refactor: migrate ReportsPage to TanStack Query

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/hooks/useReports.ts

@@ -0,0 +1,38 @@
+import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query'
+import api from '@/services/api'
+import type { ReportMeta } from '@/types'
+
+interface ReportsListResponse {
+  items: ReportMeta[]
+  total: number
+}
+
+export function useReports() {
+  return useQuery({
+    queryKey: ['reports'],
+    queryFn: () =>
+      api.get<ReportsListResponse>('/reports/list').then(r => r.data),
+  })
+}
+
+export function useGenerateReport() {
+  const queryClient = useQueryClient()
+  return useMutation({
+    mutationFn: (params: { jahr: number; kw: number }) =>
+      api.post<ReportMeta>('/reports/generate', null, { params }).then(r => r.data),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ['reports'] })
+    },
+  })
+}
+
+export function useDeleteReports() {
+  const queryClient = useQueryClient()
+  return useMutation({
+    mutationFn: (ids: number[]) =>
+      api.delete('/reports/delete', { data: ids }),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ['reports'] })
+    },
+  })
+}

frontend/src/pages/ReportsPage.tsx

@@ -1,8 +1,8 @@
-import { useState, useEffect } from 'react'
+import { useState } from 'react'
 import { Download, FileSpreadsheet, Loader2, Plus, Trash2 } from 'lucide-react'
 import api from '@/services/api'
-import type { ReportMeta } from '@/types'
 import { useAuth } from '@/context/AuthContext'
+import { useReports, useGenerateReport, useDeleteReports } from '@/hooks/useReports'
 import { Button } from '@/components/ui/button'
 import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card'
 import { Checkbox } from '@/components/ui/checkbox'
@@ -19,54 +19,31 @@ export function ReportsPage() {
   const currentYear = new Date().getFullYear()
   const currentKw = getISOWeek(new Date())
 
-  const [reports, setReports] = useState<ReportMeta[]>([])
-  const [totalReports, setTotalReports] = useState(0)
-  const [loading, setLoading] = useState(true)
+  // TanStack Query hooks
+  const { data, isLoading: loading } = useReports()
+  const reports = data?.items ?? []
+  const totalReports = data?.total ?? 0
+
+  const generateMutation = useGenerateReport()
+  const deleteMutation = useDeleteReports()
 
   // Report generation state
   const [genJahr, setGenJahr] = useState(currentYear)
   const [genKw, setGenKw] = useState(currentKw)
-  const [generating, setGenerating] = useState(false)
   const [genError, setGenError] = useState('')
   const [genSuccess, setGenSuccess] = useState('')
 
   // Selection state for deletion
   const [selectedIds, setSelectedIds] = useState<Set<number>>(new Set())
-  const [deleting, setDeleting] = useState(false)
-
-  // Fetch reports list
-  const fetchReports = () => {
-    setLoading(true)
-    api.get<{ items: ReportMeta[]; total: number }>('/reports/list')
-      .then((res) => {
-        setReports(res.data.items)
-        setTotalReports(res.data.total)
-      })
-      .catch(() => {
-        setReports([])
-        setTotalReports(0)
-      })
-      .finally(() => setLoading(false))
-  }
-
-  useEffect(() => {
-    fetchReports()
-  }, [])
 
   const generateReport = async () => {
-    setGenerating(true)
     setGenError('')
     setGenSuccess('')
     try {
-      const res = await api.post<ReportMeta>('/reports/generate', null, {
-        params: { jahr: genJahr, kw: genKw },
-      })
-      setGenSuccess(`Bericht für KW ${res.data.kw}/${res.data.jahr} wurde generiert.`)
-      fetchReports()
+      const result = await generateMutation.mutateAsync({ jahr: genJahr, kw: genKw })
+      setGenSuccess(`Bericht für KW ${result.kw}/${result.jahr} wurde generiert.`)
     } catch {
       setGenError('Fehler beim Generieren des Berichts.')
-    } finally {
-      setGenerating(false)
     }
   }
 
@@ -122,15 +99,11 @@ export function ReportsPage() {
 
   const deleteSelected = async () => {
     if (selectedIds.size === 0) return
-    setDeleting(true)
     try {
-      await api.delete('/reports/delete', { data: Array.from(selectedIds) })
+      await deleteMutation.mutateAsync(Array.from(selectedIds))
       setSelectedIds(new Set())
-      fetchReports()
     } catch {
       setGenError('Fehler beim Löschen der Berichte.')
-    } finally {
-      setDeleting(false)
     }
   }
 
@@ -173,8 +146,8 @@ export function ReportsPage() {
                   max={53}
                 />
               </div>
-              <Button onClick={generateReport} disabled={generating}>
-                {generating ? (
+              <Button onClick={generateReport} disabled={generateMutation.isPending}>
+                {generateMutation.isPending ? (
                   <>
                     <Loader2 className="mr-2 h-4 w-4 animate-spin" />
                     Wird generiert...
@@ -213,9 +186,9 @@ export function ReportsPage() {
                 variant="destructive"
                 size="sm"
                 onClick={deleteSelected}
-                disabled={deleting}
+                disabled={deleteMutation.isPending}
               >
-                {deleting ? (
+                {deleteMutation.isPending ? (
                   <Loader2 className="mr-2 h-4 w-4 animate-spin" />
                 ) : (
                   <Trash2 className="mr-2 h-4 w-4" />