Added derive_xprv & derive_xpub methods to ExtendedPrivKey

Author: dhruv-1001

src/bdk.udl

@@ -11,6 +11,8 @@ interface DerivationPath {
 interface ExtendedPrivKey {
   [Throws=BdkError]
   constructor(Network network, string mnemonic, string? password);
+  ExtendedPrivKey derive_xprv([ByRef] DerivationPath? derivation_path);
+  ExtendedPubKey derive_xpub([ByRef] DerivationPath? derivation_path);
   string to_string();
 };
 

src/lib.rs

@@ -326,6 +326,44 @@ impl ExtendedPrivKey {
         })
     }
 
+    fn derive_xprv(
+        &self,
+        derivation_path: &Option<DerivationPath>,
+    ) -> Arc<ExtendedPrivKey> {
+        let secp = Secp256k1::new();
+        if let Some(derivation_path) = derivation_path {
+            let path = derivation_path.derivation_path.lock().unwrap().clone();
+            let derived_xprv = self.xprv.lock().unwrap().derive_priv(&secp, &path).unwrap();
+            Arc::new(ExtendedPrivKey { 
+                xprv: Mutex::new(derived_xprv),
+            })
+        } else {
+            Arc::new (ExtendedPrivKey { 
+                xprv: Mutex::new(self.xprv.lock().unwrap().to_owned())
+            })
+        }
+    }
+
+    fn derive_xpub(
+        &self,
+        derivation_path: &Option<&DerivationPath>,
+    ) -> Arc<ExtendedPubKey> {
+        let secp = Secp256k1::new();
+        if let Some(derivation_path) = derivation_path {
+            let path = derivation_path.derivation_path.lock().unwrap().clone();
+            let derived_xprv = self.xprv.lock().unwrap().derive_priv(&secp, &path).unwrap();
+            let derived_xpub = BdkExtendedPubKey::from_private(&secp, &derived_xprv);
+            Arc::new(ExtendedPubKey { 
+                xpub: Mutex::new(derived_xpub)
+            })
+        } else {
+            let derived_xpub = BdkExtendedPubKey::from_private(&secp, &self.xprv.lock().unwrap().clone());
+            Arc::new(ExtendedPubKey { 
+                xpub: Mutex::new(derived_xpub) 
+            })
+        }
+    }
+
     fn to_string(&self) -> String {
         self.xprv.lock().unwrap().to_string()
     }