fix: prevent Duplicate Block Explorer Entries and Ensure Proper Input…

… Validation (#11995)

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## **Description**

When editing a network and attempting to add a new block explorer URL,
the 'Add Block Explorer URL +' button allows users to add a duplicate
entry even if no input is provided. This results in duplicate block
explorer URLs being added to the list. The expected behavior is that the
'Add Block Explorer URL' button should remain disabled until valid input
is provided, and existing URLs should not be re-added.

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also include relevant motivation and context. Have in mind the following
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## **Related issues**

Fixes: #11990 

## **Manual testing steps**

1. Go to network add form
2. go to add block explorer url
3. The 'Add Block Explorer URL' button should be disabled until a valid
URL is inputted into the field.

## **Screenshots/Recordings**

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before and after of your change. -->

### **Before**

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### **After**



https://github.com/user-attachments/assets/05f72bf8-8046-40a4-a941-51f39cfc9a09




<!-- [screenshots/recordings] -->

## **Pre-merge author checklist**

- [x] I’ve followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask Mobile
Coding
Standards](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [x] I've completed the PR template to the best of my ability
- [x] I’ve included tests if applicable
- [x] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [x] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

app/components/Views/Settings/NetworksSettings/NetworkSettings/index.js

@@ -447,6 +447,7 @@ export class NetworkSettings extends PureComponent {
     blockExplorerUrls: [],
     selectedRpcEndpointIndex: 0,
     blockExplorerUrl: undefined,
+    blockExplorerUrlForm: undefined,
     nickname: undefined,
     chainId: undefined,
     ticker: undefined,
@@ -714,7 +715,11 @@ export class NetworkSettings extends PureComponent {
       // in an error message in the form.
       if (!formChainId.startsWith('0x')) {
         try {
-          endpointChainId = new BigNumber(endpointChainId, 16).toString(10);
+          const endpointChainIdNumber = new BigNumber(endpointChainId, 16);
+          if (endpointChainIdNumber.isNaN()) {
+            throw new Error('Invalid endpointChainId');
+          }
+          endpointChainId = endpointChainIdNumber.toString(10);
         } catch (err) {
           Logger.error(err, {
             endpointChainId,
@@ -1288,10 +1293,21 @@ export class NetworkSettings extends PureComponent {
   };
 
   onBlockExplorerItemAdd = async (url) => {
+    // If URL is empty or undefined, return early
     if (!url) {
       return;
     }
 
+    // Check if the URL already exists in blockExplorerUrls
+    const { blockExplorerUrls } = this.state;
+    const urlExists = blockExplorerUrls.includes(url);
+
+    if (urlExists) {
+      // If the URL already exists, return early
+      return;
+    }
+
+    // If the URL doesn't exist, proceed with adding it
     await this.setState((prevState) => ({
       blockExplorerUrls: [...prevState.blockExplorerUrls, url],
     }));
@@ -1351,6 +1367,7 @@ export class NetworkSettings extends PureComponent {
   onBlockExplorerUrlChange = async (url) => {
     const { addMode } = this.state;
     await this.setState({
+      blockExplorerUrlForm: url,
       blockExplorerUrl: url,
     });
 
@@ -1486,7 +1503,10 @@ export class NetworkSettings extends PureComponent {
   };
 
   closeAddBlockExplorerRpcForm = () => {
-    this.setState({ showAddBlockExplorerForm: { isVisible: false } });
+    this.setState({
+      showAddBlockExplorerForm: { isVisible: false },
+      blockExplorerUrlForm: undefined,
+    });
   };
 
   closeRpcModal = () => {
@@ -1603,6 +1623,7 @@ export class NetworkSettings extends PureComponent {
       rpcUrlForm,
       rpcNameForm,
       rpcName,
+      blockExplorerUrlForm,
     } = this.state;
     const { route, networkConfigurations } = this.props;
     const isCustomMainnet = route.params?.isCustomMainnet;
@@ -2204,6 +2225,7 @@ export class NetworkSettings extends PureComponent {
                   ref={this.inputBlockExplorerURL}
                   style={inputStyle}
                   autoCapitalize={'none'}
+                  value={blockExplorerUrlForm}
                   autoCorrect={false}
                   onChangeText={this.onBlockExplorerUrlChange}
                   placeholder={strings(
@@ -2214,23 +2236,28 @@ export class NetworkSettings extends PureComponent {
                   onSubmitEditing={this.toggleNetworkDetailsModal}
                   keyboardAppearance={themeAppearance}
                 />
-                {blockExplorerUrl && !isUrl(blockExplorerUrl) && (
-                  <View>
+                {blockExplorerUrl &&
+                  (!isUrl(blockExplorerUrl) ||
+                    blockExplorerUrls.includes(blockExplorerUrlForm)) && (
                     <Text style={styles.warningText}>
                       {strings('app_settings.invalid_block_explorer_url')}
                     </Text>
-                  </View>
-                )}
+                  )}
+
                 <View style={styles.addRpcNameButton}>
                   <ButtonPrimary
                     label={strings('app_settings.add_block_explorer_url')}
                     size={ButtonSize.Lg}
                     onPress={() => {
-                      this.onBlockExplorerItemAdd(blockExplorerUrl);
+                      this.onBlockExplorerItemAdd(blockExplorerUrlForm);
                     }}
                     width={ButtonWidthTypes.Full}
                     labelTextVariant={TextVariant.DisplayMD}
-                    isDisabled={!blockExplorerUrl || !isUrl(blockExplorerUrl)}
+                    isDisabled={
+                      !blockExplorerUrl ||
+                      !blockExplorerUrlForm ||
+                      !isUrl(blockExplorerUrl)
+                    }
                   />
                 </View>
               </SafeAreaView>