// Where the flow editor's canvas puts each node. Run by `npm test`.
import assert from "node:assert/strict";
import { test } from "node:test";
import {
  layoutFlow,
  NODE_HEIGHT,
  NODE_WIDTH,
} from "../src/pages/notifications/FlowLayout.ts";

const match = (id) => ({ id, kind: "match", when: [] });
const source = { id: "s", kind: "source", events: ["issues"] };
const flow = (nodes, edges) => ({
  id: "f",
  name: "f",
  enabled: true,
  nodes,
  edges: edges.map(([from, to]) => ({ from, to })),
});
const at = (layout, id) => layout.nodes.find((n) => n.id === id);

test("a lone source sits top left", () => {
  const l = layoutFlow(flow([source], []));
  assert.equal(l.nodes.length, 1);
  assert.equal(at(l, "s").depth, 0);
  assert.equal(l.edges.length, 0);
  assert.ok(l.width > NODE_WIDTH && l.height > NODE_HEIGHT);
});

test("leaves take rows in edge order and a parent sits between its children", () => {
  const l = layoutFlow(
    flow(
      [source, match("a"), match("b"), match("c")],
      [
        ["s", "a"],
        ["s", "b"],
        ["a", "c"],
      ],
    ),
  );
  // c (under a) is the first leaf, b the second; a follows c, s the middle.
  assert.ok(at(l, "c").y < at(l, "b").y);
  assert.equal(at(l, "a").y, at(l, "c").y);
  assert.equal(at(l, "s").y, (at(l, "a").y + at(l, "b").y) / 2);
  assert.equal(at(l, "c").depth, 2);
  assert.ok(at(l, "c").x > at(l, "a").x && at(l, "a").x > at(l, "s").x);
});

test("no two nodes overlap", () => {
  const nodes = [source];
  const edges = [];
  for (let i = 0; i < 6; i += 1) {
    nodes.push(match(`m${i}`), match(`n${i}`));
    edges.push(["s", `m${i}`], [`m${i}`, `n${i}`]);
  }
  const l = layoutFlow(flow(nodes, edges));
  for (const a of l.nodes) {
    for (const b of l.nodes) {
      if (a === b) continue;
      const apart =
        a.x + NODE_WIDTH <= b.x ||
        b.x + NODE_WIDTH <= a.x ||
        a.y + NODE_HEIGHT <= b.y ||
        b.y + NODE_HEIGHT <= a.y;
      assert.ok(apart, `${a.id} overlaps ${b.id}`);
    }
  }
});

test("an edge runs from the parent's right side to the child's left", () => {
  const l = layoutFlow(flow([source, match("a")], [["s", "a"]]));
  const [e] = l.edges;
  assert.equal(e.x1, at(l, "s").x + NODE_WIDTH);
  assert.equal(e.x2, at(l, "a").x);
  assert.equal(e.y1, at(l, "s").y + NODE_HEIGHT / 2);
  assert.equal(e.y2, at(l, "a").y + NODE_HEIGHT / 2);
});

test("a node nothing reaches yet still gets a place, below the tree", () => {
  const l = layoutFlow(flow([source, match("a"), match("lost")], [["s", "a"]]));
  assert.equal(l.nodes.length, 3);
  assert.ok(at(l, "lost").y > at(l, "a").y);
  assert.equal(l.edges.length, 1);
});

test("edges to unknown nodes are left out, and a cycle terminates", () => {
  const l = layoutFlow(
    flow(
      [source, match("a"), match("b")],
      [
        ["s", "a"],
        ["a", "b"],
        ["b", "a"],
        ["s", "ghost"],
      ],
    ),
  );
  assert.equal(l.nodes.length, 3);
  assert.ok(l.edges.every((e) => e.to !== "ghost"));
});

test("a node with two parents is placed once", () => {
  const l = layoutFlow(
    flow(
      [source, match("a"), match("b"), match("x")],
      [
        ["s", "a"],
        ["s", "b"],
        ["a", "x"],
        ["b", "x"],
      ],
    ),
  );
  assert.equal(l.nodes.length, 4);
  const spots = new Set(l.nodes.map((n) => `${n.x},${n.y}`));
  assert.equal(spots.size, 4, "no two nodes share a spot");
});

test("an empty flow has an empty layout", () => {
  const l = layoutFlow(flow([], []));
  assert.deepEqual(l.nodes, []);
  assert.ok(l.width >= 0 && l.height >= 0);
});