#!/usr/bin/env node
/**
 * doc-drift.js — detects documentation drift by cross-checking verifiable
 * code references in CLAUDE.md and PRD.md against the filesystem and source tree.
 *
 * Usage: node scripts/doc-drift.js
 * Exits non-zero if any drift is found.
 */

'use strict';

const fs = require('fs');
const path = require('path');
const { execSync } = require('child_process');

const ROOT = path.resolve(__dirname, '..');
const DOCS = ['CLAUDE.md', 'PRD.md'].map(f => path.join(ROOT, f));

// ── Result tracking ──────────────────────────────────────────────────────────

const results = [];

function record(doc, line, kind, ref, pass, reason) {
  results.push({ doc: path.basename(doc), line, kind, ref, pass, reason });
}

// ── Extraction helpers ───────────────────────────────────────────────────────

/** Extract all backtick spans from a line (may be multiple). */
function backtickSpans(line) {
  const spans = [];
  const re = /`([^`]+)`/g;
  let m;
  while ((m = re.exec(line)) !== null) spans.push(m[1]);
  return spans;
}

/** Return true if a span looks like a file/dir path we can verify. */
function isFilePath(span) {
  // Must contain a slash and start with a recognisable project prefix.
  return (
    /[/\\]/.test(span) &&
    /^(client|server|db|scripts|docker-compose)/.test(span) &&
    // Exclude shell commands, URLs, SQL snippets, etc.
    !/\s/.test(span) &&
    !span.includes('=') &&
    !span.startsWith('http')
  );
}

/** Return true if a span looks like a component/page reference (*.jsx). */
function isJsxRef(span) {
  return /\w+\.jsx$/.test(span) && !/[/]/.test(span); // bare name, no path
}

/** Extract HTTP API route patterns like `GET /api/paychecks`. */
function extractApiRoutes(line) {
  const routes = [];
  const re = /\b(GET|POST|PUT|DELETE|PATCH)\s+(\/api\/[^\s,`'")\]]+)/g;
  let m;
  while ((m = re.exec(line)) !== null) routes.push({ method: m[1], path: m[2] });
  return routes;
}

// ── Verification helpers ─────────────────────────────────────────────────────

function fileExists(relPath) {
  return fs.existsSync(path.join(ROOT, relPath));
}

/**
 * For API routes: grep server/src/routes/ for the route path string.
 * We look for the path fragment (everything after /api) as a string literal.
 */
function apiRouteExists(routePath) {
  // Strip query-string placeholders like ?year=&month=
  const clean = routePath.replace(/\?.*$/, '').replace(/:id/g, ':id');
  // Build a grep-friendly pattern: look for the path minus leading /api
  const fragment = clean.replace(/^\/api/, '');
  try {
    const out = execSync(
      `grep -r --include="*.js" -l "${clean}\\|${fragment}" "${path.join(ROOT, 'server/src/routes')}"`,
      { stdio: ['pipe', 'pipe', 'pipe'] }
    ).toString().trim();
    return out.length > 0;
  } catch {
    return false;
  }
}

/**
 * For bare *.jsx component names: check that a file with that name exists
 * somewhere under client/src/.
 */
function jsxComponentExists(name) {
  try {
    const out = execSync(
      `find "${path.join(ROOT, 'client/src')}" -name "${name}" -type f`,
      { stdio: ['pipe', 'pipe', 'pipe'] }
    ).toString().trim();
    return out.length > 0;
  } catch {
    return false;
  }
}

// ── Main ─────────────────────────────────────────────────────────────────────

for (const docPath of DOCS) {
  if (!fs.existsSync(docPath)) {
    console.error(`WARN: doc not found: ${docPath}`);
    continue;
  }

  const lines = fs.readFileSync(docPath, 'utf8').split('\n');

  lines.forEach((rawLine, idx) => {
    const lineNo = idx + 1;

    // 1. Backtick file paths
    for (const span of backtickSpans(rawLine)) {
      if (isFilePath(span)) {
        const exists = fileExists(span);
        record(
          docPath,
          lineNo,
          'file-path',
          span,
          exists,
          exists ? 'found on filesystem' : `not found: ${span}`
        );
        continue;
      }

      if (isJsxRef(span)) {
        const exists = jsxComponentExists(span);
        record(
          docPath,
          lineNo,
          'component',
          span,
          exists,
          exists ? 'found under client/src' : `no file named ${span} in client/src`
        );
      }
    }

    // 2. API routes (inside or outside backticks)
    for (const { method, path: routePath } of extractApiRoutes(rawLine)) {
      const ref = `${method} ${routePath}`;
      const exists = apiRouteExists(routePath);
      record(
        docPath,
        lineNo,
        'api-route',
        ref,
        exists,
        exists ? 'found in server/src/routes' : `route not found in server/src/routes`
      );
    }
  });
}

// ── Report ───────────────────────────────────────────────────────────────────

const padDoc  = Math.max(...results.map(r => r.doc.length), 9);
const padKind = Math.max(...results.map(r => r.kind.length), 9);
const padRef  = Math.min(60, Math.max(...results.map(r => r.ref.length), 10));

const header = [
  'STATUS'.padEnd(6),
  'DOC'.padEnd(padDoc),
  'LINE'.padStart(4),
  'KIND'.padEnd(padKind),
  'REFERENCE',
].join('  ');

console.log('\n' + header);
console.log('─'.repeat(header.length + 10));

let failures = 0;

for (const r of results) {
  const status = r.pass ? 'PASS' : 'FAIL';
  const ref = r.ref.length > padRef ? r.ref.slice(0, padRef - 1) + '…' : r.ref;
  const line = [
    (r.pass ? '\x1b[32m' : '\x1b[31m') + status.padEnd(6) + '\x1b[0m',
    r.doc.padEnd(padDoc),
    String(r.line).padStart(4),
    r.kind.padEnd(padKind),
    ref,
  ].join('  ');
  console.log(line);
  if (!r.pass) {
    console.log(`       \x1b[33m↳ ${r.reason}\x1b[0m`);
    failures++;
  }
}

console.log('─'.repeat(header.length + 10));
console.log(`\n${results.length} references checked — ${failures} failure(s)\n`);

process.exit(failures > 0 ? 1 : 0);