import * as I from 'immutable';

import {Vector} from '@avocado/math';
import {Property} from '@avocado/mixins';
import {Resource} from '@avocado/resource';
import {Synchronized} from '@avocado/state';

export class Trait extends Synchronized {

  constructor(entity, params, state) {
    super();
    this.entity = entity;
    const ctor = this.constructor;
    this.params = I.fromJS(ctor.defaultParams()).merge(I.fromJS(params));
    this.state = I.fromJS(ctor.defaultState()).merge(I.fromJS(state));
    this.$$stateDirty = true;
  }

  destroy() {}

  hooks() {
    return {};
  }

  hydrate() {
    return Promise.resolve();
  }

  initialize() {}

  label() {
    return this.constructor.name;
  }

  listeners() {
    return {};
  }

  methods() {
    return {};
  }

  patchStateStep(key, step) {
    if ('state' !== key) {
      return;
    }
    const stateKey = step.path.substr(1);
    const value = this.transformPatchValue(stateKey, step.value);
    if (stateKey in this.entity) {
      this.entity[stateKey] = value;
    }
    else {
      this.state = this.state.set(stateKey, value);
    }
  }

  tick(elapsed) {}

  toJSON() {
    return {
      params: this.params.toJS(),
      state: this.state.toJS(),
    };
  }

  transformPatchValue(key, value) {
    return value;
  }

  static contextType() {
    return {};
  }

  static defaultParams() {
    return {};
  }

  static defaultState() {
    return {};
  }

  static dependencies() {
    return [];
  }

  static type() {
    return this.name.toLowerCase();
  }

}

export function StateProperty(key, meta = {}) {
  let transformedProperty;
  if (meta.transformProperty) {
    transformedProperty = meta.transformProperty(key);
  }
  else {
    transformedProperty = `$$avocado_state_property_${key}`;
  }
  return (Superclass) => {
    meta.emit = meta.emit || function(...args) {
      this.entity.emit(...args);
    };
    meta.initialize = meta.initialize || function() {
      this[transformedProperty] = this.state.get(key);
    }
    meta.get = meta.get || new Function(`
      return this.${transformedProperty};
    `);
    meta.set = meta.set || new Function('value', `
      this.$$stateDirty = true;
      this.${transformedProperty} = value;
      this.state = this.state.set('${key}', value);
    `);
    return Property(key, meta)(Superclass);
  }
}

StateProperty.Vector = (vector, x, y, meta = {}) => {
  return (Superclass) => {
    meta.default = undefined;
    meta.emit = meta.emit || function(...args) {
      this.entity.emit(...args);
    };
    meta.get = meta.get || function() {
      return [
        this.state.get(x),
        this.state.get(y),
      ];
    };
    meta.set = meta.set || function(vector) {
      if (meta.track && meta.emit) {
        if (this.state.get(x) !== vector[0]) {
          meta.emit.call(this, `${x}Changed`, this.state.get(x), vector[0]);
        }
        if (this.state.get(y) !== vector[1]) {
          meta.emit.call(this, `${y}Changed`, this.state.get(y), vector[1]);
        }
      }
      this.$$stateDirty = true;
      this.state = this.state.merge({
        [x]: vector[0],
        [y]: vector[1],
      });
    };
    return Vector.Mixin(vector, x, y, meta)(Superclass);
  };
}