered = KURIFilter::self()->filterURI( "kde.org" );
 * </pre>
 * 
 * You can alternatively use a KURL:
 * <pre>
 * KURL url = "kde.org";
 * bool filtered = KURIFilter::self()->filterURI( url );
 * </pre>
 *
 * If you have a constant string or a constant URL,
 * simply invoke the corresponding function to obtain
 * the filtered string or URL instead of a boolean flag:
 * <pre>
 * QString u = KURIFilter::self()->filteredURI( "kde.org" );
 * </pre>
 *
 * You can also specify only specific filter(s) to be applied
 * by supplying the name(s) of the filter(s).  By defualt all
 * filters that are found are loaded when the KURIFilter object
 * is created will be used.  These names are taken from the
 * enteries in the \".desktop\" files.  Here are a couple of
 * examples:
 * <pre>
 * QString text = "kde.org";
 * bool filtered = KURIFilter::self()->filterURI( text, "KShortURIFilter" );
 *
 * QStringList list;
 * list << "KShortURIFilter" << "MyFilter";
 * bool filtered = KURIFilter::self()->filterURI( text, list );
 * </pre>
 *
 * KURIFilter also allows richer data exchange through a simple
 * meta-object called @p KURIFilterData.  Using this meta-object
 * you can find out more information about the URL you want to
 * filter.  See @ref KURIFilterData for examples and details.
 *
 * @short Filters a given URL into its proper format whenever possible.
 */

class KURIFilter
{
public:
    /**
     *  Destructor
     */
    ~KURIFilter ();

    /**
     * Return a static instance of KURIFilter.
     */
    static KURIFilter* self();

    /**
     * Filters the URI given by the object URIFilterData.
     *
     * This filters the given data based on the specified
     * filter list.  If the list is empty all avaliable
     * filter plugins would be used.  If not, only those
     * given in the list are used.
     *
     * @param data object that contains the URI to be filtered.
     * @param filters specify the list filters to be used
     *
     * @return a boolean indicating whether the URI has been changed
     */
    bool filterURI( KURIFilterData& data, const QStringList& filters = QStringList() );

    /**
     * Filters the URI given by the URL.
     *
     * This filters the given URL based on the specified
     * filter list.  If the list is empty all avaliable
     * filter plugins would be used.  If not, only those
     * given in the list are used.
     *
     * @param uri the URI to filter.
     * @param filters specify the list of filters to be used
     *
     * @return a boolean indicating whether the URI has been changed
     */
    bool filterURI( KURL &uri, const QStringList& filters = QStringList() );

    /**
     * Filters a string representing a URI.
     *
     * This filters the given string based on the specified
     * filter list.  If the list is empty all avaliable
     * filter plugins would be used.  If not, only those
     * given in the list are used.
     *
     * @param uri The URI to filter.
     * @param filters specify the list filters to be used
     *
     * @return a boolean indicating whether the URI has been changed
     */
    bool filterURI( QString &uri, const QStringList& filters = QStringList() );

    /**
     * Returns the filtered URI.
     *
     * This filters the given URL based on the specified
     * filter list.  If the list is empty all avaliable
     * filter plugins would be used.  If not, only those
     * given in the list are used.
     *
     * @param uri The URI to filter.
     * @param filters specify the list filters to be used
     *
     * @return the filtered URI or null if it cannot be filtered
     */
    KURL filteredURI( const KURL &uri, const QStringList& filters = QStringList() );

    /**
     * Return a filtered string representation of a URI.
     *
     * This filters the given URL based on the specified
     * filter list.  If the list is empty all avaliable
     * filter plugins would be used.  If not, only those
     * given in the list are used.
     *
     * @param uri the URI to filter.
     * @param filters specify the list filters to be used
     *
     * @return the filtered URI or null if it cannot be filtered
     */
    QString filteredURI( const QString &uri, const QStringList& filters = QStringList() );

    /**
     * Return an iterator to iterate over all loaded
     * plugins.
     *
     * @return a plugin iterator.
     */
    QPtrListIterator<KURIFilterPlugin> pluginsIterator() const;

    /**
     * Return a list of the names of all loaded plugins
     *
     * @since 3.1
     *
     * @return a QStringList of plugin names
     */
    QStringList pluginNames() const;

protected:

    /**
     * A protected constructor.
     *
     * This constructor creates a KURIFilter and
     * initializes all plugins it can find by invoking
     * @ref loadPlugins.
     */
    KURIFilter();

    /**
     * Loads all allowed plugins.
     *
     * This function loads all filters that have not
     * been dis
     */
    void loadPlugins();

private:

    static KURIFilter *m_self;
    KURIFilterPluginList m_lstPlugins;
    KURIFilterPrivate *d;

};

#endif