class GraphRouter {
  constructor(state) {
    this.vertices = {};
    this.sortedVerticies = [];
    this.visitedVerticies = [];
  }

  addNode(path, dependencies, resolve) {
    const vertex = {
      name: path.split('/').pop(),
      path,
      edges: dependencies,
      resolve,
    };
    this.vertices[path] = vertex;
  }

  _visitForSort(vertex) {
    if (this.visitedVerticies[vertex.path] === 2) return;
    if (this.visitedVerticies[vertex.path] === 1) throw new Error(`CYCLE FOUND AT ${vertex}`);

    this.visitedVerticies[vertex.path] = 1;
    vertex.edges.length && vertex.edges.map((v) => this._visitForSort(this.vertices[v]));
    this.visitedVerticies[vertex.path] = 2;
    this.sortedVerticies.push(vertex);
  }

  sort() {
    // Reverse topological sort
    this.sortedVerticies = [];
    this.visitedVerticies = [];
    const vertices = Object.values(this.vertices);
    while (vertices.length > 0) {
      this._visitForSort(vertices.shift());
    }
  }

  _sortIfNotSorted() {
    if (Object.keys(this.vertices).length > this.sortedVerticies.length) {
      this.sort();
    }
  }

  get order() {
    this._sortIfNotSorted();
    return this.sortedVerticies;
  }

  next() {
    this._sortIfNotSorted();
  }
  goTo(route) {
    this._sortIfNotSorted();
    const verticies = this.sortedVerticies;
    let curr = verticies.shift();
    while (curr.path !== route) {
      console.log('Visiting', curr.path);
      curr.resolve('some render root', {internet: true}, () => {});
      curr = verticies.shift();
    }
    console.log('Visiting', curr.path);
    curr.resolve('some render root', {internet: true}, () => {});
  }

  _findRouteIndex(route) {
    this._sortIfNotSorted();
    return this.sortedVerticies.findIndex(route);
  }
}

const router = new GraphRouter();
const internetDeps = [];
const tvDeps = ['/tv-internet/internet'];
const phoneDeps = ['/tv-internet/tv'];
const tvInterenetDeps =
  ['/tv-internet/internet', '/tv-internet/tv', '/tv-internet/phone', '/sign-up'];
const doneDeps = ['/tv-internet', '/promotions', '/sign-up'];
const resolveNow = (_, __, resolve) => resolve(true);
router.addNode('/tv-internet/internet', internetDeps, (div, state, resolve) => {
  if (state.internet) {
    return resolve();
  } else {
    div.innerHTML = `<div> internet </div>`
  }
});
router.addNode('/tv-internet/tv', tvDeps, resolveNow);
router.addNode('/tv-internet/phone', phoneDeps, resolveNow);
router.addNode('/tv-internet', tvInterenetDeps, resolveNow);
router.addNode('/promotions', ['/sign-up'], resolveNow);
router.addNode('/sign-up', [], resolveNow);
router.addNode('/done', doneDeps, resolveNow)

console.log(router.order.map((v) => v.path));
router.goTo('/promotions');
/*
[ '/tv-internet/internet',
  '/tv-internet/tv',
  '/tv-internet/phone',
  '/sign-up',
  '/tv-internet',
  '/promotions',
  '/done' ]
Visiting /tv-internet/internet
Visiting /tv-internet/tv
Visiting /tv-internet/phone
Visiting /sign-up
Visiting /tv-internet
Visiting /promotions
*/