import uuid from 'uuid/v4';

export class Resource {

  static load(uri) {
    return this.read(uri).then((json) => {
      const instance = new this();
      return instance.fromJSON(json);
    });
  }

  static read(uri) {
    if (!this.loadCache) {
      this.loadCache = {};
    }
    if (this.loadCache[uri]) {
      return Promise.resolve(JSON.parse(JSON.stringify(this.loadCache[uri])));
    }
    if ('undefined' !== typeof window) {
      return fetch(uri).then((response) => {
        return response.json();
      }).then((json) => {
        return this.loadCache[uri] = json;
      });
    }
    else {
      return new Promise((resolve, reject) => {
        const fs = require('fs');
        const path = require('path');
        const resourcePath = path.resolve(process.cwd(), 'resource');
        fs.readFile(`${resourcePath}${uri}`, (error, buffer) => {
          if (error) {
            return reject(error);
          }
          resolve(this.loadCache[uri] = JSON.parse(buffer.toString('utf8')));
        });
      });
    }
  }

  constructor() {
    this.uri_PRIVATE = undefined;
    this.uuid_PRIVATE = undefined;
    this.instanceUuid_PRIVATE = uuid();
  }

  fromJSON({uri, uuid}) {
    this.uri_PRIVATE = uri;
    this.uuid_PRIVATE = uuid;
    return this;
  }

  get instanceUuid() {
    return this.instanceUuid_PRIVATE;
  }

  regenerateUuid() {
    this.uuid_PRIVATE = uuid();
  }

  get uuid() {
    return this.uuid_PRIVATE;
  }

  set uuid(uuid) {
    this.uuid_PRIVATE = uuid;
  }

  get uri() {
    return this.uri_PRIVATE;
  }

  set uri(uri) {
    this.uri_PRIVATE = uri;
  }

  toJSON() {
    return {
      uuid: this.uuid_PRIVATE,
      uri: this.uri_PRIVATE,
    };
  }

}