import { cacheAge, CacheAge, isCacheAge } from '../types/CacheAge';
import { on } from '../types/Constructor';
import { entries } from '../types/Object';
import { ifDefined } from '../utils/If';

export class CacheControl {
  name = 'Cache-Control';

  protected constructor(
    readonly enabled = true,
    private directives: Record<string, boolean | CacheAge | undefined> = {}
  ) {}

  static disabled = () => new CacheControl(false);

  static OneSecond = () => new CacheControl().maxAge(1).staleWhileRevalidate(1);

  static fiveSeconds = () => new CacheControl().maxAge(5).staleWhileRevalidate(5);

  static tenSeconds = () => new CacheControl().maxAge(10).staleWhileRevalidate(10);

  static thirtySeconds = () => new CacheControl().maxAge(30).staleWhileRevalidate(30);

  static sixtySeconds = () => new CacheControl().maxAge(60).staleWhileRevalidate(60);

  static custom = (maxAge?: CacheAge, staleWhileRevalidate?: CacheAge) => new CacheControl().maxAge(maxAge).staleWhileRevalidate(staleWhileRevalidate);

  readonly maxAge = (ca?: CacheAge): this => on(this, t => (t.directives['max-age'] = ca));

  readonly sharedMaxAge = (ca?: CacheAge): this => on(this, t => (t.directives['s-maxage'] = ca));

  readonly noCache = (a?: boolean): this => on(this, t => (t.directives['no-cache'] = a));

  readonly mustRevalidate = (a?: boolean): this => on(this, t => (t.directives['must-revalidate'] = a));

  readonly private = (a?: boolean): this => on(this, t => (t.directives['private'] = a));

  readonly public = (a?: boolean): this => on(this, t => (t.directives['public'] = a));

  readonly immutable = (a?: boolean): this => on(this, t => (t.directives['immutable'] = a));

  readonly staleWhileRevalidate = (ca?: CacheAge): this => on(this, t => (t.directives['stale-while-revalidate'] = ca));

  value = (): string => this.toString();

  toString(): string {
    return entries(this.directives)
      .mapDefined(([k, v]) => ifDefined(v, isCacheAge(v) ? `${k}=${cacheAge.toSeconds(v)}` : k))
      .join(',');
  }
}