(() => {
  const dim = 7;
  const graph = {};
  const path = [];

  // create graph
  for (let i = 0; i < dim*dim; i++) {
    const row = i % dim;
    const col = Math.floor(i / dim);
    const edges = [
      getIndex(row + 1, col),
      getIndex(row -1, col),
      getIndex(row, col + 1),
      getIndex(row, col - 1),
    ].filter(e => e != null);
    graph[i] = {
      edges: shuffle(edges),
    };
  }

  // create maze path
  explore(graph, 0);

  console.log('graph:', graph);
  console.log('path:', path);

  function getIndex(row, col) {
    if (row >= dim || row < 0 || col >= dim || col < 0) return null;
    return (col * dim) + row;
  }

  function shuffle(array) {
    for(let i = 0; i < array.length; i++){
      const randomIndex = Math.floor(Math.random() * array.length);
      const temp = array[i];
      array[i] = array[randomIndex];
      array[randomIndex] = temp;
    }
    return array;
  }

  function explore(graph, currentIndex) {
    const current = graph[currentIndex];
    current.visited = true;
    for (let i = 0; i < current.edges.length; i++) {
      const nextIndex = current.edges[i];
      const next = graph[nextIndex];
      if (!next.visited) {
        path.push([currentIndex, nextIndex]);
        explore(graph, nextIndex);
      }
    }
  }

})();