import fs from 'fs';
import path from 'path';

import {Resource} from './resource';

export class ResourceRegistry {

  constructor() {
    this.idToUriMap = {};
    this.resources = {};
    this.uriToOtherMap = {};
    this.id = 1;
  }

  load(uri) {
    return Resource.read(uri).then((json) => {
      for (const uri in json) {
        this.register(uri, json.uuid, json.id);
      }
    });
  }

  flush() {
    const RESOURCE_PATH = path.resolve(process.cwd(), 'resource');
    fs.writeFileSync(
      path.join(RESOURCE_PATH, 'registry.json'),
      JSON.stringify(this.uriToOtherMap)
    );
  }

  idToUri(id) {
    return this.idToUriMap[id];
  }

  register(uri, uuid, id) {
    id = id || this.id++;
    this.idToUriMap[id] = uri;
    this.uriToOtherMap[uri] = {
      id,
      uuid,
    };
  }

  uriToId(uri) {
    const entry = this.uriToOtherMap[uri];
    return entry && entry.id;
  }

  uriToUuid(uri) {
    const entry = this.uriToOtherMap[uri];
    return entry && entry.uuid;
  }

}

export const globalRegistry = new ResourceRegistry();