fix: prevent accidental signatures (#1515)

![CleanShot 2024-12-06 at 03 30
39](https://github.com/user-attachments/assets/d47dc820-f19d-43b7-a60d-914fc9ab24b8)

![CleanShot 2024-12-06 at 03 32
34](https://github.com/user-attachments/assets/0db98735-8c91-469b-873c-adb19d0fff7b)

apps/web/src/app/(signing)/sign/[token]/form.tsx

@@ -12,7 +12,7 @@ import { useAnalytics } from '@documenso/lib/client-only/hooks/use-analytics';
 import type { DocumentAndSender } from '@documenso/lib/server-only/document/get-document-by-token';
 import type { TRecipientActionAuth } from '@documenso/lib/types/document-auth';
 import { sortFieldsByPosition, validateFieldsInserted } from '@documenso/lib/utils/fields';
-import { type Field, type Recipient, RecipientRole } from '@documenso/prisma/client';
+import { type Field, FieldType, type Recipient, RecipientRole } from '@documenso/prisma/client';
 import { trpc } from '@documenso/trpc/react';
 import { FieldToolTip } from '@documenso/ui/components/field/field-tooltip';
 import { cn } from '@documenso/ui/lib/utils';
@@ -44,7 +44,8 @@ export const SigningForm = ({
   const analytics = useAnalytics();
   const { data: session } = useSession();
 
-  const { fullName, signature, setFullName, setSignature } = useRequiredSigningContext();
+  const { fullName, signature, setFullName, setSignature, signatureValid, setSignatureValid } =
+    useRequiredSigningContext();
 
   const [validateUninsertedFields, setValidateUninsertedFields] = useState(false);
 
@@ -56,6 +57,8 @@ export const SigningForm = ({
   // Keep the loading state going if successful since the redirect may take some time.
   const isSubmitting = formState.isSubmitting || formState.isSubmitSuccessful;
 
+  const hasSignatureField = fields.some((field) => field.type === FieldType.SIGNATURE);
+
   const uninsertedFields = useMemo(() => {
     return sortFieldsByPosition(fields.filter((field) => !field.inserted));
   }, [fields]);
@@ -68,6 +71,10 @@ export const SigningForm = ({
   const onFormSubmit = async () => {
     setValidateUninsertedFields(true);
 
+    if (hasSignatureField && !signatureValid) {
+      return;
+    }
+
     const isFieldsValid = validateFieldsInserted(fields);
 
     if (!isFieldsValid) {
@@ -142,7 +149,7 @@ export const SigningForm = ({
                 <div className="flex flex-col gap-4 md:flex-row">
                   <Button
                     type="button"
-                    className="dark:bg-muted dark:hover:bg-muted/80 w-full  bg-black/5 hover:bg-black/10"
+                    className="dark:bg-muted dark:hover:bg-muted/80 w-full bg-black/5 hover:bg-black/10"
                     variant="secondary"
                     size="lg"
                     disabled={typeof window !== 'undefined' && window.history.length <= 1}
@@ -198,20 +205,33 @@ export const SigningForm = ({
                           className="h-44 w-full"
                           disabled={isSubmitting}
                           defaultValue={signature ?? undefined}
+                          onValidityChange={(isValid) => {
+                            setSignatureValid(isValid);
+                          }}
                           onChange={(value) => {
-                            setSignature(value);
+                            if (signatureValid) {
+                              setSignature(value);
+                            }
                           }}
                           allowTypedSignature={document.documentMeta?.typedSignatureEnabled}
                         />
                       </CardContent>
                     </Card>
+
+                    {hasSignatureField && !signatureValid && (
+                      <div className="text-destructive mt-2 text-sm">
+                        <Trans>
+                          Signature is too small. Please provide a more complete signature.
+                        </Trans>
+                      </div>
+                    )}
                   </div>
                 </div>
 
                 <div className="flex flex-col gap-4 md:flex-row">
                   <Button
                     type="button"
-                    className="dark:bg-muted dark:hover:bg-muted/80 w-full  bg-black/5 hover:bg-black/10"
+                    className="dark:bg-muted dark:hover:bg-muted/80 w-full bg-black/5 hover:bg-black/10"
                     variant="secondary"
                     size="lg"
                     disabled={typeof window !== 'undefined' && window.history.length <= 1}

apps/web/src/app/(signing)/sign/[token]/provider.tsx

@@ -9,6 +9,8 @@ export type SigningContextValue = {
   setEmail: (_value: string) => void;
   signature: string | null;
   setSignature: (_value: string | null) => void;
+  signatureValid: boolean;
+  setSignatureValid: (_valid: boolean) => void;
 };
 
 const SigningContext = createContext<SigningContextValue | null>(null);
@@ -43,6 +45,7 @@ export const SigningProvider = ({
   const [fullName, setFullName] = useState(initialFullName || '');
   const [email, setEmail] = useState(initialEmail || '');
   const [signature, setSignature] = useState(initialSignature || null);
+  const [signatureValid, setSignatureValid] = useState(true);
 
   useEffect(() => {
     if (initialSignature) {
@@ -59,6 +62,8 @@ export const SigningProvider = ({
         setEmail,
         signature,
         setSignature,
+        signatureValid,
+        setSignatureValid,
       }}
     >
       {children}

apps/web/src/app/(signing)/sign/[token]/signature-field.tsx

@@ -55,8 +55,12 @@ export const SignatureField = ({
   const containerRef = useRef<HTMLDivElement>(null);
   const [fontSize, setFontSize] = useState(2);
 
-  const { signature: providedSignature, setSignature: setProvidedSignature } =
-    useRequiredSigningContext();
+  const {
+    signature: providedSignature,
+    setSignature: setProvidedSignature,
+    signatureValid,
+    setSignatureValid,
+  } = useRequiredSigningContext();
 
   const { executeActionAuthProcedure } = useRequiredDocumentAuthContext();
 
@@ -90,7 +94,7 @@ export const SignatureField = ({
   }, [field.inserted, signature?.signatureImageAsBase64]);
 
   const onPreSign = () => {
-    if (!providedSignature) {
+    if (!providedSignature || !signatureValid) {
       setShowSignatureModal(true);
       return false;
     }
@@ -117,7 +121,7 @@ export const SignatureField = ({
     try {
       const value = signature || providedSignature;
 
-      if (!value) {
+      if (!value || (signature && !signatureValid)) {
         setShowSignatureModal(true);
         return;
       }
@@ -282,12 +286,23 @@ export const SignatureField = ({
               <Trans>Signature</Trans>
             </Label>
 
-            <SignaturePad
-              id="signature"
-              className="border-border mt-2 h-44 w-full rounded-md border"
-              onChange={(value) => setLocalSignature(value)}
-              allowTypedSignature={typedSignatureEnabled}
-            />
+            <div className="border-border mt-2 rounded-md border">
+              <SignaturePad
+                id="signature"
+                className="h-44 w-full"
+                onChange={(value) => setLocalSignature(value)}
+                allowTypedSignature={typedSignatureEnabled}
+                onValidityChange={(isValid) => {
+                  setSignatureValid(isValid);
+                }}
+              />
+            </div>
+
+            {!signatureValid && (
+              <div className="text-destructive mt-2 text-sm">
+                <Trans>Signature is too small. Please provide a more complete signature.</Trans>
+              </div>
+            )}
           </div>
 
           <SigningDisclosure />
@@ -307,7 +322,7 @@ export const SignatureField = ({
               <Button
                 type="button"
                 className="flex-1"
-                disabled={!localSignature}
+                disabled={!localSignature || !signatureValid}
                 onClick={() => onDialogSignClick()}
               >
                 <Trans>Sign</Trans>