/* -*-c++-*- */
/* osgEarth - Geospatial SDK for OpenSceneGraph
 * Copyright 2020 Pelican Mapping
 * http://osgearth.org
 *
 * osgEarth is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 */

#ifndef OSGEARTH_TILE_SOURCE_H
#define OSGEARTH_TILE_SOURCE_H 1

// Need to undef Status in case it has been defined in Xlib.h. This can happen on Linux
#undef Status

#include <limits.h>

#include <osg/Version>

#include <osgEarth/Common>
#include <osgEarth/CachePolicy>
#include <osgEarth/TileKey>
#include <osgEarth/Profile>
#include <osgEarth/Threading>
#include <osgEarth/MemCache>
#include <osgEarth/Status>
#include <osgEarth/Containers>

#include <osg/Referenced>
#include <osg/Object>
#include <osg/Image>
#include <osg/Shape>
#include <osgDB/Options>
#include <string>

namespace osgEarth
{
    class ProgressCallback;
    class Map;
}

namespace osgEarth { namespace Contrib
{
    /**
     * Configuration options for a tile source driver.
     * @deprecated For legacy application support only
     */
    class OSGEARTH_EXPORT TileSourceOptions : public DriverConfigOptions
    {
    public:

        /** File in which to store a tile blacklist. */
        optional<std::string>& blacklistFilename() { return _blacklistFilename; }
        const optional<std::string>& blacklistFilename() const { return _blacklistFilename; }

        /** Define a profile for this source, overriding the one reported by the source. */
        optional<ProfileOptions>& profile() { return _profileOptions; }
        const optional<ProfileOptions>& profile() const { return _profileOptions; }

        /** Size of the in-memory cache (in entries; default=16) */
        optional<int>& L2CacheSize() { return _L2CacheSize; }
        const optional<int>& L2CacheSize() const { return _L2CacheSize; }

        /** Whether to use bilinear sampling when reprojecting data from this source
         *  (default = true) */
        optional<bool>& bilinearReprojection() { return _bilinearReprojection; }
        const optional<bool>& bilinearReprojection() const { return _bilinearReprojection; }

        /** Whether to rasterize into coverage data, which contains discrete non-interpolable values. */
        optional<bool>& coverage() { return _coverage; }
        const optional<bool>& coverage() const { return _coverage; }

        /** osgDB::Options option string to pass through to osgDB reader/writers. */
        optional<std::string>& osgOptionString() { return _osgOptionString; }
        const optional<std::string>& osgOptionString() const { return _osgOptionString; }

    public:
        TileSourceOptions( const ConfigOptions& options =ConfigOptions() );

        /** dtor */
        virtual ~TileSourceOptions() { }

    public:
        virtual Config getConfig() const;

    protected:
        virtual void mergeConfig( const Config& conf );

    private:
        void fromConfig( const Config& conf );

        optional<ProfileOptions> _profileOptions;
        optional<std::string>    _blacklistFilename;
        optional<int>            _L2CacheSize;
        optional<bool>           _bilinearReprojection;
        optional<bool>           _coverage;
        optional<std::string>    _osgOptionString;
    };
} }

OSGEARTH_SPECIALIZE_CONFIG(osgEarth::Contrib::TileSourceOptions);

namespace osgEarth { namespace Contrib
{
    /**
     * A collection of tiles that should be considered blacklisted
     */
    class OSGEARTH_EXPORT TileBlacklist : public osg::Referenced
    {
    public:
        /**
         *Creates a new TileBlacklist
         */
        TileBlacklist();

        /** dtor */
        virtual ~TileBlacklist() { }

        /**
         *Adds the given tile to the blacklist
         */
        void add(const TileKey& key);

        /**
         *Removes the given tile from the blacklist
         */
        void remove(const TileKey& key);

        /**
         *Removes all tiles from the blacklist
         */
        void clear();

        /**
         *Returns whether the given tile is in the blacklist
         */
        bool contains(const TileKey& key) const;

        /**
         *Reads a TileBlacklist from the given istream
         */
        static TileBlacklist* read(std::istream &in);

        /**
         *Reads a TileBlacklist from the given filename
         */
        static TileBlacklist* read(const std::string &filename);

        /**
         *Writes this TileBlacklist to the given ostream
         */
        void write(std::ostream &output) const;

        /**
         *Writes this TileBlacklist to the given filename
         */
        void write(const std::string &filename) const;

    private:
        mutable LRUCache<TileKey, bool> _tiles; // using as a set (value unused)
    };

    /**
     * A TileSource is an object that can create image and/or heightfield tiles. Driver
     * plugins are responsible for creating and returning a TileSource that the Map
     * will then use to create tiles for tile keys.
     * @deprecated For legacy application support only
     */
    class OSGEARTH_EXPORT TileSource : public virtual osg::Object
    {
    public:
        /** Modes: OR these together when you call open(). */
        typedef unsigned Mode;

        /** Open for reading only */
        static const Mode MODE_READ;

        /** Open for writing */
        static const Mode MODE_WRITE;

        /** When using MODE_WRITE, create the data store if necessary */
        static const Mode MODE_CREATE;

        /** interface name, used by the plugin system. */
        static const char* INTERFACE_NAME;

    public:
        struct ImageOperation : public osg::Referenced {
            virtual void operator()( osg::ref_ptr<osg::Image>& in_out_image ) =0;
        };

        struct HeightFieldOperation : public osg::Referenced {
            virtual void operator()( osg::ref_ptr<osg::HeightField>& in_out_hf ) =0;
        };

    public:
        /** Constructor */
        TileSource(const TileSourceOptions& options);

        /**
         * Opens the tile source and returns the initial status.
         */
        const Status& open(
            const Mode&           openMode  =MODE_READ,
            const osgDB::Options* dbOptions =0L);

        //! Gets the status of this tile source.
        const Status& getStatus() const { return _status; }

        //! Gets the number of pixels per tile for this TileSource.
        virtual int getPixelsPerTile() const;
        virtual void setPixelsPerTile(unsigned size);

        //! Gets the list of areas with data for this TileSource
        const DataExtentList& getDataExtents() const { return _dataExtents; }
        DataExtentList& getDataExtents() { return _dataExtents; }

        //! Value representing no data
        float getNoDataValue() const { return _noDataValue; }
        void setNoDataValue(float value) { _noDataValue = value; }

        //! Values less than this are considered "no data"
        float getMinValidValue() const { return _minValidValue; }
        void setMinValidValue(float value) { _minValidValue = value; }

        //! Values greater than this are considered "no data"
        float getMaxValidValue() const { return _maxValidValue; }
        void setMaxValidValue(float value) { _maxValidValue = value; }

        //! The attribution string to be displayed for this TileSource
        virtual std::string getAttribution() const { return ""; }

        /**
         * Creates an image for the given TileKey. The TileKey's profile must match
         * the profile of the TileSource.
         */
        virtual osg::Image* createImage(
            const TileKey&        key,
            ImageOperation*       op        =0L,
            ProgressCallback*     progress  =0L );

        /**
         * Creates a heightfield for the given TileKey. The TileKey's profile must match
         * the profile of the TileSource.
         */
        virtual osg::HeightField* createHeightField(
            const TileKey&        key,
            HeightFieldOperation* op        =0L,
            ProgressCallback*     progress  =0L );

        /**
         * Stores an image in the tile source for the given TileKey.
         * The driver must support writing or this method will return false.
         */
        virtual bool storeImage(const TileKey&    key,
                                osg::Image*       image,
                                ProgressCallback* progress) { return false; }

        /**
         * Stores a heightfield in the tile source for the given TileKey.
         * The driver must support writing or this method will return false.
         * (Note: The default implementation will convert the heightfield to an
         * image with one 32-bit channel and call storeImage.)
         */
        virtual bool storeHeightField(const TileKey&    key,
                                      const osg::HeightField* hf,
                                      ProgressCallback* progress);

    public:

        /**
         * Returns True if this tile source initialized properly and has a valid
         * profile.
         */
        virtual bool isOK() const;
        bool isValid() const { return isOK(); }

        /**
         * TimeStamp indicating the last time the data at this source changed
         * Default is 0, i.e. the beginning of time itself (1970). It is up to
         * the TileSource implementation whether to populate this field. The
         * Map engine can use it for per-session caching purposes.
         */
        virtual TimeStamp getLastModifiedTime() const { return 0; }

        /**
         * Gets the Profile of the TileSource
         */
        virtual const Profile* getProfile() const;

        /**
         * Gets the blacklist for this TileSource
         */
        TileBlacklist* getBlacklist();
        const TileBlacklist* getBlacklist() const;

        /**
         * Whether this TileSource produces tiles whose data can change after
         * it's been created.
         */
        virtual bool isDynamic() const { return false; }

        /**
         * A hint as to what kind of caching policy would be appropriate to employ
         * on this data source. By default, this is the default, which is to use a
         * cache if one is configured. But a TileSource can report that caching should
         * not be used (for whatever reason) by returning CachePolicy::NO_CACHE.
         */
        virtual CachePolicy getCachePolicyHint(const Profile* targetProfile) const
            { return CachePolicy::DEFAULT; }

        /**
         * The open mode (passed to startup).
         */
        const Mode& getMode() const { return _mode; }

        /**
         * The options used to construct this tile source.
         */
        const TileSourceOptions& getOptions() const { return _options; }

        /**
         * Set the L2 cache size default (if the size was not set in
         * the options or environment). Must call this before open().
         */
        void setDefaultL2CacheSize(int size);

    public:

        /* methods required by osg::Object */
        virtual osg::Object* cloneType() const { return 0; } // cloneType() not appropriate
        virtual osg::Object* clone(const osg::CopyOp&) const { return 0; } // clone() not appropriate
        virtual bool isSameKindAs(const osg::Object* obj) const { return dynamic_cast<const TileSource*>(obj)!=NULL; }
        virtual const char* className() const { return "TileSource"; }
        virtual const char* libraryName() const { return "osgEarth"; }

    protected:

        /**
         * Initializes the tile source (called by open)
         *
         * The osgEarth engine calls this function to initialize a TileSource using an
         * active osgDB::Options. The method returns a status code indicating whether
         * intialization succeeded (in which case the owning layer will become enabled)
         * or failed (in which case the owning layer will become disabled.
         *
         * The Subclass should override this to report a correct initialization status.
         * The default implementation reports STATUS_OK (for compatibility).
         */
        virtual Status initialize(const osgDB::Options* readOptions) =0;

        /**
         * Creates an image for the given TileKey.
         * The returned object is new and is the responsibility of the caller.
         */
        virtual osg::Image* createImage(
            const TileKey&        key,
            ProgressCallback*     progress );

        /**
         * Creates a heightfield for the given TileKey
         * The returned object is new and is the responsibility of the caller.
         */
        virtual osg::HeightField* createHeightField(
            const TileKey&        key,
            ProgressCallback*     progress );

    protected:

        virtual ~TileSource();

        /**
         * Subclass can call this to set a Profile after opening the
         * data store.
         */
        void setProfile( const Profile* profile );

        /**
         * Subclass can call this to set the status. Normally you set the
         * status by returning it from initialize(), but you can call this
         * later, e.g. in the event of an unrecoverable error.
         */
        void setStatus(const Status& value) { _status = value; }

        //! Compat - do not override
        unsigned getTileSize() const { return getPixelsPerTile(); }

    private:

        osg::ref_ptr<const Profile> _profile;
        TileSourceOptions _options;

        friend class Map;
        friend class TileSourceFactory;

        osg::ref_ptr< TileBlacklist > _blacklist;
        std::string _blacklistFilename;

        osg::ref_ptr<MemCache> _memCache;

        DataExtentList  _dataExtents;
        Status          _status;
        Mode            _mode;
        unsigned        _tileSize;
        float           _noDataValue;
        float           _minValidValue;
        float           _maxValidValue;

        bool _openCalled;

        mutable std::mutex _mutex;
    };

    //--------------------------------------------------------------------

    class OSGEARTH_EXPORT TileSourceDriver : public osgDB::ReaderWriter
    {
    protected:
        const TileSourceOptions& getTileSourceOptions(const osgDB::Options* options) const;

        const std::string getInterfaceName(const osgDB::Options* options) const;

        TileSource::Mode getOpenMode(const osgDB::Options* options) const;
    };

    //--------------------------------------------------------------------

    /**
     * Creates TileSource instances.
     */
    class OSGEARTH_EXPORT TileSourceFactory
    {
    public:
        /**
         * Creates a TileSource instance by loading the driver plugin
         * specified in the options.
         */
        static TileSource* create(const TileSourceOptions& options);
    };
} }

#endif // OSGEARTH_TILE_SOURCE_H