import type { Ary } from ".";
import type { Args, Fn } from "../HKT";
import type { AssertBool } from "../helpers";

/**
 * Check if an {@link Ary} (i.e., `Array` or `ReadonlyArray`) is writable (i.e., not readonly).
 *
 * Sig: `(a: Ary) => boolean`
 *
 * @example
 * ```typescript
 * type R1 = IsWritable<string[]>;
 * //   ^?: true
 * type R2 = IsWritable<readonly number[]>;
 * //   ^?: false
 * type R3 = IsWritable<["foo", "bar"]>;
 * //   ^?: true
 * type R4 = IsWritable<readonly [42, 1337, ...string[]]>;
 * //   ^?: false
 * ```
 */
export type IsWritable<T extends Ary> = AssertBool<T extends unknown[] ? true : false>;

/**
 * Check if an {@link Ary} (i.e., `Array` or `ReadonlyArray`) is writable (i.e., not readonly).
 *
 * Sig: `(a: Ary) => boolean`
 */
export default interface IsWritableFn extends Fn<[Ary], boolean> {
  def: ([a]: Args<this>) => IsWritable<typeof a>;
}