cleaned up signing logic for more readability and easier editing

Author: Danny Diekroeger

app/sign.js

@@ -114,40 +114,44 @@ const handleSignUtxo = function(recoveryRequest, key, skipConfirm) {
   })
 
   const txBuilder = utxoLib.TransactionBuilder.fromTransaction(transaction, network);
-  const isBCH = recoveryRequest.coin === 'bch' || recoveryRequest.coin === 'tbch';
 
   _.forEach(recoveryRequest.inputs, function(input, i) {
-    const isBech32 = !input.redeemScript;
-    const isSegwit = !!input.witnessScript;
-
-    // chain paths come from the SDK with a leading /, which is technically not allowed by BIP32
+    
+    // Set up chain path: chain paths come from the SDK with a leading /, which is technically not allowed by BIP32
     if (input.chainPath.startsWith('/')) {
       input.chainPath = input.chainPath.slice(1);
     }
 
+    // Derive signing key from chain path
     const derivedHDNode = backupKeyNode.derivePath(input.chainPath);
-
     console.log(`Signing input ${ i + 1 } of ${ recoveryRequest.inputs.length } with ${ derivedHDNode.neutered().toBase58() } (${ input.chainPath })`);
 
-    if (isBCH) {
+    // Handle BCH
+    if (recoveryRequest.coin === 'bch' || recoveryRequest.coin === 'tbch') {
       const redeemScript = new Buffer(input.redeemScript, 'hex');
       txBuilder.sign(i, derivedHDNode.keyPair, redeemScript, utxoLib.Transaction.SIGHASH_BITCOINCASHBIP143 | utxoLib.Transaction.SIGHASH_ALL, input.amount);
-    } else {
-      if (isBech32) {
-        const witnessScript = Buffer.from(input.witnessScript, 'hex');
-        const witnessScriptHash = utxoLib.crypto.sha256(witnessScript);
-        const prevOutScript = utxoLib.script.witnessScriptHash.output.encode(witnessScriptHash);
-        txBuilder.sign(i, derivedHDNode.keyPair, prevOutScript, utxoLib.Transaction.SIGHASH_ALL, input.amount, witnessScript);
-      } else {
-        const redeemScript = new Buffer(input.redeemScript, 'hex');
-        if (isSegwit) {
-          const witnessScript = new Buffer(input.witnessScript, 'hex');
-          txBuilder.sign(i, derivedHDNode.keyPair, redeemScript, utxoLib.Transaction.SIGHASH_ALL, input.amount, witnessScript)
-        } else {
-          txBuilder.sign(i, derivedHDNode.keyPair, redeemScript, utxoLib.Transaction.SIGHASH_ALL, input.amount);
-        }
-      }
+      return; // in a Lodash forEach loop, 'return' operates like 'continue' does in a regular javascript loop. It finishes this iteration and moves to the next iteration
+    }
+
+    // Handle Bech32
+    if (!input.redeemScript) {
+      const witnessScript = Buffer.from(input.witnessScript, 'hex');
+      const witnessScriptHash = utxoLib.crypto.sha256(witnessScript);
+      const prevOutScript = utxoLib.script.witnessScriptHash.output.encode(witnessScriptHash);
+      txBuilder.sign(i, derivedHDNode.keyPair, prevOutScript, utxoLib.Transaction.SIGHASH_ALL, input.amount, witnessScript);
+      return;
     }
+
+    // Handle Segwit
+    const redeemScript = new Buffer(input.redeemScript, 'hex');
+    if (input.witnessScript) {
+      const witnessScript = new Buffer(input.witnessScript, 'hex');
+      txBuilder.sign(i, derivedHDNode.keyPair, redeemScript, utxoLib.Transaction.SIGHASH_ALL, input.amount, witnessScript);
+      return;
+    }
+
+    // Handle all other requests
+    txBuilder.sign(i, derivedHDNode.keyPair, redeemScript, utxoLib.Transaction.SIGHASH_ALL, input.amount);
   });
 
   return txBuilder.build().toHex();