import test from "node:test";
import assert from "node:assert/strict";
import { changedLightSections } from "../light-changes.js";

function field(min = [-2, -2, -2], size = [54, 36, 36]) {
  const count = size.reduce((product, value) => product * value, 1);
  return {
    min,
    size,
    data: new Uint8Array(count * 4),
    skyLevels: new Uint8Array(count).fill(15),
  };
}
const index = (field, [x, y, z]) =>
  x -
  field.min[0] +
  field.size[0] * (y - field.min[1] + field.size[1] * (z - field.min[2]));

test("initial lighting marks current sections, while equal fields retain every mesh", () => {
  const sections = new Map([
    ["0,0,0", { vao: "first" }],
    ["1,0,0", { vao: "retained" }],
  ]);
  assert.deepEqual(changedLightSections(null, field(), sections.keys()), [
    ...sections.keys(),
  ]);
  const before = [...sections.values()];
  assert.deepEqual(changedLightSections(field(), field(), sections.keys()), []);
  assert.deepEqual([...sections.values()], before);
});

test("a corner light delta invalidates all eight sharing neighborhoods but no distant section", () => {
  const previous = field(),
    next = field();
  next.skyLevels[index(next, [15, 15, 15])] = 14;
  const neighbors = [];
  for (let x = 0; x <= 1; x++)
    for (let y = 0; y <= 1; y++)
      for (let z = 0; z <= 1; z++) neighbors.push(`${x},${y},${z}`);
  assert.deepEqual(
    changedLightSections(previous, next, [...neighbors, "2,0,0"]),
    neighbors,
  );
});

test("a tint-only change crosses the section boundary and preserves distant retained sections", () => {
  const previous = field(),
    next = field();
  next.data[index(next, [16, 4, 4]) * 4 + 2] = 180;
  const sections = ["0,0,0", "1,0,0", "2,0,0"];
  assert.deepEqual(changedLightSections(previous, next, sections), [
    "0,0,0",
    "1,0,0",
  ]);
});

test("moving field bounds compares world coordinates and only invalidates lost coverage", () => {
  const previous = field();
  const shifted = field([-1, -2, -2], [55, 36, 36]);
  assert.deepEqual(
    changedLightSections(previous, shifted, ["0,0,0", "1,0,0"]),
    [],
  );
  const clipped = field([0, -2, -2], [54, 36, 36]);
  assert.deepEqual(
    changedLightSections(previous, clipped, ["0,0,0", "1,0,0"]),
    ["0,0,0"],
  );
});