import * as React from 'react';

export function useSet<T = unknown>(
  initialValues: readonly T[] | null,
): ISet<T> {
  const [set, setSet] = React.useState(() => new Set(initialValues));
  return {
    raw: set,
    add: React.useCallback((value: T) => {
      setSet((set) => {
        if (set.has(value)) {
          return set;
        }
        const copy = new Set(set);
        copy.add(value);
        return copy;
      });
    }, []),
    clear: React.useCallback(() => {
      setSet((set) => {
        return set.size === 0 ? set : new Set();
      });
    }, []),
    delete: React.useCallback(
      (value: T) =>
        setSet((set) => {
          if (!set.has(value)) {
            return set;
          }
          const copy = new Set(set);
          copy.delete(value);
          return copy;
        }),
      [],
    ),
    has: React.useCallback((value: T) => set.has(value), [set]),
    map: React.useCallback(
      (callbackFn) => {
        const result: ReturnType<typeof callbackFn>[] = [];
        for (const value of set) {
          result.push(callbackFn(value, result.length, set));
        }
        return result;
      },
      [set],
    ),
    size: set.size,
  };
}

interface ISet<T> {
  raw: Set<T>;
  add(value: T): void;
  clear(): void;
  delete(value: T): void;
  has(value: T): boolean;
  map<U>(callbackFn: (value: T, index: number, set: Set<T>) => U): U[];
  readonly size: number;
}

function isFunction(value: unknown): value is (...args: any[]) => any {
  return typeof value === 'function';
}