#!/usr/bin/env node
// plan-skill-op.mjs — Spor B / B3 CLI: GATED DRY-RUN for skill-lifecycle ops.
//
// Sesjon 16 ships merge_skills. The dry-run loads refs/descriptions/taxonomy
// READ-ONLY, plans the merge, prints the full diff + guardrail, and with
// --write records a PENDING entry in decisions.json (the operator gate's queue).
// It NEVER writes under skills/ — the destructive apply is a separate approved
// step. Verify after a run: `git status skills/` must be clean.
//
// Usage:
//   node scripts/kb-eval/plan-skill-op.mjs merge <absorber> <absorbed>
//   node scripts/kb-eval/plan-skill-op.mjs merge <absorber> <absorbed> --json
//   node scripts/kb-eval/plan-skill-op.mjs merge <absorber> <absorbed> --write [--date YYYY-MM-DD]

import { readFileSync, readdirSync, existsSync } from 'node:fs';
import { join, dirname } from 'node:path';
import { fileURLToPath } from 'node:url';
import { splitFrontmatter, extractDescription } from './eval.mjs';
import { loadTaxonomy } from '../kb-update/lib/taxonomy.mjs';
import { runMergePlan } from './lib/skill-ops.mjs';

const __dirname = dirname(fileURLToPath(import.meta.url));
const PLUGIN_ROOT = join(__dirname, '..', '..');
const SKILLS_DIR = join(PLUGIN_ROOT, 'skills');
const LEDGER_DATA_DIR = join(__dirname, '..', 'kb-update', 'data');
const TAX_DATA_DIR = LEDGER_DATA_DIR;

/** Read the SKILL.md descriptions from disk (read-only). */
function loadDescriptions() {
  const out = {};
  for (const e of readdirSync(SKILLS_DIR, { withFileTypes: true })) {
    if (!e.isDirectory()) continue;
    const md = join(SKILLS_DIR, e.name, 'SKILL.md');
    if (!existsSync(md)) continue;
    out[e.name] = extractDescription(splitFrontmatter(readFileSync(md, 'utf8')).frontmatter);
  }
  return out;
}

function printPlan({ entry, diff, guardrail }) {
  const g = guardrail;
  console.log(`\nmerge_skills — DRY-RUN: ${entry.targets.absorbed}  ->  ${entry.targets.absorber}\n`);
  console.log(`Guardrail (ingen kuratert verdi tapt):`);
  console.log(`  absorber-refs=${g.preCountAbsorber}  absorbed-refs=${g.preCountAbsorbed}  forventet post=${g.expectedPostCount}  faktisk post=${g.postCount}`);
  console.log(`  count-invariant=${g.countInvariant}  set-equality=${g.setEquality}  kollisjoner=${g.collisions.length ? g.collisions.join(', ') : '0'}`);
  console.log(`  => ${g.ok ? 'OK (trygt å merge)' : 'FAILED (ville tapt/klobret innhold — blokkert)'}\n`);
  console.log(`Diff:`);
  console.log(`  fil-flytt: ${diff.fileMoves.length} (alle ${entry.targets.absorbed}/references/* -> ${entry.targets.absorber}/references/*)`);
  if (diff.taxonomyReassignments.length) {
    console.log(`  taksonomi-reassign:`);
    for (const t of diff.taxonomyReassignments) console.log(`    • ${t.category}: ${t.from} -> ${t.to}`);
  }
  console.log(`  retire: ${diff.retire}`);
  console.log(`  description-reconciliation: MANUELL (planner auto-merger aldri semantisk scope)`);
  console.log(`    ${entry.targets.absorber}: ${diff.descriptionReconciliation.absorber?.slice(0, 80) ?? '(mangler)'}…`);
  console.log(`    ${entry.targets.absorbed}: ${diff.descriptionReconciliation.absorbed?.slice(0, 80) ?? '(mangler)'}…\n`);
  console.log(`Status: ${entry.status} (forslag — anvender INGENTING; krever operatør-godkjenning + apply-sesjon).\n`);
}

function main() {
  const args = process.argv.slice(2);
  const op = args[0];
  const positional = args.filter((a) => !a.startsWith('--'));
  const jsonOut = args.includes('--json');
  const doWrite = args.includes('--write');
  const dateIdx = args.indexOf('--date');
  const decided_at = doWrite ? (dateIdx >= 0 ? args[dateIdx + 1] : new Date().toISOString().slice(0, 10)) : null;

  if (op !== 'merge' || positional.length < 3) {
    console.error('Usage: node scripts/kb-eval/plan-skill-op.mjs merge <absorber> <absorbed> [--json] [--write [--date YYYY-MM-DD]]');
    process.exit(2);
  }
  const [, absorber, absorbed] = positional;

  const result = runMergePlan(absorber, absorbed, {
    skillsDir: SKILLS_DIR,
    dataDir: LEDGER_DATA_DIR,
    write: doWrite,
    decided_at,
    descriptions: loadDescriptions(),
    categorySkill: loadTaxonomy(TAX_DATA_DIR).category_skill,
  });

  if (jsonOut) {
    process.stdout.write(JSON.stringify(result) + '\n');
    return;
  }
  printPlan(result);
  if (doWrite) console.log(`(Pending merge_skills-entry skrevet til decisions.json — 0 skriving til skills/.)\n`);
}

if (process.argv[1] && fileURLToPath(import.meta.url) === process.argv[1]) {
  main();
}