package main

import (
	"flag"
	"fmt"
	"log"
	"os"
	"strconv"
)

// CLI responsible for processing command line arguments
type CLI struct {
	bc *Blockchain
}

func (cli *CLI) printUsage() {
	fmt.Println("Usage:")
	fmt.Println("  printchain - print all the blocks of the blockchain")
	fmt.Println("  send -from FROM -to TO -amount AMOUNT - send AMOUNT of coins from FROM address to TO")
}

func (cli *CLI) validateArgs() {
	if len(os.Args) < 2 {
		cli.printUsage()
		os.Exit(1)
	}
}

func (cli *CLI) printChain() {
	bci := cli.bc.Iterator()

	for {
		block := bci.Next()

		fmt.Printf("Prev. hash: %x\n", block.PrevBlockHash)
		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
		}
	}
}

func (cli *CLI) send(from, to string, amount int) {
	tx := NewUTXOTransaction(from, to, amount)
	cli.bc.AddBlock([]*Transaction{tx})
	fmt.Println("Success!")
}

// Run parses command line arguments and processes commands
func (cli *CLI) Run() {
	cli.validateArgs()

	sendCmd := flag.NewFlagSet("send", flag.ExitOnError)
	printChainCmd := flag.NewFlagSet("printchain", flag.ExitOnError)

	sendFrom := sendCmd.String("from", "", "Source wallet address")
	sendTo := sendCmd.String("to", "", "Destination wallet address")
	sendAmount := sendCmd.Int("amount", 0, "Amount to send")

	switch os.Args[1] {
	case "printchain":
		err := printChainCmd.Parse(os.Args[2:])
		if err != nil {
			log.Panic(err)
		}
	case "send":
		err := sendCmd.Parse(os.Args[2:])
		if err != nil {
			log.Panic(err)
		}
	default:
		cli.printUsage()
		os.Exit(1)
	}

	if printChainCmd.Parsed() {
		cli.printChain()
	}

	if sendCmd.Parsed() {
		if *sendFrom == "" || *sendTo == "" || *sendAmount <= 0 {
			sendCmd.Usage()
			os.Exit(1)
		}

		cli.send(*sendFrom, *sendTo, *sendAmount)
	}
}