import { useState, useEffect, useCallback } from 'react'
import { databases, DATABASE_ID, COLLECTIONS, ID, Query } from '../lib/appwrite'

const DEMO_MODE = !import.meta.env.VITE_APPWRITE_PROJECT_ID

// Demo-Kunden für Testing
const DEMO_CUSTOMERS = [
  { $id: '1', code: 'C001', name: 'Kunde A', location: 'Berlin', email: 'kunde.a@example.com', phone: '030-123456' },
  { $id: '2', code: 'C002', name: 'Kunde B', location: 'München', email: 'kunde.b@example.com', phone: '089-654321' }
]

export function useCustomers() {
  const [customers, setCustomers] = useState([])
  const [loading, setLoading] = useState(true)
  const [error, setError] = useState(null)

  const fetchCustomers = useCallback(async () => {
    if (DEMO_MODE) {
      setCustomers(DEMO_CUSTOMERS)
      setLoading(false)
      return
    }

    try {
      const response = await databases.listDocuments(
        DATABASE_ID,
        COLLECTIONS.CUSTOMERS,
        [Query.orderAsc('name')]
      )
      setCustomers(response.documents)
      setError(null)
    } catch (err) {
      console.error('Error fetching customers:', err)
      // Wenn Collection nicht existiert, setze leeres Array (kein Fehler)
      if (err.code === 404 || err.message?.includes('not found')) {
        setCustomers([])
        setError(null) // Kein Fehler, Collection existiert einfach noch nicht
      } else {
        setError(err.message)
        setCustomers([])
      }
    } finally {
      setLoading(false)
    }
  }, [])

  useEffect(() => {
    fetchCustomers()
  }, [fetchCustomers])

  const createCustomer = async (data) => {
    if (DEMO_MODE) {
      const newCustomer = { ...data, $id: Date.now().toString() }
      setCustomers(prev => [...prev, newCustomer])
      return { success: true, data: newCustomer }
    }

    try {
      const response = await databases.createDocument(
        DATABASE_ID,
        COLLECTIONS.CUSTOMERS,
        ID.unique(),
        data
      )
      setCustomers(prev => [...prev, response])
      return { success: true, data: response }
    } catch (err) {
      return { success: false, error: err.message }
    }
  }

  const updateCustomer = async (id, data) => {
    if (DEMO_MODE) {
      setCustomers(prev => prev.map(c => c.$id === id ? { ...c, ...data } : c))
      return { success: true }
    }

    try {
      const response = await databases.updateDocument(
        DATABASE_ID,
        COLLECTIONS.CUSTOMERS,
        id,
        data
      )
      setCustomers(prev => prev.map(c => c.$id === id ? response : c))
      return { success: true, data: response }
    } catch (err) {
      return { success: false, error: err.message }
    }
  }

  const deleteCustomer = async (id) => {
    if (DEMO_MODE) {
      setCustomers(prev => prev.filter(c => c.$id !== id))
      return { success: true }
    }

    try {
      await databases.deleteDocument(
        DATABASE_ID,
        COLLECTIONS.CUSTOMERS,
        id
      )
      setCustomers(prev => prev.filter(c => c.$id !== id))
      return { success: true }
    } catch (err) {
      return { success: false, error: err.message }
    }
  }

  return {
    customers,
    loading,
    error,
    refresh: fetchCustomers,
    createCustomer,
    updateCustomer,
    deleteCustomer
  }
}