feat: add PDF viewing functionality for invoices in finance management

src/app/admin/finance-management/page.tsx

@@ -120,6 +120,33 @@ export default function FinanceManagementPage() {
     URL.revokeObjectURL(url)
   }
 
+  const [pdfLoading, setPdfLoading] = useState<string | number | null>(null)
+
+  const viewInvoicePdf = async (inv: AdminInvoice) => {
+    setPdfLoading(inv.id)
+    try {
+      const base = process.env.NEXT_PUBLIC_API_BASE_URL || ''
+      const res = await fetch(`${base}/api/invoices/${inv.id}/pdf`, {
+        method: 'GET',
+        credentials: 'include',
+        headers: {
+          ...(accessToken ? { Authorization: `Bearer ${accessToken}` } : {}),
+        },
+      })
+      if (!res.ok) {
+        const body = await res.json().catch(() => ({}))
+        throw new Error(body?.message || `Failed to load PDF (${res.status})`)
+      }
+      const blob = await res.blob()
+      const blobUrl = URL.createObjectURL(blob)
+      window.open(blobUrl, '_blank', 'noopener,noreferrer')
+    } catch (e: any) {
+      setReportMsg({ type: 'error', text: e?.message || 'Failed to load invoice PDF.' })
+    } finally {
+      setPdfLoading(null)
+    }
+  }
+
   const sendEmailReport = async () => {
     if (!reportEmail.trim()) return
     setReportMsg(null)
@@ -385,11 +412,18 @@ export default function FinanceManagementPage() {
                           </span>
                         </td>
                         <td className="px-3 py-2 space-x-2">
+                          <button
+                            onClick={() => viewInvoicePdf(inv)}
+                            disabled={pdfLoading === inv.id || !inv.pdf_storage_key}
+                            className="text-xs rounded border px-2 py-1 hover:bg-gray-50 disabled:opacity-50 disabled:cursor-not-allowed"
+                          >
+                            {pdfLoading === inv.id ? 'Loading…' : 'View PDF'}
+                          </button>
                           <button
                             onClick={() => { setSelectedInvoice(inv); setDetailModalOpen(true) }}
                             className="text-xs rounded border px-2 py-1 hover:bg-gray-50"
                           >
-                            View
+                            Details
                           </button>
                         </td>
                       </tr>

src/app/profile/components/financeInvoices.tsx

@@ -28,8 +28,10 @@ const isAbsUrl = (url: string) => /^https?:\/\//i.test(url)
 
 const resolveInvoiceUrl = (invoice: AboInvoice) => {
   const raw = invoice.pdfUrl || invoice.downloadUrl || invoice.htmlUrl || invoice.fileUrl
-  if (!raw) return null
+  if (raw) return isAbsUrl(raw) ? raw : `${BASE_URL}${raw.startsWith('/') ? '' : '/'}${raw}`
-  return isAbsUrl(raw) ? raw : `${BASE_URL}${raw.startsWith('/') ? '' : '/'}${raw}`
+  // Fallback: use the backend PDF proxy endpoint if an id is available
+  if (invoice.id) return `${BASE_URL}/api/invoices/${invoice.id}/pdf`
+  return null
 }
 
 type UiLifecycleStatus = 'issued' | 'ongoing' | 'finished' | 'pause' | 'cancelled'
@@ -80,14 +82,25 @@ export default function FinanceInvoices({ abonementId }: Props) {
   const [busyId, setBusyId] = React.useState<string | number | null>(null)
   const [actionError, setActionError] = React.useState<string | null>(null)
 
-  const onView = (invoice: AboInvoice) => {
+  const onView = async (invoice: AboInvoice) => {
     setActionError(null)
     const url = resolveInvoiceUrl(invoice)
     if (!url) {
       setActionError('No view URL is available for this invoice.')
       return
     }
-    window.open(url, '_blank', 'noopener,noreferrer')
+    setBusyId(invoice.id)
+    try {
+      const res = await authFetch(url, { method: 'GET' })
+      if (!res.ok) throw new Error(`Failed to load PDF: ${res.status}`)
+      const blob = await res.blob()
+      const blobUrl = URL.createObjectURL(blob)
+      window.open(blobUrl, '_blank', 'noopener,noreferrer')
+    } catch (e: any) {
+      setActionError(e?.message || 'Failed to load invoice PDF.')
+    } finally {
+      setBusyId(null)
+    }
   }
 
   const onDownload = async (invoice: AboInvoice) => {