// The sectionEnter rule, against the shape of the one manifest that uses it.
import assert from "node:assert/strict";
import test from "node:test";
import { applySectionEnter, sectionEnterFlags, usesSectionEnter } from "./sections.mjs";

const clip = (id, section, extra = {}) => ({ type: "clip", id, section, ...extra });

test("a clip enters a section when its section differs from the previous clip's", () => {
  const tl = [
    { type: "card", id: "t0" },
    clip("a", 1),
    clip("b", 1),
    { type: "card", id: "mid" },
    clip("c", 1),
    clip("d", 2),
    clip("e"),
    clip("f", 2),
    { type: "scroll", id: "s" },
  ];
  assert.deepEqual(sectionEnterFlags(tl), [false, true, false, false, false, true, false, true, false]);
});

test("applySectionEnter leaves a timeline that never used the flag alone", () => {
  const tl = [clip("a", 1), clip("b", 2)];
  assert.deepEqual(applySectionEnter(tl), []);
  assert.equal(usesSectionEnter(tl), false);
  assert.equal("sectionEnter" in tl[0], false);
});

test("applySectionEnter is the identity on a timeline already in order, and fixes a move", () => {
  const tl = [clip("a", 1, { sectionEnter: true }), clip("b", 1), clip("c", 2, { sectionEnter: true }), clip("d", 2)];
  assert.deepEqual(applySectionEnter(tl), []);
  // d moved to the front: d enters 2, a enters 1, c no longer enters (b was 1, c is 2 -> still enters)
  const moved = [tl[3], tl[0], tl[1], tl[2]];
  assert.deepEqual(applySectionEnter(moved).sort(), ["d"]);
  assert.equal(moved[0].sectionEnter, true);
  assert.equal(moved[3].sectionEnter, true);
  // and moving it back removes the flag again (deleted, never written false)
  const back = [moved[1], moved[2], moved[3], moved[0]];
  assert.deepEqual(applySectionEnter(back), ["d"]);
  assert.equal("sectionEnter" in back[3], false);
});