/* ============================================================
 *
 * This file is a part of digiKam project
 * http://www.digikam.org
 *
 * Date        : 2006-09-15
 * Description : Exiv2 library interface
 *               Exiv2: http://www.exiv2.org
 *               Exif : http://www.exif.org/Exif2-2.PDF
 *               Iptc : http://www.iptc.org/std/IIM/4.1/specification/IIMV4.1.pdf
 *               Xmp  : http://www.adobe.com/devnet/xmp/pdfs/xmp_specification.pdf
 *                      http://www.iptc.org/std/Iptc4xmpCore/1.0/specification/Iptc4xmpCore_1.0-spec-XMPSchema_8.pdf
 *               Paper: http://www.metadataworkinggroup.com/pdf/mwg_guidance.pdf
 *
 * Copyright (C) 2006-2018 by Gilles Caulier <caulier dot gilles at gmail dot com>
 * Copyright (C) 2006-2013 by Marcel Wiesweg <marcel dot wiesweg at gmx dot de>
 *
 * 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, 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.
 *
 * ============================================================ */

#ifndef META_ENGINE_H
#define META_ENGINE_H

// QT includes

#include <QByteArray>
#include <QString>
#include <QDateTime>
#include <QMap>
#include <QSharedDataPointer>
#include <QStringList>
#include <QVariant>
#include <QRegExp>
#include <QUrl>
#include <QImage>

// Local includes

#include "metaengine_data.h"
#include "digikam_export.h"

namespace Digikam
{

class DIGIKAM_EXPORT MetaEngine
{

public:

    /** The image metadata writing mode, between image file metadata and XMP sidecar file, depending on the context.
     * @sa MetadataWritingMode(), metadataWritingMode()
     */
    enum MetadataWritingMode
    {
        /// Write metadata to image file only.
        WRITETOIMAGEONLY                 = 0,

        /// Write metadata to sidecar file only.
        WRITETOSIDECARONLY               = 1,

        /// Write metadata to image and sidecar files.
        WRITETOSIDECARANDIMAGE           = 2,

        /// Write metadata to sidecar file only for read only images such as RAW files for example.
        WRITETOSIDECARONLY4READONLYFILES = 3
    };

    /** The image color workspace values given by Exif metadata.
     */
    enum ImageColorWorkSpace
    {
        WORKSPACE_UNSPECIFIED  = 0,
        WORKSPACE_SRGB         = 1,
        WORKSPACE_ADOBERGB     = 2,
        WORKSPACE_UNCALIBRATED = 65535
    };

    /** The image orientation values given by Exif metadata.
     */
    enum ImageOrientation
    {
        ORIENTATION_UNSPECIFIED  = 0,
        ORIENTATION_NORMAL       = 1,
        ORIENTATION_HFLIP        = 2,
        ORIENTATION_ROT_180      = 3,
        ORIENTATION_VFLIP        = 4,
        ORIENTATION_ROT_90_HFLIP = 5,
        ORIENTATION_ROT_90       = 6,
        ORIENTATION_ROT_90_VFLIP = 7,
        ORIENTATION_ROT_270      = 8
    };

    /**
     * Xmp tag types, used by setXmpTag, only first three types are used
     */
    enum XmpTagType
    {
        NormalTag               = 0,
        ArrayBagTag             = 1,
        StructureTag            = 2,
        ArrayLangTag            = 3,
        ArraySeqTag             = 4
    };

    /** A map used to store Tags Key and Tags Value.
     */
    typedef QMap<QString, QString> MetaDataMap;

    /** A map used to store a list of Alternative Language values.
        The map key is the language code following RFC3066 notation
        (like "fr-FR" for French), and the map value the text.
     */
    typedef QMap<QString, QString> AltLangMap;

    /** A map used to store Tags Key and a list of Tags properties :
        - name,
        - title,
        - description.
     */
    typedef QMap<QString, QStringList> TagsMap;

public:

    /** Standard constructor.
     */
    MetaEngine();

    /** Copy constructor.
     */
    MetaEngine(const MetaEngine& metadata);

    /** Constructor to load from parsed data.
     */
    MetaEngine(const MetaEngineData& data);

    /** Contructor to Load Metadata from image file.
     */
    MetaEngine(const QString& filePath);

    /** Standard destructor
     */
    virtual ~MetaEngine();

    /** Create a copy of container
     */
    MetaEngine& operator=(const MetaEngine& metadata);

public:

    //-----------------------------------------------------------------
    /// @name Static methods
    //@{

    /** Return true if Exiv2 library initialization is done properly.
        This method must be called before using libMetaEngine with multithreading.
        It initialize several non re-entrancy code from Adobe XMP SDK
        See B.K.O #166424 for details. Call cleanupExiv2() to clean things up later.
     */
    static bool initializeExiv2();

    /** Return true if Exiv2 library memory allocations are cleaned properly.
        This method must be called after using libMetaEngine with multithreading.
        It cleans up memory used by Adobe XMP SDK
        See B.K.O #166424 for details.
     */
    static bool cleanupExiv2();

    /** Return true if library can handle Xmp metadata
     */
    static bool supportXmp();

    /** Return true if library can write metadata to typeMime file format.
     */
    static bool supportMetadataWritting(const QString& typeMime);

    /** Return a string version of Exiv2 release in format "major.minor.patch"
     */
    static QString Exiv2Version();

    /** Return the XMP Sidecar file path for a image file path.
     *  If image file path do not include a file name or is empty, this function return a null string.
     */
    static QString sidecarFilePathForFile(const QString& path);

    /** Like sidecarFilePathForFile(), but works for local file path.
     */
    static QString sidecarPath(const QString& path);

    /** Like sidecarFilePathForFile(), but works for remote URLs.
     */
    static QUrl sidecarUrl(const QUrl& url);

    /** Gives a file url for a local path.
     */
    static QUrl sidecarUrl(const QString& path);

    /** Performs a QFileInfo based check if the given local file has a sidecar.
     */
    static bool hasSidecar(const QString& path);

    //@}

    //-----------------------------------------------------------------
    /// @name General methods
    //@{

    MetaEngineData data() const;
    void setData(const MetaEngineData& data);

    /** Load all metadata (Exif, Iptc, Xmp, and JFIF Comments) from a byte array.
        Return true if metadata have been loaded successfully from image data.
     */
    bool loadFromData(const QByteArray& imgData) const;

    /** Load all metadata (Exif, Iptc, Xmp, and JFIF Comments) from a picture (JPEG, RAW, TIFF, PNG,
        DNG, etc...). Return true if metadata have been loaded successfully from file.
     */
    virtual bool load(const QString& filePath) const;

    /** Save all metadata to a file. This one can be different than original picture to perform
        transfert operation Return true if metadata have been saved into file.
     */
    bool save(const QString& filePath) const;

    /** The same than save() method, but it apply on current image. Return true if metadata
        have been saved into file.
     */
    bool applyChanges() const;

    /** Return 'true' if metadata container in memory as no Comments, Exif, Iptc, and Xmp.
     */
    bool isEmpty() const;

    /** Set the file path of current image.
     */
    void setFilePath(const QString& path);

    /** Return the file path of current image.
     */
    QString getFilePath() const;

    /** Returns the pixel size of the current image. This information is read from the file,
     *  not from the metadata. The returned QSize is valid if the MetaEngine object was _constructed_
     *  by reading a file or image data; the information is not available when the object
     *  was created from MetaEngineData.
     *  Note that in the Exif or XMP metadata, there may be fields describing the image size.
     *  These fields are not accessed by this method.
     *  When replacing the metadata with setData(), the metadata may change; this information
     *  always keeps referring to the file it was initially read from.
     */
    QSize getPixelSize() const;

    /** Returns the mime type of this image. The information is read from the file;
     *  see the docs for getPixelSize() to know when it is available.
     */
    QString getMimeType() const;

    /** Enable or disable writing metadata operations to RAW tiff based files.
        It requires Exiv2 0.18. By default RAW files are untouched.
     */
    void setWriteRawFiles(const bool on);

    /** Return true if writing metadata operations on RAW tiff based files is enabled.
        It's require Exiv2 0.18.
     */
    bool writeRawFiles() const;

    /** Enable or disable using XMP sidecar for reading metadata
     */
    void setUseXMPSidecar4Reading(const bool on);

    /** Return true if using XMP sidecar for reading metadata is enabled.
     */
    bool useXMPSidecar4Reading() const;

    /** Set metadata writing mode.
     * @param mode Metadata writing mode as defined by the #MetadataWritingMode enum.
     * @sa MetadataWritingMode, metadataWritingMode()
     */
    void setMetadataWritingMode(const int mode);

    /** Return the metadata writing mode.
     * @returns Metadata writing mode as defined by the #MetadataWritingMode enum.
     * @sa MetadataWritingMode, setMetadataWritingMode()
     */
    int metadataWritingMode() const;

    /** Enable or disable file timestamp updating when metadata are saved.
        By default files timestamp are untouched.
     */
    void setUpdateFileTimeStamp(bool on);

    /** Return true if file timestamp is updated when metadata are saved.
     */
    bool updateFileTimeStamp() const;

    //@}

    //-------------------------------------------------------------------
    /// @name Metadata image information manipulation methods
    //@{

    /** Set Program name and program version in Exif and Iptc Metadata. Return true if information
        have been changed in metadata.
     */
    bool setImageProgramId(const QString& program, const QString& version) const;

    /** Return the size of image in pixels using Exif tags. Return a null dimmension if size cannot
        be found.
     */
    QSize getImageDimensions() const;

    /** Set the size of image in pixels in Exif tags. Return true if size have been changed
        in metadata.
     */
    bool setImageDimensions(const QSize& size, bool setProgramName=true) const;

    /** Return the image orientation set in Exif metadata. The makernotes of image are also parsed to
        get this information. See ImageOrientation values for details.
     */
    MetaEngine::ImageOrientation getImageOrientation() const;

    /** Set the Exif orientation tag of image. See ImageOrientation values for details
        Return true if orientation have been changed in metadata.
     */
    bool setImageOrientation(ImageOrientation orientation, bool setProgramName=true) const;

    /** Return the image color-space set in Exif metadata. The makernotes of image are also parsed to
        get this information. See ImageColorWorkSpace values for details.
     */
    MetaEngine::ImageColorWorkSpace getImageColorWorkSpace() const;

    /** Set the Exif color-space tag of image. See ImageColorWorkSpace values for details
        Return true if work-space have been changed in metadata.
     */
    bool setImageColorWorkSpace(ImageColorWorkSpace workspace, bool setProgramName=true) const;

    /** Return the time stamp of image. Exif information are check in first, IPTC in second
        if image don't have Exif information. If no time stamp is found, a null date is returned.
     */
    QDateTime getImageDateTime() const;

    /** Set the Exif and Iptc time stamp. If 'setDateTimeDigitized' parameter is true, the 'Digitalized'
        time stamp is set, else only 'Created' time stamp is set.
     */
    bool setImageDateTime(const QDateTime& dateTime, bool setDateTimeDigitized=false,
                          bool setProgramName=true) const;

    /** Return the digitization time stamp of the image. First Exif information is checked, then IPTC.
        If no digitization time stamp is found, getImageDateTime() is called if fallbackToCreationTime
        is true, or a null QDateTime is returned if fallbackToCreationTime is false.
     */
    QDateTime getDigitizationDateTime(bool fallbackToCreationTime=false) const;

    /** Return a QImage copy of Iptc preview image. Return a null image if preview cannot
        be found.
     */
    bool getImagePreview(QImage& preview) const;

    /** Set the Iptc preview image. The thumbnail image must have the right size before (64Kb max
        with JPEG file, else 256Kb). Look Iptc specification for details. Return true if preview
        have been changed in metadata.
        Re-implemente this method if you want to use another image file format than JPEG to
        save preview.
    */
    virtual bool setImagePreview(const QImage& preview, bool setProgramName=true) const;

    //@}

    //-----------------------------------------------------------------
    /// @name Comments manipulation methods
    //@{

    /** Return 'true' if Comments can be written in file.
     */
    static bool canWriteComment(const QString& filePath);

    /** Return 'true' if metadata container in memory as Comments.
     */
    bool hasComments() const;

    /** Clear the Comments metadata container in memory.
     */
    bool clearComments() const;

    /** Return a Qt byte array copy of Comments container get from current image.
        Comments are JFIF section of JPEG images. Look Exiv2 API for more information.
        Return a null Qt byte array if there is no Comments metadata in memory.
     */
    QByteArray getComments() const;

    /** Return a Qt string object of Comments from current image decoded using
        the 'detectEncodingAndDecode()' method. Return a null string if there is no
        Comments metadata available.
     */
    QString getCommentsDecoded() const;

    /** Set the Comments data using a Qt byte array. Return true if Comments metadata
        have been changed in memory.
     */
    bool setComments(const QByteArray& data) const;

    /** Language Alternative autodetection. Return a QString without language alternative
        header. Header is saved into 'lang'. If no language alternative is founf, value is returned
        as well and 'lang' is set to a null string.
     */
    static QString detectLanguageAlt(const QString& value, QString& lang);

    //@}

    //-----------------------------------------------------------------
    /// @name Exif manipulation methods
    //@{

    /** Return a map of all standard Exif tags supported by Exiv2.
     */
    TagsMap getStdExifTagsList() const;

    /** Return a map of all non-standard Exif tags (makernotes) supported by Exiv2.
     */
    TagsMap getMakernoteTagsList() const;

    /** Return 'true' if Exif can be written in file.
     */
    static bool canWriteExif(const QString& filePath);

    /** Return 'true' if metadata container in memory as Exif.
     */
    bool hasExif() const;

    /** Clear the Exif metadata container in memory.
     */
    bool clearExif() const;

    /** Returns the exif data encoded to a QByteArray in a form suitable
        for storage in a JPEG image.
        Note that this encoding is a lossy operation.

        Set true 'addExifHeader' parameter to add an Exif header to Exif metadata.
        Returns a null Qt byte array if there is no Exif metadata in memory.
     */
    QByteArray getExifEncoded(bool addExifHeader=false) const;

    /** Set the Exif data using a Qt byte array. Return true if Exif metadata
        have been changed in memory.
     */
    bool setExif(const QByteArray& data) const;

    /** Return a QImage copy of Exif thumbnail image. Return a null image if thumbnail cannot
        be found. The 'fixOrientation' parameter will rotate automatically the thumbnail if Exif
        orientation tags information are attached with thumbnail.
     */
    QImage getExifThumbnail(bool fixOrientation) const;

    /** Fix orientation of a QImage image accordingly with Exif orientation tag.
        Return true if image is rotated, else false.
     */
    bool rotateExifQImage(QImage& image, ImageOrientation orientation) const;

    /** Set the Exif Thumbnail image. The thumbnail image must have the right dimensions before.
        Look Exif specification for details. Return true if thumbnail have been changed in metadata.
     */
    bool setExifThumbnail(const QImage& thumb, bool setProgramName=true) const;

    /** Remove the Exif Thumbnail from the image */
    bool removeExifThumbnail() const;

    /** Adds a JPEG thumbnail to a TIFF images. Use this instead of setExifThumbnail for TIFF images. */
    bool setTiffThumbnail(const QImage& thumb, bool setProgramName=true) const;

    /** Return a QString copy of Exif user comments. Return a null string if user comments cannot
        be found.
     */
    QString getExifComment() const;

    /** Set the Exif user comments from image. Look Exif specification for more details about this tag.
        Return true if Exif user comments have been changed in metadata.
     */
    bool setExifComment(const QString& comment, bool setProgramName=true) const;

    /** Get an Exif tags content like a string. If 'escapeCR' parameter is true, the CR characters
        will be removed. If Exif tag cannot be found a null string is returned.
     */
    QString getExifTagString(const char* exifTagName, bool escapeCR=true) const;

    /** Set an Exif tag content using a string. Return true if tag is set successfully.
     */
    bool setExifTagString(const char* exifTagName, const QString& value, bool setProgramName=true) const;

    /** Get an Exif tag content like a long value. Return true if Exif tag be found.
     */
    bool getExifTagLong(const char* exifTagName, long &val) const;

    /** Get an Exif tag content like a long value. Return true if Exif tag be found.
     */
    bool getExifTagLong(const char* exifTagName, long &val, int component) const;

    /** Set an Exif tag content using a long value. Return true if tag is set successfully.
     */
    bool setExifTagLong(const char* exifTagName, long val, bool setProgramName=true) const;

    /** Get the 'component' index of an Exif tags content like a rational value.
        'num' and 'den' are the numerator and the denominator of the rational value.
        Return true if Exif tag be found.
     */
    bool getExifTagRational(const char* exifTagName, long int& num, long int& den, int component=0) const;

    /** Set an Exif tag content using a rational value.
        'num' and 'den' are the numerator and the denominator of the rational value.
        Return true if tag is set successfully.
     */
    bool setExifTagRational(const char* exifTagName, long int num, long int den, bool setProgramName=true) const;

    /** Get an Exif tag content like a bytes array. Return an empty bytes array if Exif
        tag cannot be found.
     */
    QByteArray getExifTagData(const char* exifTagName) const;

    /** Set an Exif tag content using a bytes array. Return true if tag is set successfully.
     */
    bool setExifTagData(const char* exifTagName, const QByteArray& data, bool setProgramName=true) const;

    /** Get an Exif tags content as a QVariant. Returns a null QVariant if the Exif
        tag cannot be found.
        For string and integer values the matching QVariant types will be used,
        for date and time values QVariant::DateTime.
        Rationals will be returned as QVariant::List with two integer QVariants (numerator, denominator)
        if rationalAsListOfInts is true, as double if rationalAsListOfInts is false.
        An exif tag of numerical type may contain more than one value; set component to the desired index.
     */
    QVariant getExifTagVariant(const char* exifTagName, bool rationalAsListOfInts=true, bool escapeCR=true, int component=0) const;

    /** Set an Exif tag content using a QVariant. Returns true if tag is set successfully.
        All types described for the getExifTagVariant() method are supported.
        Calling with a QVariant of type ByteArray is equivalent to calling setExifTagData.
        For the meaning of rationalWantSmallDenominator, see the documentation of the convertToRational methods.
        Setting a value with multiple components is currently not supported.
     */
    bool setExifTagVariant(const char* exifTagName, const QVariant& data,
                           bool rationalWantSmallDenominator=true, bool setProgramName=true) const;

    /** Remove the Exif tag 'exifTagName' from Exif metadata. Return true if tag is
        removed successfully or if no tag was present.
     */
    bool removeExifTag(const char* exifTagName, bool setProgramName=true) const;

    /** Return the Exif Tag title or a null string.
     */
    QString getExifTagTitle(const char* exifTagName);

    /** Return the Exif Tag description or a null string.
     */
    QString getExifTagDescription(const char* exifTagName);

    /** Takes a QVariant value as it could have been retrieved by getExifTagVariant with the given exifTagName,
        and returns its value properly converted to a string (including translations from Exiv2).
        This is equivalent to calling getExifTagString directly.
        If escapeCR is true CR characters will be removed from the result.
     */
    QString createExifUserStringFromValue(const char* exifTagName, const QVariant& val, bool escapeCR=true);

    /** Return a map of Exif tags name/value found in metadata sorted by
        Exif keys given by 'exifKeysFilter'.

        'exifKeysFilter' is a QStringList of Exif keys.
        For example, if you use the string list given below:

        "Iop"
        "Thumbnail"
        "Image"
        "Photo"

        List can be empty to not filter output.

        ... this method will return a map of all Exif tags witch :

        - include "Iop", or "Thumbnail", or "Image", or "Photo" in the Exif tag keys
          if 'inverSelection' is false.
        - not include "Iop", or "Thumbnail", or "Image", or "Photo" in the Exif tag keys
          if 'inverSelection' is true.
     */
    MetaEngine::MetaDataMap getExifTagsDataList(const QStringList& exifKeysFilter=QStringList(), bool invertSelection=false) const;

    //@}

    //-------------------------------------------------------------
    /// @name IPTC manipulation methods
    //@{

    /** Return a map of all standard Iptc tags supported by Exiv2.
     */
    MetaEngine::TagsMap getIptcTagsList() const;

    /** Return 'true' if Iptc can be written in file.
     */
    static bool canWriteIptc(const QString& filePath);

    /** Return 'true' if metadata container in memory as Iptc.
     */
    bool hasIptc() const;

    /** Clear the Iptc metadata container in memory.
     */
    bool clearIptc() const;

    /** Return a Qt byte array copy of Iptc container get from current image.
        Set true 'addIrbHeader' parameter to add an Irb header to Iptc metadata.
        Return a null Qt byte array if there is no Iptc metadata in memory.
     */
    QByteArray  getIptc(bool addIrbHeader=false) const;

    /** Set the Iptc data using a Qt byte array. Return true if Iptc metadata
        have been changed in memory.
     */
    bool setIptc(const QByteArray& data) const;

    /** Get an Iptc tag content like a string. If 'escapeCR' parameter is true, the CR characters
        will be removed. If Iptc tag cannot be found a null string is returned.
     */
    QString getIptcTagString(const char* iptcTagName, bool escapeCR=true) const;

    /** Set an Iptc tag content using a string. Return true if tag is set successfully.
     */
    bool setIptcTagString(const char* iptcTagName, const QString& value, bool setProgramName=true) const;

    /** Returns a strings list with of multiple Iptc tags from the image. Return an empty list if no tag is found. */
    /** Get the values of all IPTC tags with the given tag name in a string list.
        (In Iptc, there can be multiple tags with the same name)
        If the 'escapeCR' parameter is true, the CR characters
        will be removed.
        If no tag can be found an empty list is returned.
     */
    QStringList getIptcTagsStringList(const char* iptcTagName, bool escapeCR=true) const;

    /** Set multiple Iptc tags contents using a strings list. 'maxSize' is the max characters size
        of one entry. Return true if all tags have been set successfully.
     */
    bool setIptcTagsStringList(const char* iptcTagName, int maxSize,
                               const QStringList& oldValues, const QStringList& newValues,
                               bool setProgramName=true) const;

    /** Get an Iptc tag content as a bytes array. Return an empty bytes array if Iptc
        tag cannot be found.
     */
    QByteArray getIptcTagData(const char* iptcTagName) const;

    /** Set an Iptc tag content using a bytes array. Return true if tag is set successfully.
     */
    bool setIptcTagData(const char* iptcTagName, const QByteArray& data, bool setProgramName=true) const;

    /** Remove the all instance of Iptc tags 'iptcTagName' from Iptc metadata. Return true if all
        tags have been removed successfully (or none were present).
     */
    bool removeIptcTag(const char* iptcTagName, bool setProgramName=true) const;

    /** Return the Iptc Tag title or a null string.
     */
    QString getIptcTagTitle(const char* iptcTagName);

    /** Return the Iptc Tag description or a null string.
     */
    QString getIptcTagDescription(const char* iptcTagName);

    /** Return a map of Iptc tags name/value found in metadata sorted by
        Iptc keys given by 'iptcKeysFilter'.

        'iptcKeysFilter' is a QStringList of Iptc keys.
        For example, if you use the string list given below:

        "Envelope"
        "Application2"

        List can be empty to not filter output.

        ... this method will return a map of all Iptc tags witch :

        - include "Envelope", or "Application2" in the Iptc tag keys
          if 'inverSelection' is false.
        - not include "Envelope", or "Application2" in the Iptc tag keys
          if 'inverSelection' is true.
     */
    MetaEngine::MetaDataMap getIptcTagsDataList(const QStringList& iptcKeysFilter=QStringList(), bool invertSelection=false) const;

    /** Return a strings list of Iptc keywords from image. Return an empty list if no keyword are set.
     */
    QStringList getIptcKeywords() const;

    /** Set Iptc keywords using a list of strings defined by 'newKeywords' parameter. Use 'getImageKeywords()'
        method to set 'oldKeywords' parameter with existing keywords from image. The method will compare
        all new keywords with all old keywords to prevent duplicate entries in image. Return true if keywords
        have been changed in metadata.
     */
    bool setIptcKeywords(const QStringList& oldKeywords, const QStringList& newKeywords,
                         bool setProgramName=true) const;

    /** Return a strings list of Iptc subjects from image. Return an empty list if no subject are set.
     */
    QStringList getIptcSubjects() const;

    /** Set Iptc subjects using a list of strings defined by 'newSubjects' parameter. Use 'getImageSubjects()'
        method to set 'oldSubjects' parameter with existing subjects from image. The method will compare
        all new subjects with all old subjects to prevent duplicate entries in image. Return true if subjects
        have been changed in metadata.
     */
    bool setIptcSubjects(const QStringList& oldSubjects, const QStringList& newSubjects,
                         bool setProgramName=true) const;

    /** Return a strings list of Iptc sub-categories from image. Return an empty list if no sub-category
        are set.
     */
    QStringList getIptcSubCategories() const;

    /** Set Iptc sub-categories using a list of strings defined by 'newSubCategories' parameter. Use
        'getImageSubCategories()' method to set 'oldSubCategories' parameter with existing sub-categories
        from image. The method will compare all new sub-categories with all old sub-categories to prevent
        duplicate entries in image. Return true if sub-categories have been changed in metadata.
     */
    bool setIptcSubCategories(const QStringList& oldSubCategories, const QStringList& newSubCategories,
                              bool setProgramName=true) const;

    //@}

    //------------------------------------------------------------
    /// @name XMP manipulation methods
    //@{

    /** Return a map of all standard Xmp tags supported by Exiv2.
     */
    MetaEngine::TagsMap getXmpTagsList() const;

    /** Return 'true' if Xmp can be written in file.
     */
    static bool canWriteXmp(const QString& filePath);

    /** Return 'true' if metadata container in memory as Xmp.
     */
    bool hasXmp() const;

    /** Clear the Xmp metadata container in memory.
     */
    bool clearXmp() const;

    /** Return a Qt byte array copy of XMp container get from current image.
        Return a null Qt byte array if there is no Xmp metadata in memory.
     */
    QByteArray getXmp() const;

    /** Set the Xmp data using a Qt byte array. Return true if Xmp metadata
        have been changed in memory.
     */
    bool setXmp(const QByteArray& data) const;

    /** Get a Xmp tag content like a string. If 'escapeCR' parameter is true, the CR characters
        will be removed. If Xmp tag cannot be found a null string is returned.
     */
    QString getXmpTagString(const char* xmpTagName, bool escapeCR=true) const;

    /** Set a Xmp tag content using a string. Return true if tag is set successfully.
     */
    bool setXmpTagString(const char* xmpTagName, const QString& value,
                         bool setProgramName=true) const;

    /** Set a Xmp tag with a specific type. Return true if tag is set successfully.
     *  This method only accept NormalTag, ArrayBagTag and StructureTag.
     *  Other XmpTagTypes do nothing
     */
    bool setXmpTagString(const char* xmpTagName, const QString& value,
                         XmpTagType type,bool setProgramName=true) const;

    /** Return the Xmp Tag title or a null string.
     */
    QString getXmpTagTitle(const char* xmpTagName);

    /** Return the Xmp Tag description or a null string.
     */
    QString getXmpTagDescription(const char* xmpTagName);

    /** Return a map of Xmp tags name/value found in metadata sorted by
        Xmp keys given by 'xmpKeysFilter'.

        'xmpKeysFilter' is a QStringList of Xmp keys.
        For example, if you use the string list given below:

        "dc"           // Dubling Core schema.
        "xmp"          // Standard Xmp schema.

        List can be empty to not filter output.

        ... this method will return a map of all Xmp tags witch :

        - include "dc", or "xmp" in the Xmp tag keys
          if 'inverSelection' is false.
        - not include "dc", or "xmp" in the Xmp tag keys
          if 'inverSelection' is true.
     */
    MetaEngine::MetaDataMap getXmpTagsDataList(const QStringList& xmpKeysFilter=QStringList(), bool invertSelection=false) const;

    /** Get all redondant Alternative Language Xmp tags content like a map.
        See AltLangMap class description for details.
        If 'escapeCR' parameter is true, the CR characters will be removed from strings.
        If Xmp tag cannot be found a null string list is returned.
     */
    MetaEngine::AltLangMap getXmpTagStringListLangAlt(const char* xmpTagName, bool escapeCR=true) const;

    /** Set an Alternative Language Xmp tag content using a map. See AltLangMap class
        description for details. If tag already exist, it wil be removed before.
        Return true if tag is set successfully.
     */
    bool setXmpTagStringListLangAlt(const char* xmpTagName, const MetaEngine::AltLangMap& values,
                                    bool setProgramName) const;

    /** Get a Xmp tag content like a string set with an alternative language
        header 'langAlt' (like "fr-FR" for French - RFC3066 notation)
        If 'escapeCR' parameter is true, the CR characters will be removed.
        If Xmp tag cannot be found a null string is returned.
     */
    QString getXmpTagStringLangAlt(const char* xmpTagName, const QString& langAlt, bool escapeCR) const;

    /** Set a Xmp tag content using a string with an alternative language header. 'langAlt' contain the
        language alternative information (like "fr-FR" for French - RFC3066 notation) or is null to
        set alternative language to default settings ("x-default").
        Return true if tag is set successfully.
     */
    bool setXmpTagStringLangAlt(const char* xmpTagName, const QString& value,
                                const QString& langAlt, bool setProgramName=true) const;

    /** Get a Xmp tag content like a sequence of strings. If 'escapeCR' parameter is true, the CR characters
        will be removed from strings. If Xmp tag cannot be found a null string list is returned.
     */
    QStringList getXmpTagStringSeq(const char* xmpTagName, bool escapeCR=true) const;

    /** Set a Xmp tag content using the sequence of strings 'seq'.
        Return true if tag is set successfully.
     */
    bool setXmpTagStringSeq(const char* xmpTagName, const QStringList& seq,
                            bool setProgramName=true) const;

    /** Get a Xmp tag content like a bag of strings. If 'escapeCR' parameter is true, the CR characters
        will be removed from strings. If Xmp tag cannot be found a null string list is returned.
     */
    QStringList getXmpTagStringBag(const char* xmpTagName, bool escapeCR) const;

    /** Set a Xmp tag content using the bag of strings 'bag'.
        Return true if tag is set successfully.
     */
    bool setXmpTagStringBag(const char* xmpTagName, const QStringList& bag,
                            bool setProgramName=true) const;

    /** Set an Xmp tag content using a list of strings defined by the 'entriesToAdd' parameter.
        The existing entries are preserved. The method will compare
        all new with all already existing entries to prevent duplicates in the image.
        Return true if the entries have been added to metadata.
     */
    bool addToXmpTagStringBag(const char* xmpTagName, const QStringList& entriesToAdd,
                              bool setProgramName) const;

    /** Remove those Xmp tag entries that are listed in entriesToRemove from the entries in metadata.
        Return true if tag entries are no longer contained in metadata.
        All other entries are preserved.
     */
    bool removeFromXmpTagStringBag(const char* xmpTagName, const QStringList& entriesToRemove,
                                   bool setProgramName) const;

    /** Get an Xmp tag content as a QVariant. Returns a null QVariant if the Xmp
        tag cannot be found.
        For string and integer values the matching QVariant types will be used,
        for date and time values QVariant::DateTime.
        Rationals will be returned as QVariant::List with two integer QVariants (numerator, denominator)
        if rationalAsListOfInts is true, as double if rationalAsListOfInts is false.
        Arrays (ordered, unordered, alternative) are returned as type StringList.
        LangAlt values will have type Map (QMap<QString, QVariant>) with the language
        code as key and the contents as value, of type String.
     */
    QVariant getXmpTagVariant(const char* xmpTagName, bool rationalAsListOfInts=true, bool stringEscapeCR=true) const;

    /** Return a strings list of Xmp keywords from image. Return an empty list if no keyword are set.
     */
    QStringList getXmpKeywords() const;

    /** Set Xmp keywords using a list of strings defined by 'newKeywords' parameter.
        The existing keywords from image are preserved. The method will compare
        all new keywords with all already existing keywords to prevent duplicate entries in image.
        Return true if keywords have been changed in metadata.
     */
    bool setXmpKeywords(const QStringList& newKeywords, bool setProgramName=true) const;

    /** Remove those Xmp keywords that are listed in keywordsToRemove from the keywords in metadata.
        Return true if keywords are no longer contained in metadata.
     */
    bool removeXmpKeywords(const QStringList& keywordsToRemove, bool setProgramName=true);

    /** Return a strings list of Xmp subjects from image. Return an empty list if no subject are set.
     */
    QStringList getXmpSubjects() const;

    /** Set Xmp subjects using a list of strings defined by 'newSubjects' parameter.
        The existing subjects from image are preserved. The method will compare
        all new subject with all already existing subject to prevent duplicate entries in image.
        Return true if subjects have been changed in metadata.
     */
    bool setXmpSubjects(const QStringList& newSubjects, bool setProgramName=true) const;

    /** Remove those Xmp subjects that are listed in subjectsToRemove from the subjects in metadata.
        Return true if subjects are no longer contained in metadata.
     */
    bool removeXmpSubjects(const QStringList& subjectsToRemove, bool setProgramName=true);

    /** Return a strings list of Xmp sub-categories from image. Return an empty list if no sub-category
        are set.
     */
    QStringList getXmpSubCategories() const;

    /** Set Xmp sub-categories using a list of strings defined by 'newSubCategories' parameter.
        The existing sub-categories from image are preserved. The method will compare
        all new sub-categories with all already existing sub-categories to prevent duplicate entries in image.
        Return true if sub-categories have been changed in metadata.
     */
    bool setXmpSubCategories(const QStringList& newSubCategories, bool setProgramName=true) const;

    /** Remove those Xmp sub-categories that are listed in categoriesToRemove from the sub-categories in metadata.
        Return true if subjects are no longer contained in metadata.
     */
    bool removeXmpSubCategories(const QStringList& categoriesToRemove, bool setProgramName=true);

    /** Remove the Xmp tag 'xmpTagName' from Xmp metadata. Return true if tag is
        removed successfully or if no tag was present.
     */
    bool removeXmpTag(const char* xmpTagName, bool setProgramName=true) const;


    /** Register a namespace which Exiv2 doesn't know yet. This is only needed
        when new Xmp properties are added manually. 'uri' is the namespace url and prefix the
        string used to construct new Xmp key (ex. "Xmp.digiKam.tagList").
        NOTE: If the Xmp metadata is read from an image, namespaces are decoded and registered
        by Exiv2 at the same time.
     */
    static bool registerXmpNameSpace(const QString& uri, const QString& prefix);

    /** Unregister a previously registered custom namespace */
    static bool unregisterXmpNameSpace(const QString& uri);

    //@}

    //------------------------------------------------------------
    /// @name GPS manipulation methods
    //@{

    /** Make sure all static required GPS EXIF and XMP tags exist
     */
    bool initializeGPSInfo(const bool setProgramName);

    /** Get all GPS location information set in image. Return true if all information can be found.
     */
    bool getGPSInfo(double& altitude, double& latitude, double& longitude) const;

    /** Get GPS location information set in the image, in the GPSCoordinate format
        as described in the XMP specification. Returns a null string in the information cannot be found.
     */
    QString getGPSLatitudeString() const;
    QString getGPSLongitudeString() const;

    /** Get GPS location information set in the image, as a double floating point number as in degrees
        where the sign determines the direction ref (North + / South - ; East + / West -).
        Returns true if the information is available.
    */
    bool getGPSLatitudeNumber(double* const latitude) const;
    bool getGPSLongitudeNumber(double* const longitude) const;

    /** Get GPS altitude information, in meters, relative to sea level (positive sign above sea level)
     */
    bool getGPSAltitude(double* const altitude) const;

    /** Set all GPS location information into image. Return true if all information have been
        changed in metadata.
     */
    bool setGPSInfo(const double altitude, const double latitude, const double longitude, const bool setProgramName=true);

    /** Set all GPS location information into image. Return true if all information have been
        changed in metadata. If you do not want altitude to be set, pass a null pointer.
     */
    bool setGPSInfo(const double* const altitude, const double latitude, const double longitude, const bool setProgramName=true);

    /** Set all GPS location information into image. Return true if all information have been
        changed in metadata.
     */
    bool setGPSInfo(const double altitude, const QString& latitude, const QString& longitude, const bool setProgramName=true);

    /** Remove all Exif tags relevant of GPS location information. Return true if all tags have been
        removed successfully in metadata.
     */
    bool removeGPSInfo(const bool setProgramName=true);

    /** This method converts 'number' to a rational value, returned in the 'numerator' and
        'denominator' parameters. Set the precision using 'rounding' parameter.
        Use this method if you want to retrieve a most exact rational for a number
        without further properties, without any requirements to the denominator.
     */
    static void convertToRational(const double number, long int* const numerator,
                                  long int* const denominator, const int rounding);

    /** This method convert a 'number' to a rational value, returned in 'numerator' and
        'denominator' parameters.
        This method will be able to retrieve a rational number from a double - if you
        constructed your double with 1.0 / 4786.0, this method will retrieve 1 / 4786.
        If your number is not expected to be rational, use the method above which is just as
        exact with rounding = 4 and more exact with rounding > 4.
     */
    static void convertToRationalSmallDenominator(const double number, long int* const numerator,
                                                  long int* const denominator);

    /** Converts a GPS position stored as rationals in Exif to the form described
        as GPSCoordinate in the XMP specification, either in the from "256,45,34N" or "256,45.566667N"
     */
    static QString convertToGPSCoordinateString(const long int numeratorDegrees, const long int denominatorDegrees,
                                                const long int numeratorMinutes, const long int denominatorMinutes,
                                                const long int numeratorSeconds, long int denominatorSeconds,
                                                const char directionReference);

    /** Converts a GPS position stored as double floating point number in degrees to the form described
        as GPSCoordinate in the XMP specification.
     */
    static QString convertToGPSCoordinateString(const bool isLatitude, double coordinate);

    /** Converts a GPSCoordinate string as defined by XMP to three rationals and the direction reference.
        Returns true if the conversion was successful.
        If minutes is given in the fractional form, a denominator of 1000000 for the minutes will be used.
     */
    static bool convertFromGPSCoordinateString(const QString& coordinate,
                                               long int* const numeratorDegrees, long int* const denominatorDegrees,
                                               long int* const numeratorMinutes, long int* const denominatorMinutes,
                                               long int* const numeratorSeconds, long int* const denominatorSeconds,
                                               char* const directionReference);

    /** Convert a GPSCoordinate string as defined by XMP to a double floating point number in degrees
        where the sign determines the direction ref (North + / South - ; East + / West -).
        Returns true if the conversion was successful.
     */
    static bool convertFromGPSCoordinateString(const QString& gpsString, double* const coordinate);

    /** Converts a GPSCoordinate string to user presentable numbers, integer degrees and minutes and
        double floating point seconds, and a direction reference ('N' or 'S', 'E' or 'W')
     */
    static bool convertToUserPresentableNumbers(const QString& coordinate,
                                                int* const degrees, int* const minutes,
                                                double* const seconds, char* const directionReference);

    /** Converts a double floating point number to user presentable numbers, integer degrees and minutes and
        double floating point seconds, and a direction reference ('N' or 'S', 'E' or 'W').
        The method needs to know for the direction reference
        if the latitude or the longitude is meant by the double parameter.
     */
    static void convertToUserPresentableNumbers(const bool isLatitude, double coordinate,
                                                int* const degrees, int* const minutes,
                                                double* const seconds, char* const directionReference);

    //@}

protected:

    /** Re-implement this method to set automatically the Program Name and Program Version
        information in Exif and Iptc metadata if 'on' argument is true. This method is called by all methods which
        change tags in metadata. By default this method does nothing and returns true.

        In digiKam this method is re-implementated like this:

        if (on)
        {
            QString version(digikam_version);
            QString software("digiKam");
            return setImageProgramId(software, version);
        }

        return true;
     */
    virtual bool setProgramId(bool on=true) const;

private:

    /** Internal container to store private members. Used to improve binary compatibility
     */
    class Private;
    Private* const d;

    friend class MetaEnginePreviews;
};

} // namespace Digikam

#endif /* META_ENGINE_H */
