'use client'

import { useEffect, useMemo, useState } from 'react'
import Image from 'next/image'

export interface ViewerAssetItem {
  id: string
  fileName: string
  fileUrl: string
  fileKind: 'pdf' | 'image'
}

interface DocumentAssetViewerProps {
  title: string
  items: ViewerAssetItem[]
}

function formatLabel(fileName: string, index: number): string {
  const normalized = String(fileName || '').trim()
  return normalized || `文件 ${index + 1}`
}

export default function DocumentAssetViewer({ title, items }: DocumentAssetViewerProps) {
  const normalizedItems = useMemo(
    () =>
      items
        .filter((item) => item.fileUrl)
        .map((item, index) => ({
          ...item,
          fileName: formatLabel(item.fileName, index),
        })),
    [items],
  )

  const [selectedId, setSelectedId] = useState(normalizedItems[0]?.id || '')

  useEffect(() => {
    setSelectedId(normalizedItems[0]?.id || '')
  }, [normalizedItems])

  const selectedItem = normalizedItems.find((item) => item.id === selectedId) || normalizedItems[0]

  const handleOpenFile = () => {
    if (!selectedItem?.fileUrl) {
      return
    }
    window.open(selectedItem.fileUrl, '_blank', 'noopener,noreferrer')
  }

  const handleDownloadFile = async () => {
    if (!selectedItem?.fileUrl) {
      return
    }

    try {
      const response = await fetch(selectedItem.fileUrl)
      if (!response.ok) {
        throw new Error('文件下载失败')
      }

      const blob = await response.blob()
      const objectUrl = URL.createObjectURL(blob)
      const anchor = document.createElement('a')
      anchor.href = objectUrl
      anchor.download = selectedItem.fileName
      document.body.appendChild(anchor)
      anchor.click()
      document.body.removeChild(anchor)
      URL.revokeObjectURL(objectUrl)
    } catch (error) {
      console.error('[DocumentAssetViewer] 下载失败，改为直接打开原文件:', error)
      window.open(selectedItem.fileUrl, '_blank', 'noopener,noreferrer')
    }
  }

  if (!selectedItem) {
    return (
      <div className="flex min-h-[400px] items-center justify-center bg-[#fafafa] text-sm text-[#86898e]">
        暂无可预览文件
      </div>
    )
  }

  return (
    <div className="w-full bg-white">
      <div className="border-b border-[#e7e8ea] px-4 py-3">
        <div className="mb-3 text-sm font-medium text-[#1a1c1d]">{title}</div>
        <div className="flex flex-wrap gap-2">
          {normalizedItems.map((item) => {
            const isActive = item.id === selectedItem.id
            return (
              <button
                key={item.id}
                type="button"
                onClick={() => setSelectedId(item.id)}
                className={`rounded-[8px] px-3 py-1.5 text-xs transition-colors ${
                  isActive
                    ? 'bg-[#1a1c1d] text-white'
                    : 'border border-[#e7e8ea] text-[#6b7075] hover:border-[#1a1c1d] hover:text-[#1a1c1d]'
                }`}
              >
                {item.fileKind === 'pdf' ? 'PDF' : '图片'} · {item.fileName}
              </button>
            )
          })}
        </div>
      </div>

      <div className="flex items-center justify-between border-b border-[#e7e8ea] px-4 py-3">
        <div className="min-w-0">
          <div className="truncate text-sm font-medium text-[#1a1c1d]">{selectedItem.fileName}</div>
          <div className="mt-1 text-xs text-[#86898e]">
            {selectedItem.fileKind === 'pdf' ? 'PDF 文档预览' : '图片原图预览'}
          </div>
        </div>
        <div className="flex items-center gap-2">
          <button
            type="button"
            onClick={handleOpenFile}
            className="rounded-[8px] border border-[#e7e8ea] px-3 py-2 text-sm text-[#1a1c1d] transition-colors hover:border-[#1a1c1d]"
          >
            打开原文件
          </button>
          <button
            type="button"
            onClick={() => {
              void handleDownloadFile()
            }}
            className="rounded-[8px] bg-[#1a1c1d] px-3 py-2 text-sm text-white transition-colors hover:bg-[#2a2d2f]"
          >
            下载原文件
          </button>
        </div>
      </div>

      <div className="bg-[#fafafa]">
        {selectedItem.fileKind === 'pdf' ? (
          <iframe
            src={`${selectedItem.fileUrl}#toolbar=0&navpanes=0&scrollbar=1`}
            className="w-full"
            style={{ height: '980px', border: 'none' }}
            title={selectedItem.fileName}
          />
        ) : (
          <div className="flex items-center justify-center p-6">
            <Image
              src={selectedItem.fileUrl}
              alt={selectedItem.fileName}
              width={790}
              height={1200}
              unoptimized
              className="h-auto w-full object-contain"
              style={{ maxWidth: '790px' }}
            />
          </div>
        )}
      </div>
    </div>
  )
}