filter-per-type.pipe.ts

import { Pipe, PipeTransform } from '@angular/core';
import { TODO } from './todo.model';

@Pipe({
  name: 'filterPerType',
  pure: true
})
export class FilterPerTypePipe implements PipeTransform {

  transform(allTodos: TODO[], type: string): TODO[] {
    return allTodos.filter(todo => {
      if (type === 'Coding' || type === 'Reading') {
        return todo.type !== 'Writing';
      } else {
        return true;
      }
    });
  }
}