import { closeToast, showLoadingToast, showToast } from 'vant'
import { detectEnvironment } from './environment'
import { getAttachmentDisplayName } from './fileType'
import { mobileUtil } from './mobileUtil'
import { resolveResourceUrl } from './resourceUrl'

export interface AttachmentDownloadSource {
  url?: string
  f_downloadpath?: string
  real_name?: string
  name?: string
}

/**
 * 解析附件下载地址：
 * - /resource 开头：保持相对路径，由 nginx 转发，不拼接 origin
 * - http/https 开头：直接使用
 * - 其他情况：走 resolveResourceUrl 正常处理
 */
function getDownloadUrl(file: AttachmentDownloadSource): string {
  const raw = file.url || file.f_downloadpath || ''
  if (!raw)
    return ''
  if (raw.startsWith('/resource/') || /^https?:\/\//i.test(raw))
    return raw
  return resolveResourceUrl(raw)
}

/**
 * 浏览器环境：fetch 文件内容后用隐藏 <a> 标签触发保存
 * WebView 环境此方法无效（WebView 没有下载管理器）
 */
function triggerBlobDownload(blob: Blob, filename: string) {
  const blobUrl = URL.createObjectURL(blob)
  const link = document.createElement('a')
  link.href = blobUrl
  link.download = filename
  link.style.display = 'none'
  document.body.appendChild(link)
  link.click()
  document.body.removeChild(link)
  setTimeout(() => URL.revokeObjectURL(blobUrl), 1000)
}

/**
 * 用其他应用打开文件（方式二：传 url+name，Flutter 端自动下载后调起系统分享面板）
 * 非 http/https 路径由 Flutter 端拼接 AppConfig.webUrl
 */
export function openFileWithApp(url: string, name: string): void {
  mobileUtil.execute({
    funcName: 'openFileWithApp',
    param: { url, name },
    callbackFunc: (result: any) => {
      console.log('>>>> openFileWithApp: result: ', JSON.stringify(result))
    },
  })
}

/**
 * 下载附件，自动区分 Flutter WebView 和普通浏览器：
 * - Flutter WebView：通过 mobileUtil 调用原生 downloadFile channel
 * - 普通浏览器：fetch + blob 触发浏览器保存对话框
 */
export async function downloadAttachment(file: AttachmentDownloadSource): Promise<void> {
  const url = getDownloadUrl(file)
  const filename = getAttachmentDisplayName(file)

  if (!url) {
    showToast('附件地址无效')
    return
  }

  // Flutter WebView 环境：交给原生层下载
  if (detectEnvironment().isApp) {
    const toast = showLoadingToast({ message: '下载中...', forbidClick: true, duration: 0 })
    try {
      await new Promise<void>((resolve, reject) => {
        mobileUtil.execute({
          funcName: 'downloadFile',
          param: { url, name: filename },
          callbackFunc: (result: any) => {
            result?.status === 'error'
              ? reject(new Error(result.msg || '下载失败'))
              : resolve()
          },
        })
      })
      showToast('下载成功')
    }
    catch (e: any) {
      showToast(e?.message || '下载失败')
    }
    finally {
      closeToast()
    }
    return
  }

  // 普通浏览器环境：fetch + blob
  const toast = showLoadingToast({ message: '下载中...', forbidClick: true, duration: 0 })
  try {
    const response = await fetch(url, { credentials: 'include' })
    if (!response.ok)
      throw new Error(`下载失败(${response.status})`)
    const blob = await response.blob()
    triggerBlobDownload(blob, filename)
    showToast('下载成功')
  }
  catch {
    window.open(url, '_blank')
    showToast('已打开文件，可在浏览器中保存到本地')
  }
  finally {
    closeToast()
  }
}