import * as I from 'immutable';

import {Trait} from '@avocado/entity';
import {hasGraphics, TextNodeRenderer} from '@avocado/graphics';

import {DamageEmitter} from './emitter';

export class Vulnerable extends Trait {

  static defaultState() {
    return {
      damageList: I.Map(),
    };
  }

  initialize() {
    this.damageId = 0;
    this.damageList = {};
    this.locks = new Map();
    if (hasGraphics) {
      this.emitter = new DamageEmitter();
      this.setRenderer();
    }
  }

  patchStateStep(key, step) {
    if ('state' !== key) {
      return;
    }
    const stateKey = step.path.substr(1);
    const value = this.transformPatchValue(stateKey, step.value);
    const stateKeyParts = stateKey.split('/');
    switch (stateKeyParts[0]) {
      case 'damageList':
        for (let i = 0; i < value.length; ++i) {
          const damage = value[i];
          this.emitter.emit(this.entity.position, damage);
        }
        break;
      default:
        super.patchStateStep(key, step);
        break;
    }
  }

  setRenderer() {
    if (this.entity.is('staged') && this.entity.stage) {
      const renderer = new TextNodeRenderer('.damage', this.entity.stage);
      this.emitter.addRenderer(renderer);
    }
  }

  hooks() {
    return {

      afterDestructionTickers: () => {
        return (elapsed) => {
          if (!hasGraphics) {
            return true;
          }
          this.emitter.tick(elapsed);
          return !this.emitter.hasParticles();
        };
      },

    }
  }

  listeners() {
    return {

      stageChanged: () => {
        this.setRenderer();
      },

    };
  }

  methods() {
    return {

      takeDamageFrom: (entity) => {
        const damageSpecs = entity.damageSpecs;
        for (let i = 0; i < damageSpecs.length; ++i) {
          const damageSpec = damageSpecs[i];
          if (this.locks.has(damageSpec)) {
            return;
          }
          this.locks.set(damageSpec, damageSpec.lock);
          const variance = Math.random() * damageSpec.variance * 2 - damageSpec.variance;
          const difference = damageSpec.power * variance;
          // Account for variance past 0, so track if it's damage or not.
          let amount = Math.round(damageSpec.power + difference);
          let isDamage;
          if (damageSpec.power < 0) {
            isDamage = false;
            if (amount > 0) {
              amount = 0;
            }
          }
          else {
            isDamage = true;
            if (amount < 0) {
              amount = 0;
            }
          }
          amount = Math.abs(amount);
          if (!this.damageList[entity.instanceUuid]) {
            this.damageList[entity.instanceUuid] = [];
          }
          const damage = {
            id: this.damageId++,
            isDamage,
            amount,
            damageSpec,
          };
          this.damageList[entity.instanceUuid].push(damage);
          this.entity.emit('tookDamage', damage);
        }
      },

    };
  }

  tick(elapsed) {
    if (hasGraphics) {
      this.emitter.tick(elapsed);
    }
    if (this.state.get('damageList').size > 0) {
      this.state = this.state.set('damageList', I.Map());
    }
    if (Object.keys(this.damageList).length > 0) {
      this.state = this.state.set('damageList', I.Map(this.damageList));
      this.isDirty = true;
      this.damageList = {};
    }
    const keys = Array.from(this.locks.keys());
    for (let i = 0; i < keys.length; ++i) {
      const key = keys[i];
      const remaining = this.locks.get(key) - elapsed;
      if (remaining <= 0) {
        this.locks.delete(key);
      }
      else {
        this.locks.set(key, remaining);
      }
    }
  }

}