package game

import (
	"crypto/ed25519"
	"encoding/base64"
	"errors"
	"strings"

	petname "github.com/dustinkirkland/golang-petname"
)

var lastSessionId int = 0
var sessionStorage []Session = []Session{}
var nameToSession map[string]*Session = make(map[string]*Session)

type Session struct {
	id    int
	Name  string
	Users []User

	phrase           []string
	AskedLetters     []string
	DiscoveredPhrase []string
	Mistakes         int

	userIndex   int
	CurrentUser *User
}

func NewSession(phrase string) Session {
	sessionName := petname.Generate(3, "-")

	s := Session{
		id:               lastSessionId,
		Name:             sessionName,
		Users:            []User{},
		phrase:           []string{phrase},
		AskedLetters:     []string{},
		DiscoveredPhrase: make([]string, len(phrase)),
		Mistakes:         0,
		userIndex:        0,
		CurrentUser:      nil,
	}

	sessionStorage = append(sessionStorage, s)
	nameToSession[sessionName] = &s
	lastSessionId++

	return s
}

func GetSession(name string) *Session {
	return nameToSession[name]
}

func (s *Session) AddUser(user User) {
	s.Users = append(s.Users, user)

	if s.CurrentUser == nil {
		s.CurrentUser = &s.Users[s.userIndex]
	}
}

func (s Session) VerifySignature(signature string, message []byte) *User {
	for _, u := range s.Users {
		sig, _ := base64.StdEncoding.DecodeString(signature)

		if ed25519.Verify(u.PublicKey, message, sig) {
			return &u
		}
	}

	return nil
}

func (s *Session) GuessLetter(letter string) (*Session, error) {
	letter = strings.ToLower(letter)
	if len(letter) != 1 {
		return s, errors.New("the letter needs to have a length of one")
	}
	for _, asked := range s.AskedLetters {
		if letter == asked {
			return s, errors.New("the letter " + letter + " was already asked")
		}
	}

	s.AskedLetters = append(s.AskedLetters, letter)

	found := false
	for i, l := range s.phrase {
		if l == letter {
			found = true
			s.DiscoveredPhrase[i] = s.phrase[i]
		}
	}

	if !found {
		s.Mistakes++
	}

	s.userIndex = (s.userIndex + 1) % len(s.Users)
	s.CurrentUser = &s.Users[s.userIndex]
	return s, nil
}