'use client'

import { useState, useCallback, useEffect } from 'react'
import { ProcessTask, TaskStats, TaskFormData, CompleteFormData, API } from '../_components/types'

export function useProcessTasks() {
  const [activeTab, setActiveTab] = useState<'overview' | 'all' | 'calendar'>('overview')
  const [tasks, setTasks] = useState<ProcessTask[]>([])
  const [totalTasks, setTotalTasks] = useState(0)
  const [stats, setStats] = useState<TaskStats | null>(null)
  const [upcomingTasks, setUpcomingTasks] = useState<ProcessTask[]>([])
  const [filterStatus, setFilterStatus] = useState('')
  const [filterCategory, setFilterCategory] = useState('')
  const [filterFrequency, setFilterFrequency] = useState('')
  const [page, setPage] = useState(0)
  const PAGE_SIZE = 25
  const [loading, setLoading] = useState(true)
  const [toast, setToast] = useState<string | null>(null)
  const [showForm, setShowForm] = useState(false)
  const [editTask, setEditTask] = useState<ProcessTask | null>(null)
  const [detailTask, setDetailTask] = useState<ProcessTask | null>(null)
  const [completeTask, setCompleteTask] = useState<ProcessTask | null>(null)
  const [skipTask, setSkipTask] = useState<ProcessTask | null>(null)

  const loadStats = useCallback(async () => {
    try {
      const res = await fetch(`${API}/stats`)
      if (res.ok) setStats(await res.json())
    } catch { /* ignore */ }
  }, [])

  const loadUpcoming = useCallback(async () => {
    try {
      const res = await fetch(`${API}/upcoming?days=30`)
      if (res.ok) { const data = await res.json(); setUpcomingTasks(data.tasks || []) }
    } catch { /* ignore */ }
  }, [])

  const loadTasks = useCallback(async () => {
    setLoading(true)
    try {
      const params = new URLSearchParams()
      if (filterStatus) params.set('status', filterStatus)
      if (filterCategory) params.set('category', filterCategory)
      if (filterFrequency) params.set('frequency', filterFrequency)
      params.set('limit', String(PAGE_SIZE))
      params.set('offset', String(page * PAGE_SIZE))
      const res = await fetch(`${API}?${params}`)
      if (res.ok) { const data = await res.json(); setTasks(data.tasks || []); setTotalTasks(data.total || 0) }
    } catch { /* ignore */ }
    setLoading(false)
  }, [filterStatus, filterCategory, filterFrequency, page])

  useEffect(() => {
    loadStats()
    loadUpcoming()
    loadTasks()
  }, [loadStats, loadUpcoming, loadTasks])

  const handleCreate = async (data: TaskFormData) => {
    const res = await fetch(API, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(data),
    })
    if (!res.ok) {
      const err = await res.json().catch(() => ({}))
      throw new Error(err.detail || 'Fehler beim Erstellen')
    }
    setToast('Aufgabe erstellt')
    loadTasks(); loadStats(); loadUpcoming()
  }

  const handleUpdate = async (data: TaskFormData) => {
    if (!editTask) return
    const res = await fetch(`${API}/${editTask.id}`, {
      method: 'PUT',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(data),
    })
    if (!res.ok) {
      const err = await res.json().catch(() => ({}))
      throw new Error(err.detail || 'Fehler beim Speichern')
    }
    setEditTask(null)
    setToast('Aufgabe aktualisiert')
    loadTasks(); loadStats(); loadUpcoming()
  }

  const handleComplete = async (data: CompleteFormData) => {
    if (!completeTask) return
    const res = await fetch(`${API}/${completeTask.id}/complete`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(data),
    })
    if (!res.ok) throw new Error('Fehler')
    setCompleteTask(null)
    setToast('Aufgabe als erledigt markiert')
    loadTasks(); loadStats(); loadUpcoming()
  }

  const handleSkip = async (reason: string) => {
    if (!skipTask) return
    const res = await fetch(`${API}/${skipTask.id}/skip`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ reason }),
    })
    if (!res.ok) throw new Error('Fehler')
    setSkipTask(null)
    setToast('Aufgabe uebersprungen')
    loadTasks(); loadStats(); loadUpcoming()
  }

  const handleDelete = async (id: string) => {
    const res = await fetch(`${API}/${id}`, { method: 'DELETE' })
    if (!res.ok) throw new Error('Fehler beim Loeschen')
    setToast('Aufgabe geloescht')
    loadTasks(); loadStats(); loadUpcoming()
  }

  const handleSeed = async () => {
    const res = await fetch(`${API}/seed`, { method: 'POST' })
    if (res.ok) {
      const data = await res.json()
      setToast(`${data.seeded} Standard-Aufgaben erstellt`)
      loadTasks(); loadStats(); loadUpcoming()
    }
  }

  const totalPages = Math.ceil(totalTasks / PAGE_SIZE)

  return {
    activeTab, setActiveTab,
    tasks, totalTasks, stats, upcomingTasks,
    filterStatus, setFilterStatus,
    filterCategory, setFilterCategory,
    filterFrequency, setFilterFrequency,
    page, setPage, PAGE_SIZE, totalPages,
    loading, toast, setToast,
    showForm, setShowForm,
    editTask, setEditTask,
    detailTask, setDetailTask,
    completeTask, setCompleteTask,
    skipTask, setSkipTask,
    handleCreate, handleUpdate, handleComplete, handleSkip, handleDelete, handleSeed,
  }
}