/**
 * Copyright Microsoft Corporation. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import { installTransform } from './transform';
import { Config, FullConfig } from './types';
import { prependErrorMessage } from './util';
import { configFile, setCurrentFile, RunListDescription } from './spec';

type SerializedLoaderData = {
  configs: (string | Config)[];
};

export class Loader {
  globalSetup?: () => any;
  globalTeardown?: (globalSetupResult: any) => any;

  private _mergedConfig: FullConfig;
  private _layeredConfigs: { config: Config, source?: string }[] = [];

  constructor() {
    this._mergedConfig = {} as any;
  }

  deserialize(data: SerializedLoaderData) {
    for (const config of data.configs) {
      if (typeof config === 'string')
        this.loadConfigFile(config);
      else
        this.addConfig(config);
    }
  }

  loadConfigFile(file: string) {
    const revertBabelRequire = installTransform();
    try {
      require(file);
      this.addConfig(configFile.config || {});
      this._layeredConfigs[this._layeredConfigs.length - 1].source = file;
      this.globalSetup = configFile.globalSetup;
      this.globalTeardown = configFile.globalTeardown;
    } catch (e) {
      // Drop the stack.
      throw new Error(e.message);
    } finally {
      revertBabelRequire();
    }
  }

  addConfig(config: Config) {
    this._layeredConfigs.push({ config });
    this._mergedConfig = { ...this._mergedConfig, ...config };
  }

  loadTestFile(file: string) {
    const revertBabelRequire = installTransform();
    setCurrentFile(file);
    try {
      require(file);
    } catch (e) {
      prependErrorMessage(e, `Error while reading ${file}:\n`);
      throw e;
    } finally {
      setCurrentFile();
      revertBabelRequire();
    }
  }

  config(): FullConfig {
    return this._mergedConfig;
  }

  runLists(): RunListDescription[] {
    return configFile.runLists;
  }

  serialize(): SerializedLoaderData {
    return {
      configs: this._layeredConfigs.map(c => c.source || c.config),
    };
  }
}