/*
 * SPDX-FileName:terrain_stg.cxx -- data structures and routines for managing terrain scenery.
 * SPDX-FileCopyrightText: 1997  Curtis L. Olson  - http://www.flightgear.org/~curt
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#pragma once

#include <osg/ref_ptr>
#include <osg/Switch>

#include <simgear/compiler.h>
#include <simgear/math/SGMath.hxx>
#include <simgear/scene/model/particles.hxx>
#include <simgear/structure/subsystem_mgr.hxx>

#include "terrain.hxx"
#include "SceneryPager.hxx"
#include "tilemgr.hxx"

namespace simgear {
class BVHMaterial;
}

// Define a structure containing global scenery parameters
class FGStgTerrain : public FGTerrain
{
public:

    FGStgTerrain();
    virtual ~FGStgTerrain();

    // Implementation of SGSubsystem.
    void init ( osg::Group* terrain );
    void reinit();
    void shutdown ();
    void bind ();
    void unbind ();
    void update (double dt);

    /// Compute the elevation of the scenery at geodetic latitude lat,
    /// geodetic longitude lon and not higher than max_alt.
    /// If the exact flag is set to true, the scenery center is moved to
    /// gain a higher accuracy of that query. The center is restored past
    /// that to the original value.
    /// The altitude hit is returned in the alt argument.
    /// The method returns true if the scenery is available for the given
    /// lat/lon pair. If there is no scenery for that point, the altitude
    /// value is undefined.
    /// All values are meant to be in meters or degrees.
    bool get_elevation_m(const SGGeod& geod, double& alt,
                         const simgear::BVHMaterial** material,
                         const osg::Node* butNotFrom = 0);

    /// Compute the elevation of the scenery below the cartesian point pos.
    /// you the returned scenery altitude is not higher than the position
    /// pos plus an offset given with max_altoff.
    /// If the exact flag is set to true, the scenery center is moved to
    /// gain a higher accuracy of that query. The center is restored past
    /// that to the original value.
    /// The altitude hit is returned in the alt argument.
    /// The method returns true if the scenery is available for the given
    /// lat/lon pair. If there is no scenery for that point, the altitude
    /// value is undefined.
    /// All values are meant to be in meters.
    bool get_cart_elevation_m(const SGVec3d& pos, double max_altoff,
                              double& elevation,
                              const simgear::BVHMaterial** material,
                              const osg::Node* butNotFrom = 0);

    /// Compute the nearest intersection point of the line starting from
    /// start going in direction dir with the terrain.
    /// The input and output values should be in cartesian coordinates in the
    /// usual earth centered wgs84 coordinate system. Units are meters.
    /// On success, true is returned.
    bool get_cart_ground_intersection(const SGVec3d& start, const SGVec3d& dir,
                                      SGVec3d& nearestHit,
                                      const osg::Node* butNotFrom = 0);

    /// Returns true if scenery is available for the given lat, lon position
    /// within a range of range_m.
    /// lat and lon are expected to be in degrees.
    bool scenery_available(const SGGeod& position, double range_m);

    // tile mgr api
    bool schedule_scenery(const SGGeod& position, double range_m, double duration=0.0);
    void materialLibChanged();

    static const char* staticSubsystemClassId() { return "scenery"; }

private:
    // tile manager
    FGTileMgr _tilemgr;

    // terrain branch of scene graph
    osg::ref_ptr<osg::Group> terrain_branch;

    bool _inited;
};
