From 01b9dd2eabd2ce5a9bb371b0f35a4d606353c756 Mon Sep 17 00:00:00 2001
From: Ivan Kuznetsov <me@jeiwan.ru>
Date: Sun, 17 Sep 2017 10:04:28 +0700
Subject: [PATCH] Implement Blockchain.FindAllUTXO

---
 blockchain.go | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/blockchain.go b/blockchain.go
index 543ddc2..bd2e721 100644
--- a/blockchain.go
+++ b/blockchain.go
@@ -203,6 +203,50 @@ func (bc *Blockchain) FindUTXO(pubKeyHash []byte) []TXOutput {
 	return UTXOs
 }
 
+// FindAllUTXO finds all unspent transaction outputs and returns transactions with spent outputs removed
+func (bc *Blockchain) FindAllUTXO() map[string]TXOutputs {
+	UTXO := make(map[string]TXOutputs)
+	spentTXOs := make(map[string][]int)
+	bci := bc.Iterator()
+
+	for {
+		block := bci.Next()
+
+		for _, tx := range block.Transactions {
+			txID := hex.EncodeToString(tx.ID)
+
+		Outputs:
+			for outIdx, out := range tx.Vout {
+				// Was the output spent?
+				if spentTXOs[txID] != nil {
+					for _, spentOutIdx := range spentTXOs[txID] {
+						if spentOutIdx == outIdx {
+							continue Outputs
+						}
+					}
+				}
+
+				outs := UTXO[txID]
+				outs.Outputs = append(outs.Outputs, out)
+				UTXO[txID] = outs
+			}
+
+			if tx.IsCoinbase() == false {
+				for _, in := range tx.Vin {
+					inTxID := hex.EncodeToString(in.Txid)
+					spentTXOs[inTxID] = append(spentTXOs[inTxID], in.Vout)
+				}
+			}
+		}
+
+		if len(block.PrevBlockHash) == 0 {
+			break
+		}
+	}
+
+	return UTXO
+}
+
 // Iterator returns a BlockchainIterat
 func (bc *Blockchain) Iterator() *BlockchainIterator {
 	bci := &BlockchainIterator{bc.tip, bc.db}