doodle/pkg/savegame/savegame.go

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2022-01-03 00:28:43 +00:00
package savegame
import (
"bufio"
"crypto/sha1"
"encoding/hex"
"encoding/json"
"errors"
"fmt"
"os"
"path/filepath"
"strings"
"time"
"git.kirsle.net/apps/doodle/pkg/usercfg"
"git.kirsle.net/apps/doodle/pkg/userdir"
)
// SaveGame holds the user's progress thru level packs.
type SaveGame struct {
LevelPacks map[string]*LevelPack `json:"levelPacks"`
}
// LevelPack holds savegame process for a level pack.
type LevelPack struct {
Levels map[string]*Level `json:"levels"`
}
// Level holds high score information for a level.
type Level struct {
Completed bool `json:"completed"`
BestTime *time.Duration `json:"bestTime"`
PerfectTime *time.Duration `json:"perfectTime"`
}
// New creates a new SaveGame.
func New() *SaveGame {
return &SaveGame{
LevelPacks: map[string]*LevelPack{},
}
}
// NewLevelPack initializes a LevelPack struct.
func NewLevelPack() *LevelPack {
return &LevelPack{
Levels: map[string]*Level{},
}
}
// GetOrCreate the save game JSON. If the save file isn't found OR has an
// invalid checksum, it is created. Always returns a valid SaveGame struct
// and the error may communicate if there was a problem reading an existing file.
func GetOrCreate() (*SaveGame, error) {
if sg, err := Load(); err == nil {
return sg, nil
} else {
return New(), err
}
}
// Load the save game JSON from the user's profile directory.
func Load() (*SaveGame, error) {
fh, err := os.Open(userdir.SaveFile)
if err != nil {
return nil, err
}
// Read the checksum line.
scanner := bufio.NewScanner(fh)
scanner.Scan()
var (
checksum = scanner.Text()
jsontext []byte
)
for scanner.Scan() {
jsontext = append(jsontext, scanner.Bytes()...)
}
// Validate the checksum.
if !verifyChecksum(jsontext, checksum) {
return nil, errors.New("checksum error")
}
// Parse the JSON.
var sg = New()
err = json.Unmarshal(jsontext, sg)
if err != nil {
return nil, err
}
return sg, nil
}
// Save the savegame.json to disk.
func (sg *SaveGame) Save() error {
// Encode to JSON.
text, err := json.Marshal(sg)
if err != nil {
return err
}
// Create the checksum.
checksum := makeChecksum(text)
// Write the file.
fh, err := os.Create(userdir.SaveFile)
if err != nil {
return err
}
defer fh.Close()
fh.Write([]byte(checksum))
fh.Write([]byte{'\n'})
fh.Write(text)
return nil
}
// MarkCompleted is a helper function to mark a levelpack level completed.
// Parameters are the filename of the levelpack and the level therein.
// Extra path info except the base filename is stripped from both.
func (sg *SaveGame) MarkCompleted(levelpack, filename string) {
lvl := sg.GetLevelScore(levelpack, filename)
lvl.Completed = true
}
// NewHighScore may set a new highscore for a level.
//
// The level will be marked Completed and if the given score is better
// than the stored one it will update.
//
// Returns true if a new high score was logged.
func (sg *SaveGame) NewHighScore(levelpack, filename string, isPerfect bool, elapsed time.Duration) bool {
levelpack = filepath.Base(levelpack)
filename = filepath.Base(filename)
score := sg.GetLevelScore(levelpack, filename)
score.Completed = true
var newHigh bool
if isPerfect {
if score.PerfectTime == nil || *score.PerfectTime > elapsed {
score.PerfectTime = &elapsed
newHigh = true
}
} else {
if score.BestTime == nil || *score.BestTime > elapsed {
score.BestTime = &elapsed
newHigh = true
}
}
if newHigh {
if sg.LevelPacks[levelpack] == nil {
sg.LevelPacks[levelpack] = NewLevelPack()
}
sg.LevelPacks[levelpack].Levels[filename] = score
}
return newHigh
}
// GetLevelScore finds or creates a default Level score.
func (sg *SaveGame) GetLevelScore(levelpack, filename string) *Level {
levelpack = filepath.Base(levelpack)
filename = filepath.Base(filename)
if _, ok := sg.LevelPacks[levelpack]; !ok {
sg.LevelPacks[levelpack] = NewLevelPack()
}
if row, ok := sg.LevelPacks[levelpack].Levels[filename]; ok {
return row
} else {
row = &Level{}
sg.LevelPacks[levelpack].Levels[filename] = row
return row
}
}
// CountCompleted returns the number of completed levels in a levelpack.
func (sg *SaveGame) CountCompleted(levelpack string) int {
var count int
levelpack = filepath.Base(levelpack)
if lp, ok := sg.LevelPacks[levelpack]; ok {
for _, lvl := range lp.Levels {
if lvl.Completed {
count++
}
}
}
return count
}
// FormatDuration pretty prints a time.Duration in MM:SS format.
func FormatDuration(d time.Duration) string {
var (
millisecond = d.Milliseconds()
second = (millisecond / 1000) % 60
minute = (millisecond / (1000 * 60)) % 60
hour = (millisecond / (1000 * 60 * 60)) % 24
ms = fmt.Sprintf("%d", millisecond%1000)
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)
// Limit milliseconds to 2 digits.
if len(ms) > 2 {
ms = ms[:2]
}
return strings.TrimPrefix(
fmt.Sprintf("%02d:%02d:%02d.%s", hour, minute, second, ms),
"00:",
)
}
// Hashing key that goes into the level's save data.
var secretKey = []byte(`Sc\x96R\x8e\xba\x96\x8e\x1fg\x01Q\xf5\xcbIX`)
func makeChecksum(jsontext []byte) string {
h := sha1.New()
h.Write(jsontext)
h.Write(secretKey)
h.Write(usercfg.Current.Entropy)
return hex.EncodeToString(h.Sum(nil))
}
func verifyChecksum(jsontext []byte, checksum string) bool {
expect := makeChecksum(jsontext)
return expect == checksum
}