#!/usr/bin/env node
// dedup-dato.mjs — Enhet 3b (2026-07-16, ⊥ R7). Resolve the dual-**Dato:** header on the 5
// mlops-genaiops files that carry BOTH a bold **Dato:** (creation) AND a bold **Last updated:**
// (modification).
//
// Ground truth 2026-07-16, re-measured against the committed corpus + the git first-commit
// "Created-map" (git first-commit = 2026-04-08 for all 5):
//   - 4 files carry a DISTINCT creation date — **Dato:** 2026-02-04, authored BEFORE the git
//     first-commit → a genuine creation date. Action: RELABEL **Dato:** → **Created:**, value
//     byte-preserved (the same norsk→english label-rename class as Enhet 1/2; **Created:** is a
//     new-but-additive header label — no validator enforces a closed field list).
//   - 1 file (mlops-security-access-control) carries IDENTICAL dates — **Dato:** = **Last updated:**
//     = 2026-06-19, both AFTER the git first-commit → NOT a genuine creation date (a metadata-pass
//     artifact). Action: DROP the redundant **Dato:**. Relabeling it to **Created:** 2026-06-19
//     would assert a FALSE creation date, so removal is the truthful action (the Created-map is
//     what distinguishes the two cases).
//
// Never derives a value; never deletes a field it cannot prove redundant (dropRedundantBoldField
// THROWS unless a bold **Last updated:** with the IDENTICAL value proves it). A hard per-file
// invariant is asserted BEFORE any write:
//   relabel — exactly ONE line changed, that line is the old line with ONLY the label token
//             swapped (**Dato:**→**Created:**) and the frozen value intact; line count unchanged;
//             body byte-identical.
//   drop    — exactly ONE line removed (the **Dato:** line); no **Dato:** remains in the header;
//             **Last updated:** survives; body byte-identical.
// Idempotent: a re-run finds **Dato:** gone and is a no-op. Aborts, writing nothing, on any drift.
//
// Recovery contract: writes are crash-safe (atomicWriteSync tmp+rename — a reader sees the old
// file or the new one, never a partial); an interrupted run is recovered by re-running (idempotent).
//
// Usage:  node scripts/kb-update/dedup-dato.mjs [--dry]
import { readFileSync, existsSync, realpathSync } from 'node:fs';
import { join, dirname } from 'node:path';
import { fileURLToPath } from 'node:url';
import { dropRedundantBoldField } from './lib/transform.mjs';
import { relabelHeaderDialect } from './relabel-dialect.mjs';
import { atomicWriteSync } from './lib/atomic-write.mjs';

const __dirname = dirname(fileURLToPath(import.meta.url));
const PLUGIN_ROOT = join(__dirname, '..', '..');
const DIR = 'skills/ms-ai-engineering/references/mlops-genaiops';

// The single norsk→english label pair for the relabel action. **Created:** is intentionally NOT in
// relabel-dialect.mjs's LABEL_MAP (that pass is Sist oppdatert/Kategori) nor relabel-dato.mjs's map
// (that maps **Dato:**→**Last updated:** for the 16 "rene" single-date files) — the 5 dual files
// were deliberately excluded there and are resolved only here.
export const CREATED_MAP = [['**Dato:**', '**Created:**']];

// The label whose identical value proves a **Dato:** redundant in the drop case.
export const DROP_LABEL = 'Dato';
export const PROOF_LABEL = 'Last updated';

// Frozen manifest — the 5 dual-**Dato:** mlops-genaiops files (ground truth 2026-07-16). `created`
// freezes the authored creation date the relabel must preserve; a corpus drift where the value
// changed is caught by the per-file invariant below.
export const MANIFEST = [
  { rel: `${DIR}/feedback-loops-continuous-improvement.md`, action: 'relabel', created: '2026-02-04' },
  { rel: `${DIR}/genaiops-llm-specific-practices.md`, action: 'relabel', created: '2026-02-04' },
  { rel: `${DIR}/model-deployment-strategies-azure.md`, action: 'relabel', created: '2026-02-04' },
  { rel: `${DIR}/prompt-flow-production-deployment.md`, action: 'relabel', created: '2026-02-04' },
  { rel: `${DIR}/mlops-security-access-control.md`, action: 'drop' },
];

/**
 * The pure per-file op: relabel **Dato:**→**Created:** or drop the redundant bold **Dato:**. Pure.
 * @param {string} content
 * @param {'relabel'|'drop'} action
 * @returns {string}
 */
export function applyOp(content, action) {
  if (action === 'relabel') return relabelHeaderDialect(content, CREATED_MAP).content;
  if (action === 'drop') return dropRedundantBoldField(content, DROP_LABEL, PROOF_LABEL);
  throw new Error(`applyOp: unknown action '${action}'`);
}

// Header region = lines above the first `## `/`---` (mirrors transform.mjs headerEndIndex).
function splitHeaderBody(content) {
  const lines = content.split('\n');
  let i = 0;
  for (; i < lines.length; i++) {
    if (/^##\s/.test(lines[i]) || /^---\s*$/.test(lines[i])) break;
  }
  return { header: lines.slice(0, i).join('\n'), body: lines.slice(i).join('\n') };
}

// Assert the hard per-file invariant. Throws (aborting the run) on any breach.
function assertInvariant(m, oldC, newC) {
  const { rel, action } = m;
  const o = oldC.split('\n');
  const n = newC.split('\n');
  const oldH = splitHeaderBody(oldC);
  const newH = splitHeaderBody(newC);
  if (oldH.body !== newH.body) throw new Error(`ABORT ${rel}: body not byte-identical`);
  if (/\*\*Dato:\*\*/.test(newH.header)) throw new Error(`ABORT ${rel}: header still carries **Dato:** after op`);

  if (action === 'relabel') {
    if (n.length !== o.length) throw new Error(`ABORT ${rel}: line count changed (${o.length}→${n.length})`);
    let diffs = 0;
    let changedLine = -1;
    for (let i = 0; i < o.length; i++) {
      if (o[i] === n[i]) continue;
      diffs++;
      changedLine = i;
    }
    if (diffs !== 1) throw new Error(`ABORT ${rel}: expected exactly one line changed, got ${diffs}`);
    // The changed line must be the old line with ONLY the label token swapped.
    if (n[changedLine].replace('**Created:**', '**Dato:**') !== o[changedLine]) {
      throw new Error(`ABORT ${rel}: changed line ${changedLine} altered beyond the **Dato:**→**Created:** label token`);
    }
    if (!new RegExp(`\\*\\*Created:\\*\\* ${m.created}(?:\\s|$)`).test(newH.header)) {
      throw new Error(`ABORT ${rel}: **Created:** ${m.created} (frozen value) missing after relabel`);
    }
  } else {
    // drop
    if (n.length !== o.length - 1) throw new Error(`ABORT ${rel}: expected exactly one line removed (was ${o.length}, now ${n.length})`);
    if (!/\*\*Last updated:\*\*\s*\S/.test(newH.header)) throw new Error(`ABORT ${rel}: **Last updated:** missing after drop`);
    if (/\*\*Created:\*\*/.test(newH.header)) throw new Error(`ABORT ${rel}: drop must not introduce **Created:**`);
  }
}

function run({ dry }) {
  const planned = [];
  const skipped = [];
  const missing = [];

  for (const m of MANIFEST) {
    const abs = join(PLUGIN_ROOT, m.rel);
    if (!existsSync(abs)) { missing.push(m.rel); continue; }
    const old = readFileSync(abs, 'utf8');
    const out = applyOp(old, m.action);
    if (out === old) { skipped.push(m.rel); continue; } // idempotent: already resolved
    assertInvariant(m, old, out);
    planned.push({ rel: m.rel, action: m.action, out });
  }

  if (missing.length) {
    console.error(`ABORT — ${missing.length} manifest target(s) not found (corpus drift):`);
    missing.forEach((x) => console.error('  ' + x));
    process.exit(1);
  }
  if (planned.length + skipped.length !== MANIFEST.length) {
    throw new Error(`ABORT — accounted ${planned.length + skipped.length} ≠ manifest ${MANIFEST.length}`);
  }

  const relabels = planned.filter((p) => p.action === 'relabel').length;
  const drops = planned.filter((p) => p.action === 'drop').length;
  console.log(`Manifest: ${MANIFEST.length} | to resolve: ${planned.length} (${relabels} relabel + ${drops} drop) | already resolved (skipped): ${skipped.length}`);
  if (dry) {
    console.log('\n(dry run — no writes)');
    for (const p of planned) console.log(`  ~ ${p.rel}  [${p.action}]`);
    return;
  }
  for (const p of planned) atomicWriteSync(join(PLUGIN_ROOT, p.rel), p.out);
  console.log(`\nWrote ${planned.length} files.`);
}

const isMain = (() => {
  try {
    return realpathSync(process.argv[1]) === realpathSync(fileURLToPath(import.meta.url));
  } catch {
    return false;
  }
})();
if (isMain) run({ dry: process.argv.includes('--dry') });