import { NextRequest, NextResponse } from 'next/server'
import { getDb } from '@/lib/db'
import { initDatabase } from '@/lib/db-schema'
import { getCurrentUser } from '@/lib/auth'
import { hasPermission } from '@/lib/permissions'
import { parseExcelTickets } from '@/lib/excel'

function validateTicketNo(ticketNo: string): string | null {
  if (!/^\d{14}$/.test(ticketNo)) {
    return '工单号必须为 14 位纯数字'
  }
  const y = parseInt(ticketNo.slice(0, 4))
  const m = parseInt(ticketNo.slice(4, 6))
  const d = parseInt(ticketNo.slice(6, 8))
  const dt = new Date(y, m - 1, d)
  if (dt.getFullYear() !== y || dt.getMonth() !== m - 1 || dt.getDate() !== d) {
    return '工单号前 8 位必须为合法日期（YYYYMMDD）'
  }
  return null
}

export async function POST(request: NextRequest) {
  try {
    initDatabase()
    const user = await getCurrentUser()
    if (!user) return NextResponse.json({ error: '未登录' }, { status: 401 })
    if (!hasPermission(user, 'tickets:write')) return NextResponse.json({ error: '权限不足' }, { status: 403 })

    const formData = await request.formData()
    const file = formData.get('file') as File | null
    const overwrite = formData.get('overwrite') === 'true'

    if (!file) return NextResponse.json({ error: '请上传文件' }, { status: 400 })

    const buffer = Buffer.from(await file.arrayBuffer())
    const parsed = parseExcelTickets(buffer)

    if (parsed.length === 0) return NextResponse.json({ error: '文件中没有有效工单数据' }, { status: 400 })

    const db = getDb()

    // 校验工单号
    const validationErrors: string[] = []
    const validTickets: typeof parsed = []

    for (let i = 0; i < parsed.length; i++) {
      const t = parsed[i]
      if (!t.ticket_no) {
        validationErrors.push(`第 ${i + 2} 行: 缺少工单号`)
        continue
      }
      const err = validateTicketNo(t.ticket_no)
      if (err) {
        validationErrors.push(`第 ${i + 2} 行: ${err}（${t.ticket_no}）`)
        continue
      }
      validTickets.push(t)
    }

    if (validTickets.length === 0) {
      return NextResponse.json({
        success: false,
        error: '所有工单号校验失败',
        validationErrors,
      }, { status: 400 })
    }

    // 检查重复
    const existingIds = new Set(
      (db.prepare('SELECT id FROM tickets').all() as { id: number }[]).map(r => r.id)
    )

    const conflicts = validTickets.filter(t => existingIds.has(parseInt(t.ticket_no!)))

    if (conflicts.length > 0 && !overwrite) {
      return NextResponse.json({
        success: false,
        conflicts: conflicts.map(t => t.ticket_no),
        message: `${conflicts.length} 个工单号已存在，是否覆盖？`,
        requireOverwrite: true,
        validationErrors: validationErrors.length > 0 ? validationErrors : undefined,
      }, { status: 409 })
    }

    // 执行导入
    const insertStmt = db.prepare(`
      INSERT OR REPLACE INTO tickets (id, device_ip, device_sn, device_name, content, assign_time,
        fault_category, fault_subcategory, responsibility, current_status, counted_in_sla, created_by, updated_by)
      VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
    `)

    const imported: string[] = []
    const errors: string[] = []

    const transaction = db.transaction(() => {
      for (const t of validTickets) {
        try {
          const ticketId = parseInt(t.ticket_no!)
          insertStmt.run(
            ticketId,
            t.device_ip || null,
            t.device_sn || null,
            t.device_name || null,
            t.content || null,
            t.assign_time || new Date(Date.now() + 8 * 60 * 60 * 1000).toISOString().slice(0, 19),
            t.fault_category || null,
            t.fault_subcategory || null,
            t.responsibility || null,
            t.current_status || 'open',
            t.counted_in_sla ?? 1,
            user.id,
            user.id,
          )
          imported.push(t.ticket_no!)
        } catch (e) {
          errors.push(`第 ${validTickets.indexOf(t) + 2} 行: ${e instanceof Error ? e.message : '导入失败'}`)
        }
      }
    })

    transaction()

    return NextResponse.json({
      success: true,
      imported: imported.length,
      overwritten: conflicts.length,
      errors: errors.length > 0 ? errors : undefined,
      validationErrors: validationErrors.length > 0 ? validationErrors : undefined,
    })
  } catch (e) {
    const msg = e instanceof Error ? e.message : '导入失败'
    return NextResponse.json({ error: msg }, { status: 500 })
  }
}