import assert from 'node:assert/strict';
import test from 'node:test';

import { FrameRenderer } from '../../YouleNexus/assets/framework/presentation/frame-renderer.ts';

test('coalesces frames and invalidates callbacks even if scheduler delivers late', () => {
  const callbacks: (() => void)[] = [];
  let cancelled = 0;
  let rendered = 0;
  const renderer = new FrameRenderer({
    request(cb) { callbacks.push(cb); return () => { cancelled++; }; },
  }, () => { rendered++; }, e => { throw e; });
  renderer.request(); renderer.request();
  assert.equal(callbacks.length, 1);
  renderer.flush();
  assert.equal(rendered, 1);
  callbacks[0]!();
  assert.equal(rendered, 1);
  renderer.request();
  renderer.dispose(); renderer.dispose();
  callbacks[1]!();
  assert.equal(rendered, 1);
  assert.equal(cancelled, 2);
});

test('releases the current frame before render can request the next frame', () => {
  const callbacks: (() => void)[] = [];
  let rendered = 0;
  let renderer!: FrameRenderer;
  renderer = new FrameRenderer({
    request(callback) { callbacks.push(callback); return () => {}; },
  }, () => {
    rendered += 1;
    renderer.request();
  }, error => { throw error; });

  renderer.request();
  callbacks[0]!();

  assert.equal(rendered, 1);
  assert.equal(callbacks.length, 2);

  callbacks[1]!();
  assert.equal(rendered, 2);
  assert.equal(callbacks.length, 3);
});

test('dispose during render prevents a reentrant frame request', () => {
  const callbacks: (() => void)[] = [];
  let rendered = 0;
  let renderer!: FrameRenderer;
  renderer = new FrameRenderer({
    request(callback) { callbacks.push(callback); return () => {}; },
  }, () => {
    rendered += 1;
    renderer.dispose();
    renderer.request();
  }, error => { throw error; });

  renderer.request();
  callbacks[0]!();

  assert.equal(rendered, 1);
  assert.equal(callbacks.length, 1);
  renderer.flush();
  assert.equal(rendered, 1);
});

test('a throwing dispose cancellation still makes every callback stale', () => {
  const callbacks: (() => void)[] = [];
  const cancelError = new Error('cancel failed');
  let rendered = 0;
  const renderer = new FrameRenderer({
    request(callback) {
      callbacks.push(callback);
      return () => { throw cancelError; };
    },
  }, () => { rendered += 1; }, error => { throw error; });

  renderer.request();
  let thrown: unknown;
  try {
    renderer.dispose();
  } catch (error) {
    thrown = error;
  }

  assert.equal(thrown, cancelError);
  callbacks[0]!();
  assert.equal(rendered, 0);
  renderer.request();
  assert.equal(callbacks.length, 1);
});

test('a throwing flush cancellation invalidates the old frame before rethrowing', () => {
  const callbacks: (() => void)[] = [];
  const cancelError = new Error('cancel failed');
  let rendered = 0;
  const renderer = new FrameRenderer({
    request(callback) {
      callbacks.push(callback);
      return () => { throw cancelError; };
    },
  }, () => { rendered += 1; }, error => { throw error; });

  renderer.request();
  let thrown: unknown;
  try {
    renderer.flush();
  } catch (error) {
    thrown = error;
  }

  assert.equal(thrown, cancelError);
  callbacks[0]!();
  assert.equal(rendered, 0);
  renderer.request();
  assert.equal(callbacks.length, 2);
});

test('flush does not render when cancellation disposes the renderer', () => {
  let rendered = 0;
  let renderer!: FrameRenderer;
  renderer = new FrameRenderer({
    request() { return () => { renderer.dispose(); }; },
  }, () => { rendered += 1; }, error => { throw error; });

  renderer.request();
  renderer.flush();

  assert.equal(rendered, 0);
});

test('a cancellation that reenters flush supersedes the outer render', () => {
  let rendered = 0;
  let renderer!: FrameRenderer;
  renderer = new FrameRenderer({
    request() { return () => { renderer.flush(); }; },
  }, () => { rendered += 1; }, error => { throw error; });

  renderer.request();
  renderer.flush();

  assert.equal(rendered, 1);
});

test('reports an asynchronous render error once and terminates future frames', () => {
  const callbacks: (() => void)[] = [];
  const renderError = new Error('render failed');
  const faults: unknown[] = [];
  let rendered = 0;
  const renderer = new FrameRenderer({
    request(callback) { callbacks.push(callback); return () => {}; },
  }, () => {
    rendered += 1;
    throw renderError;
  }, error => { faults.push(error); });

  renderer.request();
  let thrown: unknown;
  try {
    callbacks[0]!();
  } catch (error) {
    thrown = error;
  }

  assert.equal(thrown, undefined);
  assert.deepEqual(faults, [renderError]);
  callbacks[0]!();
  renderer.request();
  assert.equal(rendered, 1);
  assert.deepEqual(faults, [renderError]);
  assert.equal(callbacks.length, 1);
});

test('aggregates an asynchronous render error with reentrant cancellation failure', () => {
  const callbacks: (() => void)[] = [];
  const renderError = new Error('render failed');
  const cancelError = new Error('cancel failed');
  const faults: unknown[] = [];
  let rendered = 0;
  let renderer!: FrameRenderer;
  renderer = new FrameRenderer({
    request(callback) {
      callbacks.push(callback);
      return () => { throw cancelError; };
    },
  }, () => {
    rendered += 1;
    renderer.request();
    throw renderError;
  }, error => { faults.push(error); });

  renderer.request();
  let thrown: unknown;
  try {
    callbacks[0]!();
  } catch (error) {
    thrown = error;
  }

  assert.equal(thrown, undefined);
  assert.equal(faults.length, 1);
  const fault = faults[0];
  assert.ok(fault instanceof Error);
  assert.ok('errors' in fault);
  assert.deepEqual(fault.errors, [renderError, cancelError]);
  callbacks[1]!();
  assert.equal(rendered, 1);
  assert.equal(faults.length, 1);
});

test('flush rethrows a synchronous render error without reporting an async fault', () => {
  const callbacks: (() => void)[] = [];
  const renderError = new Error('render failed');
  const faults: unknown[] = [];
  let rendered = 0;
  const renderer = new FrameRenderer({
    request(callback) { callbacks.push(callback); return () => {}; },
  }, () => {
    rendered += 1;
    throw renderError;
  }, error => { faults.push(error); });

  renderer.request();
  let thrown: unknown;
  try {
    renderer.flush();
  } catch (error) {
    thrown = error;
  }

  assert.equal(thrown, renderError);
  assert.deepEqual(faults, []);
  callbacks[0]!();
  assert.equal(rendered, 1);
});

test('does not swallow an onFault callback error', () => {
  const callbacks: (() => void)[] = [];
  const renderError = new Error('render failed');
  const callbackError = new Error('fault callback failed');
  const reported: unknown[] = [];
  const renderer = new FrameRenderer({
    request(callback) { callbacks.push(callback); return () => {}; },
  }, () => { throw renderError; }, error => {
    reported.push(error);
    throw callbackError;
  });

  renderer.request();
  let thrown: unknown;
  try {
    callbacks[0]!();
  } catch (error) {
    thrown = error;
  }

  assert.equal(thrown, callbackError);
  assert.deepEqual(reported, [renderError]);
  renderer.request();
  assert.equal(callbacks.length, 1);
});