// tests/kb-update/test-backfill-last-updated.test.mjs
// TDD for the Last-updated backfill mechanism (Enhet 4, ⊥ R7). The applier
// (backfill-last-updated.mjs) is a manifest-driven driver over the already-tested
// insertMetaField primitive — the same shape as backfill-status.mjs. The ONLY new production
// data is the frozen single-entry MANIFEST whose value is a git "content-commit" date.
//
// Scope: decision-trees.md is the corpus's ONE dateless file — the only skills/**/*.md whose
// header lacks an English **Last updated:** (ground truth 2026-07-16). Its date is the authored
// date of the last commit that changed the BODY (03d596e, 2026-06-23 — a Foundry namesweep),
// EXCLUDING the R20/R21 metadata passes (a583599/5a0e8d7, which inserted only a header meta line
// and changed no body). The "never today" rule is enforced against MEASURED_TODAY so a naive
// last-commit date can never leak in.
//
// This suite pins:
//   - MANIFEST self-consistency: one distinct entry, the known dateless path, a YYYY-MM-DD value
//     that is not MEASURED_TODAY.
//   - insertMetaField placement/idempotency on an advisor-shaped header fixture.
//   - Corpus-state guard (the gap-discipline lock): the committed decision-trees.md carries
//     **Last updated:** 2026-06-23 in its 500-byte header window, with title + Category + Status
//     and body intact.

import { test } from 'node:test';
import assert from 'node:assert/strict';
import { readFileSync } from 'node:fs';
import { join, dirname } from 'node:path';
import { fileURLToPath } from 'node:url';
import { MANIFEST, MEASURED_TODAY } from '../../scripts/kb-update/backfill-last-updated.mjs';
import { insertMetaField } from '../../scripts/kb-update/lib/transform.mjs';

const __dirname = dirname(fileURLToPath(import.meta.url));
const PLUGIN_ROOT = join(__dirname, '..', '..');

const RE_ISO_DATE = /^\d{4}-\d{2}-\d{2}$/;
const DECISION_TREES = 'skills/ms-ai-advisor/references/architecture/decision-trees.md';

test('MANIFEST: exactly one distinct entry, the known dateless advisor file', () => {
  assert.equal(MANIFEST.length, 1);
  const paths = new Set(MANIFEST.map((m) => m.path));
  assert.equal(paths.size, 1, 'duplicate path in MANIFEST');
  assert.equal(MANIFEST[0].path, DECISION_TREES);
});

test('MANIFEST: value is a YYYY-MM-DD date and NOT MEASURED_TODAY (never-today guard)', () => {
  for (const { path, lastUpdated } of MANIFEST) {
    assert.ok(RE_ISO_DATE.test(lastUpdated), `${path}: '${lastUpdated}' is not YYYY-MM-DD`);
    assert.notEqual(lastUpdated, MEASURED_TODAY, `${path}: date must never equal 'today'`);
  }
});

test('MANIFEST: the frozen date is the measured content-commit date 2026-06-23', () => {
  assert.equal(MANIFEST[0].lastUpdated, '2026-06-23');
});

test('insertMetaField: Last updated lands after the meta run, one line, body byte-identical', () => {
  const fixture = [
    '# Decision Trees for Microsoft AI',
    '**Category:** Solution Architecture & Advisory',
    '**Status:** Established Practice',
    '',
    'Akkumulerte beslutningstrær.',
    '',
    '## 1. Section',
    'body',
  ].join('\n');
  const out = insertMetaField(fixture, 'Last updated', '2026-06-23');
  const o = fixture.split('\n');
  const n = out.split('\n');
  // Exactly one line added.
  assert.equal(n.length, o.length + 1);
  // It lands immediately after the last meta line (Status), before the blank line.
  assert.equal(n[3], '**Last updated:** 2026-06-23');
  assert.equal(n[1], '**Category:** Solution Architecture & Advisory');
  assert.equal(n[2], '**Status:** Established Practice');
  // Everything from the insertion point down is byte-identical to the original tail.
  assert.equal(o.slice(3).join('\n'), n.slice(4).join('\n'));
});

test('insertMetaField: idempotent — a file already carrying Last updated is unchanged', () => {
  const withField = [
    '# Title',
    '**Last updated:** 2026-06-23',
    '**Status:** Established Practice',
    '',
    '## S',
  ].join('\n');
  assert.equal(insertMetaField(withField, 'Last updated', '2026-01-01'), withField);
});

test('corpus guard: committed decision-trees.md carries Last updated 2026-06-23 in header window', () => {
  const content = readFileSync(join(PLUGIN_ROOT, DECISION_TREES), 'utf8');
  const head = content.slice(0, 500);
  assert.match(head, /\*\*Last updated:\*\* 2026-06-23/, 'missing frozen Last updated in header window');
  // Title + the R20/R21 base fields survive, body intact (regression lock).
  assert.match(head, /^# Decision Trees for Microsoft AI/);
  assert.match(head, /\*\*Category:\*\*/);
  assert.match(head, /\*\*Status:\*\*/);
  assert.match(content, /## 1\. Plattformvalg/);
});