import mammoth from "mammoth"
import {
  extractDocxPageSetup,
  type DocPageSetup,
} from "@/lib/drive/doc-page-setup"

export type TipTapJSON = Record<string, unknown>

export type RichTextImportResult = {
  content: TipTapJSON
  pageSetup?: DocPageSetup | null
}

const IMAGE_ATTR_KEYS = ["src", "alt", "title", "width", "height"] as const

function imageNodeFromElement(el: HTMLElement): TipTapJSON | null {
  const src = el.getAttribute("src")
  if (!src) return null
  const attrs: Record<string, unknown> = {
    src,
    alt: el.getAttribute("alt") ?? "",
  }
  const title = el.getAttribute("title")
  if (title) attrs.title = title
  const width = el.getAttribute("width")
  const height = el.getAttribute("height")
  if (width) attrs.width = Number(width) || width
  if (height) attrs.height = Number(height) || height
  return { type: "image", attrs }
}

function inlineContentFromElement(el: HTMLElement): TipTapJSON[] {
  const content: TipTapJSON[] = []
  for (const node of el.childNodes) {
    if (node.nodeType === Node.TEXT_NODE) {
      const text = node.textContent ?? ""
      if (text) content.push({ type: "text", text })
      continue
    }
    if (node.nodeType !== Node.ELEMENT_NODE) continue
    const child = node as HTMLElement
    const tag = child.tagName.toLowerCase()
    if (tag === "img") {
      const image = imageNodeFromElement(child)
      if (image) content.push(image)
      continue
    }
    content.push(...inlineContentFromElement(child))
  }
  return content
}

/** Keep only attrs supported by @tiptap/extension-image. */
export function normalizeImportedTipTap(content: TipTapJSON): TipTapJSON {
  const walk = (node: unknown): unknown => {
    if (!node || typeof node !== "object") return node
    if (Array.isArray(node)) return node.map(walk)
    const record = node as TipTapJSON
    if (record.type === "image" && record.attrs && typeof record.attrs === "object") {
      const raw = record.attrs as Record<string, unknown>
      const attrs: Record<string, unknown> = {}
      for (const key of IMAGE_ATTR_KEYS) {
        const value = raw[key]
        if (value != null && value !== "") attrs[key] = value
      }
      if (typeof attrs.src !== "string" || !attrs.src) {
        return null
      }
      return { ...record, attrs }
    }
    if (Array.isArray(record.content)) {
      const nextContent = record.content.map(walk).filter(Boolean)
      return { ...record, content: nextContent }
    }
    return record
  }
  const normalized = walk(content)
  if (!normalized || typeof normalized !== "object") {
    return { type: "doc", content: [{ type: "paragraph" }] }
  }
  return normalized as TipTapJSON
}

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 === "img") {
      const image = imageNodeFromElement(el)
      if (image) {
        blocks.push({ type: "paragraph", content: [image] })
      }
      return
    }
    if (tag === "p" || tag === "div") {
      const content = inlineContentFromElement(el)
      blocks.push({
        type: "paragraph",
        content: content.length ? content : [],
      })
      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: inlineContentFromElement(li) }],
      }))
      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 normalizeImportedTipTap({ type: "doc", content: blocks })
}

export async function importDocxToTipTap(buffer: ArrayBuffer): Promise<RichTextImportResult> {
  const pageSetup = await extractDocxPageSetup(buffer)
  try {
    const { parseDOCX } = await import("@docen/import-docx")
    const content = await parseDOCX(buffer, { image: { crop: false } })
    if (content && typeof content === "object") {
      return { content: normalizeImportedTipTap(content as TipTapJSON), pageSetup }
    }
  } catch (error) {
    if (process.env.NODE_ENV !== "production") {
      console.warn("[richtext-import] parseDOCX failed, falling back to mammoth", error)
    }
  }
  const result = await mammoth.convertToHtml(
    { arrayBuffer: buffer },
    {
      convertImage: mammoth.images.imgElement((image) =>
        image.read("base64").then((imageBuffer) => ({
          src: `data:${image.contentType};base64,${imageBuffer}`,
        }))
      ),
    }
  )
  return { content: htmlToTipTapDoc(result.value), pageSetup }
}

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<RichTextImportResult> {
  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 { content: htmlToTipTapDoc(text) }
  }
  const lines = text.split(/\r?\n/)
  return {
    content: {
      type: "doc",
      content: lines.map((line) => ({
        type: "paragraph",
        content: line ? [{ type: "text", text: line }] : [],
      })),
    },
  }
}