import mammoth from "mammoth"

export type TipTapJSON = Record<string, unknown>

function htmlToTipTapDoc(html: string): TipTapJSON {
  const parser = typeof DOMParser !== "undefined" ? new DOMParser() : null
  if (!parser) {
    return {
      type: "doc",
      content: [{ type: "paragraph", content: [{ type: "text", text: html.replace(/<[^>]+>/g, " ") }] }],
    }
  }
  const doc = parser.parseFromString(html, "text/html")
  const blocks: TipTapJSON[] = []

  const walk = (node: Node) => {
    if (node.nodeType === Node.TEXT_NODE) {
      const text = node.textContent ?? ""
      if (text.trim()) {
        blocks.push({ type: "paragraph", content: [{ type: "text", text }] })
      }
      return
    }
    if (node.nodeType !== Node.ELEMENT_NODE) return
    const el = node as HTMLElement
    const tag = el.tagName.toLowerCase()
    if (tag === "p" || tag === "div") {
      const text = el.textContent ?? ""
      blocks.push({
        type: "paragraph",
        content: text ? [{ type: "text", text }] : [],
      })
      return
    }
    if (/^h[1-6]$/.test(tag)) {
      const level = Number(tag[1])
      blocks.push({
        type: "heading",
        attrs: { level },
        content: [{ type: "text", text: el.textContent ?? "" }],
      })
      return
    }
    if (tag === "ul" || tag === "ol") {
      const listType = tag === "ul" ? "bulletList" : "orderedList"
      const items = Array.from(el.querySelectorAll(":scope > li")).map((li) => ({
        type: "listItem",
        content: [{ type: "paragraph", content: [{ type: "text", text: li.textContent ?? "" }] }],
      }))
      blocks.push({ type: listType, content: items })
      return
    }
    Array.from(el.childNodes).forEach(walk)
  }

  Array.from(doc.body.childNodes).forEach(walk)
  if (blocks.length === 0) {
    blocks.push({ type: "paragraph" })
  }
  return { type: "doc", content: blocks }
}

export async function importDocxToTipTap(buffer: ArrayBuffer): Promise<TipTapJSON> {
  try {
    const { parseDOCX } = await import("@docen/import-docx")
    const content = await parseDOCX(buffer)
    if (content && typeof content === "object") {
      return content as TipTapJSON
    }
  } catch {
    /* fallback mammoth */
  }
  const result = await mammoth.convertToHtml({ arrayBuffer: buffer })
  return htmlToTipTapDoc(result.value)
}

export async function exportTipTapToDocx(content: TipTapJSON): Promise<Blob> {
  try {
    const { generateDOCX } = await import("@docen/export-docx")
    const buf = await generateDOCX(content, { outputType: "blob" })
    if (buf instanceof Blob) return buf
  } catch {
    /* fallback unavailable */
  }
  throw new Error("Export DOCX indisponible")
}

export async function importFileToTipTap(
  fileName: string,
  buffer: ArrayBuffer
): Promise<TipTapJSON> {
  const ext = fileName.split(".").pop()?.toLowerCase() ?? ""
  if (ext === "docx" || ext === "docm") {
    return importDocxToTipTap(buffer)
  }
  const text = new TextDecoder().decode(buffer)
  if (ext === "html" || ext === "htm") {
    return htmlToTipTapDoc(text)
  }
  const lines = text.split(/\r?\n/)
  return {
    type: "doc",
    content: lines.map((line) => ({
      type: "paragraph",
      content: line ? [{ type: "text", text: line }] : [],
    })),
  }
}