import { Module, DynamicModule, Provider, Global } from '@nestjs/common';
import { NestGdatastoreService } from './nest-gdatastore.service';
import {
  NestGdatastoreOptions,
  NestGdatastoreAsyncOptions,
} from './interfaces';

@Global()
@Module({
  providers: [NestGdatastoreService],
  exports: [NestGdatastoreService],
})
export class NestGdatastoreModule {
  /**
   * Registers a configured NestGdatastore Module for import into the current module
   */
  public static register(options: NestGdatastoreOptions): DynamicModule {
    return {
      module: NestGdatastoreModule,
      providers: [{ provide: 'datastoreKeys', useValue: options }],
      imports: [],
    };
  }

  /**
   * Registers a configured NestGdatastore Module for import into the current module
   * using dynamic options (factory, etc)
   */
  public static registerAsync(
    dbOptions: NestGdatastoreAsyncOptions,
  ): DynamicModule {
    return {
      module: NestGdatastoreModule,
      providers: [...this.createProviders(dbOptions)],
      imports: [],
    };
  }

  private static createProviders(
    options: NestGdatastoreAsyncOptions,
  ): Provider[] {
    if (options.useExisting || options.useFactory) {
      return [this.createOptionsProvider(options)];
    }

    return [
      this.createOptionsProvider(options),
      {
        provide: options.useClass,
        useClass: options.useClass,
      },
    ];
  }

  private static createOptionsProvider(
    options: NestGdatastoreAsyncOptions,
  ): Provider {
    if (options.useFactory) {
      return {
        provide: 'datastoreKeys',
        useFactory: options.useFactory,
        inject: options.inject || [],
      };
    }

    // For useExisting...
    return {
      provide: 'datastoreKeys',
      useFactory: (configService: { get: (get) => string }) => {
        const extractionKeys = [
          'PROJECT_ID',
          'DATASTOREKEY',
          'DATASTORE_NAMESPACE',
        ];
        let configObject = {};

        extractionKeys.forEach(key => {
          configObject[key] = configService.get(key);
        });

        return configObject;
      },
      inject: [options.useExisting || options.useClass],
    };
  }
}