import createRBTree from "functional-red-black-tree";
import { inspect } from "node:util";

export class RBTreeWrapper {
  constructor(tree) {
    this.tree = tree;
  }
  // pretty print to console
  [inspect.custom](depth, options, inspect) {
    const entries = [];
    this.tree.forEach((key,val) => {entries.push(`${inspect(key)} => ${inspect(val)}`);});
    return `RBTree(${this.tree.length}) {${entries.join(', ')}}`;
  }
}

// (a -> a -> Int) -> Set(a)
export const emptySet = compareFn => new RBTreeWrapper(createRBTree((x, y) => compareFn(x)(y)));


export const has = set => key => set.tree.get(key) === true;
export const add = set => key => set.tree.get(key) === true ? set : new RBTreeWrapper(set.tree.insert(key, true));
export const remove = set => key => new RBTreeWrapper(set.tree.remove(key));
export const length = set => set.tree.length;

export const first = set => set.tree.begin;
export const last  = set => set.tree.end;

// test if iterator is 'done', and if not, get element and advance iterator.
export const read = iter => ifNotDone => ifDone => {
  if (iter !== undefined && iter.valid) {
    return ifNotDone(iter.key)(iter.clone().next());
  }
  else {
    return ifDone();
  }
};

export const forEach = set => fn => {
  set.tree.forEach(key => { fn(key); });
};