// 文件访问API - 提供本地上传文件的访问
import { NextRequest } from 'next/server'
import { getServerSession } from 'next-auth'
import fs from 'fs'
import path from 'path'
import { lookup as mimeTypeLookup } from 'mime-types'
import { authOptions } from '@/lib/auth'
import { prisma } from '@/lib/prisma'
import {
  canUserDownloadMaterial,
  canUserDownloadSource,
  hasSystemAdminPermission,
} from '@/lib/department-permission'
import { DownloadErrorCode } from '@/lib/download-errors'
import { is3DOriginalType, isProductPackageType } from '@/lib/material-type-mapper'
import { findBlockedVideoPreviewByUrl, isVideoMediaPath } from '@/lib/video-preview-access'
import { userHasVideoEarlyAccess } from '@/lib/video-download-policy'

export const runtime = 'nodejs'
export const dynamic = 'force-dynamic'

type FileAccessKind = 'preview' | 'source'

interface FileMaterial {
  id: string
  materialType: string
}

interface ResolvedFileAccess {
  kind: FileAccessKind
  material: FileMaterial
}

function isPathInside(basePath: string, targetPath: string): boolean {
  return targetPath === basePath || targetPath.startsWith(`${basePath}${path.sep}`)
}

function normalizeStoredPath(value: unknown): string {
  return String(value || '').trim().replace(/\\/g, '/').replace(/^\.\//, '')
}

function buildStoredPathCandidates(relativePath: string, filePath: string): string[] {
  const normalizedRelativePath = normalizeStoredPath(relativePath).replace(/^\/+/, '')
  const candidates = new Set<string>([
    normalizedRelativePath,
    `uploads/${normalizedRelativePath}`,
    `/uploads/${normalizedRelativePath}`,
    `/api/uploads/${normalizedRelativePath}`,
    normalizeStoredPath(filePath),
  ])

  for (const candidate of Array.from(candidates)) {
    candidates.add(candidate.replace(/\//g, '\\'))
  }

  return Array.from(candidates).filter(Boolean)
}

function isPreviewAssetType(assetType: unknown): boolean {
  const normalized = String(assetType || '').trim()
  return (
    ['preview', 'main-preview', 'sku-preview', 'detail-preview', 'report-image'].includes(normalized) ||
    normalized.startsWith('standard-model-white-bg-view:') ||
    normalized.startsWith('standard-model-white-bg-other:')
  )
}

async function resolveFileAccess(
  candidates: string[],
): Promise<ResolvedFileAccess | null> {
  const normalizedCandidates = new Set(candidates.map(normalizeStoredPath))
  const matchesCandidate = (value: unknown) => normalizedCandidates.has(normalizeStoredPath(value))

  const materials = await prisma.material.findMany({
    where: {
      deletedAt: null,
      OR: [
        { previewUrl: { in: candidates } },
        { zipFileName: { in: candidates } },
        { zipFilePath: { in: candidates } },
        { videoSourceUrl: { in: candidates } },
        { videoPreview540Url: { in: candidates } },
        { videoPreviewClipUrl: { in: candidates } },
        { videoCoverUrl: { in: candidates } },
        { displayImages: { hasSome: candidates } },
      ],
    } as any,
    select: {
      id: true,
      materialType: true,
      previewUrl: true,
      zipFileName: true,
      zipFilePath: true,
      videoSourceUrl: true,
      videoPreview540Url: true,
      videoPreviewClipUrl: true,
      videoCoverUrl: true,
      displayImages: true,
    },
    take: 20,
  })

  const assetMatches = await prisma.materialAsset.findMany({
    where: {
      fileUrl: { in: candidates },
      material: { deletedAt: null },
    } as any,
    select: {
      assetType: true,
      material: {
        select: {
          id: true,
          materialType: true,
        },
      },
    },
    take: 20,
  })

  for (const material of materials as any[]) {
    if (
      matchesCandidate(material.zipFileName) ||
      matchesCandidate(material.zipFilePath) ||
      matchesCandidate(material.videoSourceUrl)
    ) {
      return { kind: 'source', material }
    }
  }

  for (const asset of assetMatches as any[]) {
    if (!isPreviewAssetType(asset.assetType)) {
      return { kind: 'source', material: asset.material }
    }
  }

  for (const material of materials as any[]) {
    if (
      matchesCandidate(material.previewUrl) ||
      matchesCandidate(material.videoPreview540Url) ||
      matchesCandidate(material.videoPreviewClipUrl) ||
      matchesCandidate(material.videoCoverUrl) ||
      (Array.isArray(material.displayImages) && material.displayImages.some(matchesCandidate))
    ) {
      return { kind: 'preview', material }
    }
  }

  const previewAsset = (assetMatches as any[]).find((asset) => isPreviewAssetType(asset.assetType))
  return previewAsset ? { kind: 'preview', material: previewAsset.material } : null
}

async function authorizeSourceAccess(
  request: NextRequest,
  material: FileMaterial,
): Promise<Response | null> {
  const session = await getServerSession(authOptions)
  if (!session?.user) {
    return Response.json(
      { error: '请先登录' },
      { status: 401, headers: { 'Cache-Control': 'no-store' } },
    )
  }

  const sessionUser = session.user as any
  const user = await prisma.user.findUnique({
    where: { id: String(sessionUser.id || '') },
    select: {
      role: true,
      department: true,
      managedDepartment: true,
      canDownload: true,
      isSuperAdmin: true,
    },
  })

  if (!user) {
    return Response.json(
      { error: '用户不存在' },
      { status: 403, headers: { 'Cache-Control': 'no-store' } },
    )
  }

  if (hasSystemAdminPermission(user.role, Boolean(user.isSuperAdmin))) {
    return null
  }

  if (!user.canDownload) {
    return Response.json(
      { error: '无权限下载该文件' },
      { status: 403, headers: { 'Cache-Control': 'no-store' } },
    )
  }

  const canDownload = await canUserDownloadMaterial(
    user.department,
    user.role,
    user.managedDepartment,
    material.materialType,
    String(sessionUser.id),
  )
  if (!canDownload) {
    return Response.json(
      { error: '无权限下载该文件' },
      { status: 403, headers: { 'Cache-Control': 'no-store' } },
    )
  }

  if (isProductPackageType(material.materialType) || is3DOriginalType(material.materialType)) {
    const canDownloadSource = await canUserDownloadSource(
      user.department,
      user.role,
      user.managedDepartment,
      material.materialType,
      String(sessionUser.id),
    )
    if (!canDownloadSource) {
      return Response.json(
        { error: '无权限下载源文件' },
        { status: 403, headers: { 'Cache-Control': 'no-store' } },
      )
    }
  }

  return null
}

async function handleFileRequest(
  request: NextRequest,
  pathSegments: string[],
  headOnly: boolean,
): Promise<Response> {
  if (pathSegments.length === 1 && pathSegments[0] === 'health') {
    return new Response(headOnly ? null : 'OK', { status: 200 })
  }

  if (
    pathSegments.length === 0 ||
    pathSegments.some((segment) => !segment || segment === '.' || segment === '..' || /[\\/]/.test(segment))
  ) {
    return new Response(headOnly ? null : 'Forbidden', { status: 403 })
  }

  const uploadDir = path.resolve(process.env.UPLOAD_DIR || '/app/uploads')
  const relativePath = path.join(...pathSegments)
  const normalizedRelativePath = relativePath.replace(/\\/g, '/')
  const filePath = path.resolve(uploadDir, relativePath)
  if (!isPathInside(uploadDir, filePath)) {
    return new Response(headOnly ? null : 'Forbidden', { status: 403 })
  }

  const access = await resolveFileAccess(buildStoredPathCandidates(relativePath, filePath))
  if (!access) {
    return new Response(headOnly ? null : 'Not Found', { status: 404 })
  }

  if (access.kind === 'source') {
    const deniedResponse = await authorizeSourceAccess(request, access.material)
    if (deniedResponse) {
      return headOnly
        ? new Response(null, {
            status: deniedResponse.status,
            headers: { 'Cache-Control': 'no-store' },
          })
        : deniedResponse
    }
  }

  if (isVideoMediaPath(normalizedRelativePath)) {
    // 懒获取登录态：只有视频文件才需要判定 15 天保护期豁免。
    const videoSession = await getServerSession(authOptions)
    const blockedPreview = await findBlockedVideoPreviewByUrl(
      [
        request.url,
        `/api/uploads/${normalizedRelativePath}`,
        `/uploads/${normalizedRelativePath}`,
        normalizedRelativePath,
      ],
      new Date(),
      { bypassWaitPeriod: userHasVideoEarlyAccess(videoSession?.user) },
    )

    if (blockedPreview) {
      return headOnly
        ? new Response(null, { status: 403, headers: { 'Cache-Control': 'no-store' } })
        : Response.json(
            {
              error: '视频类素材上传后满 15 天才能预览和下载',
              code: DownloadErrorCode.VIDEO_WAIT_PERIOD,
              details: blockedPreview.message,
            },
            { status: 403, headers: { 'Cache-Control': 'no-store' } },
          )
    }
  }

  try {
    const stats = await fs.promises.stat(filePath)
    if (!stats.isFile()) {
      return new Response(headOnly ? null : 'Not Found', { status: 404 })
    }

    const contentType = mimeTypeLookup(path.extname(filePath)) || 'application/octet-stream'
    const cacheControl =
      access.kind === 'source' ? 'private, no-store' : 'public, max-age=31536000, immutable'

    if (headOnly) {
      return new Response(null, {
        status: 200,
        headers: {
          'Content-Length': String(stats.size),
          'Content-Type': contentType,
          'Cache-Control': cacheControl,
        },
      })
    }

    const range = request.headers.get('range')
    if (range) {
      const parts = range.match(/bytes=(\d*)-(\d*)/)
      const start = parts && parts[1] ? Number.parseInt(parts[1], 10) : 0
      const end = parts && parts[2] ? Number.parseInt(parts[2], 10) : stats.size - 1
      if (Number.isNaN(start) || Number.isNaN(end) || start > end || end >= stats.size) {
        return new Response('Invalid Range', { status: 416 })
      }

      const stream = fs.createReadStream(filePath, { start, end })
      return new Response(stream as any, {
        status: 206,
        headers: {
          'Content-Range': `bytes ${start}-${end}/${stats.size}`,
          'Accept-Ranges': 'bytes',
          'Content-Length': String(end - start + 1),
          'Content-Type': contentType,
          'Cache-Control': cacheControl,
        },
      })
    }

    const stream = fs.createReadStream(filePath)
    return new Response(stream as any, {
      status: 200,
      headers: {
        'Content-Length': String(stats.size),
        'Content-Type': contentType,
        'Cache-Control': cacheControl,
      },
    })
  } catch (error: any) {
    if (error?.code === 'ENOENT') {
      return new Response(headOnly ? null : 'Not Found', { status: 404 })
    }
    return new Response(headOnly ? null : 'Server Error', { status: 500 })
  }
}

export async function GET(
  request: NextRequest,
  { params }: { params: { path: string[] } },
) {
  return handleFileRequest(request, params.path || [], false)
}

export async function HEAD(
  request: NextRequest,
  { params }: { params: { path: string[] } },
) {
  return handleFileRequest(request, params.path || [], true)
}