package ceccs;

import javafx.animation.AnimationTimer;
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.input.KeyEvent;
import javafx.scene.layout.Pane;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.scene.text.Font;
import javafx.stage.Stage;
import org.jbox2d.collision.shapes.PolygonShape;
import org.jbox2d.common.Vec2;
import org.jbox2d.dynamics.*;

public class JFXBox2dDemo extends Application {

    float physScale = 10f;
    World world;
    Body boxBody, floorBody;
    //visuals
    Rectangle boxNode, floorNode;
    AnimationTimer aTimer;


    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage primaryStage) throws Exception {
        double boxPositionXInit = 300, boxPositionYinit = 100;
        Vec2 boxPositionInitial = 
	  new Vec2((float)boxPositionXInit/physScale,(float)boxPositionYinit/physScale);

        double wBox = 40,hBox = 15;
        boxNode = new Rectangle(wBox,hBox, Color.RED);

        double wFloor = 250, hFloor=10;
        floorNode = new Rectangle(wFloor,hFloor, Color.BLUE);

        world = new World(new Vec2(0,20/physScale));

        //making a single box.
        BodyDef boxBodyDef = new BodyDef();
        boxBodyDef.type = BodyType.DYNAMIC;
        boxBodyDef.position = boxPositionInitial;
        boxBodyDef.gravityScale = 1;
        boxBody = world.createBody(boxBodyDef);
        FixtureDef boxFixtureDef = new FixtureDef();
        boxFixtureDef.density = 1;
        boxFixtureDef.restitution = .1f;
        PolygonShape ps = new PolygonShape();
        Vec2[] vertices = {
                new Vec2(-(float)wBox/2/physScale,-(float)hBox/2/physScale),
                new Vec2((float)wBox/2/physScale,-(float)hBox/2/physScale),
                new Vec2((float)wBox/2/physScale,(float)hBox/2/physScale),
                new Vec2(-(float)wBox/2/physScale,(float)hBox/2/physScale),
                };
        ps.set(vertices, 4);
        boxFixtureDef.shape = ps;
        boxBody.createFixture(boxFixtureDef);

        //making the floor
        BodyDef floorBodyDef = new BodyDef();
        //floorBodyDef.fixedRotation = true;
        //floorBodyDef.gravityScale = 0;
        floorBodyDef.type = BodyType.STATIC;
        floorBodyDef.position = new Vec2(300/physScale, ((350-(float)hFloor))/physScale);
        floorBody = world.createBody(floorBodyDef);
        FixtureDef floorFixtureDef = new FixtureDef();
        PolygonShape psFloor = new PolygonShape();
        Vec2[] floorVertices = {
                new Vec2(-(float)wFloor/2/physScale,-(float)hFloor/2/physScale),
                new Vec2((float)wFloor/2/physScale,-(float)hFloor/2/physScale),
                new Vec2((float)wFloor/2/physScale,(float)hFloor/2/physScale),
                new Vec2(-(float)wFloor/2/physScale,(float)hFloor/2/physScale),
        };
        //EdgeShape es = new EdgeShape();
        //es.set(new Vec2(0,0), new Vec2((float)floorNode.getWidth()/physScale, 0));
        floorFixtureDef.shape = psFloor;
        psFloor.set(floorVertices, 4);
        floorBody.createFixture(floorFixtureDef);

        //scene setup
        StackPane root = new StackPane();
        root.setAlignment(Pos.TOP_CENTER);
        Pane physPane = new Pane();
        physPane.getChildren().addAll(floorNode,boxNode);
        root.getChildren().add(physPane);
        Scene scn = new Scene(root, 600,400);
        primaryStage.setScene(scn);
        primaryStage.setTitle("JavaFX - Box2D Basic Demonstration");
        primaryStage.setResizable(false);
        primaryStage.show();

        //time control
        aTimer = new AnimationTimer() {
            long prevTimeNanos;

            @Override
            public void start() {
                super.start();
                prevTimeNanos = System.nanoTime();
            }

            @Override
            public void handle(long now) {
                //framerate limit: 33,000 nanosec. = .033s per refresh
                //.033s period is approx. 30 frames per second.
                if(now - prevTimeNanos > 33_000) {
                    //update physics
                    float timeStep = .05f;
                    world.step(timeStep, 1, 1);

                    //graphics
                    boxNode.setLayoutX(boxBody.getPosition().x * physScale - wBox / 2);
                    boxNode.setLayoutY(boxBody.getPosition().y * physScale - hBox / 2);
                    boxNode.setRotate(Math.toDegrees(boxBody.getAngle()));

                    floorNode.setLayoutX(floorBody.getPosition().x * physScale - wFloor / 2);
                    floorNode.setLayoutY(floorBody.getPosition().y * physScale - hFloor / 2);
                    floorNode.setRotate(Math.toDegrees(floorNode.getRotate()));

                    prevTimeNanos = now;
                }

            }
        };

        //introduce some rotation to make things more interesting
        boxBody.setAngularVelocity(-1.75f);
        aTimer.start();

        //control instructions
        Label controlsLabel = new Label("Press Space to Reset Rectangle");
        controlsLabel.setFont(new Font(20));
        controlsLabel.setPadding(new Insets(50));
        root.getChildren().add(controlsLabel);

        //hotkey to respawn block
        scn.addEventHandler(KeyEvent.KEY_PRESSED, keyEvent -> {
            switch (keyEvent.getCode()){
                case SPACE -> {
                    //reset position and rotation
                    boxBody.setTransform(boxPositionInitial,0);

                    //randomize spin
                    float randSpin = ((float)Math.random() -.5f) * 4.0f;
                    boxBody.setAngularVelocity(randSpin);

                    //randomize initial velocity
                    float randVelX = (((float)Math.random() - .5f)*50)/physScale;
                    float randVelY = (((float)Math.random() - .5f)*50)/physScale;
                    Vec2 velInit = new Vec2(randVelX,randVelY);
                    boxBody.setLinearVelocity(velInit);
                }
            }
        });
    }
}