import * as path from 'path'
import PresentationFileChecksums from './PresentationFileChecksums'
import * as fsExtra from 'fs-extra-promise'
import * as Promise from 'bluebird'

const COBALT_FOLDER_NAME = '.cobalt';

export default class CobaltFilesHandler {

  private presentationPath: string;

  public constructor(presentationPath: string) {
    this.setPresentationPath(presentationPath);
  }

  public setPresentationPath(presentationPath: string): void {
    this.presentationPath = presentationPath;
  }

  public readChecksums(): Promise<PresentationFileChecksums> {
    const checksumPath = this.getChecksumPath();
    return fsExtra.readJsonAsync(checksumPath)
             .then((content: Object) => {
               return new PresentationFileChecksums(content);
             })
             .catch(() => {
               return new PresentationFileChecksums()
             });
  }

  public saveChecksums(checksums: PresentationFileChecksums): Promise<void> {
    const checksumPath = this.getChecksumPath();
    return this.ensureCobaltFolderExists(checksumPath)
             .then(() => {
               return fsExtra.writeJsonAsync(checksumPath, checksums.getChecksums());
             });
  }

  public getCobaltFolderRelativePath() {
    return COBALT_FOLDER_NAME;
  }

  private getChecksumPath() {
    return path.join(this.presentationPath, COBALT_FOLDER_NAME, 'checksums.json');
  }

  private ensureCobaltFolderExists(checksumPath: string): Promise<void> {
    const checksumsDir = path.dirname(checksumPath);
    return fsExtra.ensureDirAsync(checksumsDir);
  }
}