import { NextRequest, NextResponse } from 'next/server'
import { withAdminAuth } from '@/lib/admin-middleware'
import { connectDB } from '@/lib/mongodb'
import { User } from '@/models/user'
import { z } from 'zod'

const UserUpdateSchema = z.object({
  name: z.string().min(1).optional(),
  email: z.string().email().optional(),
  role: z.enum(['user', 'admin']).optional(),
  isVerified: z.boolean().optional(),
  balance: z.number().min(0).optional(),
})

const UserCreateSchema = z.object({
  name: z.string().min(1),
  email: z.string().email(),
  password: z.string().min(6),
  role: z.enum(['user', 'admin']).default('user'),
  isVerified: z.boolean().default(false),
  balance: z.number().min(0).default(0),
})

export async function GET(request: NextRequest) {
  return withAdminAuth(request, async (req, admin) => {
    try {
      await connectDB()

      const { searchParams } = new URL(request.url)
      const page = parseInt(searchParams.get('page') || '1')
      const limit = parseInt(searchParams.get('limit') || '20')
      const search = searchParams.get('search') || ''
      const role = searchParams.get('role') || ''
      const verified = searchParams.get('verified') || ''

      const skip = (page - 1) * limit

      // Build filter query
      const filter: any = {}

      if (search) {
        filter.$or = [
          { name: { $regex: search, $options: 'i' } },
          { email: { $regex: search, $options: 'i' } },
          { siliconId: { $regex: search, $options: 'i' } },
        ]
      }

      if (role && role !== 'all') {
        filter.role = role
      }

      if (verified && verified !== 'all') {
        filter.isVerified = verified === 'true'
      }

      const [users, totalUsers] = await Promise.all([
        User.find(filter)
          .select('-password -refreshToken')
          .sort({ createdAt: -1 })
          .skip(skip)
          .limit(limit),
        User.countDocuments(filter),
      ])

      const totalPages = Math.ceil(totalUsers / limit)

      return NextResponse.json({
        users,
        pagination: {
          currentPage: page,
          totalPages,
          totalUsers,
          hasNext: page < totalPages,
          hasPrev: page > 1,
        },
      })
    } catch (error) {
      console.error('Admin users fetch error:', error)
      return NextResponse.json({ error: 'Failed to fetch users' }, { status: 500 })
    }
  })
}

export async function POST(request: NextRequest) {
  return withAdminAuth(request, async (req, admin) => {
    try {
      await connectDB()

      const body = await request.json()
      const { action, userId, data } = body

      if (action === 'update') {
        const validatedData = UserUpdateSchema.parse(data)

        const user = await User.findByIdAndUpdate(userId, validatedData, {
          new: true,
          runValidators: true,
        }).select('-password -refreshToken')

        if (!user) {
          return NextResponse.json({ error: 'User not found' }, { status: 404 })
        }

        return NextResponse.json({ user })
      }

      if (action === 'create') {
        const validatedData = UserCreateSchema.parse(data)

        // Check if user already exists
        const existingUser = await User.findOne({ email: validatedData.email })
        if (existingUser) {
          return NextResponse.json(
            { error: 'User with this email already exists' },
            { status: 400 }
          )
        }

        // Generate unique Silicon ID
        const generateSiliconId = () => {
          const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
          let result = 'SP'
          for (let i = 0; i < 8; i++) {
            result += chars.charAt(Math.floor(Math.random() * chars.length))
          }
          return result
        }

        let siliconId = generateSiliconId()
        while (await User.findOne({ siliconId })) {
          siliconId = generateSiliconId()
        }

        const user = new User({
          ...validatedData,
          siliconId,
          provider: 'local',
        })

        await user.save()

        const userResponse = await User.findById(user._id).select('-password -refreshToken')
        return NextResponse.json({ user: userResponse })
      }

      if (action === 'delete') {
        const user = await User.findByIdAndDelete(userId)

        if (!user) {
          return NextResponse.json({ error: 'User not found' }, { status: 404 })
        }

        return NextResponse.json({ message: 'User deleted successfully' })
      }

      return NextResponse.json({ error: 'Invalid action' }, { status: 400 })
    } catch (error) {
      console.error('Admin user action error:', error)
      return NextResponse.json({ error: 'Failed to perform user action' }, { status: 500 })
    }
  })
}