tins2021/score.go

package tins2021

import (
	"crypto/sha256"
	"encoding/base64"
	"fmt"
)

const scoreFileName = "score.json"

type Highscores []Score

func (h Highscores) AddScore(score, difficulty int) (Highscores, bool) {
	highscores := len(h)
	var rank = highscores
	for ; rank > 0; rank-- {
		if score <= h[rank-1].Score {
			break
		}
	}
	highscore := NewScore(score, difficulty)
	if rank == highscores && highscores < 10 {
		return append(h, highscore), true
	}
	if rank < 10 {
		h = append(h[:rank], append([]Score{highscore}, h[rank:highscores]...)...)
		if len(h) > 10 {
			h = h[:10]
		}
		return h, true
	}
	return h, false
}

type Score struct {
	Score      int
	Difficulty int
	Hash       string
}

func NewScore(score, difficulty int) Score {
	s := Score{Score: score, Difficulty: difficulty}
	s.Hash = s.hash()
	return s
}

func (s *Score) hash() string {
	hashText := fmt.Sprintf("tins2021_qbitter, %d, %d", s.Score, s.Difficulty)
	hash := sha256.Sum256([]byte(hashText))
	return base64.StdEncoding.EncodeToString(hash[:])
}

func (s *Score) Validate() bool {
	hash := s.hash()
	if hash == s.Hash {
		return true
	}
	s.Score = 0
	s.Difficulty = 0
	return false
}

type ScoreState struct {
	Current      Score
	CurrentLives int
	Highscores   Highscores
}

func LoadScores() (ScoreState, error) {
	var state ScoreState
	if err := LoadUserFileJSON(scoreFileName, &state); err != nil {
		return ScoreState{}, err
	}
	state.Current.Validate()
	for i := 0; i < len(state.Highscores); {
		if !state.Highscores[i].Validate() {
			state.Highscores = append(state.Highscores[:i], state.Highscores[i+1:]...)
		} else {
			i++
		}
	}

	return state, nil
}

func SaveScores(s *ScoreState) error {
	return SaveUserFileJSON(scoreFileName, s)
}