import katex from 'katex'
import { sanitizePublishedHtml } from '@/lib/sanitize-content'
import { preprocessMathInHtml } from '@/lib/text/math-preprocess'
import { transformEditorBlocksForPublish } from '@/lib/publish/transform-editor-blocks'

function decodeHtml(text: string): string {
  const map: Record<string, string> = { '&quot;': '"', '&amp;': '&', '&lt;': '<', '&gt;': '>', '&#39;': "'" }
  return text.replace(/&[a-z#0-9]+;/gi, (m) => map[m] || m)
}

function extractLatex(attrs: string, inner: string): string {
  const fromAttr = attrs.match(/data-latex=["']([^"']*)["']/i)?.[1]
  if (fromAttr) return decodeHtml(fromAttr)
  const text = inner.replace(/<[^>]+>/g, '').trim()
  return decodeHtml(text)
}

function isAlreadyKatex(html: string): boolean {
  return /class=["'][^"']*\bkatex\b/i.test(html)
}

function renderKatexDisplay(latex: string): string {
  const trimmed = latex.trim()
  if (!trimmed) return ''
  try {
    const rendered = katex.renderToString(trimmed, { displayMode: true, throwOnError: false })
    return `<div class="r-math-display">${rendered}</div>`
  } catch {
    return `<div class="r-math-display r-math-fallback">${trimmed}</div>`
  }
}

function renderKatexInline(latex: string): string {
  const trimmed = latex.trim()
  if (!trimmed) return ''
  try {
    const rendered = katex.renderToString(trimmed, { displayMode: false, throwOnError: false })
    return `<span class="r-math-inline">${rendered}</span>`
  } catch {
    return `<span class="r-math-inline r-math-fallback">${trimmed}</span>`
  }
}

/** Convertit nœuds éditeur + délimiteurs LaTeX en HTML KaTeX. */
export function renderMathInHtml(html: string): string {
  if (!html?.trim()) return ''

  let result = preprocessMathInHtml(html)

  // Blocs : data-type="math-equation" ou .math-equation-block
  result = result.replace(
    /<div\b([^>]*(?:data-type=["']math-equation["']|class=["'][^"']*math-equation-block)[^>]*)>([\s\S]*?)<\/div>/gi,
    (full, attrs, inner) => {
      if (isAlreadyKatex(full)) return full
      const latex = extractLatex(attrs, inner)
      return latex ? renderKatexDisplay(latex) : full
    },
  )

  // Inline : data-type="inline-math" ou .inline-math
  result = result.replace(
    /<span\b([^>]*(?:data-type=["']inline-math["']|class=["'][^"']*inline-math)[^>]*)>([\s\S]*?)<\/span>/gi,
    (full, attrs, inner) => {
      if (isAlreadyKatex(full)) return full
      const latex = extractLatex(attrs, inner)
      return latex ? renderKatexInline(latex) : full
    },
  )

  return result
}

/** Prépare le HTML de la note pour affichage public (KaTeX, callouts, nettoyage éditeur). */
export function processNoteHtmlForPublish(html: string): string {
  if (!html?.trim()) return ''

  let result = renderMathInHtml(html)

  // Blocs éditeur TipTap → HTML publication (exercices, toggles, callouts…)
  result = transformEditorBlocksForPublish(result)

  result = result.replace(/<div[^>]*class="link-preview-searchable"[^>]*>[\s\S]*?<\/div>/g, '')

  // Figures éditeur → sémantique publication (img déjà traités ignorés)
  result = result.replace(/<img([^>]*?)>/gi, (match, attrs) => {
    if (/class=["'][^"']*pub-/i.test(match)) return match
    const altMatch = attrs.match(/\balt=["']([^"']*)["']/i)
    const alt = altMatch?.[1] || ''
    return `<figure class="pub-figure"><img${attrs} loading="lazy" class="pub-figure-img" />${alt ? `<figcaption class="pub-figure-caption">${alt}</figcaption>` : ''}</figure>`
  })

  return sanitizePublishedHtml(result)
}

export function extractPublishImageUrls(html: string): string[] {
  if (!html) return []
  const urls = new Set<string>()
  for (const match of html.matchAll(/<img[^>]+src=["']([^"'>]+)["']/gi)) {
    const src = match[1]?.trim()
    if (src && isAllowedImageSrc(src)) urls.add(src)
  }
  return Array.from(urls)
}

export function isAllowedImageSrc(src: string): boolean {
  const t = src.trim()
  return t.startsWith('/uploads/')
    || t.startsWith('https://')
    || t.startsWith('http://')
    || t.startsWith('/api/')
}