/***************************************************************************
                                  qgsproject.h

                      Implements persistent project state.

                              -------------------
  begin                : July 23, 2004
  copyright            : (C) 2004 by Mark Coletti
  email                : mcoletti at gmail.com
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program 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.                                   *
 *                                                                         *
 ***************************************************************************/
/* $Id$ */

#ifndef QGSPROJECT_H
#define QGSPROJECT_H

#include <memory>
#include "qgsprojectversion.h"
#include <QObject>
#include <QList>
#include <QPair>

//#include <QDomDocument>

class QFileInfo;
class QDomDocument;
class QDomNode;

class QgsProjectBadLayerHandler;

/** \ingroup core
 * Reads and writes project states.


  @note

  Has two general kinds of state to make persistent.  (I.e., to read and
  write.)  First, Qgis proprietary information.  Second plug-in information.

  A singleton since there shall only be one active project at a time; and
  provides canonical location for plug-ins and main app to find/set
  properties.

  Might want to consider moving from Singleton; i.e., allowing more than one
  project.  Just as the GIMP can have simultaneous multiple images, perhaps
  qgis can one day have simultaneous multiple projects.

*/
class CORE_EXPORT QgsProject : public QObject
{
    Q_OBJECT

  public:

    /**
       @todo XXX Should have semantics for saving project if dirty as last gasp?
    */
    ~QgsProject();

    /// access to canonical QgsProject instance
    static QgsProject * instance();

    /**
       Every project has an associated title string

       @todo However current dialogs don't allow setting of it yet
     */
    //@{
    void title( QString const & title );

    /** returns title */
    QString const & title() const;
    //@}

    /**
       the dirty flag is true if the project has been modified since the last
       write()
     */
    //@{
    bool isDirty() const;

    void dirty( bool b );
    //@}


    /**
       Every project has an associated file that contains its XML
     */
    //@{
    void setFileName( QString const & name );

    /** returns file name */
    QString fileName() const;
    //@}


    /** read project file

       @note Any current plug-in state is erased

       @note dirty set to false after successful invocation

       @note file name argument implicitly sets file

       (Is that really desirable behavior?  Maybe prompt to save before
       reading new one?)

       Should we presume the file is opened elsewhere?  Or do we open it
       ourselves?

       XXX How to best get modify access to Qgis state?  Actually we can finagle
       that by searching for qgisapp in object hiearchy.

       @note

       - Gets the extents
       - Creates maplayers
       - Registers maplayers

       @note it's presumed that the caller has already reset the map canvas, map registry, and legend
     */
    //@{
    bool read( QFileInfo const & file );
    bool read( );
    //@}


    /** read the layer described in the associated Dom node

        @param layerNode   represents a QgsProject Dom node that maps to a specific layer.

        QgsProject raises an exception when one of the QgsProject::read()
        implementations fails.  Since the read()s are invoked from qgisapp,
        then qgisapp handles the exception.  It prompts the user for the new
        location of the data, if any.  If there is a new location, the Dom
        node associated with the layer has its datasource tag corrected.
        Then that node is passed to this member function to be re-opened.

     */
    bool read( QDomNode & layerNode );


    /** write project file

       XXX How to best get read access to Qgis state?  Actually we can finagle
       that by searching for qgisapp in object hiearchy.

       @note file name argument implicitly sets file

       @note dirty set to false after successful invocation
     */
    //@{
    bool write( QFileInfo const & file );
    bool write( );
    //@}


    /// syntactic sugar for property lists
    // DEPRECATED typedef QPair< QString, QVariant >  PropertyValue;
    // DEPRECATED typedef QValueList< PropertyValue > Properties;

    /** extra properties, typically added by plug-ins

       This allows for extra properties to be associated with projects.  Think
       of it as a registry bound to a project.

       Properties are arbitrary values keyed by a name and associated with a
       scope.  The scope would presumably refer to your plug-in.
       E.g., "openmodeller".

       @note

       E.g., open modeller might use:

       <code>"QgsProject::instance()->properties("openmodeller")["foo"]</code>.

       @todo "properties" is, overall, a good name; but that might imply that
       the qgis specific state properites are different since they aren't
       accessible here.  Actually, what if we make "qgis" yet another
       scope that stores its state in the properties list?  E.g.,
       QgsProject::instance()->properties()["qgis"]?


     */
    // DEPRECATED Properties & properties( QString const & scope );

    /**
       removes all project properties
    */
    void clearProperties();


    /* key value mutators

      keys would be the familiar QSettings-like '/' delimited entries, implying
      a hierarchy of keys and corresponding values

      @note The key string <em>must</em> include '/'s.  E.g., "/foo" not "foo".
    */
    //@{
    bool writeEntry( QString const & scope, const QString & key, bool value );
    bool writeEntry( QString const & scope, const QString & key, double value );
    bool writeEntry( QString const & scope, const QString & key, int value );
    bool writeEntry( QString const & scope, const QString & key, const QString & value );
    bool writeEntry( QString const & scope, const QString & key, const QStringList & value );
    //@}

    /** key value accessors

        keys would be the familiar QSettings-like '/' delimited entries,
        implying a hierarchy of keys and corresponding values


        @note The key string <em>must</em> include '/'s.  E.g., "/foo" not "foo".
    */
    //@{
    QStringList readListEntry( QString const & scope, const QString & key, bool * ok = 0 ) const;

    QString readEntry( QString const & scope, const QString & key, const QString & def = QString::null, bool * ok = 0 ) const;
    int readNumEntry( QString const & scope, const QString & key, int def = 0, bool * ok = 0 ) const;
    double readDoubleEntry( QString const & scope, const QString & key, double def = 0, bool * ok = 0 ) const;
    bool readBoolEntry( QString const & scope, const QString & key, bool def = false, bool * ok = 0 ) const;
    //@}


    /** remove the given key */
    bool removeEntry( QString const & scope, const QString & key );


    /** return keys with values -- do not return keys that contain other keys

      @note equivalent to QSettings entryList()
    */
    QStringList entryList( QString const & scope, QString const & key ) const;

    /** return keys with keys -- do not return keys that contain only values

      @note equivalent to QSettings subkeyList()
    */
    QStringList subkeyList( QString const & scope, QString const & key ) const;


    /** dump out current project properties to stderr

      @todo XXX Now slightly broken since re-factoring.  Won't print out top-level key
                and redundantly prints sub-keys.
    */
    void dumpProperties() const;


    /** prepare a filename to save it to the project file
      @note added in 1.3 */
    QString writePath( QString filename ) const;

    /** turn filename read from the project file to an absolute path
      @note added in 1.3 */
    QString readPath( QString filename ) const;

    /** Return error message from previous read/write
      @note added in 1.4 */
    QString error() const;

    /** Change handler for missing layers.
      Deletes old handler and takes ownership of the new one.
      @note added in 1.4 */
    void setBadLayerHandler( QgsProjectBadLayerHandler* handler );

  protected:

    /** Set error message from read/write operation
      @note added in 1.4 */
    void setError( QString errorMessage );

    /** Clear error message
      @note added in 1.4 */
    void clearError();

  signals:

    //! emitted when project is being read
    void readProject( const QDomDocument & );

    //! emitted when project is being written
    void writeProject( QDomDocument & );

    //! emitted when an old project file is read.
    void oldProjectVersionWarning( QString );

    //! emitted when a layer from a projects was read
    // @param i current layer
    // @param n number of layers
    void layerLoaded( int i, int n );

  private:

    QgsProject(); // private 'cause it's a singleton

    QgsProject( QgsProject const & ); // private 'cause it's a singleton

    struct Imp;

    /// implementation handle
    std::auto_ptr<Imp> imp_;

    static QgsProject * theProject_;

    QPair< bool, QList<QDomNode> > _getMapLayers( QDomDocument const &doc );

    QString mErrorMessage;

    QgsProjectBadLayerHandler* mBadLayerHandler;

}; // QgsProject


/** Interface for classes that handle missing layer files when reading project file.
  @note added in 1.4 */
class CORE_EXPORT QgsProjectBadLayerHandler
{
  public:
    virtual void handleBadLayers( QList<QDomNode> layers, QDomDocument projectDom ) = 0;
    virtual ~QgsProjectBadLayerHandler() {}
};


/** Default bad layer handler which ignores any missing layers.
  @note added in 1.4 */
class CORE_EXPORT QgsProjectBadLayerDefaultHandler : public QgsProjectBadLayerHandler
{
  public:
    virtual void handleBadLayers( QList<QDomNode> layers, QDomDocument projectDom );

};

#endif
