From 4ac9b6016b7c7cb9205b878c3981bd4447a2b36b Mon Sep 17 00:00:00 2001
From: Gabriele Genta <gabriele.genta@gmail.com>
Date: Fri, 16 Jul 2021 14:01:36 +0200
Subject: [PATCH] ADD: default derivation path for watch only wallets

---
 class/wallets/abstract-wallet.js     | 11 +++++++++++
 tests/unit/watch-only-wallet.test.js | 21 +++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/class/wallets/abstract-wallet.js b/class/wallets/abstract-wallet.js
index aa4701bbb..4f33eec7e 100644
--- a/class/wallets/abstract-wallet.js
+++ b/class/wallets/abstract-wallet.js
@@ -224,6 +224,17 @@ export class AbstractWallet {
         if (parsedSecret.CoboVaultFirmwareVersion) this.use_with_hardware_wallet = true;
       }
     } catch (_) {}
+
+    if (!this._derivationPath) {
+      if (this.secret.startsWith('xpub')) {
+        this._derivationPath = "m/44'/0'/0'"; // Assume default BIP44 path for legacy wallets
+      } else if (this.secret.startsWith('ypub')) {
+        this._derivationPath = "m/49'/0'/0'"; // Assume default BIP49 path for segwit wrapped wallets
+      } else if (this.secret.startsWith('zpub')) {
+        this._derivationPath = "m/84'/0'/0'"; // Assume default BIP84 for native segwit wallets
+      }
+    }
+
     return this;
   }
 
diff --git a/tests/unit/watch-only-wallet.test.js b/tests/unit/watch-only-wallet.test.js
index 51a2160ab..00aad36dc 100644
--- a/tests/unit/watch-only-wallet.test.js
+++ b/tests/unit/watch-only-wallet.test.js
@@ -340,6 +340,27 @@ describe('Watch only wallet', () => {
     );
     assert.strictEqual(psbt.data.outputs[1].bip32Derivation[0].path, "m/49'/0'/0'/1/46");
   });
+
+  it('xpub watch only has derivation path set to BIP44 default', () => {
+    const w = new WatchOnlyWallet();
+    w.setSecret('xpub6CQdfC3v9gU86eaSn7AhUFcBVxiGhdtYxdC5Cw2vLmFkfth2KXCMmYcPpvZviA89X6DXDs4PJDk5QVL2G2xaVjv7SM4roWHr1gR4xB3Z7Ps');
+
+    assert.strictEqual(w.getDerivationPath(), "m/44'/0'/0'");
+  });
+
+  it('ypub watch only has derivation path set to BIP49 default', () => {
+    const w = new WatchOnlyWallet();
+    w.setSecret('ypub6Y9u3QCRC1HkZv3stNxcQVwmw7vC7KX5Ldz38En5P88RQbesP2oy16hNyQocVCfYRQPxdHcd3pmu9AFhLv7NdChWmw5iNLryZ2U6EEHdnfo');
+
+    assert.strictEqual(w.getDerivationPath(), "m/49'/0'/0'");
+  });
+
+  it('zpub watch only has derivation path set to BIP84 default', () => {
+    const w = new WatchOnlyWallet();
+    w.setSecret('zpub6rjLjQVqVnj7crz9E4QWj4WgczmEseJq22u2B6k2HZr6NE2PQx3ZYg8BnbjN9kCfHymSeMd2EpwpM5iiz5Nrb3TzvddxW2RMcE3VXdVaXHk');
+
+    assert.strictEqual(w.getDerivationPath(), "m/84'/0'/0'");
+  });
 });
 
 describe('BC-UR', () => {