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

const prisma = new PrismaClient()

// PUT /api/users/[id] - update user
export async function PUT(
  request: NextRequest,
  { params }: { params: Promise<{ id: string }> }
) {
  try {
    const session = await auth()
    
    if (!session || (session.user.role !== 'ADMIN' && session.user.role !== 'SUPER_ADMIN')) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
    }

    const { id: rawId } = await params
    const id = parseInt(rawId)
    if (isNaN(id)) {
      return NextResponse.json({ error: 'Ungültige ID' }, { status: 400 })
    }

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

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

    if (!existingUser) {
      return NextResponse.json(
        { error: 'Benutzer nicht gefunden' },
        { status: 404 }
      )
    }

    // Check if email is already taken by another user
    if (email && email !== existingUser.email) {
      const emailExists = await prisma.user.findUnique({
        where: { email }
      })

      if (emailExists) {
        return NextResponse.json(
          { error: 'E-Mail wird bereits verwendet' },
          { status: 400 }
        )
      }
    }

    // Prepare update data
    const updateData: any = {}
    
    if (email) updateData.email = email
    if (name !== undefined) updateData.name = name || null
    if (role) updateData.role = role
    if (isActive !== undefined) updateData.isActive = isActive

    // Hash new password if provided
    if (password) {
      if (password.length < 6) {
        return NextResponse.json(
          { error: 'Passwort muss mindestens 6 Zeichen lang sein' },
          { status: 400 }
        )
      }
      updateData.password = await bcrypt.hash(password, 12)
    }

    // Update user
    const updatedUser = await prisma.user.update({
      where: { id },
      data: updateData,
      select: {
        id: true,
        email: true,
        name: true,
        role: true,
        isActive: true,
        createdAt: true,
        updatedAt: true
      }
    })

    return NextResponse.json(updatedUser)
  } catch (error) {
    console.error('Error updating user:', error)
    return NextResponse.json(
      { error: 'Fehler beim Aktualisieren des Benutzers' },
      { status: 500 }
    )
  }
}

// DELETE /api/users/[id] - delete user
export async function DELETE(
  request: NextRequest,
  { params }: { params: Promise<{ id: string }> }
) {
  try {
    const session = await auth()
    
    if (!session || (session.user.role !== 'ADMIN' && session.user.role !== 'SUPER_ADMIN')) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
    }

    const { id: rawId } = await params
    const id = parseInt(rawId)
    if (isNaN(id)) {
      return NextResponse.json({ error: 'Ungültige ID' }, { status: 400 })
    }

    // Prevent self-deletion
    if (id === parseInt(session.user.id)) {
      return NextResponse.json(
        { error: 'Sie können sich nicht selbst löschen' },
        { status: 400 }
      )
    }

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

    if (!existingUser) {
      return NextResponse.json(
        { error: 'Benutzer nicht gefunden' },
        { status: 404 }
      )
    }

    // Delete user
    await prisma.user.delete({
      where: { id }
    })

    return NextResponse.json({ message: 'Benutzer erfolgreich gelöscht' })
  } catch (error) {
    console.error('Error deleting user:', error)
    return NextResponse.json(
      { error: 'Fehler beim Löschen des Benutzers' },
      { status: 500 }
    )
  }
}