👌 IMPROVE: Simplify the sign transactions api to make it more easy to…

… use.

src/lib/actions/sign-transactions.ts

@@ -1,17 +1,12 @@
 import { getAddress, getCurrentAccount, privateKey } from '../account'
 import connector from '../connector'
-import { signTransaction } from '../crypto'
+import { signTransaction, signTransactions } from '../crypto'
 
 export async function process(params: any, host: string) {
   const wif = await getCurrentAccount().then((account) => privateKey.value)
 
   const signingTransactions = params.transactions
+  const signedTransactions = signTransactions(wif, signingTransactions)
 
-  const signatures = signingTransactions.map((transaction: any) => {
-    const signature = signTransaction(wif, transaction)
-
-    return signature
-  })
-
-  return { signatures }
+  return { signedTransactions }
 }

src/lib/crypto.ts

@@ -66,23 +66,16 @@ export const verifySignature = (
   return { verified }
 }
 
+type ToSignTransaction = {
+  txHex: string
+  scriptHex: string
+  inputIndex: number
+  satoshis: number
+  sigtype?: number
+}
 export const signTransaction = (
   wif: string,
-  {
-    txHex,
-    scriptHex,
-    address,
-    inputIndex,
-    satoshis,
-    sigtype,
-  }: {
-    txHex: string
-    scriptHex: string
-    address?: string
-    inputIndex: number
-    satoshis: number
-    sigtype?: number
-  },
+  { txHex, scriptHex, inputIndex, satoshis, sigtype }: ToSignTransaction,
   returnsTransaction: boolean = false
 ) => {
   if (!sigtype) sigtype = mvc.crypto.Signature.SIGHASH_ALL | mvc.crypto.Signature.SIGHASH_FORKID
@@ -120,3 +113,70 @@ export const signTransaction = (
     txid: tx.id,
   }
 }
+
+export const signTransactions = (wif: string, toSignTransactions: ToSignTransaction[]) => {
+  const privateKey = mvc.PrivateKey.fromWIF(wif)
+  const publicKey = privateKey.toPublicKey()
+
+  // find out if transactions other than the first one are dependent on previous ones
+  // if so, we need to sign them in order, and sequentially update the prevTxId of the later ones
+  // so that the signature of the previous one can be calculated correctly
+  const toSignTransactionsWithDependsOn: (ToSignTransaction & {
+    dependsOn?: number
+  })[] = []
+  const txids = toSignTransactions.map((tx) => new mvc.Transaction(tx.txHex).id)
+  for (let i = 0; i < toSignTransactions.length; i++) {
+    const { txHex, inputIndex } = toSignTransactions[i]
+    const tx = new mvc.Transaction(txHex)
+    const prevTxId = tx.inputs[inputIndex].prevTxId.toString('hex')
+    if (txids.includes(prevTxId)) {
+      toSignTransactionsWithDependsOn.push({
+        ...toSignTransactions[i],
+        dependsOn: txids.indexOf(prevTxId),
+      })
+    } else {
+      toSignTransactionsWithDependsOn.push(toSignTransactions[i])
+    }
+  }
+
+  const signedTransactions: {
+    txHex: string
+    txid: string
+  }[] = []
+  for (let i = 0; i < toSignTransactionsWithDependsOn.length; i++) {
+    let { txHex, scriptHex, inputIndex, satoshis, sigtype } = toSignTransactionsWithDependsOn[i]
+    const toSign = toSignTransactionsWithDependsOn[i]
+
+    if (!sigtype) {
+      sigtype = mvc.crypto.Signature.SIGHASH_ALL | mvc.crypto.Signature.SIGHASH_FORKID
+    }
+
+    const tx = new mvc.Transaction(txHex)
+
+    // find out if this transaction depends on previous ones
+    // if so, we need to update the prevTxId of the current one
+    if (toSign.dependsOn !== undefined) {
+      const prevTxId = signedTransactions[toSign.dependsOn].txid
+      tx.inputs[inputIndex].prevTxId = Buffer.from(prevTxId, 'hex')
+    }
+
+    // Build signature of this input
+    const signature = mvc.Transaction.Sighash.sign(
+      tx,
+      privateKey,
+      sigtype,
+      inputIndex,
+      new mvc.Script(scriptHex),
+      new BN(satoshis)
+    )
+    const signatureScript = mvc.Script.buildPublicKeyHashIn(publicKey, signature, sigtype)
+    tx.inputs[inputIndex].setScript(signatureScript)
+
+    signedTransactions.push({
+      txHex: tx.toString(),
+      txid: tx.id,
+    })
+  }
+
+  return signedTransactions
+}