RSP.go

package main

import (
	"fmt"
	"math/rand"
	"strings"
	"time"
)

type turn uint8

const (
	undefined turn = 0
	paper          = 1
	scissors       = 2
	rock           = 3
)

type gameResult uint8

const (
	unknownResult gameResult = iota
	draw
	playersWin
	computersWin
)

// todo rename me!
var usersTurnMap = map[string]turn{
	"rock":     rock,
	"камень":   rock,
	"scissors": scissors,
	"ножницы":  scissors,
	"paper":    paper,
	"бумага":   paper,
	"бамага":   paper,
}

var turnReadableNames = map[turn]string{
	undefined: "Undefined",
	paper:     "Paper",
	scissors:  "Scissors",
	rock:      "Rock",
}

var gameResultsReadableNames = map[gameResult]string{
	unknownResult: "Unknown",
	draw:          "Draw",
	playersWin:    "Players win",
	computersWin:  "Computers win",
}

func init() {
	rand.Seed(int64(time.Now().Nanosecond()))
}

func main() {
	fmt.Println("Hi there. Welcome to the rock scissor paper game. Make your turn.")
	printAvailableTurns()

	runGameRound()
}

func runGameRound() {
	playersTurn, err := playersTurn()
	if err != nil {
		fmt.Println(err)
		return
	}

	move := computerMove()
	fmt.Println("Computer move: ", turnReadableNames[move])

	result := calculateResult(playersTurn, move)
	fmt.Println("Game result: ", gameResultsReadableNames[result])
}

var resultTable = [][]gameResult{
	{draw, playersWin, computersWin},
	{computersWin, draw, playersWin},
	{playersWin, computersWin, draw},
}

func calculateResult(playersTurn, computersTurn turn) gameResult {
	return resultTable[computersTurn-1][playersTurn-1]
}

var possibleTurns = []turn{rock, scissors, paper}

func computerMove() turn {
	index := rand.Intn(len(possibleTurns))

	return possibleTurns[index]
}

func playersTurn() (turn, error) {
	var usersTurn string

	_, err := fmt.Scanln(&usersTurn)
	if err != nil {
		return undefined, fmt.Errorf("failed to read users turn: %v", err)
	}

	result, ok := usersTurnMap[usersTurn]
	if !ok {
		return undefined, fmt.Errorf("unknown turn: %v", usersTurn)
	}

	return result, nil
}

func printAvailableTurns() {
	availableMoves := make([]string, 0, len(usersTurnMap))

	for turn := range usersTurnMap {
		availableMoves = append(availableMoves, turn)
	}

	fmt.Println("Available moves: ", strings.Join(availableMoves, ", "))
}