// Tiny wrapper around function-red-black-tree that overrides the [inspect.custom] symbol so when we print it (during debugging) we just see the (key=>value)-pairs instead of the tree structure.

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

function defaultPrintf(depth, options, inspect) {
  const entries = [];
  this.tree.forEach((key, val) => { entries.push(`${inspect(key)} => ${inspect(val)}`); });
  return `RBTree(${this.tree.length}) {${entries.join(', ')}}`;
}

export class RBTreeWrapper {
  constructor(tree, printf = defaultPrintf) {
    this.tree = tree;
    this[inspect.custom] = printf;
  }

  static new(compareFn) {
    return new RBTreeWrapper(createRBTree(compareFn))
  }

  // only for debugging:
  keys() {
    return this.tree.keys;
  }

  // only for debugging:
  entries() {
    return this.tree.keys.map(key => [key, this.tree.get(key)]);
  }
}

// Can be used as drop-in replacement for Map
// Why create a mutable adapter for a purely-functional data structure?
// Because the builtin Map does not allow custom comparison functions and this one does.
export class MutableRBTree {
  constructor(tree, printf = defaultPrintf) {
    this.tree = tree;
    this[inspect.custom] = printf;
  }

  static new(cmp) {
    return new MutableRBTree(createRBTree(cmp));
  }

  set(key, value) {
    this.tree = this.tree.remove(key).insert(key, value);
  }

  delete(key) {
    this.tree = this.tree.remove(key);
  }

  get(key) {
    return this.tree.get(key);
  }

  has(key) {
    return this.tree.get(key) !== undefined;
  }

  clear() {
    this.tree = createRBTree(this.tree._compare);
  }

  *[Symbol.iterator]() {
    const iter = this.tree.begin;
    while (iter !== undefined && iter.valid) {
      yield [iter.key, iter.value];
      iter.next();
    }
  }
}