import type { NextRequest } from 'next/server'
import { NextResponse } from 'next/server'
import { getServerSession } from 'next-auth'
import { authOptions } from '@/lib/auth'
import { isDepartmentAdmin, isSystemAdmin } from '@/lib/department-permission'
import { getMaterialUploadStats } from '@/lib/admin-material-stats'
import { prisma } from '@/lib/prisma'

interface StatsSessionUser {
  role?: string | null
  managedDepartment?: string | null
  department?: string | null
}

function toDateStart(dateString: string): Date {
  return new Date(`${dateString}T00:00:00`)
}

function toDateEnd(dateString: string): Date {
  return new Date(`${dateString}T23:59:59.999`)
}

function escapeCsvValue(value: unknown): string {
  if (value === null || value === undefined) {
    return ''
  }

  const stringValue = String(value)
  if (/[",\n]/.test(stringValue)) {
    return `"${stringValue.replace(/"/g, '""')}"`
  }

  return stringValue
}

function formatDateTime(value: Date): string {
  return value.toLocaleString('sv-SE', {
    timeZone: 'Asia/Shanghai',
    hour12: false,
  })
}

export async function GET(request: NextRequest) {
  try {
    const session = await getServerSession(authOptions)
    const sessionUser = session?.user as StatsSessionUser | undefined
    const role = sessionUser?.role
    const canViewAllDepartments = isSystemAdmin(role)
    const canViewDepartmentScope = isDepartmentAdmin(role)
    const canViewStats = canViewAllDepartments || canViewDepartmentScope
    const scopeDepartmentName = canViewDepartmentScope
      ? String(sessionUser?.managedDepartment || sessionUser?.department || '').trim()
      : null

    if (!session?.user || !canViewStats) {
      return NextResponse.json({ error: '无权限' }, { status: 403 })
    }

    if (canViewDepartmentScope && !scopeDepartmentName) {
      return NextResponse.json({ error: '当前账号未绑定部门，无法导出统计数据' }, { status: 400 })
    }

    const { searchParams } = new URL(request.url)
    const startDate = searchParams.get('startDate')
    const endDate = searchParams.get('endDate')
    const departmentKey = searchParams.get('departmentKey')

    const stats = await getMaterialUploadStats({
      startDate,
      endDate,
      departmentKey,
      scopeDepartmentName,
    })

    const selectedUserIds = Array.from(new Set(stats.selectedUsers.map((user) => user.userId)))
    if (selectedUserIds.length === 0) {
      const lines = ['素材ID,上传时间,产品型号,素材类型,店铺,场景,平台,品类,作者,上传账号,上传姓名,上传部门,下载次数,点赞数']
      const csvContent = `\uFEFF${lines.join('\n')}`
      const rangeStart = startDate || 'all'
      const rangeEnd = endDate || 'all'
      const fileName = `material-details-${rangeStart}-${rangeEnd}.csv`

      return new NextResponse(csvContent, {
        status: 200,
        headers: {
          'Content-Type': 'text/csv; charset=utf-8',
          'Content-Disposition': `attachment; filename="${encodeURIComponent(fileName)}"`,
        },
      })
    }

    const createdAtFilter: { gte?: Date; lte?: Date } = {}
    if (startDate) {
      createdAtFilter.gte = toDateStart(startDate)
    }
    if (endDate) {
      createdAtFilter.lte = toDateEnd(endDate)
    }

    const materials = await prisma.material.findMany({
      where: {
        deletedAt: null,
        userId: { in: selectedUserIds },
        ...(createdAtFilter.gte || createdAtFilter.lte ? { createdAt: createdAtFilter } : {}),
      },
      orderBy: { createdAt: 'desc' },
      select: {
        id: true,
        productModel: true,
        materialType: true,
        categoryName: true,
        sceneName: true,
        platformName: true,
        productCategoryName: true,
        authorName: true,
        createdAt: true,
        downloadCount: true,
        likeCount: true,
        user: {
          select: {
            username: true,
            realName: true,
            department: true,
            departmentRef: {
              select: {
                name: true,
              },
            },
          },
        },
      },
    })

    const lines: string[] = []
    lines.push('素材ID,上传时间,产品型号,素材类型,店铺,场景,平台,品类,作者,上传账号,上传姓名,上传部门,下载次数,点赞数')
    for (const material of materials) {
      const departmentName = material.user.departmentRef?.name || material.user.department || '未分配部门'
      lines.push(
        [
          material.id,
          formatDateTime(material.createdAt),
          material.productModel,
          material.materialType,
          material.categoryName,
          material.sceneName,
          material.platformName,
          material.productCategoryName,
          material.authorName,
          material.user.username,
          material.user.realName || '',
          departmentName,
          material.downloadCount,
          material.likeCount,
        ]
          .map(escapeCsvValue)
          .join(',')
      )
    }

    const csvContent = `\uFEFF${lines.join('\n')}`
    const rangeStart = startDate || 'all'
    const rangeEnd = endDate || 'all'
    const fileName = `material-details-${rangeStart}-${rangeEnd}.csv`

    return new NextResponse(csvContent, {
      status: 200,
      headers: {
        'Content-Type': 'text/csv; charset=utf-8',
        'Content-Disposition': `attachment; filename="${encodeURIComponent(fileName)}"`,
      },
    })
  } catch (error) {
    console.error('[Admin Data Stats Export] GET error:', error)
    return NextResponse.json({ error: '导出 CSV 失败' }, { status: 500 })
  }
}