import {fromJSON as behaviorItemFromJSON} from './registry';

export class Traversal {

  constructor() {
    this.hash = undefined;
    this.steps = [];
    this.value = undefined;
  }

  fromJSON(json) {
    this.steps = json.steps.map((step) => {
      switch (step.type) {
        case 'key':
          return step;
        case 'invoke':
          return {
            type: 'invoke',
            args: step.args.map((arg) => behaviorItemFromJSON(arg)),
          };
      }
    });
    if (json.value) {
      this.value = behaviorItemFromJSON(json.value);
    }
    if (json.hash) {
      this.hash = json.hash;
    }
    return this;
  }

  get(context) {
    return this.traverse(context);
  }

  traverse(context) {
    if (context) {
      return context.traverse(this);
    }
  }

  toJSON() {
    return {
      type: 'traversal',
      steps: this.steps.map((step) => {
        switch (step.type) {
          case 'key':
            return step;
          case 'invoke':
            return {
              type: 'invoke',
              args: step.args.map((arg) => arg.toJSON()),
            };
        }
      }),
      value: this.value ? this.value.toJSON() : undefined,
    };
  }
}