import React, { Component } from 'react';
import { StyleSheet } from 'react-native';

import Animated, { Easing } from 'react-native-reanimated';
import { PanGestureHandler, State } from 'react-native-gesture-handler';

const {
  sin,
  add,
  cos,
  block,
  set,
  cond,
  eq,
  multiply,
  spring,
  startClock,
  stopClock,
  clockRunning,
  sub,
  defined,
  Value,
  Clock,
  event,
  proc,
} = Animated;

function runSpring(clock, value, velocity, dest) {
  const state = {
    finished: new Value(0),
    velocity: new Value(0),
    position: new Value(0),
    time: new Value(0),
  };

  const config = {
    damping: 30,
    mass: 3,
    stiffness: 21.6,
    overshootClamping: false,
    restSpeedThreshold: 0.001,
    restDisplacementThreshold: 0.001,
    toValue: new Value(0),
  };

  return [
    cond(clockRunning(clock), 0, [
      set(state.finished, 0),
      set(state.velocity, velocity),
      set(state.position, value),
      set(config.toValue, dest),
      startClock(clock),
    ]),
    spring(clock, state, config),
    cond(state.finished, stopClock(clock)),
    state.position,
  ];
}

export default class Example extends Component {
  static navigationOptions = {
    title: 'Native solar system',
    headerTitleStyle: {
      color: 'white',
    },
    headerStyle: {
      backgroundColor: 'black',
    },
  };
  constructor(props) {
    super(props);
    this.ellipsis = proc((progress, speed, radius, ratio, x, y) =>
      block([
        set(x, multiply(sin(multiply(progress, speed)), radius)),
        set(y, multiply(cos(multiply(progress, speed)), radius, ratio)),
      ])
    );
    this.traversePlanets = planets =>
      planets.map(p => ({
        ...p,
        x: new Value(0),
        y: new Value(0),
        satellites: p.satellites && this.traversePlanets(p.satellites),
      }));

    this.planets = this.traversePlanets(PLANETS);

    const TOSS_SEC = 0.2;

    const dragX = new Value(0);
    const dragY = new Value(0);
    const state = new Value(-1);
    const dragVX = new Value(0);
    const dragVY = new Value(0);

    this._onGestureEvent = event([
      {
        nativeEvent: {
          translationX: dragX,
          velocityX: dragVX,
          translationY: dragY,
          velocityY: dragVY,
          state: state,
        },
      },
    ]);

    const drag = multiply(add(dragX, dragY), 0.05);
    const dragV = multiply(add(dragVX, dragVY), 0.1);

    const trans = new Value();
    const prevDrag = new Value(0);

    const clock = new Clock();
    this._transX = cond(
      eq(state, State.ACTIVE),
      [
        stopClock(clock),
        set(trans, add(trans, sub(drag, prevDrag))),
        set(prevDrag, drag),
        trans,
      ],
      [
        set(prevDrag, 0),
        set(
          trans,
          cond(
            defined(trans),
            runSpring(
              clock,
              trans,
              dragV,
              add(trans, multiply(TOSS_SEC, dragV)),
              0
            ),
            0
          )
        ),
      ]
    );
  }
  renderPlanets = planets => (
    <React.Fragment>
      {planets.map((p, k) => (
        <React.Fragment key={`planet ${k}`}>
          <Animated.Code
            exec={this.ellipsis(
              this._transX,
              p.speed,
              p.radius,
              p.ratio,
              p.x,
              p.y
            )}
          />
          <Animated.View
            style={[
              styles.box,
              {
                width: p.size,
                backgroundColor: p.color,
                height: p.size,
                borderRadius: p.size,
                transform: [
                  {
                    translateX: p.x,
                  },
                  {
                    translateY: p.y,
                  },
                ],
              },
            ]}>
            {!!p.satellites && this.renderPlanets(p.satellites)}
          </Animated.View>
        </React.Fragment>
      ))}
    </React.Fragment>
  );
  render() {
    return (
      <PanGestureHandler
        onGestureEvent={this._onGestureEvent}
        onHandlerStateChange={this._onGestureEvent}>
        <Animated.View style={styles.container}>
          {this.renderPlanets(this.planets)}
        </Animated.View>
      </PanGestureHandler>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#000000',
  },
  box: {
    position: 'absolute',
    borderColor: '#F5FCFF',
    backgroundColor: 'plum',
  },
});

const PLANETS = [
  {
    radius: 2,
    size: 20,
    speed: 0.1,
    ratio: 1,
    rotation: '0deg',
    color: '#c7b755',
  },
  {
    radius: 25,
    size: 5,
    speed: 2,
    ratio: 1,
    rotation: '0deg',
    color: '#c74e43',
  },
  {
    radius: 35,
    size: 5,
    speed: 2.2,
    ratio: 1.2,
    rotation: '12deg',
    color: '#4e76c7',
  },
  {
    radius: 45,
    size: 5,
    speed: 1.7,
    ratio: 1.1,
    rotation: '50deg',
    color: '#0ec700',
  },
  {
    radius: 43,
    size: 5,
    speed: 1,
    ratio: 3,
    rotation: '120deg',
    color: '#c76c03',
  },
  {
    radius: 30,
    size: 12,
    speed: 0.6,
    ratio: 1.4,
    rotation: '40deg',
    color: '#c741a4',
  },
  {
    radius: 200,
    size: 12,
    speed: 1.3,
    ratio: 0.2,
    rotation: '120deg',
    color: '#c73621',
  },
  {
    radius: 50,
    size: 32,
    speed: 1.2,
    ratio: 2,
    rotation: '120deg',
    color: '#c78213',
    satellites: [
      {
        radius: 22,
        size: 8,
        speed: 1,
        ratio: 1.3,
        rotation: '15deg',
        color: '#c70035',
      },
      {
        radius: 35,
        size: 12,
        speed: 1.4,
        ratio: 0.8,
        rotation: '112deg',
        color: '#c6c79b',
      },
    ],
  },
  {
    radius: 100,
    size: 42,
    speed: 1,
    ratio: 1.1,
    rotation: '40deg',
    color: '#c7b342',
  },
  {
    radius: 200,
    size: 82,
    speed: 1.5,
    ratio: 1.1,
    rotation: '120deg',
    color: '#001ac7',
    satellites: [
      {
        radius: 42,
        size: 20,
        speed: 1,
        ratio: 1,
        rotation: '0deg',
        color: '#c7c7e5',
      },
      {
        radius: 35,
        size: 12,
        speed: 1.4,
        ratio: 0.8,
        rotation: '152deg',
        color: '#c6c79b',
      },
      {
        radius: 42,
        size: 8,
        speed: 1.1,
        ratio: 1.3,
        rotation: '55deg',
        color: '#c7be6f',
      },
      {
        radius: 35,
        size: 15,
        speed: 1.8,
        ratio: 0.8,
        rotation: '132deg',
        color: '#73304a',
      },
      {
        radius: 42,
        size: 4,
        speed: 1,
        ratio: 1,
        rotation: '0deg',
        color: '#dbdbff',
      },
      {
        radius: 35,
        size: 3,
        speed: 1.4,
        ratio: 0.8,
        rotation: '152deg',
        color: '#c6c79b',
      },
      {
        radius: 42,
        size: 7,
        speed: 1.1,
        ratio: 1.3,
        rotation: '55deg',
        color: '#c7be6f',
        satellites: [
          {
            radius: 40,
            size: 8,
            speed: 1,
            ratio: 1,
            rotation: '0deg',
            color: '#c70035',
          },
          {
            radius: 50,
            size: 12,
            speed: 2,
            ratio: 1,
            rotation: '0deg',
            color: '#c6c79b',
          },
        ],
      },
      {
        radius: 35,
        size: 5,
        speed: 1.8,
        ratio: 0.8,
        rotation: '132deg',
        color: '#5b730d',
      },
    ],
  },
];