Implement basic blocks

main.go

@@ -1,7 +1,55 @@
 package main
 
-import "fmt"
+import (
+	"crypto/sha256"
+	"fmt"
+	"log"
+	"strconv"
+	"time"
+)
+
+// Block keeps block headers
+type Block struct {
+	Timestamp int64
+	Data      []byte
+	PrevBlock []byte
+	hash      []byte
+}
+
+// SetHash calculates and sets block hash
+func (b *Block) SetHash() {
+	h := sha256.New()
+	timestamp := []byte(strconv.FormatInt(b.Timestamp, 10))
+	var data []byte
+	data = append(data, b.PrevBlock...)
+	data = append(data, b.Data...)
+	data = append(data, timestamp...)
+
+	_, err := h.Write(data)
+	if err != nil {
+		log.Panic(err)
+	}
+	b.hash = h.Sum(nil)
+}
+
+// NewBlock creates and returns Block
+func NewBlock(data string, prevBlock []byte) *Block {
+	block := &Block{time.Now().Unix(), []byte(data), prevBlock, []byte("")}
+	block.SetHash()
+	return block
+}
+
+// NewGenesisBlock creates and returns genesis Block
+func NewGenesisBlock() *Block {
+	return NewBlock("Genesis Block", []byte("0"))
+}
 
 func main() {
-	fmt.Println("Blockchain")
+	gb := NewGenesisBlock()
+	b1 := NewBlock("Send 1 BTC to Ivan", gb.hash)
+
+	fmt.Printf("%s\n", gb.Data)
+	fmt.Printf("%x\n", gb.hash)
+	fmt.Printf("%s\n", b1.Data)
+	fmt.Printf("%x\n", b1.hash)
 }