/**
 * Workspace layout test — locks in the [E00-S01-T11] apps/packages/extensions
 * separation for the workspace.
 *
 * Acceptance criteria covered (each test fails without the committed layout):
 *   - "apps, packages and extensions are separated in the workspace layout" →
 *     the repo root contains exactly the three top-level package group
 *     directories apps/, packages/, extensions/; every workspace package.json
 *     lives exactly one level below one of them (never at the root, never in
 *     another directory, never nested deeper); `pnpm-workspace.yaml` declares
 *     one glob per group and `dependency-boundaries.json` maps the same three
 *     groups to the same three directories.
 *   - "each package sits in the correct top-level directory" → the bootstrap
 *     packages are found where their group says: `@personal-blog/server` in
 *     apps/, `@personal-blog/core` in packages/, `@personal-blog/example-
 *     extension` in extensions/; the discovered workspace package set is
 *     exactly the expected one, and every discovered package has a lockfile
 *     importer (layout ↔ lockfile parity).
 *
 * Run: `node --test tests/workspace-layout.test.mjs`
 * (node:test — built into Node >= 18; no dependencies, lockfile untouched.)
 */

import test from 'node:test';
import assert from 'node:assert/strict';
import { readFileSync, readdirSync, statSync } from 'node:fs';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const REPO_ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');

const read = (relPath) => readFileSync(path.join(REPO_ROOT, relPath), 'utf8');

/** The three top-level package group directories of the separated layout. */
const TOP_LEVEL_GROUPS = ['apps', 'packages', 'extensions'];

/** Expected bootstrap packages: package name -> top-level directory it must sit in. */
const EXPECTED_PACKAGES = {
  '@personal-blog/server': 'apps/server',
  '@personal-blog/core': 'packages/core',
  '@personal-blog/database-postgres': 'packages/database-postgres',
  '@personal-blog/example-extension': 'extensions/example',
};

/** Directories never scanned as package sources. */
const IGNORED_DIRS = new Set(['node_modules', 'dist', 'coverage', '.git', '.pnpm-store']);

// ---------------------------------------------------------------------------
// Layout helpers
// ---------------------------------------------------------------------------

function isDirectory(p) {
  try {
    return statSync(p).isDirectory();
  } catch {
    return false;
  }
}

/**
 * Recursively collects every package.json path under a directory, as a
 * repo-root-relative posix path (the root workspace manifest itself is
 * included as "package.json").
 */
function collectPackageJsonPaths(dir) {
  const results = [];
  for (const entry of readdirSync(dir, { withFileTypes: true })) {
    if (entry.isDirectory()) {
      if (!IGNORED_DIRS.has(entry.name)) {
        results.push(...collectPackageJsonPaths(path.join(dir, entry.name)));
      }
    } else if (entry.name === 'package.json') {
      results.push(path.relative(REPO_ROOT, path.join(dir, entry.name)).split(path.sep).join('/'));
    }
  }
  return results;
}

/**
 * Validates the placement of a repo-root-relative package.json path. A
 * workspace package must be exactly `<group>/<name>/package.json` under one of
 * the three top-level groups; the root workspace manifest ("package.json") is
 * the one allowed exception. Returns an error message, or null when the
 * placement is correct.
 */
function placementError(relPath) {
  if (relPath === 'package.json') return null; // workspace root manifest, not a package
  const parts = relPath.split('/');
  if (parts.length !== 3 || parts[2] !== 'package.json') {
    return `"${relPath}" must be <group>/<name>/package.json (exactly one level below a top-level group directory)`;
  }
  if (!TOP_LEVEL_GROUPS.includes(parts[0])) {
    return `"${relPath}" must sit under apps/, packages/ or extensions/ (got "${parts[0]}")`;
  }
  return null;
}

// ---------------------------------------------------------------------------
// Tests
// ---------------------------------------------------------------------------

test('the workspace root contains exactly the three separated top-level group directories', () => {
  for (const group of TOP_LEVEL_GROUPS) {
    assert.ok(
      isDirectory(path.join(REPO_ROOT, group)),
      `top-level directory "${group}/" must exist (apps/packages/extensions separated)`,
    );
  }
});

test('every workspace package.json sits exactly one level below its top-level group directory', () => {
  const manifests = collectPackageJsonPaths(REPO_ROOT);
  const packageManifests = manifests.filter((rel) => rel !== 'package.json');
  assert.ok(packageManifests.length > 0, 'the workspace must contain at least one package manifest');
  for (const rel of packageManifests) {
    const error = placementError(rel);
    assert.equal(error, null, error);
  }
});

test('each expected package sits in the correct top-level directory', () => {
  for (const [name, dir] of Object.entries(EXPECTED_PACKAGES)) {
    const manifest = JSON.parse(read(path.join(dir, 'package.json')));
    assert.equal(
      manifest.name,
      name,
      `"${dir}/package.json" must declare name "${name}" (each package sits in its correct top-level directory)`,
    );
  }
});

test('the discovered workspace package set is exactly the expected bootstrap set', () => {
  const manifests = collectPackageJsonPaths(REPO_ROOT).filter((rel) => rel !== 'package.json');
  const discoveredDirs = new Set(manifests.map((rel) => rel.replace(/\/package\.json$/, '')));
  assert.deepEqual(discoveredDirs, new Set(Object.values(EXPECTED_PACKAGES)));
});

test('pnpm-workspace.yaml declares one group glob per top-level group directory', () => {
  const workspace = read('pnpm-workspace.yaml');
  const packagesSection = workspace.slice(workspace.indexOf('packages:'));
  const globs = [...packagesSection.matchAll(/^\s*-\s*'([^']+)'\s*$/gm)].map((m) => m[1]);
  assert.deepEqual(
    globs,
    TOP_LEVEL_GROUPS.map((g) => `${g}/*`),
    'pnpm-workspace.yaml must declare exactly apps/*, packages/* and extensions/*',
  );
});

test('dependency-boundaries.json maps the three groups to the same top-level directories', () => {
  const rule = JSON.parse(read('dependency-boundaries.json'));
  for (const group of TOP_LEVEL_GROUPS) {
    assert.equal(
      rule.groups?.[group]?.path,
      `${group}/`,
      `dependency-boundaries.json must map group "${group}" to path "${group}/"`,
    );
  }
});

test('every discovered workspace package has a lockfile importer (layout ↔ lockfile parity)', () => {
  const lockfile = read('pnpm-lock.yaml');
  const manifests = collectPackageJsonPaths(REPO_ROOT).filter((rel) => rel !== 'package.json');
  for (const rel of manifests) {
    const importer = rel.replace(/\/package\.json$/, '');
    assert.ok(
      lockfile.includes(`  ${importer}:`),
      `pnpm-lock.yaml must contain an importer for "${importer}" (every package in the layout must be a workspace member)`,
    );
  }
});

test('the placement validation flags mis-placed packages (non-vacuous probe)', () => {
  const valid = [
    'apps/server/package.json',
    'packages/core/package.json',
    'extensions/example/package.json',
    'package.json', // workspace root manifest
  ];
  for (const rel of valid) {
    assert.equal(placementError(rel), null, `"${rel}" must be a valid placement`);
  }
  const invalid = [
    'lib/shared/package.json', // no top-level group at all
    'apps/package.json', // manifest directly in a group dir (no package name level)
    'packages/a/b/package.json', // nested deeper than one level
    'docs/package.json', // outside the three groups
  ];
  for (const rel of invalid) {
    assert.notEqual(placementError(rel), null, `"${rel}" must be flagged as mis-placed`);
  }
});