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The JavaFX implementation of the Interacto library
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/*
 * Interacto
 * Copyright (C) 2020 Arnaud Blouin
 * 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 3 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 General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see .
 */
package io.github.interacto.jfx.interaction.library;

import io.github.interacto.fsm.CancellingState;
import io.github.interacto.fsm.InputState;
import io.github.interacto.fsm.OutputState;
import io.github.interacto.fsm.StdState;
import io.github.interacto.fsm.TerminalState;
import io.github.interacto.jfx.interaction.DragTransition;
import io.github.interacto.jfx.interaction.EscapeKeyPressureTransition;
import io.github.interacto.jfx.interaction.FSMDataHandler;
import io.github.interacto.jfx.interaction.JfxFSM;
import io.github.interacto.jfx.interaction.PressureTransition;
import io.github.interacto.jfx.interaction.ReleaseTransition;
import javafx.event.Event;
import javafx.scene.input.MouseButton;
import javafx.scene.input.MouseEvent;

/**
 * The FSM for DnD interactions.
 */
public class DnDFSM extends JfxFSM {
	private final boolean cancellable;
	private MouseButton buttonToCheck;

	/**
	 * Creates the FSM
	 * @param cancellable True: the FSM can be cancelled using the ESC key.
	 */
	public DnDFSM(final boolean cancellable) {
		super();
		this.cancellable = cancellable;
	}

	@Override
	protected void buildFSM(final DnDFSMHandler dataHandler) {
		if(states.size() > 1) {
			return;
		}

		super.buildFSM(dataHandler);

		final StdState pressed = new StdState<>(this, "pressed");
		final StdState dragged = new StdState<>(this, "dragged");
		final TerminalState released = new TerminalState<>(this, "released");
		final CancellingState cancelled = new CancellingState<>(this, "cancelled");

		addState(pressed);
		addState(dragged);
		addState(released);
		addState(cancelled);

		startingState = dragged;

		new PressureTransition(initState, pressed) {
			@Override
			protected void action(final MouseEvent event) {
				buttonToCheck = event.getButton();
				if(dataHandler != null) {
					dataHandler.onPress(event);
				}
			}
		};
		new ReleaseTransition(pressed, cancelled) {
			@Override
			protected boolean isGuardOK(final MouseEvent event) {
				return event.getButton() == buttonToCheck;
			}
		};
		new DnDFSMDragTransition(pressed, dragged);
		new DnDFSMDragTransition(dragged, dragged);
		new ReleaseTransition(dragged, released) {
			@Override
			protected boolean isGuardOK(final MouseEvent event) {
				return event.getButton() == buttonToCheck;
			}

			@Override
			protected void action(final MouseEvent event) {
				if(dataHandler != null) {
					dataHandler.onRelease(event);
				}
			}
		};

		if(cancellable) {
			new EscapeKeyPressureTransition(pressed, cancelled);
			new EscapeKeyPressureTransition(dragged, cancelled);
		}

		super.buildFSM(dataHandler);
	}

	@Override
	public void reinit() {
		super.reinit();
		buttonToCheck = null;
	}

	class DnDFSMDragTransition extends DragTransition {
		DnDFSMDragTransition(final OutputState srcState, final InputState tgtState) {
			super(srcState, tgtState);
		}

		@Override
		protected boolean isGuardOK(final MouseEvent event) {
			return event.getButton() == buttonToCheck;
		}

		@Override
		protected void action(final MouseEvent event) {
			if(dataHandler != null) {
				dataHandler.onDrag(event);
			}
		}
	}

	interface DnDFSMHandler extends FSMDataHandler {
		void onPress(final MouseEvent event);

		void onDrag(final MouseEvent event);

		void onRelease(final MouseEvent event);
	}
}