// lib/validators/review-validator.mjs
// Validate trekreview frontmatter + body invariants.
// 3-layer pattern (Content → File → CLI shim) mirroring brief-validator.
//
// Schema is forward-compatible: unknown top-level frontmatter keys are
// tolerated silently. Strict-key checks are intentionally avoided so new
// optional fields (jf. the source_findings precedent) can be added without
// a review_version bump.
//
// K7 (ordre 5, review_version 1.1): `verdict: ALLOW | WARN | BLOCK` is REQUIRED.
// Strict (write-time) mode rejects a review without it; soft (read-time) mode
// warns, so a 1.0 review can still seed a plan (N-1 window, Handover 6). The
// gate that decides on the verdict is lib/review/verdict-gate.mjs, which never
// reads a missing verdict as ALLOW.

import { readFileSync, existsSync } from 'node:fs';
import { parseDocument } from '../util/frontmatter.mjs';
import { issue, ok, fail } from '../util/result.mjs';
import { isMain } from '../util/is-main.mjs';
import { extractFindingsBlock } from '../review/findings-schema.mjs';

export const REVIEW_REQUIRED_FRONTMATTER = [
  'type',
  'review_version',
  'task',
  'slug',
  'project_dir',
  'brief_path',
  'scope_sha_end',
  'reviewed_files_count',
  'findings',
];
export const REVIEW_BODY_SECTIONS = ['Executive Summary', 'Coverage', 'Remediation Summary'];
export const VERDICT_VALUES = Object.freeze(['ALLOW', 'WARN', 'BLOCK']);

const HEX_ID_RE = /^[0-9a-f]{40}$/;
/**
 * IDs of BLOCKER findings in the trailing JSON block ([] when absent/unparseable).
 * Read with the one block reader, so three backticks inside a JSON string do
 * not end the block early and hide a BLOCKER (release review of 6.3.0, round 8).
 */
function blockerIdsFromBody(body) {
  const last = extractFindingsBlock(body);
  if (last === null) return [];
  try {
    const payload = JSON.parse(last);
    return (Array.isArray(payload?.findings) ? payload.findings : [])
      .filter((f) => f?.severity === 'BLOCKER' && typeof f.id === 'string')
      .map((f) => f.id);
  } catch {
    return [];
  }
}

/** Finding IDs named by `Source finding:` lines under `## Remediation Steps` step headings. */
function remediationStepSources(body) {
  const start = body.search(/^##\s+Remediation Steps\b/m);
  if (start === -1) return new Set();
  const rest = body.slice(start).replace(/^##\s+Remediation Steps[^\n]*\n/, '');
  const next = rest.search(/^##\s+/m);
  const section = next === -1 ? rest : rest.slice(0, next);
  const ids = new Set();
  for (const step of section.split(/^###\s+Step\s+R\d+\b/m).slice(1)) {
    const m = step.match(/Source finding:\**\s*`?([0-9a-f]{40})`?/);
    if (m) ids.add(m[1]);
  }
  return ids;
}

export function validateReviewContent(text, opts = {}) {
  const strict = opts.strict !== false;
  const doc = parseDocument(text);
  if (!doc.valid) return doc;

  const fm = doc.parsed.frontmatter || {};
  const body = doc.parsed.body || '';
  const errors = [];
  const warnings = [];

  for (const k of REVIEW_REQUIRED_FRONTMATTER) {
    if (!(k in fm)) {
      errors.push(issue('REVIEW_MISSING_FIELD', `Required frontmatter field missing: ${k}`));
    }
  }

  if (fm.type !== undefined && fm.type !== 'trekreview') {
    errors.push(issue('REVIEW_WRONG_TYPE', `frontmatter.type must be "trekreview", got "${fm.type}"`));
  }

  if (fm.findings !== undefined) {
    if (!Array.isArray(fm.findings)) {
      errors.push(issue(
        'REVIEW_BAD_FINDINGS_TYPE',
        `Field "findings" must be an array of finding-IDs, got ${typeof fm.findings}`,
        'Use block-style YAML: `findings:\\n  - <id1>\\n  - <id2>`',
      ));
    } else {
      for (let i = 0; i < fm.findings.length; i++) {
        const id = fm.findings[i];
        if (typeof id !== 'string' || !HEX_ID_RE.test(id)) {
          errors.push(issue(
            'REVIEW_BAD_FINDING_ID',
            `findings[${i}] is not a 40-char hex ID: ${JSON.stringify(id)}`,
          ));
        }
      }
    }
  }

  if (!('verdict' in fm) || fm.verdict === null || fm.verdict === '') {
    const issueObj = issue(
      'REVIEW_MISSING_VERDICT',
      'Required frontmatter field missing: verdict (ALLOW | WARN | BLOCK)',
      'Copy the coordinator verdict from the trailing JSON block into the frontmatter.',
    );
    if (strict) errors.push(issueObj);
    else warnings.push(issueObj);
  } else if (!VERDICT_VALUES.includes(fm.verdict)) {
    errors.push(issue(
      'REVIEW_BAD_VERDICT',
      `frontmatter.verdict must be one of ${VERDICT_VALUES.join('|')}, got ${JSON.stringify(fm.verdict)}`,
    ));
  }

  // Every BLOCKER is written as a numbered remediation step that Handover 6 can
  // append to a plan unchanged: `### Step R<n>: …` with `Source finding: <id>`.
  // Borrowed: review gaps become appended, numbered tasks with a source-ref,
  // never rewriting earlier ones (Spec Kit `templates/commands/converge.md:156-163`, MIT).
  // 1.1+ only (N-1 window): a 1.0 review never carried the section.
  const v = typeof fm.review_version === 'string' ? fm.review_version.match(/^(\d+)\.(\d+)$/) : null;
  const atLeast11 = v && (Number(v[1]) > 1 || (Number(v[1]) === 1 && Number(v[2]) >= 1));
  const blockerIds = atLeast11 ? blockerIdsFromBody(body) : [];
  if (blockerIds.length > 0) {
    const steps = remediationStepSources(body);
    for (const id of blockerIds) {
      if (!steps.has(id)) {
        const issueObj = issue(
          'REVIEW_MISSING_REMEDIATION_STEP',
          `BLOCKER ${id} has no "### Step R<n>" with "Source finding: ${id}" under ## Remediation Steps`,
          'Write one numbered remediation step per BLOCKER (Handover 6).',
        );
        if (strict) errors.push(issueObj);
        else warnings.push(issueObj);
      }
    }
  }

  // 1.1+: what the coordinator set aside is listed, never left out (ordre 5).
  if (atLeast11 && !/^##\s+Declined to Judge\b/m.test(body)) {
    const issueObj = issue('REVIEW_MISSING_SECTION', 'Required body section missing: ## Declined to Judge (review_version ≥ 1.1)');
    if (strict) errors.push(issueObj);
    else warnings.push(issueObj);
  }

  for (const section of REVIEW_BODY_SECTIONS) {
    const re = new RegExp(`^##\\s+${section}\\b`, 'm');
    if (!re.test(body)) {
      const issueObj = issue('REVIEW_MISSING_SECTION', `Required body section missing: ## ${section}`);
      if (strict) errors.push(issueObj);
      else warnings.push(issueObj);
    }
  }

  if (typeof fm.review_version === 'string') {
    const m = fm.review_version.match(/^(\d+)\.(\d+)$/);
    if (!m) {
      warnings.push(issue('REVIEW_VERSION_FORMAT', `review_version "${fm.review_version}" not in N.M form`));
    }
  }

  return { valid: errors.length === 0, errors, warnings, parsed: { frontmatter: fm, body } };
}

export function validateReview(filePath, opts = {}) {
  if (!existsSync(filePath)) return fail(issue('REVIEW_NOT_FOUND', `File not found: ${filePath}`));
  let text;
  try { text = readFileSync(filePath, 'utf-8'); }
  catch (e) { return fail(issue('REVIEW_READ_ERROR', `Cannot read ${filePath}: ${e.message}`)); }
  const r = validateReviewContent(text, opts);
  return { ...r, parsed: { ...r.parsed, filePath } };
}

if (isMain(import.meta.url)) {
  const args = process.argv.slice(2);
  const strict = !args.includes('--soft');
  const filePath = args.find(a => !a.startsWith('--'));
  if (!filePath) {
    process.stderr.write('Usage: review-validator.mjs [--soft] [--json] <review.md>\n');
    process.exit(2);
  }
  const r = validateReview(filePath, { strict });
  if (args.includes('--json')) {
    process.stdout.write(JSON.stringify({ valid: r.valid, errors: r.errors, warnings: r.warnings }, null, 2) + '\n');
  } else {
    process.stdout.write(`review-validator: ${r.valid ? 'PASS' : 'FAIL'} ${filePath}\n`);
    for (const e of r.errors) process.stderr.write(`  ERROR  [${e.code}] ${e.message}\n`);
    for (const w of r.warnings) process.stderr.write(`  WARN   [${w.code}] ${w.message}\n`);
  }
  process.exit(r.valid ? 0 : 1);
}