// lib/review/threat-model.mjs
// One reader of the brief's optional `## Threat Model` (E, decisions 164, 218),
// for both gates: the plan gate (lib/validators/plan-gate.mjs) and the review's
// verdict gate (lib/review/verdict-gate.mjs).
//
// The section is `- Inside: <text>` / `- Outside: <text>` bullets
// (brief-validator.mjs `parseThreatModel`, the same reader the validator uses).
// Voyage's own security findings (plan-critic, scope-guardian, the code
// reviewer's part for command texts) block inside it; one that quotes an
// `Outside:` line's text exactly in `threat_model_ref` is backed by that line
// and becomes a listed known issue instead of a blocker. Engine findings
// (Claude Code's `/security-review`, Claude Security) block as before: only a
// security finding not from an engine can be outside (218).
//
//   readThreatModel(briefText) -> {present, inside, outside, problems}
//   usable(briefPath, repo)    -> {usable, why, threatModel}
//     usable = the section is present and well formed, AND the intent approval
//     is current: the two checks /trekplan Phase 1 runs (the marker,
//     checkIntentApprovalContent; and the approval log, verifyLog kind
//     `intent` with the hash's `sha256:` stripped and the subject normalized).
//     Otherwise every security finding counts, and `why` says why.
//   backedLine(finding, tm)    -> the `Outside:` text the finding's
//     `threat_model_ref` equals exactly, else null.
//
// Lifting a finding back in is the operator's: change (or remove) that
// `Outside:` line and approve the intent again. Both gates re-read the brief on
// every run, so a finding whose line is gone counts in full.

import { readFileSync } from 'node:fs';
import { parseDocument } from '../util/frontmatter.mjs';
import { verifyLog, normalizeHex, normalizeSubject, resolveRepo } from '../util/approval-log.mjs';
import { checkIntentApprovalContent } from '../validators/intent-approval.mjs';
import { parseThreatModel } from '../validators/brief-validator.mjs';
import { isSecurityKey, keysOf } from './plan-review-dedup.mjs';

/** The engines' catalogue key (/security-review, Claude Security): never Voyage's own. */
export const ENGINES_SECURITY_KEY = 'SECURITY_REVIEW_VULNERABILITY';

const EMPTY = Object.freeze({ present: false, inside: [], outside: [], problems: [] });

/**
 * Read the brief's `## Threat Model`.
 * @param {string} briefText - the whole brief (frontmatter optional)
 * @returns {{present: boolean, inside: string[], outside: string[], problems: string[]}}
 */
export function readThreatModel(briefText) {
  const text = typeof briefText === 'string' ? briefText : '';
  const doc = parseDocument(text);
  const body = doc.parsed?.body ?? text;
  return parseThreatModel(body);
}

/**
 * May the brief's threat model be applied? Present, well formed, and the
 * intent approval current (marker and log). Otherwise every security finding
 * counts, and `why` says why.
 * @param {string} briefPath
 * @param {string} [repo] - the repo whose approval log to read (default: the git top level of the working directory)
 * @returns {{usable: boolean, why: string|null, threatModel: {present: boolean, inside: string[], outside: string[], problems: string[]}}}
 */
export function usable(briefPath, repo) {
  const no = (why, threatModel = EMPTY) => ({ usable: false, why, threatModel });
  if (typeof briefPath !== 'string' || briefPath === '') return no('no brief path was given');
  let text;
  try { text = readFileSync(briefPath, 'utf8'); } catch (e) { return no(`cannot read the brief ${briefPath}: ${e.message}`); }
  const tm = readThreatModel(text);
  if (!tm.present) return no('the brief has no ## Threat Model', tm);
  if (tm.problems.length > 0) return no(`the brief's ## Threat Model is malformed: ${tm.problems.join('; ')}`, tm);
  const marker = checkIntentApprovalContent(text);
  if (!marker.valid) {
    return no(`the intent approval is not current (${marker.errors.map((e) => e.code).join(', ')})`, tm);
  }
  const sha = normalizeHex(marker.parsed?.frontmatter?.intent_approved_hash);
  if (!sha) return no('the brief carries no intent approval hash', tm);
  let log;
  try {
    const root = resolveRepo(repo);
    log = verifyLog({ repo: root, kind: 'intent', subject: normalizeSubject(root, briefPath), sha });
  } catch (e) {
    return no(`the approval log could not be read: ${e.message}`, tm);
  }
  if (log.exit !== 0) {
    return no(`the intent approval is not in the approval log (${log.status}${log.detail ? `: ${log.detail}` : ''})`, tm);
  }
  return { usable: true, why: null, threatModel: tm };
}

/** A security finding that is Voyage's own: a security key, no engine, not the engines' key (218). */
export function isOwnSecurityFinding(f) {
  if (!f || typeof f !== 'object') return false;
  if (typeof f.engine === 'string' && f.engine.trim() !== '') return false;
  const keys = keysOf(f);
  if (keys.some((k) => k.trim().toUpperCase() === ENGINES_SECURITY_KEY)) return false;
  return keys.some(isSecurityKey);
}

/**
 * The `Outside:` text a finding is backed by: its `threat_model_ref` equals it
 * exactly. Only Voyage's own security findings can be backed.
 * @param {object} finding
 * @param {{present?: boolean, outside?: string[]}|null} tm - from readThreatModel / usable
 * @returns {string|null}
 */
export function backedLine(finding, tm) {
  if (!tm || tm.present !== true || !Array.isArray(tm.outside)) return null;
  if (!isOwnSecurityFinding(finding)) return null;
  const ref = finding.threat_model_ref;
  if (typeof ref !== 'string' || ref === '') return null;
  return tm.outside.find((line) => line === ref) ?? null;
}