Show the "No signing certs" warning earlier

No need to ask for the user to draw a rectangle for the signature
if there's no certs to sign anyway

CCBUGS: 446549

core/signatureutils.cpp

@@ -175,3 +175,20 @@ QList<CertificateInfo *> CertificateStore::signingCertificates(bool *userCancell
     *userCancelled = false;
     return QList<CertificateInfo *>();
 }
+
+QList<CertificateInfo *> CertificateStore::signingCertificatesForNow(bool *userCancelled, bool *nonDateValidCerts) const
+{
+    const QDateTime now = QDateTime::currentDateTime();
+    QList<Okular::CertificateInfo *> certs = signingCertificates(userCancelled);
+    auto it = certs.begin();
+    *nonDateValidCerts = false;
+    while (it != certs.end()) {
+        if ((*it)->validityStart() > now || now > (*it)->validityEnd()) {
+            it = certs.erase(it);
+            *nonDateValidCerts = true;
+        } else {
+            ++it;
+        }
+    }
+    return certs;
+}

core/signatureutils.h

@@ -266,6 +266,15 @@ public:
      */
     virtual QList<CertificateInfo *> signingCertificates(bool *userCancelled) const;
 
+    /**
+     * Returns list of valid, usable signing certificates for current date and time.
+     *
+     * This can ask the user for a password, userCancelled will be true if the user decided not to enter it.
+     *
+     * nonDateValidCerts is true if the user has signing certificates but their validity start date is in the future or past their validity end date.
+     */
+    QList<CertificateInfo *> signingCertificatesForNow(bool *userCancelled, bool *nonDateValidCerts) const;
+
 protected:
     CertificateStore();
 

part/pageview.cpp

@@ -4880,6 +4880,20 @@ void PageView::slotSetMouseTableSelect()
     d->annotator->detachAnnotation();
 }
 
+void PageView::showNoSigningCertificatesDialog(bool nonDateValidCerts)
+{
+    if (nonDateValidCerts) {
+        KMessageBox::information(this, i18n("All your signing certificates are either not valid yet or are past their validity date."));
+    } else {
+        KMessageBox::information(this,
+                                 i18n("There are no available signing certificates.<br/>For more information, please see the section about <a href=\"%1\">Adding Digital Signatures</a> in the manual.",
+                                      QStringLiteral("help:/okular/signatures.html#adding_digital_signatures")),
+                                 QString(),
+                                 QString(),
+                                 KMessageBox::Notify | KMessageBox::AllowLink);
+    }
+}
+
 void PageView::slotSignature()
 {
     if (!d->document->isHistoryClean()) {
@@ -4887,6 +4901,18 @@ void PageView::slotSignature()
         return;
     }
 
+    const Okular::CertificateStore *certStore = d->document->certificateStore();
+    bool userCancelled, nonDateValidCerts;
+    const QList<Okular::CertificateInfo *> &certs = certStore->signingCertificatesForNow(&userCancelled, &nonDateValidCerts);
+    if (userCancelled) {
+        return;
+    }
+
+    if (certs.isEmpty()) {
+        showNoSigningCertificatesDialog(nonDateValidCerts);
+        return;
+    }
+
     d->messageWindow->display(i18n("Draw a rectangle to insert the signature field"), QString(), PageViewMessage::Info, -1);
 
     d->annotator->setSignatureMode(true);

part/pageview.h

@@ -115,6 +115,8 @@ public:
 
     void highlightSignatureFormWidget(const Okular::FormFieldSignature *form);
 
+    void showNoSigningCertificatesDialog(bool nonDateValidCerts);
+
 public Q_SLOTS:
     void copyTextSelection() const;
     void selectAll();

part/pageviewannotator.cpp

@@ -355,39 +355,27 @@ public:
         }
 
         const Okular::CertificateStore *certStore = m_document->certificateStore();
-        bool userCancelled;
-        const QList<Okular::CertificateInfo *> &certs = certStore->signingCertificates(&userCancelled);
+        bool userCancelled, nonDateValidCerts;
+        const QList<Okular::CertificateInfo *> &certs = certStore->signingCertificatesForNow(&userCancelled, &nonDateValidCerts);
         if (userCancelled) {
             m_aborted = true;
             return {};
         }
 
-        QStringList items;
-        QHash<QString, Okular::CertificateInfo *> nickToCert;
-        const QDateTime now = QDateTime::currentDateTime();
-        for (auto cert : certs) {
-            if (cert->validityStart() <= now && now <= cert->validityEnd()) {
-                items.append(cert->nickName());
-                nickToCert[cert->nickName()] = cert;
-            }
-        }
-
-        if (items.isEmpty()) {
+        if (certs.isEmpty()) {
             m_creationCompleted = false;
             clicked = false;
-            if (certs.isEmpty()) {
-                KMessageBox::information(m_pageView,
-                                         i18n("There are no available signing certificates.<br/>For more information, please see the section about <a href=\"%1\">Adding Digital Signatures</a> in the manual.",
-                                              QStringLiteral("help:/okular/signatures.html#adding_digital_signatures")),
-                                         QString(),
-                                         QString(),
-                                         KMessageBox::Notify | KMessageBox::AllowLink);
-            } else {
-                KMessageBox::information(m_pageView, i18n("All your signing certificates are either not valid yet or are past their validity date."));
-            }
+            m_pageView->showNoSigningCertificatesDialog(nonDateValidCerts);
             return {};
         }
 
+        QStringList items;
+        QHash<QString, Okular::CertificateInfo *> nickToCert;
+        for (auto cert : certs) {
+            items.append(cert->nickName());
+            nickToCert[cert->nickName()] = cert;
+        }
+
         bool resok = false;
         certNicknameToUse = QInputDialog::getItem(m_pageView, i18n("Select certificate to sign with"), i18n("Certificates:"), items, 0, false, &resok);