import {
  behaviorItemFromJSON,
  buildCondition,
  buildInvoke,
  buildTraversal,
  Context,
} from '@avocado/behavior';
import {compose} from '@avocado/core';

import {StateProperty, Trait} from '../trait';
import {TraitUpdateAlivePacket} from '../packets/trait-update-alive.packet';

const decorate = compose(
  StateProperty('life', {
    track: true,
  }),
  StateProperty('maxLife', {
    track: true,
  }),
);

export class Alive extends decorate(Trait) {

  static defaultParams() {
    const playDeathSound = buildInvoke(['entity', 'playSound'], [
      buildTraversal(['entity', 'deathSound']),
    ]);
    const squeeze = buildInvoke(['entity', 'transition'], [
      {
        opacity: 0,
        visibleScaleX: .3,
        visibleScaleY: 3,
      },
      0.2,
    ]);
    const isLifeGone = buildCondition('<=', [
      buildTraversal(['entity', 'life']),
      0,
    ]);
    return {
      deathActions: {
        type: 'actions',
        traversals: [
          playDeathSound,
          squeeze,
        ],
      },
      deathCondition: isLifeGone,
      deathSound: 'deathSound',
    };
  }

  static defaultState() {
    return {
      life: 100,
      maxLife: 100,
    };
  }

  static type() {
    return 'alive';
  }

  constructor(entity, params, state) {
    super(entity, params, state);
    this._context = new Context({
      entity: this.entity,
    });
    const actionsJSON = this.params.deathActions;
    this._deathActions = behaviorItemFromJSON(actionsJSON);
    this._deathSound = this.params.deathSound;
    const conditionJSON = this.params.deathCondition;
    this._deathCondition = behaviorItemFromJSON(conditionJSON);
    this._dyingTickingPromise = false;
  }

  destroy() {
    this._context.destroy();
  }

  acceptPacket(packet) {
    if (packet instanceof TraitUpdateAlivePacket) {
      this.entity.life = packet.data.life;
      this.entity.maxLife = packet.data.maxLife;
    }
  }

  get deathSound() {
    return this._deathSound;
  }

  packets(informed) {
    const {life, maxLife} = this.stateDifferences();
    if (life || maxLife) {
      return new TraitUpdateAlivePacket(this.state);
    }
  }

  listeners() {
    return {

      tookDamage: (damage, source) => {
        if (damage.damageSpec.power > 0) {
          this.entity.life -= damage.amount;
        }
        else {
          this.entity.life += damage.amount;
        }
        // Clamp health between 0 and max.
        this.entity.life = Math.min(
          Math.max(0, this.entity.life),
          this.entity.maxLife
        );
      },

    }
  }

  methods() {
    return {

      dieIfPossible: () => {
        if (this._deathCondition.check(this._context)) {
          this.entity.forceDeath();
        }
      },

      forceDeath: () => {
        if (this._dyingTickingPromise) {
          return;
        }
        this._dyingTickingPromise = this._deathActions.tickingPromise(
          this._context
        )
        this._dyingTickingPromise.then(() => {
          this.entity.destroy();
        });
      },

    };
  }

  tick(elapsed) {
    if (this._dyingTickingPromise) {
      this._dyingTickingPromise.tick(elapsed);
    }
    else {
      this.entity.dieIfPossible();
    }
  }

}