import { Graph } from "graphlib";
import { feasibleTree } from "./feasible-tree";

describe("feasibleTree", function () {
  it("creates a tree for a trivial input graph", function () {
    const g = new Graph().setNode("a", { rank: 0 }).setNode("b", { rank: 1 }).setEdge("a", "b", { minlen: 1 });

    const tree = feasibleTree(g);
    expect(g.node("b").rank).toBe(g.node("a").rank + 1);
    expect(tree.neighbors("a")).toEqual(["b"]);
  });

  it("correctly shortens slack by pulling a node up", function () {
    const g = new Graph()
      .setNode("a", { rank: 0 })
      .setNode("b", { rank: 1 })
      .setNode("c", { rank: 2 })
      .setNode("d", { rank: 2 })
      .setPath(["a", "b", "c"], { minlen: 1 })
      .setEdge("a", "d", { minlen: 1 });

    const tree = feasibleTree(g);
    expect(g.node("b").rank).toEqual(g.node("a").rank + 1);
    expect(g.node("c").rank).toEqual(g.node("b").rank + 1);
    expect(g.node("d").rank).toEqual(g.node("a").rank + 1);
    expect((tree.neighbors("a") as string[]).sort()).toEqual(["b", "d"]);
    expect((tree.neighbors("b") as string[]).sort()).toEqual(["a", "c"]);
    expect(tree.neighbors("c")).toEqual(["b"]);
    expect(tree.neighbors("d")).toEqual(["a"]);
  });

  it("correctly shortens slack by pulling a node down", function () {
    const g = new Graph()
      .setNode("a", { rank: 2 })
      .setNode("b", { rank: 0 })
      .setNode("c", { rank: 2 })
      .setEdge("b", "a", { minlen: 1 })
      .setEdge("b", "c", { minlen: 1 });

    const tree = feasibleTree(g);
    expect(g.node("a").rank).toEqual(g.node("b").rank + 1);
    expect(g.node("c").rank).toEqual(g.node("b").rank + 1);
    expect((tree.neighbors("a") as string[]).sort()).toEqual(["b"]);
    expect((tree.neighbors("b") as string[]).sort()).toEqual(["a", "c"]);
    expect((tree.neighbors("c") as string[]).sort()).toEqual(["b"]);
  });
});