//
//  VROARDeclarativeSession.h
//  ViroKit
//
//  Created by Raj Advani on 11/3/17.
//  Copyright © 2017 Viro Media. All rights reserved.
//

#ifndef VROARDeclarativeSession_h
#define VROARDeclarativeSession_h

#include "VROARSession.h"
#include "VROARConstraintMatcher.h"

class VROARScene;
class VROARDeclarativeSessionDelegate;

/*
 VROARDeclarativeSession controls the 'declarative' style API for using AR.
 In this paradigm, instead of directly responding to ARSessionDelegate methods,
 the user simply specifies the requirements of the ARAnchor they're interested in
 via a VROARDeclarativeNode, and then the user can immediately start adding
 content to that node. Once an ARAnchor meeting the constraints is found, the
 node (and all of its content) will be made visible.
 
 This largely simplifies the state handling with AR objects. To use this:
 
 1. Create the VROARDeclarativeNode and set its requirements (e.g. min width and
    height for a plane).
 2. Add the node to the VROARDeclarativeSession via addARNode. This adds the node
    to the declarative session where it find an anchor that matches with it.
 3. Add the node to the VROARScene via VROARScene::addNode. This physically adds
    the node to the scene.
 
 To use the declarative session you must first call VROARScene->initDeclarativeSession().
 */
class VROARDeclarativeSession : public VROARSessionDelegate, public VROARConstraintMatcherDelegate,
                                public std::enable_shared_from_this<VROARDeclarativeSession> {
public:
    
    VROARDeclarativeSession();
    virtual ~VROARDeclarativeSession();
    
    void init();
    void setDelegate(std::shared_ptr<VROARDeclarativeSessionDelegate> delegate);
    void setARSession(std::shared_ptr<VROARSession> session);

    void addARImageTarget(std::shared_ptr<VROARImageTarget> target);
    void removeARImageTarget(std::shared_ptr<VROARImageTarget> target);
                                    
    void addARNode(std::shared_ptr<VROARDeclarativeNode> plane);
    void removeARNode(std::shared_ptr<VROARDeclarativeNode> plane);
    void updateARNode(std::shared_ptr<VROARDeclarativeNode> plane);
    
    void sceneWillAppear();
    void sceneWillDisappear();

    // VROARSessionDelegate methods
    virtual void anchorWasDetected(std::shared_ptr<VROARAnchor> anchor);
    virtual void anchorWillUpdate(std::shared_ptr<VROARAnchor> anchor);
    virtual void anchorDidUpdate(std::shared_ptr<VROARAnchor> anchor);
    virtual void anchorWasRemoved(std::shared_ptr<VROARAnchor> anchor);
    
    // VROARConstraintMatcherDelegate methods
    void anchorWasAttached(std::shared_ptr<VROARAnchor> anchor);
    void anchorWasDetached(std::shared_ptr<VROARAnchor> anchor);

private:
    
    std::weak_ptr<VROARSession> _arSession;
    std::weak_ptr<VROARDeclarativeSessionDelegate> _delegate;
    std::shared_ptr<VROARConstraintMatcher> _constraintMatcher;
    std::vector<std::shared_ptr<VROARDeclarativeNode>> _nodes;
    std::vector<std::shared_ptr<VROARImageTarget>> _imageTargets;
    
};

class VROARDeclarativeSessionDelegate {
public:
    
    virtual void anchorWasDetected(std::shared_ptr<VROARAnchor> anchor) = 0;
    virtual void anchorWillUpdate(std::shared_ptr<VROARAnchor> anchor) = 0;
    virtual void anchorDidUpdate(std::shared_ptr<VROARAnchor> anchor) = 0;
    virtual void anchorWasRemoved(std::shared_ptr<VROARAnchor> anchor) = 0;
    
};

#endif /* VROARDeclarativeSession_h */