import { injectable } from 'inversify';
import EventEmitter from '@antv/event-emitter';
import { generateUuid } from '../utils';
import { DATASET_MANAGER_EVENT } from './constants';
import { DatasetManagerConfig, DatasetConfig, DatasetMap } from './types';

@injectable()
export class DatasetManager extends EventEmitter {
  configs: DatasetManagerConfig;

  datasetMap: DatasetMap = {};

  init(configs: DatasetManagerConfig) {
    this.configs = configs;
    configs.forEach((datasetConfig: DatasetConfig) => {
      this.datasetMap[datasetConfig.id] = {
        config: datasetConfig,
      };
    });
  }

  private async _queryDataset(url: DatasetConfig['url']): Promise<JSON> {
    const response = await fetch(url);
    const dataset = await response.json();
    return dataset;
  }

  async getDatasetById(id: DatasetConfig['id']): Promise<JSON> {
    if (this.datasetMap[id].dataset) return this.datasetMap[id].dataset;

    const dataset = await this._queryDataset(this.datasetMap[id].config.url);
    this.datasetMap[id].dataset = dataset;
    return dataset;
  }

  addDataset(url: DatasetConfig['url'], name: DatasetConfig['name']): DatasetConfig['id'] {
    const config: DatasetConfig = {
      id: generateUuid('dataset'),
      name,
      url,
    };
    this.configs.push(config);
    this.datasetMap[config.id] = {
      config,
    };
    this.emit(DATASET_MANAGER_EVENT.AddDataset);
    return config.id;
  }
}