import co_assert from '../../utils/co-assert'
import PresentationFileDiff from './PresentationFileDiff'

export default class PresentationFileChecksums {

  private checksums: any;

  public constructor(checksumsObject: any = {}) {
    this.validateChecksumsJson(checksumsObject);

    this.checksums = checksumsObject;
  }

  public getChecksums() {
    return this.checksums;
  }

  public add(relativePath: string, fileChecksum: string): void {
    co_assert(this.checksums[relativePath] === undefined, `Checksum for file "${relativePath}" already exists.`);

    this.checksums[relativePath] = fileChecksum;
  }

  public makeDiff(checksums: PresentationFileChecksums): PresentationFileDiff {
    const diff = new PresentationFileDiff();

    for(const key in this.checksums) {
      if (!checksums.checksums.hasOwnProperty(key)) {
        diff.removed.push(key);
        continue;
      }

      if (this.checksums[key] !== checksums.checksums[key]) {
        diff.updated.push(key);
      }
    }

    for(const key in checksums.checksums) {
      if (!this.checksums.hasOwnProperty(key)) {
        diff.added.push(key);
      }
    }

    return diff;
  }

  private validateChecksumsJson(json: any) {
    const incorrectJsonErrorMessage = 'Incorrect checksums json was provided. It has to be simple' +
                                      ' json object with file paths as keys and checksum strings as values.';

    if (json.constructor !== Object) {
      throw new Error(incorrectJsonErrorMessage); 
    }

    for (const filePath in json) {
      const checksum = json[filePath];
      
      if (typeof filePath !== 'string' || typeof checksum !== 'string') {
        throw new Error(incorrectJsonErrorMessage);
      }
    }
  }
}