// prevOutVal looks up all the values of the oupoints used in the current tx
func PrevOutVal(tx *btcwire.MsgTx, client *btcrpcclient.Client) (int64, error) {
// requires an rpc client and outpoints within wallets realm
total := int64(0)
for _, txin := range tx.TxIn {
prevTxHash := txin.PreviousOutPoint.Hash
var tx *btcutil.Tx
tx, err := client.GetRawTransaction(&prevTxHash)
if err != nil {
return -1, err
}
vout := txin.PreviousOutPoint.Index
txout := tx.MsgTx().TxOut[vout]
total += txout.Value
}
return total, nil
}