import assert from 'node:assert/strict';

import { readdir } from 'node:fs/promises';

import { replaceInFile } from '../../utils/fs';

import { execWithEnv, ng } from '../../utils/process';

export default async function () {

// Case 1: 2 lazy chunks (below threshold of 3) -> should NOT optimize by default

await ng('generate', 'component', 'lazy-a');

await ng('generate', 'component', 'lazy-b');

await replaceInFile(

'src/app/app.routes.ts',

'routes: Routes = [];',

`routes: Routes = [

{

path: 'lazy-a',

loadComponent: () => import('./lazy-a/lazy-a').then(m => m.LazyA),

},

{

path: 'lazy-b',

loadComponent: () => import('./lazy-b/lazy-b').then(m => m.LazyB),

},

];`,

);

// Build without explicit flag (should use default threshold of 3)

await ng('build', '--output-hashing=none');

const files2 = await readdir('dist/test-project/browser');

const jsFiles2 = files2.filter((f) => f.endsWith('.js'));

// Build with forced optimization to see if it COULD reduce chunks

await execWithEnv('ng', ['build', '--output-hashing=none'], {

...process.env,

NG_BUILD_OPTIMIZE_CHUNKS: 'true',

});

const files2Opt = await readdir('dist/test-project/browser');

const jsFiles2Opt = files2Opt.filter((f) => f.endsWith('.js'));

// If forced optimization reduces chunks, then default should have MORE chunks (since it didn't run).

// If forced optimization doesn't reduce chunks, they will be equal.

// So we assert that default is NOT fewer than forced.

assert.ok(

jsFiles2.length >= jsFiles2Opt.length,

`Expected default build with 2 lazy chunks to NOT be optimized. Default: ${jsFiles2.length}, Forced: ${jsFiles2Opt.length}`,

);

// Case 2: 3 lazy chunks (at threshold of 3) -> should optimize by default

await ng('generate', 'component', 'lazy-c');

await replaceInFile(

'src/app/app.routes.ts',

`path: 'lazy-b',

loadComponent: () => import('./lazy-b/lazy-b').then(m => m.LazyB),

},`,

`path: 'lazy-b',

loadComponent: () => import('./lazy-b/lazy-b').then(m => m.LazyB),

},

{

path: 'lazy-c',

loadComponent: () => import('./lazy-c/lazy-c').then(m => m.LazyC),

},`,

);

// Build without explicit flag (should use default threshold of 3)

await ng('build', '--output-hashing=none');

const files3 = await readdir('dist/test-project/browser');

const jsFiles3 = files3.filter((f) => f.endsWith('.js'));

// Build with explicit disable

await execWithEnv('ng', ['build', '--output-hashing=none'], {

...process.env,

NG_BUILD_OPTIMIZE_CHUNKS: 'false',

});

const files3Unopt = await readdir('dist/test-project/browser');

const jsFiles3Unopt = files3Unopt.filter((f) => f.endsWith('.js'));

// Expect default build to be optimized (fewer chunks than explicitly disabled)

assert.ok(

jsFiles3.length < jsFiles3Unopt.length,

`Expected default build with 3 lazy chunks to be optimized. Default: ${jsFiles3.length}, Unoptimized: ${jsFiles3Unopt.length}`,

);

}