filtering.ts

import {Component} from '@angular/core';
import {filter} from 'rxjs/operators';

interface ItemType {
	[key: string]: string | Array<string>;
}

type filterType = ({ filterValue: string | string[] | null; filterTarget: string });

@Component({
	selector: 'app-root',
	templateUrl: './app.component.html',
	styleUrls: ['./app.component.css']
})
export class AppComponent {
	title = 'testing-testing';

	constructor() {
		const items: ItemType[] = [
			{
				question: 'campells soup',
				categories: 'bonnie, kyled, others',
				other: 'my name is matthew'
			},
			{
				question: 'bad soup',
				categories: 'jessie, james, me',
				other: 'my name is jaco'
			},
		];

		const filters0: filterType[] = [
			{filterValue: null, filterTarget: 'question'},
			{filterValue: null, filterTarget: 'categories'},
			{filterValue: null, filterTarget: 'other'}
		];
		const filters1: filterType[] = [
			{filterValue: 'camp', filterTarget: 'question'},
			{filterValue: ['second', 'filter'], filterTarget: 'categories'},
			{filterValue: null, filterTarget: 'other'},
		];
		const filters2: filterType[] = [
			{filterValue: 'bobbo', filterTarget: 'question'},
			{filterValue: ['jessie', 'buster'], filterTarget: 'categories'},
			{filterValue: 'nothing', filterTarget: 'other'},
		];
		const filters3: filterType[] = [
			{filterValue: 'bobbo', filterTarget: 'question'},
			{filterValue: null, filterTarget: 'categories'},
			{filterValue: ['matthew', 'jaco'], filterTarget: 'other'},
		];
		console.log(this.applyFilters(items, filters0));
		console.log(this.applyFilters(items, filters1));
		console.log(this.applyFilters(items, filters2));
		console.log(this.applyFilters(items, filters3));
		const bobbo = new Set([1, 2, 2, 3, 4]);
		for (const i of bobbo.values()) {
			console.log(i);
		}
	}

	private applyFilters(items: ItemType[], filters: filterType[]): ItemType[] {
		if (filters.every(f => f.filterValue === null)) {
			return items;
		}

		return items.filter(item =>
			filters.some(({filterTarget, filterValue}) => {
				if (filterValue === null) {
					return false;
				} else if (filterValue instanceof Array) {
					return filterValue.some(filterString => match(item, filterTarget, filterString));
				} else {
					return match(item, filterTarget, filterValue);
				}
			})
		);

		function match(item: ItemType, filterTarget: string, filterValue: string): boolean {
			const itemElement = item[filterTarget];
			if (itemElement instanceof Array) {
				return itemElement.some(element => element.includes(filterValue));
			} else {
				return itemElement.includes(filterValue);
			}
		}
	}
}