/**
 * Logique pure partagée : génération markdown, lecture meta, échappements.
 */
import fs from 'node:fs'
import path from 'node:path'

export const FEATURED_START = '<!-- FEATURED_START -->'
export const FEATURED_END = '<!-- FEATURED_END -->'

export function escMd(s) {
  if (typeof s !== 'string') return ''
  return s.replace(/\|/g, '\\|')
}

export function escHtml(s) {
  return String(s)
    .replace(/&/g, '&amp;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
}

export function pickFeatured(items) {
  const marked = items.filter((p) => p.featured).sort((a, b) => (a.order ?? 0) - (b.order ?? 0))
  if (marked.length) return marked.slice(0, 6)
  return [...items].sort((a, b) => (a.order ?? 0) - (b.order ?? 0)).slice(0, 3)
}

/** @param {Function} sitePath - ex. import { sitePath } from './site-base.mjs' */
export function buildFeaturedHtml(items, sitePath) {
  const featured = pickFeatured(items)
  if (!featured.length) return '<!-- (aucune présentation) -->'
  const lines = [
    '<section class="talks-section talks-section--home" aria-labelledby="featured-heading">',
    '  <h2 id="featured-heading" class="section-title">Présentations</h2>',
    '  <div class="talks-grid">',
  ]
  for (const p of featured) {
    const href = sitePath(`/presentations/${p.slug}/`)
    const meta = `Présentation · ${p.slug}`
    lines.push(`    <a class="talk-card" href="${escHtml(href)}">`)
    lines.push(`      <h2>${escHtml(p.title)}</h2>`)
    lines.push(`      <p>${escHtml(p.description || '')}</p>`)
    lines.push(`      <span class="meta">${escHtml(meta)}</span>`)
    lines.push('    </a>')
  }
  lines.push('  </div>', '</section>')
  return lines.join('\n')
}

export function readAllMeta(slidesRoot) {
  if (!fs.existsSync(slidesRoot)) return []
  const dirs = fs
    .readdirSync(slidesRoot, { withFileTypes: true })
    .filter((d) => d.isDirectory() && !d.name.startsWith('wip_') && !d.name.startsWith('_'))
    .map((d) => d.name)

  const list = []
  for (const dir of dirs) {
    const metaPath = path.join(slidesRoot, dir, 'meta.json')
    if (!fs.existsSync(metaPath)) continue
    const raw = fs.readFileSync(metaPath, 'utf8')
    const meta = JSON.parse(raw)
    if (meta.slug && meta.slug !== dir) {
      console.warn(`[sync] slug "${meta.slug}" ≠ dossier "${dir}", le dossier fait foi pour les URLs Slidev`)
    }
    list.push({ ...meta, slug: dir, folder: dir })
  }
  list.sort((a, b) => (a.order ?? 0) - (b.order ?? 0))
  return list
}

/** @param {Function} sitePath */
export function generateListPageMarkdown(items, sitePath) {
  const lines = [
    '---',
    'title: Présentations',
    'outline: deep',
    '---',
    '',
    '# Présentations',
    '',
    'Decks disponibles — fiche portail et build Slidev statique.',
    '',
    '<div class="talks-grid">',
  ]
  for (const p of items) {
    const detail = sitePath(`/presentations/${p.slug}/`)
    /** Première planche (`/1`) + classe `vp-raw` : le routeur VitePress ignore ces liens (navigation réelle vers Slidev). */
    const deck = sitePath(`/slides/${p.slug}/1`)
    const tags = (p.tags || []).map((t) => `\`${escMd(t)}\``).join(' · ')
    lines.push('  <article class="talk-card talk-card--list">')
    lines.push(`    <h2><a href="${detail}">${escMd(p.title)}</a></h2>`)
    lines.push(`    <p>${escMd(p.description || '')}</p>`)
    if (tags) lines.push(`    <p class="meta">${tags}</p>`)
    lines.push('    <div class="talk-card__actions">')
    lines.push(`      <a class="vp-button" href="${detail}">Fiche</a>`)
    lines.push(
      `      <a class="vp-button vp-button--alt vp-raw" href="${deck}" rel="noopener">Slides</a>`,
    )
    lines.push('    </div>')
    lines.push('  </article>')
  }
  lines.push('</div>', '')
  return lines.join('\n')
}

/** @param {Function} sitePath */
export function generateDetailPageMarkdown(p, sitePath) {
  /** `vp-raw` : VitePress ne intercepte pas le clic (sinon 404 SPA sur /slides/…). */
  const deck = sitePath(`/slides/${p.slug}/1`)
  const tags = (p.tags || []).map((t) => `\`${t}\``).join(' · ')
  const lines = [
    '---',
    `title: ${p.title.replace(/"/g, '\\"')}`,
    'outline: deep',
    '---',
    '',
    `# ${p.title}`,
    '',
    ...(tags ? [`**Tags :** ${tags}`, ''] : []),
    '## Résumé',
    '',
    p.description || '_Pas de description._',
    '',
    '## Accès',
    '',
    `<p class="pres-actions">`,
    `  <a class="vp-button vp-raw" href="${deck}">Voir les slides</a>`,
    `  <a class="vp-button vp-button--alt vp-raw" href="${deck}" target="_blank" rel="noopener noreferrer">Ouvrir dans un nouvel onglet</a>`,
    `</p>`,
    '',
    '## Partager les slides',
    '',
    'Depuis la salle, scannez le code pour ouvrir les slides sur mobile.',
    '',
    `<QrEncode path="${deck}" />`,
    '',
    '::: info À propos',
    'Les slides sont servies en SPA statique (Slidev). Les chemins d’assets suivent le `base` défini au build.',
    ':::',
    '',
  ]
  return lines.filter((l) => l !== undefined).join('\n')
}

export function patchIndexFeaturedContent(indexContent, items, sitePath) {
  const i0 = indexContent.indexOf(FEATURED_START)
  const i1 = indexContent.indexOf(FEATURED_END)
  if (i0 === -1 || i1 === -1 || i1 <= i0) {
    return { ok: false, content: indexContent }
  }
  const before = indexContent.slice(0, i0 + FEATURED_START.length)
  const after = indexContent.slice(i1)
  const block = buildFeaturedHtml(items, sitePath)
  const content = `${before}\n\n${block}\n\n${after}`
  return { ok: true, content }
}