Improve command line arguments processing

cli.go

@@ -0,0 +1,68 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+)
+
+// CLI responsible for processing command line arguments
+type CLI struct {
+	bc *Blockchain
+}
+
+func (cli *CLI) printUsage() {
+	fmt.Println("Usage:")
+	fmt.Println("  addBlock BLOCK_DATA - add a block to the blockchain")
+	fmt.Println("  printChain - print all the blocks of the blockchain")
+}
+
+func (cli *CLI) validateArgs() {
+	if len(os.Args) < 2 {
+		cli.printUsage()
+		os.Exit(1)
+	}
+}
+
+func (cli *CLI) addBlock() {
+	if len(os.Args) < 3 {
+		fmt.Println("Error: BLOCK_DATA is not specified.")
+		os.Exit(1)
+	}
+	cli.bc.AddBlock(os.Args[2])
+	fmt.Println("Success!")
+}
+
+func (cli *CLI) printChain() {
+	bci := cli.bc.Iterator()
+
+	for {
+		block := bci.Next()
+
+		fmt.Printf("Prev. hash: %x\n", block.PrevBlockHash)
+		fmt.Printf("Data: %s\n", block.Data)
+		fmt.Printf("Hash: %x\n", block.Hash)
+		pow := NewProofOfWork(block)
+		fmt.Printf("PoW: %s\n", strconv.FormatBool(pow.Validate()))
+		fmt.Println()
+
+		if len(block.PrevBlockHash) == 0 {
+			break
+		}
+	}
+}
+
+// ProcessArgs parses command line arguments and processes commands
+func (cli *CLI) ProcessArgs() {
+	cli.validateArgs()
+
+	switch os.Args[1] {
+	case "addBlock":
+		cli.addBlock()
+	case "printChain":
+		cli.printChain()
+	default:
+		cli.printUsage()
+		os.Exit(1)
+	}
+}

main.go

@@ -1,41 +1,9 @@
 package main
 
-import (
-	"fmt"
-	"os"
-	"strconv"
-)
-
 func main() {
 	bc := NewBlockchain()
 	defer bc.db.Close()
 
-	if len(os.Args) < 2 {
-		fmt.Println("Wrong!")
-		os.Exit(1)
-	}
-
-	if os.Args[1] == "addBlock" {
-		bc.AddBlock(os.Args[2])
-		fmt.Println("Success!")
-	}
-
-	if os.Args[1] == "printChain" {
-		bci := bc.Iterator()
-
-		for {
-			block := bci.Next()
-
-			fmt.Printf("Prev. hash: %x\n", block.PrevBlockHash)
-			fmt.Printf("Data: %s\n", block.Data)
-			fmt.Printf("Hash: %x\n", block.Hash)
-			pow := NewProofOfWork(block)
-			fmt.Printf("PoW: %s\n", strconv.FormatBool(pow.Validate()))
-			fmt.Println()
-
-			if len(block.PrevBlockHash) == 0 {
-				break
-			}
-		}
-	}
+	cli := CLI{bc}
+	cli.ProcessArgs()
 }