import { attachmentApi, type BxId } from '@/api/bx'
import { ElMessage } from 'element-plus'

export type BxAttachmentItem = {
  id: number | string
  fileName: string
  fileType?: string
  fileSize?: number
  previewUrl?: string
  _uploading?: boolean
  _existing?: boolean
}

const IMAGE_EXT = /\.(png|jpe?g|gif|webp|bmp|svg)$/i
const VIDEO_EXT = /\.(mp4|webm|ogg|mov|avi)$/i
const PDF_EXT = /\.pdf$/i

export function isBxImageFile(file: { fileName?: string; fileType?: string }) {
  const name = String(file.fileName || '').toLowerCase()
  const type = String(file.fileType || '').toLowerCase()
  return type.startsWith('image/') || IMAGE_EXT.test(name)
}

export function isBxVideoFile(file: { fileName?: string; fileType?: string }) {
  const name = String(file.fileName || '').toLowerCase()
  const type = String(file.fileType || '').toLowerCase()
  return type.startsWith('video/') || VIDEO_EXT.test(name)
}

export function isBxPdfFile(file: { fileName?: string; fileType?: string }) {
  const name = String(file.fileName || '').toLowerCase()
  const type = String(file.fileType || '').toLowerCase()
  return type === 'application/pdf' || type.includes('pdf') || PDF_EXT.test(name)
}

export function canBxPreview(file: BxAttachmentItem) {
  if (file._uploading) return false
  return isBxImageFile(file) || isBxVideoFile(file) || isBxPdfFile(file)
}

export async function fillBxAttachmentPreviews(
  files: Array<BxAttachmentItem & { attachmentId?: number | string }>
) {
  const tasks = files
    .filter((file) => isBxImageFile(file) && !file.previewUrl)
    .map(async (file) => {
      const id = file.id ?? file.attachmentId
      if (id == null || id === '') return
      try {
        const res: any = await attachmentApi.preview(id)
        file.previewUrl = res.data?.url || ''
      } catch {
        /* preview optional */
      }
    })
  await Promise.all(tasks)
}

export async function loadBxAttachments(bizType: string, bizId: BxId): Promise<BxAttachmentItem[]> {
  const res: any = await attachmentApi.listByBiz(bizType, bizId)
  const files: BxAttachmentItem[] = (res.data || []).map((item: any) => ({
    id: item.id,
    fileName: item.fileName,
    fileType: item.fileType || '',
    fileSize: item.fileSize,
    previewUrl: '',
    _existing: true
  }))
  await fillBxAttachmentPreviews(files)
  return files
}

export async function downloadBxAttachment(file: { id: number | string; fileName: string }) {
  try {
    const res: any = await attachmentApi.download(file.id)
    const blob = new Blob([res], { type: 'application/octet-stream' })
    const url = URL.createObjectURL(blob)
    const anchor = document.createElement('a')
    anchor.href = url
    anchor.download = file.fileName
    anchor.click()
    URL.revokeObjectURL(url)
  } catch (error: any) {
    ElMessage.error(error?.message || '下载失败')
    throw error
  }
}

export async function previewBxAttachment(file: BxAttachmentItem) {
  if (isBxVideoFile(file)) {
    try {
      const res: any = await attachmentApi.preview(file.id)
      return { type: 'video' as const, url: res.data?.url || '', fileName: file.fileName }
    } catch (error: any) {
      ElMessage.error(error?.message || '预览失败')
      throw error
    }
  }
  if (isBxImageFile(file)) {
    if (file.previewUrl) {
      return { type: 'image' as const, url: file.previewUrl, fileName: file.fileName }
    }
    try {
      const res: any = await attachmentApi.preview(file.id)
      file.previewUrl = res.data?.url || ''
      return { type: 'image' as const, url: file.previewUrl, fileName: file.fileName }
    } catch (error: any) {
      ElMessage.error(error?.message || '预览失败')
      throw error
    }
  }
  if (isBxPdfFile(file)) {
    try {
      const res: any = await attachmentApi.preview(file.id)
      return { type: 'pdf' as const, url: res.data?.url || '', fileName: file.fileName }
    } catch (error: any) {
      ElMessage.error(error?.message || '预览失败')
      throw error
    }
  }
  ElMessage.warning('该文件类型暂不支持在线预览，请使用下载查看')
  return null
}