78 lines
2.0 KiB
Go
78 lines
2.0 KiB
Go
package main
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import (
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"encoding/json"
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"fmt"
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"os"
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"path/filepath"
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"github.com/google/renameio/maybe"
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"github.com/pkg/errors"
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)
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// db is the file where the game statistics are stored.
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type db struct {
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// Guesses stores the win statistics of each game. Guesses[0] is the number
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// of games that were lost, Guesses[1] is the number of games that were won
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// with 1 guess, etc.
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Guesses [numGuesses + 1]int `json:"guesses"`
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}
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// loadDb reads the database from dbPath.
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func loadDb() (*db, error) {
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file, err := os.Open(pathDb)
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if err != nil {
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if os.IsNotExist(err) {
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return &db{}, nil
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}
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return nil, errors.Wrap(err, "could not find database")
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}
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var db db
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if err := json.NewDecoder(file).Decode(&db); err != nil {
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return nil, errors.Wrap(err, "could not read from database")
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}
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return &db, nil
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}
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// save atomically (best effort) writes the database to dbPath.
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func (db *db) save() error {
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dir := filepath.Dir(pathDb)
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if err := os.MkdirAll(dir, 0755); err != nil {
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return errors.Wrapf(err, "could not create data directory: %s", dir)
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}
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data, err := json.MarshalIndent(&db, "", " ")
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if err != nil {
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return errors.Wrap(err, "could not serialize database")
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}
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if err := maybe.WriteFile(pathDb, data, 0644); err != nil {
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return errors.Wrapf(err, "could not write to database: %s", pathDb)
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}
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return nil
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}
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// addWin adds a win to the game statistics. It also stores the number of
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// guesses it took, in the range [1,numGuesses].
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func (db *db) addWin(guesses int) {
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if !(1 <= guesses && guesses <= numGuesses) {
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panic(fmt.Sprintf("guesses out of range: %d", guesses))
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}
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db.Guesses[guesses]++
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}
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// addLoss adds a loss to the game statistics.
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func (db *db) addLoss() {
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db.Guesses[0]++
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}
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// score returns the current total score based on the statistics.
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//
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// A game that was lost provides 0 points. A game that was won provides 50
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// points, plus an extra 10 points for each remaining guess.
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func (db *db) score() int {
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score := 0
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for i, guess := range db.Guesses[1:] {
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score += (100 - 10*i) * guess
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}
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return score
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}
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