import { NextRequest, NextResponse } from 'next/server'
import { auth } from '@/lib/auth'
import { PrismaClient } from '@prisma/client'
import bcrypt from 'bcryptjs'

const prisma = new PrismaClient()

// GET /api/users - get all users (admin only)
export async function GET() {
  try {
    const session = await auth()
    
    if (!session || (session.user.role !== 'ADMIN' && session.user.role !== 'SUPER_ADMIN')) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
    }

    const users = await prisma.user.findMany({
      select: {
        id: true,
        email: true,
        name: true,
        role: true,
        isActive: true,
        createdAt: true,
        updatedAt: true,
        createdByUser: {
          select: {
            email: true,
            name: true
          }
        }
      },
      orderBy: {
        createdAt: 'desc'
      }
    })

    return NextResponse.json(users)
  } catch (error) {
    console.error('Error fetching users:', error)
    return NextResponse.json(
      { error: 'Fehler beim Abrufen der Benutzer' },
      { status: 500 }
    )
  }
}

// POST /api/users - create new user (admin only)
export async function POST(request: NextRequest) {
  try {
    const session = await auth()
    
    if (!session || (session.user.role !== 'ADMIN' && session.user.role !== 'SUPER_ADMIN')) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
    }

    const data = await request.json()
    const { email, name, password, role } = data

    // Validation
    if (!email || !password || !role) {
      return NextResponse.json(
        { error: 'E-Mail, Passwort und Rolle sind erforderlich' },
        { status: 400 }
      )
    }

    if (password.length < 6) {
      return NextResponse.json(
        { error: 'Passwort muss mindestens 6 Zeichen lang sein' },
        { status: 400 }
      )
    }

    // Check if user already exists
    const existingUser = await prisma.user.findUnique({
      where: { email }
    })

    if (existingUser) {
      return NextResponse.json(
        { error: 'Benutzer mit dieser E-Mail existiert bereits' },
        { status: 400 }
      )
    }

    // Hash password
    const hashedPassword = await bcrypt.hash(password, 12)

    // Create user
    const newUser = await prisma.user.create({
      data: {
        email,
        name: name || null,
        password: hashedPassword,
        role,
        createdBy: parseInt(session.user.id)
      },
      select: {
        id: true,
        email: true,
        name: true,
        role: true,
        isActive: true,
        createdAt: true
      }
    })

    return NextResponse.json(newUser, { status: 201 })
  } catch (error) {
    console.error('Error creating user:', error)
    return NextResponse.json(
      { error: 'Fehler beim Erstellen des Benutzers' },
      { status: 500 }
    )
  }
}