/** Isolated hook acceptance checks and full-process timing; never stages this checkout. */
import assert from 'node:assert/strict';
import { execFileSync, spawnSync } from 'node:child_process';
import { cpSync, mkdtempSync, readFileSync, writeFileSync, symlinkSync } from 'node:fs';
import { tmpdir, cpus, platform, release } from 'node:os';
import path from 'node:path';
import { fileURLToPath } from 'node:url';
import { performance } from 'node:perf_hooks';

const source = fileURLToPath(new URL('../../', import.meta.url));
const root = mkdtempSync(path.join(tmpdir(), 's2-hook-acceptance-'));
const frontend = path.join(root, 'agiledancers-fe');
const excluded = new Set([
  'node_modules',
  'dist',
  '.angular',
  'coverage',
  'test-results',
  'unit-results',
  'playwright-report',
  '_',
]);
cpSync(path.join(source, 'agiledancers-fe'), frontend, {
  recursive: true,
  filter: (file) => !excluded.has(path.basename(file)),
});
cpSync(path.join(source, '.husky'), path.join(root, '.husky'), {
  recursive: true,
  filter: (file) => !excluded.has(path.basename(file)),
});
symlinkSync(
  path.join(source, 'agiledancers-fe/node_modules'),
  path.join(frontend, 'node_modules'),
  'dir',
);
const env = { ...process.env };
delete env.CI;
delete env.HUSKY;
function run(command, args, cwd = root, environment = env) {
  return execFileSync(command, args, {
    cwd,
    env: environment,
    encoding: 'utf8',
    stdio: ['ignore', 'pipe', 'pipe'],
  }).trimEnd();
}
const git = (...args) => run('git', args);
const write = (file, content) => writeFileSync(path.join(root, file), content);
const read = (file) => readFileSync(path.join(root, file), 'utf8');
const fixture = 'agiledancers-fe/src/hook-fixture.ts';
const baseline =
  'export const hookValue = { value: 1 };\n\n// Independent edits below.\n\nexport const otherValue = 1;\n';
write(fixture, baseline);
write('unrelated.txt', 'baseline\n');
git('init', '-q');
git('config', 'user.name', 'S2 validation');
git('config', 'user.email', 's2@example.invalid');
git('add', '.');
git('-c', 'core.hooksPath=/dev/null', 'commit', '-qm', 'Fixture baseline');
git('config', 'core.hooksPath', '/dev/null');
run('node', ['tools/install-hooks.mjs'], frontend, { ...env, CI: 'true' });
assert.equal(git('config', '--get', 'core.hooksPath'), '/dev/null');
run('node', ['tools/install-hooks.mjs'], frontend, { ...env, HUSKY: '0' });
assert.equal(git('config', '--get', 'core.hooksPath'), '/dev/null');
console.log('PASS CI and HUSKY=0 skip hook installation');
run('node', ['tools/install-hooks.mjs'], frontend);
assert.equal(git('config', '--get', 'core.hooksPath'), '.husky/_');
const reset = () => git('reset', '--hard', '-q', 'HEAD');
const snapshot = () =>
  JSON.stringify([
    git('diff', '--cached', '--binary'),
    git('diff', '--binary'),
    git('status', '--porcelain'),
    git('stash', 'list'),
  ]);
function hook() {
  const start = performance.now();
  const result = spawnSync('sh', ['.husky/_/pre-commit'], { cwd: root, env, encoding: 'utf8' });
  return {
    seconds: Number(((performance.now() - start) / 1000).toFixed(3)),
    exit: result.status,
    output: result.stdout + result.stderr,
  };
}
function passed(name) {
  console.log(`PASS ${name}`);
}

// Format only the index version while independently staged/unstaged edits survive.
write(fixture, baseline.replace('{ value: 1 }', '{value:2}'));
git('add', fixture);
write(fixture, read(fixture).replace('otherValue = 1', 'otherValue = 2'));
write('unrelated.txt', 'staged\n');
git('add', 'unrelated.txt');
write('unrelated.txt', 'staged\nunstaged\n');
const result = hook();
assert.equal(result.exit, 0, result.output);
assert.match(git('show', `:${fixture}`), /hookValue = \{ value: 2 \}/);
assert.match(git('show', `:${fixture}`), /otherValue = 1/);
assert.match(read(fixture), /otherValue = 2/);
assert.equal(git('show', ':unrelated.txt'), 'staged');
assert.equal(read('unrelated.txt'), 'staged\nunstaged\n');
assert.equal(git('stash', 'list'), '');
passed('partially staged formatting preserves unrelated staged and unstaged changes');
reset();

write('unrelated.txt', 'only backend/documentation\n');
git('add', 'unrelated.txt');
let before = snapshot();
assert.equal(hook().exit, 0);
assert.equal(snapshot(), before);
passed('commits without frontend changes leave state unchanged');
reset();

write('agiledancers-fe/package-lock.json', read('agiledancers-fe/package-lock.json') + '\n\n');
git('add', 'agiledancers-fe/package-lock.json');
before = snapshot();
assert.equal(hook().exit, 0);
assert.equal(snapshot(), before);
passed('generated lockfile is excluded');
reset();

write(
  'agiledancers-fe/src/app/app.ts',
  read('agiledancers-fe/src/app/app.ts') + '\nexport const formatterCheck={value:2};\n',
);
write(fixture, 'export const broken = ;\n');
git('add', 'agiledancers-fe/src/app/app.ts', fixture);
write('unrelated.txt', 'unstaged survives failures\n');
before = snapshot();
const failed = hook();
assert.notEqual(failed.exit, 0);
assert.match(failed.output, /SyntaxError|Unexpected token/);
assert.equal(snapshot(), before);
passed('formatter failure restores index, worktree and stash');
reset();

write(fixture, baseline.replace('{ value: 1 }', '{value:2}'));
git('add', fixture);
write(fixture, read(fixture).replace('{value:2}', '{value:3}'));
before = snapshot();
const conflict = hook();
assert.notEqual(conflict.exit, 0, conflict.output);
assert.match(conflict.output, /conflict|Failed to restore unstaged/i);
assert.equal(snapshot(), before);
passed('unstaged reconciliation conflict restores original state');
reset();

// Benchmark the rejected combined candidate using the same hook and state protections.
const selectedConfig = read('agiledancers-fe/lint-staged.config.mjs');
write(
  'agiledancers-fe/lint-staged.combined.mjs',
  `import base from './lint-staged.config.mjs';
export default Object.fromEntries(Object.entries(base).map(([pattern, task]) => [pattern, files => {
  const commands = task(files);
  const lintable = files.filter(file => /\\.(ts|js|mjs|cjs|html)$/.test(file));
  return commands.length && lintable.length
    ? [...commands, 'eslint --max-warnings 0 ' + lintable.map(file => JSON.stringify(file)).join(' ')] : commands;
}]));\n`,
);
const selectedHook = read('.husky/pre-commit');
write(
  '.husky/pre-commit',
  selectedHook.replace(
    '--concurrent false',
    '--concurrent false --config lint-staged.combined.mjs',
  ),
);
write(fixture, baseline.replace('{ value: 1 }', '{value:2}'));
write(
  'agiledancers-fe/src/app/app.ts',
  read('agiledancers-fe/src/app/app.ts') + '\nexport const badLint: any = 1;\n',
);
git('add', fixture, 'agiledancers-fe/src/app/app.ts');
before = snapshot();
const lintFailure = hook();
assert.notEqual(lintFailure.exit, 0);
assert.match(lintFailure.output, /no-explicit-any/);
assert.equal(snapshot(), before);
passed('combined candidate restores formatting after ESLint failure');
reset();

const all = git('ls-files', 'agiledancers-fe')
  .split('\n')
  .filter((file) => !file.endsWith('/package-lock.json'));
const scopes = {
  single: ['agiledancers-fe/src/app/app.ts'],
  mixed: [
    'agiledancers-fe/src/app/app.ts',
    'agiledancers-fe/src/app/app.html',
    'agiledancers-fe/src/app/app.css',
    'agiledancers-fe/angular.json',
    'agiledancers-fe/eslint.config.mjs',
    'agiledancers-fe/e2e/school-management.spec.ts',
  ],
  all,
};
const timings = [];
for (const mode of ['combined', 'prettier-only']) {
  for (const [scope, files] of Object.entries(scopes)) {
    for (let repeat = 1; repeat <= 3; repeat++) {
      reset();
      write(
        '.husky/pre-commit',
        mode === 'combined'
          ? selectedHook.replace(
              '--concurrent false',
              '--concurrent false --config lint-staged.combined.mjs',
            )
          : selectedHook,
      );
      for (const file of files) {
        const addition = /\.(ts|js|mjs|cjs)$/.test(file)
          ? '\n// Hook timing fixture.\n'
          : file.endsWith('.html')
            ? '\n<!-- Hook timing fixture. -->\n'
            : file.endsWith('.css')
              ? '\n/* Hook timing fixture. */\n'
              : '\n';
        write(file, read(file) + addition);
      }
      git('add', '--', ...files);
      const measurement = hook();
      assert.equal(measurement.exit, 0, measurement.output);
      timings.push({ mode, scope, repeat, files, seconds: measurement.seconds });
      console.log(`TIMING ${mode} ${scope} ${repeat}: ${measurement.seconds}s`);
    }
  }
}
assert.equal(read('agiledancers-fe/lint-staged.config.mjs').includes(selectedConfig.trim()), true);
const report = {
  machine: cpus()[0].model,
  system: `${platform()} ${release()}`,
  node: process.version,
  npm: run('npm', ['--version']),
  root,
  timings,
};
writeFileSync(path.join(root, 'report.json'), JSON.stringify(report, null, 2) + '\n');
console.log(`Evidence: ${path.join(root, 'report.json')}`);
const selected = timings.filter((result) => result.mode === 'prettier-only');
assert.ok(
  selected.every((result) => result.seconds <= 3),
  'Prettier-only exceeds the three-second budget; do not enable the hook.',
);