import { test } from 'node:test';
import assert from 'node:assert/strict';
import type { Room, MatrixEvent } from 'matrix-js-sdk';
import { ReceiptType } from 'matrix-js-sdk/lib/@types/read_receipts';
import { computeUpdatedPositions, getReceiptUserIds } from './useRoomReadPositions';

// Fake, renderable (no reaction/edit relation) event.
const fakeEvent = (id: string) =>
  ({
    getId: () => id,
    getRelation: () => null,
  }) as unknown as MatrixEvent;

// Minimal fake room: a fixed live timeline plus a mutable per-user read-up-to map,
// which the test mutates between calls to simulate new receipts arriving.
const makeFakeRoom = (eventIds: string[]) => {
  const readUpTo = new Map<string, string>();
  const events = eventIds.map(fakeEvent);
  const room = {
    getLiveTimeline: () => ({ getEvents: () => events }),
    getEventReadUpTo: (userId: string) => readUpTo.get(userId) ?? null,
  } as unknown as Room;
  return { room, readUpTo };
};

test('getReceiptUserIds collects every userId across events/types in the content', () => {
  const content = {
    $a: {
      [ReceiptType.Read]: { '@alice:hs': { ts: 1 }, '@bob:hs': { ts: 2 } },
    },
    $b: {
      [ReceiptType.ReadPrivate]: { '@carol:hs': { ts: 3 } },
    },
  };
  const ids = getReceiptUserIds(content).sort();
  assert.deepEqual(ids, ['@alice:hs', '@bob:hs', '@carol:hs']);
});

test('getReceiptUserIds returns empty for an empty receipt content', () => {
  assert.deepEqual(getReceiptUserIds({}), []);
});

test('computeUpdatedPositions returns the SAME map reference when no named user changed position', () => {
  const { room, readUpTo } = makeFakeRoom(['$a', '$b']);
  readUpTo.set('@alice:hs', '$a');
  const prev = computeUpdatedPositions(room, '@me:hs', new Map(), ['@alice:hs']);
  assert.deepEqual(prev.get('$a'), ['@alice:hs']);

  // Alice's read-up-to did not move; recompute should be a no-op reference-wise.
  const next = computeUpdatedPositions(room, '@me:hs', prev, ['@alice:hs']);
  assert.equal(next, prev);
});

test('computeUpdatedPositions moves only the named user, leaving other entries untouched by reference', () => {
  const { room, readUpTo } = makeFakeRoom(['$a', '$b']);
  readUpTo.set('@alice:hs', '$a');
  readUpTo.set('@bob:hs', '$a');
  const prev = computeUpdatedPositions(room, '@me:hs', new Map(), ['@alice:hs', '@bob:hs']);
  const bArrayBefore = prev.get('$a');

  // Only alice moves to $b.
  readUpTo.set('@alice:hs', '$b');
  const next = computeUpdatedPositions(room, '@me:hs', prev, ['@alice:hs']);

  assert.notEqual(next, prev);
  assert.deepEqual(next.get('$a'), ['@bob:hs']);
  assert.deepEqual(next.get('$b'), ['@alice:hs']);
  // Untouched arrays for other targets should keep their old reference where possible.
  assert.notEqual(next.get('$a'), bArrayBefore); // this one WAS filtered, expected to change
});

test('computeUpdatedPositions ignores changedUserIds not present after filtering myUserId', () => {
  const { room } = makeFakeRoom(['$a']);
  const prev = new Map([['$a', ['@bob:hs']]]);
  const next = computeUpdatedPositions(room, '@me:hs', prev, ['@me:hs']);
  assert.equal(next, prev);
});

test('computeUpdatedPositions removes a user with no read-up-to event from the map', () => {
  const { room, readUpTo } = makeFakeRoom(['$a']);
  readUpTo.set('@alice:hs', '$a');
  const prev = computeUpdatedPositions(room, '@me:hs', new Map(), ['@alice:hs']);
  assert.deepEqual(prev.get('$a'), ['@alice:hs']);

  readUpTo.delete('@alice:hs');
  const next = computeUpdatedPositions(room, '@me:hs', prev, ['@alice:hs']);
  assert.equal(next.has('$a'), false);
});