cinny/src/app/utils/mediaGroups.test.ts

import { describe, it } from 'node:test';
import assert from 'node:assert/strict';
import { GroupCandidate, findMediaRun, planMediaGroups, splitRun } from './mediaGroups';

const media = (
  sender: string,
  ts: number,
  extra: Partial<GroupCandidate> = {},
): GroupCandidate => ({
  sender,
  ts,
  kind: 'media',
  hasRelation: false,
  redacted: false,
  mustEnd: false,
  ...extra,
});
const text = (sender: string, ts: number): GroupCandidate => ({
  ...media(sender, ts),
  kind: 'other',
});
const skip = (ts: number): GroupCandidate => ({ ...media('x', ts), kind: 'skip' });
const seq = (items: GroupCandidate[]) => (i: number) => items[i];

describe('findMediaRun', () => {
  it('collects contiguous same-sender media within the gap, from any member', () => {
    const at = seq([
      text('a', 0),
      media('a', 1000),
      media('a', 2000),
      media('a', 3000),
      text('a', 4000),
    ]);
    assert.deepEqual(findMediaRun(at, 1), [1, 2, 3]);
    assert.deepEqual(findMediaRun(at, 2), [1, 2, 3]);
    assert.deepEqual(findMediaRun(at, 3), [1, 2, 3]);
  });

  it('breaks on a different sender, text in between, or a long gap', () => {
    const at = seq([
      media('a', 0),
      media('b', 1000),
      media('a', 2000),
      text('a', 2500),
      media('a', 3000),
      media('a', 70_000),
    ]);
    assert.deepEqual(findMediaRun(at, 0), [0]);
    assert.deepEqual(findMediaRun(at, 2), [2]);
    assert.deepEqual(findMediaRun(at, 4), [4]);
    assert.deepEqual(findMediaRun(at, 5), [5]);
  });

  it('skips invisible filler such as reactions and edits', () => {
    const at = seq([media('a', 0), skip(100), skip(200), media('a', 1000)]);
    assert.deepEqual(findMediaRun(at, 0), [0, 3]);
  });

  it('never groups replies, thread messages, edits or redacted events', () => {
    const at = seq([
      media('a', 0),
      media('a', 500, { hasRelation: true }),
      media('a', 1000),
      media('a', 1500, { redacted: true }),
    ]);
    assert.deepEqual(findMediaRun(at, 0), [0]);
    assert.deepEqual(findMediaRun(at, 1), []);
    assert.deepEqual(findMediaRun(at, 2), [2]);
  });

  it('measures the gap between consecutive members, not from the first', () => {
    const at = seq([media('a', 0), media('a', 50_000), media('a', 100_000)]);
    assert.deepEqual(findMediaRun(at, 0), [0, 1, 2]);
  });
});

describe('splitRun', () => {
  it('caps group size and drops singles', () => {
    const items = Array.from({ length: 12 }, (_, i) => media('a', i * 1000));
    const groups = splitRun(
      Array.from({ length: 12 }, (_, i) => i),
      seq(items),
      10,
    );
    assert.deepEqual(groups, [
      [0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
      [10, 11],
    ]);
    assert.deepEqual(splitRun([0, 1, 2, 3], seq(items), 3), [[0, 1, 2]]);
  });

  it('closes a group at a member with reactions so they stay visible', () => {
    const items = [
      media('a', 0),
      media('a', 1000, { mustEnd: true }),
      media('a', 2000),
      media('a', 3000),
    ];
    assert.deepEqual(splitRun([0, 1, 2, 3], seq(items)), [
      [0, 1],
      [2, 3],
    ]);
  });
});

describe('planMediaGroups', () => {
  it('marks only the last member as the renderer', () => {
    const at = seq([media('a', 0), media('a', 1000), media('a', 2000)]);
    const plan = planMediaGroups(at, 1);
    assert.equal(plan.get(0)?.renders, false);
    assert.equal(plan.get(1)?.renders, false);
    assert.equal(plan.get(2)?.renders, true);
    assert.deepEqual(plan.get(2)?.members, [0, 1, 2]);
  });

  it('returns an empty plan for a lone image', () => {
    assert.equal(planMediaGroups(seq([text('a', 0), media('a', 1000)]), 1).size, 0);
  });
});