// lib/review/review-rounds.mjs
// /trekreview rounds (review_version 1.2, fix round 4.5b2 part B): round 2
// and later see the diff since the previous round and the previous findings,
// carry what is not resolved, and stop at one cap.
//
// `MAX_REVIEW_ROUNDS` is the one cap: /trekreview refuses a fourth round, and
// /trekexecute's review loop reads the same constant (`--cap`).
//
// prepare({projectDir, since, repo, workflow, dryRun}): the round of a run.
// `<run>` is the first 12 hex of `since` (the run's `scope_sha_start`).
//   - Same run (review.md exists and its `scope_sha_start` equals `since`): a
//     later round. The archives `review-round-<run>-<n>.md` whose bytes differ
//     from review.md are A (an archive equal to review.md was written before a
//     stop at this point). The previous review's round is P = 1 + |A|, derived,
//     never read from the `round` field alone: a `round` field that disagrees
//     is exit 2. The new round is P + 1.
//   - Round MAX_REVIEW_ROUNDS + 1 is refused (exit 1); so is round 2 or later
//     with `workflow` (exit 1): the --workflow path neither hands the reviewers
//     the round input nor writes their outputs.
//   - The round base is the previous `scope_sha_end`: a full sha that is an
//     ancestor of HEAD, else exit 2 (not measured).
//   - review.md is copied to `review-round-<run>-<P>.md`; an existing file
//     there is kept when its bytes are equal, else exit 2.
//   - Otherwise (no review.md, or another run): round 1.
//   - Clean slate, every round: the regular files `.review-engine-payload-*.json`
//     and `.review-out-*.md` of the project folder are deleted, so any such
//     file finalize finds was written this round.
//   - `dryRun` computes the same result and writes, copies and deletes nothing.
//   Nothing is written before every check has passed.
//
// carry(previous, current, {marks, ran, previousRan}): a current finding
// matches a previous one in the same file with the same rule_key, or with
// `contentOverlap` >= DEFAULT_THRESHOLD (lib/review/plan-review-dedup.mjs); ids
// are never compared, and each finding matches at most one other. A previous
// finding resolves only on positive evidence of this round (the isResolved
// rule of lib/review/critic-diff.mjs, with "every reviewer that ran then"
// standing in for the raisers):
//   - a matched previous finding is carried;
//   - an engine finding is resolved only when its engine is in `ran.engines`,
//     it was not raised again, and no reviewer marks it `resolved: false`;
//   - a reviewer-only finding is resolved only when `previousRan.reviewers` is
//     non-empty, every reviewer in it is in `ran.reviewers`, each marked it
//     `resolved: true`, and none marked it `resolved: false`;
//   - `previousRan` null (the previous review is not finalized): nothing resolves.
// An unresolved previous finding stays in `findings` with `carried_from` (the
// previous id), at the higher of the two severities; a matching current
// finding folds into it and keeps its place (and its id until finalize
// recomputes ids), so it is not counted new. A new finding keeps its severity
// wherever it cites: rule A never reaches reviews (decision 95). Two
// occurrences of one class stay two findings (`rule_key#n` ids).
//
// CLI:
//   node lib/review/review-rounds.mjs prepare --project <d> --since <sha>
//        [--repo <d>] [--workflow] [--dry-run] --json
//     prints one JSON line {round, round_base, previous, run} or {reason};
//     exit 0 = the round, 1 = refused (the cap, or round 2+ on --workflow),
//     2 = not measured (2 is never green)
//   node lib/review/review-rounds.mjs --cap      prints MAX_REVIEW_ROUNDS

import { spawnSync } from 'node:child_process';
import { copyFileSync, lstatSync, readFileSync, readdirSync, unlinkSync } from 'node:fs';
import { join } from 'node:path';
import { contentOverlap, DEFAULT_THRESHOLD } from './plan-review-dedup.mjs';
import { FULL_SHA_RE, reviewedSha } from './reviewed-commit.mjs';
import { scopeShas } from './pre-existing.mjs';
import { getRule } from './rule-catalogue.mjs';
import { isMain } from '../util/is-main.mjs';

export const MAX_REVIEW_ROUNDS = 3;

const SEVERITY_RANK = ['BLOCKER', 'MAJOR', 'MINOR', 'SUGGESTION'];
const CLEAN_SLATE_RE = /^(?:\.review-engine-payload-.+\.json|\.review-out-.+\.md)$/;

/** The run id of a round: the first 12 hex of the run's `scope_sha_start`. */
export const runId = (sha) => String(sha ?? '').toLowerCase().slice(0, 12);

/** The archive name of round `n` of run `run`. */
export const archiveName = (run, n) => `review-round-${run}-${n}.md`;

/** A frontmatter field as written (raw), or null when absent. */
export function frontmatterField(text, key) {
  const fm = /^---\r?\n([\s\S]*?)\r?\n---\r?\n/.exec(String(text ?? ''));
  if (!fm) return null;
  const m = new RegExp(`^${key}:[ \\t]*(.*?)[ \\t]*$`, 'm').exec(fm[1]);
  return m ? m[1] : null;
}

/** A regular file's bytes, or null (missing, a symlink, a directory, unreadable). */
function readRegular(p) {
  try {
    if (!lstatSync(p).isFile()) return null;
    return readFileSync(p);
  } catch { return null; }
}

/** The regular files of `dir` whose names match `re`. */
function regularFiles(dir, re) {
  let names;
  try { names = readdirSync(dir); } catch { return []; }
  return names.filter((n) => re.test(n)).filter((n) => {
    try { return lstatSync(join(dir, n)).isFile(); } catch { return false; }
  }).sort();
}

const notMeasured = (reason, detail = '') => ({ exit: 2, reason: `${reason} — not measured${detail ? ` (${detail})` : ''}` });

/**
 * The round of a run, with its archive and clean slate (see the header).
 * @returns {{exit: 0, round: number, round_base: string|null, previous: string|null, run: string, archived?: boolean, deleted: string[]} | {exit: 1|2, reason: string}}
 */
export function prepare({ projectDir, since, repo, workflow = false, dryRun = false } = {}) {
  if (!projectDir) return { exit: 2, reason: '--project is required' };
  if (!FULL_SHA_RE.test(String(since ?? ''))) return notMeasured('--since must be a full commit id');
  try {
    if (!lstatSync(projectDir).isDirectory()) return notMeasured(`--project ${projectDir} is not a directory`);
  } catch (e) { return notMeasured(`--project ${projectDir}: ${e.message}`); }
  const run = runId(since);
  const slate = regularFiles(projectDir, CLEAN_SLATE_RE);
  const clean = () => {
    if (dryRun) return [];
    for (const n of slate) unlinkSync(join(projectDir, n));
    return slate;
  };
  const reviewPath = join(projectDir, 'review.md');
  let reviewThere = true;
  try { lstatSync(reviewPath); } catch { reviewThere = false; }
  const review = readRegular(reviewPath);
  if (reviewThere && review === null) return notMeasured('review.md is not a readable regular file');
  const text = review === null ? null : review.toString('utf8');
  const sameRun = text !== null && scopeShas(text).start !== '' && scopeShas(text).start.toLowerCase() === String(since).toLowerCase();
  if (!sameRun) {
    // Round 1, on either path.
    return { exit: 0, round: 1, round_base: null, previous: null, run, deleted: clean() };
  }

  const archiveRe = new RegExp(`^review-round-${run}-(\\d+)\\.md$`);
  const archives = regularFiles(projectDir, archiveRe);
  const others = archives.filter((n) => !readRegular(join(projectDir, n)).equals(review));
  const P = 1 + others.length;
  const roundField = frontmatterField(text, 'round');
  if (roundField !== null && roundField !== String(P)) {
    return notMeasured('round count does not match the archives', `round: ${roundField}, ${others.length} earlier archive(s) of run ${run}`);
  }
  const round = P + 1;
  if (round > MAX_REVIEW_ROUNDS) {
    return { exit: 1, reason: `review round cap reached (${MAX_REVIEW_ROUNDS}) — the operator re-plans` };
  }
  if (workflow) {
    return { exit: 1, reason: 'from round 2 /trekreview runs on the standard path — re-run without --workflow' };
  }
  const base = reviewedSha(text);
  if (!base || !isAncestorOfHead(repo ?? projectDir, base)) {
    return notMeasured('round base is not an ancestor of HEAD');
  }
  const previous = archiveName(run, P);
  const target = join(projectDir, previous);
  let present = true;
  try { lstatSync(target); } catch { present = false; }
  // A file there that is not a regular file with review.md's bytes "differs".
  if (present && !readRegular(target)?.equals(review)) return notMeasured(`archive ${previous} differs`);
  let archived = false;
  if (!dryRun && !present) {
    copyFileSync(reviewPath, target);
    archived = true;
  }
  return { exit: 0, round, round_base: base, previous, run, archived, deleted: clean() };
}

/** `git merge-base --is-ancestor <sha> HEAD` in `repo` succeeded. */
function isAncestorOfHead(repo, sha) {
  const r = spawnSync('git', ['-C', repo, 'merge-base', '--is-ancestor', sha, 'HEAD'], { encoding: 'utf8' });
  return !r.error && r.status === 0;
}

// ---- carry ----------------------------------------------------------------------

const sevOf = (f) => String(f?.severity ?? '').toUpperCase();
/** The more severe of two severities; an unknown one ranks as BLOCKER (never lower). */
function higher(a, b) {
  const ra = SEVERITY_RANK.indexOf(a);
  const rb = SEVERITY_RANK.indexOf(b);
  if (ra === -1) return a || 'BLOCKER';
  if (rb === -1) return b || 'BLOCKER';
  return ra <= rb ? a : b;
}
const textOf = (f) => `${f?.title ?? ''} ${f?.detail ?? ''}`;

/**
 * The carry rule: same file, then the same rule_key or a content overlap at
 * or above the dedup threshold. Ids are never compared.
 */
export function sameFinding(a, b) {
  if (!a || !b || typeof a.file !== 'string' || a.file === '' || a.file !== b.file) return false;
  if (typeof a.rule_key === 'string' && a.rule_key !== '' && a.rule_key === b.rule_key) return true;
  return contentOverlap(textOf(a), textOf(b)) >= DEFAULT_THRESHOLD;
}

/** Lexicographic comparison of two equal-length number lists. */
function before(a, b) {
  for (let j = 0; j < a.length; j++) if (a[j] !== b[j]) return a[j] < b[j];
  return false;
}

/** The current finding `p` folds into: same rule_key first, then the nearest line, then the larger overlap, then order. */
function bestMatch(p, current, taken) {
  let best = -1;
  let key = null;
  current.forEach((c, i) => {
    if (taken.has(i) || !sameFinding(p, c)) return;
    const k = [
      c.rule_key === p.rule_key ? 0 : 1,
      Number.isInteger(c.line) && Number.isInteger(p.line) ? Math.abs(c.line - p.line) : Number.MAX_SAFE_INTEGER,
      -contentOverlap(textOf(p), textOf(c)),
    ];
    if (key === null || before(k, key)) {
      best = i;
      key = k;
    }
  });
  return best;
}

/** A security finding (the review-answers.mjs `isSecurityFinding` rule; not imported, that module imports this one). */
const isSecurityLike = (f) => getRule(f?.rule_key)?.category === 'security' || f?.engine === 'security-review';

/** The folded finding: the current one's place and text, the higher severity, a security origin never lost. */
function fold(p, c) {
  const out = { ...c, severity: higher(sevOf(p), sevOf(c)), carried_from: p.id };
  if (isSecurityLike(p) && !isSecurityLike(c)) {
    out.rule_key = p.rule_key;
    if (p.engine !== undefined) out.engine = p.engine;
  }
  return out;
}

/** A previous finding carried as it was: no id (finalize computes it), no old marks. */
function carried(p) {
  const { id: _id, pre_existing: _pre, carried_from: _cf, ...rest } = p;
  return { id: null, ...rest, severity: sevOf(p) || 'BLOCKER', carried_from: p.id };
}

/** Was previous finding `p` resolved this round (positive evidence only)? */
function resolvedNow(p, { marks, ran, previousRan }) {
  if (!previousRan || typeof previousRan !== 'object') return false;
  const ms = (Array.isArray(marks) ? marks : []).filter((m) => m && m.id === p.id);
  if (ms.some((m) => m.resolved === false)) return false;
  const ranEngines = Array.isArray(ran?.engines) ? ran.engines : [];
  const ranReviewers = Array.isArray(ran?.reviewers) ? ran.reviewers : [];
  if (typeof p.engine === 'string' && p.engine !== '') return ranEngines.includes(p.engine);
  const then = Array.isArray(previousRan.reviewers) ? previousRan.reviewers : [];
  if (then.length === 0) return false;
  return then.every((r) => ranReviewers.includes(r) && ms.some((m) => m.reviewer === r && m.resolved === true));
}

/**
 * Carry the previous round's findings into this round's (see the header).
 * @param {object[]} previous - the previous review's JSON findings
 * @param {object[]} current - this round's JSON findings
 * @param {{ marks?: Array<{id, resolved, reviewer}>, ran?: {engines, reviewers}, previousRan?: {engines, reviewers}|null }} ctx
 * @returns {{ findings: object[], resolved: string[], folded: number }}
 */
export function carry(previous, current, { marks = [], ran = { engines: [], reviewers: [] }, previousRan = null } = {}) {
  const prev = (Array.isArray(previous) ? previous : []).filter((p) => p && typeof p === 'object');
  const cur = (Array.isArray(current) ? current : []).filter((c) => c && typeof c === 'object');
  const findings = cur.map((c) => ({ ...c }));
  const taken = new Set();
  const appended = [];
  const resolved = [];
  for (const p of prev) {
    const i = bestMatch(p, cur, taken);
    if (i >= 0) {
      taken.add(i);
      findings[i] = fold(p, cur[i]);
      continue;
    }
    if (resolvedNow(p, { marks, ran, previousRan })) {
      if (typeof p.id === 'string') resolved.push(p.id);
      continue;
    }
    appended.push(carried(p));
  }
  return { findings: [...findings, ...appended], resolved, folded: taken.size };
}

// ---- CLI ------------------------------------------------------------------------

function opt(args, name) {
  const i = args.indexOf(name);
  return i >= 0 ? args[i + 1] : undefined;
}

if (isMain(import.meta.url)) {
  const args = process.argv.slice(2);
  if (args[0] === '--cap') {
    process.stdout.write(`${MAX_REVIEW_ROUNDS}\n`);
    process.exit(0);
  }
  let result;
  if (args[0] !== 'prepare') {
    process.stderr.write('Usage: review-rounds.mjs prepare --project <d> --since <sha> [--repo <d>] [--workflow] [--dry-run] --json | --cap\n');
    process.exit(2);
  }
  try {
    result = prepare({
      projectDir: opt(args, '--project'), since: opt(args, '--since'), repo: opt(args, '--repo'),
      workflow: args.includes('--workflow'), dryRun: args.includes('--dry-run'),
    });
  } catch (e) {
    result = { exit: 2, reason: `review-rounds crashed: ${e.message} — not measured` };
  }
  const { exit, ...rest } = result;
  process.stdout.write(`${JSON.stringify(rest)}\n`);
  process.exit(exit);
}