import { NextRequest, NextResponse } from 'next/server'
import { getServerSession } from 'next-auth'
import { authOptions } from '@/lib/auth'
import { prisma } from '@/lib/prisma'
import { buildDepartmentDescendants, isDepartmentWithinScope } from '@/lib/departments'

// 统一更新用户信息；历史素材作者名只允许最高权限账号显式同步。
export async function POST(req: NextRequest) {
  try {
    const session = await getServerSession(authOptions)

    if (!session || (session.user as any)?.role !== 'ADMIN') {
      return NextResponse.json(
        { error: '权限不足' },
        { status: 403 }
      )
    }

    const { userId, username, department, role, isActive, canDownload, syncMaterialAuthorName } = await req.json()

    if (!userId) {
      return NextResponse.json(
        { error: '缺少用户ID' },
        { status: 400 }
      )
    }

    // 获取当前登录用户信息
    const currentUser = await prisma.user.findUnique({
      where: { id: (session.user as any).id },
      select: { id: true, managedDepartment: true }
    }) as any

    if (!currentUser) {
      return NextResponse.json(
        { error: '当前用户不存在' },
        { status: 404 }
      )
    }

    // 获取当前用户的完整信息（包括 isSuperAdmin）
    const currentUserFull = await prisma.user.findUnique({
      where: { id: (session.user as any).id },
    }) as any

    let departmentDescendantsMap: Map<string, Set<string>> | undefined
    if (currentUser.managedDepartment && !currentUserFull?.isSuperAdmin) {
      const departments = await prisma.department.findMany({ select: { name: true } })
      departmentDescendantsMap = buildDepartmentDescendants(departments)
    }

    // 获取更新前的用户信息
    const oldUser = await prisma.user.findUnique({
      where: { id: userId },
      select: { 
        id: true,
        username: true,
        department: true
      }
    })

    if (!oldUser) {
      return NextResponse.json(
        { error: '用户不存在' },
        { status: 404 }
      )
    }

    // 获取目标用户的完整信息（包括 isSuperAdmin）
    const targetUserFull = await prisma.user.findUnique({
      where: { id: userId },
    }) as any

    // 权限检查：只有最高权限账号或目标用户所属部门的管理员可以编辑
    if (!currentUserFull?.isSuperAdmin) {
      // 如果是部门管理员，只能编辑自己管理的部门下的用户
      if (currentUser.managedDepartment) {
        const allowed = isDepartmentWithinScope(
          currentUser.managedDepartment,
          oldUser.department,
          departmentDescendantsMap
        )
        if (!allowed) {
          return NextResponse.json(
            { error: '权限不足：只能编辑自己管理的部门树范围内的用户' },
            { status: 403 }
          )
        }
      } else {
        // 没有管理部门的管理员不能编辑任何人
        return NextResponse.json(
          { error: '权限不足' },
          { status: 403 }
        )
      }
    }

    // 最高权限账号不能被非最高权限账号编辑
    if (targetUserFull?.isSuperAdmin && !currentUserFull?.isSuperAdmin) {
      return NextResponse.json(
        { error: '权限不足：不能编辑最高权限账号' },
        { status: 403 }
      )
    }

    const hasProtectedPermissionFields =
      role !== undefined ||
      (department !== undefined && (department || '') !== (oldUser.department || '')) ||
      isActive !== undefined ||
      canDownload !== undefined

    if (!currentUserFull?.isSuperAdmin && hasProtectedPermissionFields) {
      return NextResponse.json(
        { error: '权限不足：只有最高权限账号可以修改角色、部门、启用状态或下载权限' },
        { status: 403 }
      )
    }

    // 构建更新数据
    const updateData: any = {}
    if (username !== undefined) updateData.username = username
    if (department !== undefined) updateData.department = department || ''
    if (role !== undefined) updateData.role = role
    if (isActive !== undefined) updateData.isActive = isActive
    if (canDownload !== undefined) updateData.canDownload = canDownload

    const shouldSyncMaterialAuthorName =
      Boolean(syncMaterialAuthorName) &&
      Boolean(currentUserFull?.isSuperAdmin) &&
      username !== undefined &&
      username !== oldUser.username

    // 使用事务更新用户；历史素材作者名同步仅限最高权限账号显式触发。
    const result = await prisma.$transaction(async (tx) => {
      // 更新用户信息
      const updatedUser = await tx.user.update({
        where: { id: userId },
        data: updateData,
      })

      if (shouldSyncMaterialAuthorName) {
        await tx.material.updateMany({
          where: { userId: userId },
          data: { authorName: username },
        })
      }

      return updatedUser
    })

    console.log('[Update User] Success:', {
      userId: result.id,
      username: result.username,
      department: result.department,
      materialsUpdated: shouldSyncMaterialAuthorName
    })

    return NextResponse.json({
      success: true,
      user: result,
      materialsUpdated: shouldSyncMaterialAuthorName
    })
  } catch (error) {
    console.error('[Update User] Error:', error)
    return NextResponse.json(
      { error: '更新用户失败' },
      { status: 500 }
    )
  }
}