tutorbook/src/emails/handlebars.ts

Web app connecting students with expert mentors and tutors.

import Handlebars from 'handlebars';
import Utils from '@tutorbook/utils';

import { RoleAlias } from '@tutorbook/model';
import Check from './shared/check.hbs';
import Cross from './shared/cross.hbs';
import Profile from './shared/profile.hbs';

Handlebars.registerPartial('check', Check);
Handlebars.registerPartial('cross', Cross);
Handlebars.registerPartial('profile', Profile);

/**
 * Custom handlebars helper that returns the roles that a user is not.
 * @example
 * "Once they approve, you'll receive instructions for how to connect with your
 * mentor."
 */
/* eslint-disable-next-line consistent-return */
Handlebars.registerHelper('role', function role(array: RoleAlias[]): RoleAlias {
  /* eslint-disable default-case */
  switch (array[0]) {
    case 'mentor':
      return 'mentee';
    case 'tutor':
      return 'tutee';
    case 'mentee':
      return 'mentor';
    case 'tutee':
      return 'tutor';
  }
  /* eslint-enable default-case */
});

/**
 * Custom handlebars helper that joins a list together using 'and'.
 * @example
 * assert(join(['Chemistry', 'Chemistry H']) === 'Chemistry and Chemistry H');
 * assert(join(['A', 'B', 'C', 'D']) === 'A, B, C and D');
 */
Handlebars.registerHelper('join', function join(array: string[]): string {
  return Utils.join(array);
});

Handlebars.registerHelper('joinCaps', function joinCaps(
  array: string[]
): string {
  return Utils.join(array.map((item: string) => Utils.caps(item)));
});

/**
 * Custom handlebars helper that actually provides `if` functionality.
 * @todo Don't use the `any` type for `this`.
 * @see {@link https://stackoverflow.com/a/16315366/10023158}
 */
Handlebars.registerHelper('ifCond', function ifCond<T = any>(
  this: any,
  v1: T,
  operator: '===' | '!==' | '<' | '<=' | '>' | '>=' | '&&' | '||',
  v2: T,
  options: Handlebars.HelperOptions
): string {
  switch (operator) {
    case '===':
      return v1 === v2 ? options.fn(this) : options.inverse(this);
    case '!==':
      return v1 !== v2 ? options.fn(this) : options.inverse(this);
    case '<':
      return v1 < v2 ? options.fn(this) : options.inverse(this);
    case '<=':
      return v1 <= v2 ? options.fn(this) : options.inverse(this);
    case '>':
      return v1 > v2 ? options.fn(this) : options.inverse(this);
    case '>=':
      return v1 >= v2 ? options.fn(this) : options.inverse(this);
    case '&&':
      return v1 && v2 ? options.fn(this) : options.inverse(this);
    case '||':
      return v1 || v2 ? options.fn(this) : options.inverse(this);
    default:
      return options.inverse(this);
  }
});

export default Handlebars;