// tests/kb-update/test-migrate-apply.test.mjs
// Integration tests for scripts/kb-update/migrate-corpus.mjs — the unified Spor 1
// applier (Step 7). Hermetic: every case runs against a fresh mkdtemp corpus via the
// injected `--root`/`backupRoot`, so nothing ever writes to the real skills/ tree.
//
// Covers the Step-7 acceptance set: idempotency, advisor-exclusion, throw-guard,
// atomic (no *.tmp.* leftover + import-grep), backup+restore round-trip, dry-run
// default byte-identity, body-after-`---` identity + one `## Innhold`, post-write
// parse assertion (500B truncation), and normalize→insert ordering.

import { test } from 'node:test';
import assert from 'node:assert/strict';
import {
  mkdtempSync,
  mkdirSync,
  rmSync,
  writeFileSync,
  readFileSync,
  readdirSync,
  existsSync,
} from 'node:fs';
import { tmpdir } from 'node:os';
import { join, dirname } from 'node:path';
import { fileURLToPath } from 'node:url';
import {
  planFileMutation,
  migrateCorpus,
} from '../../scripts/kb-update/migrate-corpus.mjs';
import {
  parseTypeHeader,
  parseSourceHeader,
  parseVerifiedHeader,
} from '../../scripts/kb-update/lib/kb-headers.mjs';

const HERE = dirname(fileURLToPath(import.meta.url));
const SRC = join(HERE, '..', '..', 'scripts', 'kb-update', 'migrate-corpus.mjs');

function withTmp(fn) {
  const dir = mkdtempSync(join(tmpdir(), 'migrate-test-'));
  try {
    return fn(dir);
  } finally {
    rmSync(dir, { recursive: true, force: true });
  }
}

/** Materialize a corpus under `root` from a {relpath: content} map. */
function makeCorpus(root, files) {
  for (const [rel, content] of Object.entries(files)) {
    const path = join(root, rel);
    mkdirSync(dirname(path), { recursive: true });
    writeFileSync(path, content, 'utf8');
  }
}

/** Read every file under `root` into a {relpath: content} map (posix keys). */
function readAll(root) {
  const out = {};
  function walk(dir, prefix) {
    for (const entry of readdirSync(dir, { withFileTypes: true })) {
      const rel = prefix ? `${prefix}/${entry.name}` : entry.name;
      if (entry.isDirectory()) walk(join(dir, entry.name), rel);
      else if (entry.isFile()) out[rel] = readFileSync(join(dir, entry.name), 'utf8');
    }
  }
  walk(root, '');
  return out;
}

/** Canonical `skills/…` manifest key for a corpus-relative path. */
const key = (rel) => `skills/${rel}`;

const REF_SMALL = `# Azure AI Foundry Overview

**Category:** Engineering
**Status:** Active

---

## Overview

Foundry is a platform.

## Details

More detail here.
`;

const LARGE_SECTIONS = Array.from({ length: 8 }, (_, i) =>
  `## Section ${i + 1}\n\n${'body paragraph line.\n'.repeat(14)}`,
).join('\n');
const REF_LARGE = `# Big Reference

**Category:** Engineering
**Status:** Active

---

${LARGE_SECTIONS}`;

const REF_STALE_VERIFIED = `# Stale Verified File

**Category:** Engineering
**Status:** Active
**Verified:** MCP 2026-06

---

## Overview

Body.
`;

test('planFileMutation — reference entry stamps Type + Source; body after --- byte-identical', () => {
  const entry = { type: 'reference', source: 'https://learn.microsoft.com/azure/ai-foundry' };
  const plan = planFileMutation(key('ms-ai-engineering/references/a.md'), REF_SMALL, entry);
  assert.equal(plan.changed, true);
  assert.equal(parseTypeHeader(plan.content), 'reference');
  assert.equal(parseSourceHeader(plan.content), entry.source);
  // Body from the first `---` rule onward is untouched (header-only insertion; small file → no TOC).
  const marker = '\n---\n';
  assert.equal(plan.content.slice(plan.content.indexOf(marker)), REF_SMALL.slice(REF_SMALL.indexOf(marker)));
});

test('planFileMutation — deferred reference (no source) gets Type only, never Source', () => {
  const entry = { type: 'reference', deferred: true, deferReason: 'no-ms-citation' };
  const plan = planFileMutation(key('ms-ai-governance/references/d.md'), REF_SMALL, entry);
  assert.equal(parseTypeHeader(plan.content), 'reference');
  assert.equal(parseSourceHeader(plan.content), null);
  assert.equal(plan.expectSource, false);
});

test('planFileMutation — throw-guard fires on an advisor target path', () => {
  const entry = { type: 'reference', source: 'https://learn.microsoft.com/x' };
  assert.throws(
    () => planFileMutation('skills/ms-ai-advisor/references/architecture/cost-models.md', REF_SMALL, entry),
    /advisor/i,
  );
});

test('planFileMutation — normalize then insert applied in order on a **Verified:** MCP fixture', () => {
  const entry = { type: 'reference', source: 'https://learn.microsoft.com/azure/x' };
  const plan = planFileMutation(key('ms-ai-security/references/v.md'), REF_STALE_VERIFIED, entry);
  // Stale header Verified stripped (normalize ran) AND Type inserted (insert ran).
  assert.equal(parseVerifiedHeader(plan.content), null);
  assert.equal(parseTypeHeader(plan.content), 'reference');
  assert.equal(parseSourceHeader(plan.content), entry.source);
});

test('planFileMutation — already-migrated content is a no-op (idempotent)', () => {
  const entry = { type: 'reference', source: 'https://learn.microsoft.com/azure/ai-foundry' };
  const once = planFileMutation(key('ms-ai-engineering/references/a.md'), REF_SMALL, entry);
  const twice = planFileMutation(key('ms-ai-engineering/references/a.md'), once.content, entry);
  assert.equal(twice.changed, false);
  assert.equal(twice.content, once.content);
});

test('migrateCorpus — dry-run (default) leaves the corpus byte-identical on disk', () => {
  withTmp((tmp) => {
    const root = join(tmp, 'skills');
    makeCorpus(root, { 'ms-ai-engineering/references/a.md': REF_SMALL });
    const before = readAll(root);
    const manifest = { [key('ms-ai-engineering/references/a.md')]: { type: 'reference', source: 'https://learn.microsoft.com/x' } };
    const report = migrateCorpus({ root, backupRoot: join(tmp, '.kb-backup'), manifest, write: false });
    assert.equal(report.write, false);
    assert.ok(report.counts.changed > 0, 'dry-run still reports the pending change');
    assert.equal(report.backupPath, null);
    assert.deepEqual(readAll(root), before);
  });
});

test('migrateCorpus — --write stamps non-advisor files and leaves advisor byte-identical', () => {
  withTmp((tmp) => {
    const root = join(tmp, 'skills');
    makeCorpus(root, {
      'ms-ai-engineering/references/a.md': REF_SMALL,
      'ms-ai-advisor/references/architecture/cost-models.md': REF_SMALL,
    });
    const advisorBefore = readFileSync(join(root, 'ms-ai-advisor/references/architecture/cost-models.md'), 'utf8');
    const manifest = {
      [key('ms-ai-engineering/references/a.md')]: { type: 'reference', source: 'https://learn.microsoft.com/x' },
      // Advisor entry is present in the real manifest (deferred), but the walker must never reach it.
      [key('ms-ai-advisor/references/architecture/cost-models.md')]: { type: 'reference', deferred: true, deferReason: 'advisor-scope' },
    };
    const report = migrateCorpus({ root, backupRoot: join(tmp, '.kb-backup'), manifest, write: true });
    assert.equal(report.counts.written, 1);
    // Non-advisor mutated.
    const eng = readFileSync(join(root, 'ms-ai-engineering/references/a.md'), 'utf8');
    assert.equal(parseTypeHeader(eng), 'reference');
    assert.equal(parseSourceHeader(eng), 'https://learn.microsoft.com/x');
    // Advisor untouched — byte-identical.
    assert.equal(readFileSync(join(root, 'ms-ai-advisor/references/architecture/cost-models.md'), 'utf8'), advisorBefore);
  });
});

test('migrateCorpus — second --write run writes 0 files (idempotent on disk)', () => {
  withTmp((tmp) => {
    const root = join(tmp, 'skills');
    makeCorpus(root, { 'ms-ai-engineering/references/a.md': REF_SMALL });
    const manifest = { [key('ms-ai-engineering/references/a.md')]: { type: 'reference', source: 'https://learn.microsoft.com/x' } };
    const opts = { root, backupRoot: join(tmp, '.kb-backup'), manifest, write: true };
    const first = migrateCorpus(opts);
    assert.equal(first.counts.written, 1);
    const second = migrateCorpus(opts);
    assert.equal(second.counts.written, 0);
    assert.equal(second.counts.changed, 0);
  });
});

test('migrateCorpus — atomic write leaves no *.tmp.* leftover', () => {
  withTmp((tmp) => {
    const root = join(tmp, 'skills');
    makeCorpus(root, { 'ms-ai-engineering/references/a.md': REF_SMALL });
    const manifest = { [key('ms-ai-engineering/references/a.md')]: { type: 'reference', source: 'https://learn.microsoft.com/x' } };
    migrateCorpus({ root, backupRoot: join(tmp, '.kb-backup'), manifest, write: true });
    const names = Object.keys(readAll(root));
    assert.equal(names.some((n) => /\.tmp\./.test(n)), false, 'no atomic-write temp file survived');
  });
});

test('migrate-corpus source — uses atomicWriteSync, never bare writeFileSync', () => {
  const src = readFileSync(SRC, 'utf8');
  assert.match(src, /atomicWriteSync/, 'imports/uses the atomic writer');
  assert.doesNotMatch(src, /\bwriteFileSync\b/, 'never calls writeFileSync directly for corpus writes');
  assert.match(src, /ms-ai-advisor/, 'carries the advisor fence');
});

test('migrateCorpus — backup exists and restore() round-trips byte-identity', () => {
  withTmp((tmp) => {
    const root = join(tmp, 'skills');
    makeCorpus(root, {
      'ms-ai-engineering/references/a.md': REF_SMALL,
      'ms-ai-security/references/b.md': REF_STALE_VERIFIED,
    });
    const original = readAll(root);
    const manifest = {
      [key('ms-ai-engineering/references/a.md')]: { type: 'reference', source: 'https://learn.microsoft.com/x' },
      [key('ms-ai-security/references/b.md')]: { type: 'reference', source: 'https://learn.microsoft.com/y' },
    };
    const report = migrateCorpus({ root, backupRoot: join(tmp, '.kb-backup'), manifest, write: true });
    assert.ok(report.backupPath && existsSync(report.backupPath), 'backup snapshot exists');
    assert.equal(typeof report.restore, 'function');
    // Corpus is mutated now…
    assert.notDeepEqual(readAll(root), original);
    // …restore brings it back byte-identical.
    report.restore();
    assert.deepEqual(readAll(root), original);
  });
});

test('migrateCorpus — large file gains exactly one ## Innhold, sections preserved', () => {
  withTmp((tmp) => {
    const root = join(tmp, 'skills');
    makeCorpus(root, { 'ms-ai-engineering/references/big.md': REF_LARGE });
    const manifest = { [key('ms-ai-engineering/references/big.md')]: { type: 'reference', source: 'https://learn.microsoft.com/x' } };
    migrateCorpus({ root, backupRoot: join(tmp, '.kb-backup'), manifest, write: true });
    const out = readFileSync(join(root, 'ms-ai-engineering/references/big.md'), 'utf8');
    assert.equal((out.match(/^## Innhold$/gm) || []).length, 1, 'exactly one TOC heading');
    assert.equal(parseTypeHeader(out), 'reference');
    // All original sections survive.
    for (let i = 1; i <= 8; i++) assert.match(out, new RegExp(`^## Section ${i}$`, 'm'));
  });
});

test('migrateCorpus — post-write parse assertion catches a deep-preamble (>500B) file', () => {
  withTmp((tmp) => {
    const root = join(tmp, 'skills');
    // A title long enough that the inserted **Type:** line lands past the 500-byte
    // scan window → parseTypeHeader returns null on re-read → the applier must throw.
    const deep = `# ${'A'.repeat(490)}\n\n**Category:** Engineering\n\n## Section\n\nBody.\n`;
    makeCorpus(root, { 'ms-ai-engineering/references/deep.md': deep });
    const original = readAll(root);
    const manifest = { [key('ms-ai-engineering/references/deep.md')]: { type: 'reference', source: 'https://learn.microsoft.com/x' } };
    assert.throws(
      () => migrateCorpus({ root, backupRoot: join(tmp, '.kb-backup'), manifest, write: true }),
      /truncat|500|header/i,
    );
    // The applier restored the corpus on the failed assertion — no partial mutation left behind.
    assert.deepEqual(readAll(root), original);
  });
});