#!/usr/bin/env node
/**
 * Auto-generate docs/README.md index.
 * Scans docs directory for .md files (excluding README.md) and categorizes by simple heuristics.
 */
import { readdirSync, readFileSync, writeFileSync } from 'fs'
import { join } from 'path'

const DOCS_DIR = join(process.cwd(), 'docs')
const OUTPUT = join(DOCS_DIR, 'README.md')

// Basic categorization keywords
const categories = [
  { name: 'Getting Started', match: [/quickstart/i, /usermanual/i] },
  { name: 'Architecture & Engineering', match: [/architecture/i, /implementation/i, /diagram/i] },
  { name: 'Delivery & Reports', match: [/completion/i, /deployment/, /update/, /phases_all/i, /production_deployment/ ] },
  { name: 'Performance & Optimization', match: [/performance/i, /seo/i] },
  { name: 'Change History', match: [/changelog/i] },
  { name: 'AI & Advanced Features', match: [/ai/i] }
]

function categorize(file) {
  const lower = file.toLowerCase()
  for (const cat of categories) {
    if (cat.match.some(r => r.test(lower))) return cat.name
  }
  return 'Other'
}

function build() {
  const files = readdirSync(DOCS_DIR)
    .filter(f => f.endsWith('.md') && f !== 'README.md')
    .sort()

  const byCategory = {}
  for (const f of files) {
    const cat = categorize(f)
    byCategory[cat] = byCategory[cat] || []
    byCategory[cat].push(f)
  }

  const quickLinks = files.map(f => `- [${f.replace(/_/g,' ')}](./${f})`).join('\n')

  let body = '# Documentation Index\n\n(Generated by scripts/generate-doc-index.mjs)\n\n## Quick Links\n' + quickLinks + '\n\n'

  for (const cat of Object.keys(byCategory).sort()) {
    body += `### ${cat}\n` + byCategory[cat].map(f => `- ${f}`).join('\n') + '\n\n'
  }
  // Append diagram export instructions (persistent section)
  body += '## Diagram Export\n'
  body += 'The architecture diagram source is `ArchitectureDiagram.mmd`. Export updated images using:\n\n'
  body += '```bash\n'
  body += 'npm run diagram:png\n'
  body += 'npm run diagram:svg\n'
  body += '```\n\n'
  body += 'Refresh docs index and PNG in one step:\n\n'
  body += '```bash\n'
  body += 'npm run docs:refresh\n'
  body += '```\n\n'
  body += '---\nLast regenerated: ' + new Date().toISOString() + '\n'
  writeFileSync(OUTPUT, body)
  console.log('docs/README.md regenerated.')
}

build()