package game

import (
	"crypto/rand"
	"encoding/base64"
	"encoding/json"
	"errors"
	"net"
)

const (
	Success = 0
	Failure = 1
)

var (
	ErrAlreadyLoggedIn = errors.New("already logged in")
	ErrUnknownAccount  = errors.New("unknown account")
	ErrWrongPassword   = errors.New("wrong password")
)

// Login checks the account credentials and gives a network peer access to an account.
func (game *Game) Login(data []byte, address *net.UDPAddr) error {
	player := game.players.ByAddress(address)

	if player != nil {
		game.server.Send(Login, []byte{Failure}, address)
		return ErrAlreadyLoggedIn
	}

	username, password, err := getLoginData(data)

	if err != nil {
		game.server.Send(Login, []byte{Failure}, address)
		return err
	}

	account := GetAccountByName(username)

	if account == nil {
		game.server.Send(Login, []byte{Failure}, address)
		return ErrUnknownAccount
	}

	if password != "password" {
		game.server.Send(Login, []byte{Failure}, address)
		return ErrWrongPassword
	}

	player = game.players.ByAccount(account.ID)

	if player != nil {
		game.reconnect(player, address)
	} else {
		game.connect(account, address)
	}

	return nil
}

func (game *Game) reconnect(player *Player, address *net.UDPAddr) {
	player.KeepAlive()
	game.players.ChangeAddress(player, address)
	game.sendLoginSuccess(player)
	player.OnConnect()
}

func (game *Game) connect(account *Account, address *net.UDPAddr) {
	player := NewPlayer(address, account, game)
	player.authToken = createAuthToken()
	player.KeepAlive()
	game.sendLoginSuccess(player)
	game.players.Add(player)
}

func (game *Game) sendLoginSuccess(player *Player) {
	response := []byte{Success}
	response = AppendString(response, player.ID)
	response = AppendString(response, player.authToken)
	game.server.Send(Login, response, player.address)
}

func getLoginData(data []byte) (string, string, error) {
	loginRequest := [2]string{}
	err := json.Unmarshal(data, &loginRequest)

	if err != nil {
		return "", "", err
	}

	username := loginRequest[0]
	password := loginRequest[1]
	return username, password, nil
}

func createAuthToken() string {
	randomBytes := make([]byte, 32)
	rand.Read(randomBytes)
	return base64.StdEncoding.EncodeToString(randomBytes)
}