From 83240f35062dae6b89a957688982583a32092ac6 Mon Sep 17 00:00:00 2001
From: Minh Doan <daywednes@gmail.com>
Date: Tue, 12 Jun 2018 00:15:41 -0700
Subject: [PATCH] add tests and remove UTXOPool

---
 UTXOPool.go                   | 37 ---------------------------
 blockchain/blockchain.go      | 48 +++++++++++++++++++++++++++++++++++
 blockchain/blockchain_test.go | 18 +++++++++++++
 blockchain/transaction.go     |  4 +--
 4 files changed, 68 insertions(+), 39 deletions(-)
 delete mode 100644 UTXOPool.go

diff --git a/UTXOPool.go b/UTXOPool.go
deleted file mode 100644
index 79073170a..000000000
--- a/UTXOPool.go
+++ /dev/null
@@ -1,37 +0,0 @@
-package main
-
-// UTXOPool is the data structure to store the current balance.
-type UTXOPool struct {
-	utxos map[string]int
-}
-
-// func (utxoPool *UTXOPool) handleTransaction(transaction Transaction, receiver string) {
-// 	if !isValidTransaction(transaction) {
-// 		return
-// 	}
-// 	// utxoPool[]
-// }
-
-// func (utxoPool *UTXOPool) isValidTransaction(transaction Transaction) {
-// 	const { inputPublicKey, amount, fee } = transaction
-// 	const utxo = this.utxos[inputPublicKey]
-// 	return utxo !== undefined && utxo.amount >= (amount + fee) && amount > 0
-// }
-
-// func (utxoPool *UTXOPool) handleTransaction(transaction, feeReceiver) {
-//     if (!this.isValidTransaction(transaction))
-//       return
-//     const inputUTXO = this.utxos[transaction.inputPublicKey];
-//     inputUTXO.amount -= transaction.amount
-//     inputUTXO.amount -= transaction.fee
-//     if (inputUTXO.amount === 0)
-//       delete this.utxos[transaction.inputPublicKey]
-//     this.addUTXO(transaction.outputPublicKey, transaction.amount)
-//     this.addUTXO(feeReceiver, transaction.fee)
-//   }
-
-//   func (utxoPool *UTXOPool) isValidTransaction(transaction Transaction) {
-//     const { inputPublicKey, amount, fee } = transaction
-//     const utxo = utxoPool.utxos[inputPublicKey]
-//     return utxo !== undefined && utxo.amount >= (amount + fee) && amount > 0
-//   }
diff --git a/blockchain/blockchain.go b/blockchain/blockchain.go
index 1136a40e9..1ef78b77b 100644
--- a/blockchain/blockchain.go
+++ b/blockchain/blockchain.go
@@ -85,6 +85,54 @@ Work:
 	return accumulated, unspentOutputs
 }
 
+// NewUTXOTransaction creates a new transaction
+func (bc *Blockchain) NewUTXOTransaction(from, to string, amount int) *Transaction {
+	var inputs []TXInput
+	var outputs []TXOutput
+
+	acc, validOutputs := bc.FindSpendableOutputs(from, amount)
+
+	if acc < amount {
+		return nil
+	}
+
+	// Build a list of inputs
+	for txid, outs := range validOutputs {
+		txID, err := hex.DecodeString(txid)
+		if err != nil {
+			return nil
+		}
+
+		for _, out := range outs {
+			input := TXInput{txID, out, from}
+			inputs = append(inputs, input)
+		}
+	}
+
+	// Build a list of outputs
+	outputs = append(outputs, TXOutput{amount, to})
+	if acc > amount {
+		outputs = append(outputs, TXOutput{acc - amount, from}) // a change
+	}
+
+	tx := Transaction{nil, inputs, outputs}
+	tx.SetID()
+
+	return &tx
+}
+
+// AddNewTransferAmount creates a new transaction and a block of that transaction.
+// Mostly used for testing.
+func (bc *Blockchain) AddNewTransferAmount(from, to string, amount int) *Blockchain {
+	tx := bc.NewUTXOTransaction(from, to, amount)
+	if tx != nil {
+		newBlock := NewBlock([]*Transaction{tx}, bc.blocks[len(bc.blocks)-1].PrevBlockHash)
+		bc.blocks = append(bc.blocks, newBlock)
+		return bc
+	}
+	return nil
+}
+
 // CreateBlockchain creates a new blockchain DB
 func CreateBlockchain(address string) *Blockchain {
 	// TODO: We assume we have not created any blockchain before.
diff --git a/blockchain/blockchain_test.go b/blockchain/blockchain_test.go
index 08e7ef077..5d9c5f51f 100644
--- a/blockchain/blockchain_test.go
+++ b/blockchain/blockchain_test.go
@@ -37,3 +37,21 @@ func TestFindUTXO(t *testing.T) {
 		t.Error("FindUTXO failed.")
 	}
 }
+
+func TestAddNewTransferAmount(t *testing.T) {
+	bc := CreateBlockchain("minh")
+
+	bc = bc.AddNewTransferAmount("minh", "alok", 3)
+
+	if bc == nil {
+		t.Error("Failed to add new transfer")
+	}
+
+	t.Log(len(bc.blocks))
+	bc = bc.AddNewTransferAmount("minh", "rj", DefaultCoinbaseValue-2)
+
+	t.Log(len(bc.blocks))
+	if bc != nil {
+		t.Error("minh should not have enough fun to make the transfer")
+	}
+}
diff --git a/blockchain/transaction.go b/blockchain/transaction.go
index d8bce39e4..cc99b5acc 100644
--- a/blockchain/transaction.go
+++ b/blockchain/transaction.go
@@ -68,14 +68,14 @@ func NewUTXOTransaction(from, to string, amount int, bc *Blockchain) *Transactio
 	acc, validOutputs := bc.FindSpendableOutputs(from, amount)
 
 	if acc < amount {
-		log.Panic("ERROR: Not enough funds")
+		return nil
 	}
 
 	// Build a list of inputs
 	for txid, outs := range validOutputs {
 		txID, err := hex.DecodeString(txid)
 		if err != nil {
-			log.Panic(err)
+			return nil
 		}
 
 		for _, out := range outs {