Initial commit.

internal/store/store.go

@@ -0,0 +1,96 @@
+// Package store persists game state as JSON blobs in SQLite.
+package store
+
+import (
+	"database/sql"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+
+	_ "modernc.org/sqlite"
+
+	"github.com/greyson/super-auto-pets-board-game/internal/game"
+)
+
+// ErrNotFound is returned when a game doesn't exist.
+var ErrNotFound = errors.New("game not found")
+
+// Store wraps the SQLite database in the data directory.
+type Store struct {
+	db *sql.DB
+}
+
+// Open creates the data directory if needed and opens (or initializes) the
+// database inside it.
+func Open(dataDir string) (*Store, error) {
+	if err := os.MkdirAll(dataDir, 0o755); err != nil {
+		return nil, fmt.Errorf("create data dir: %w", err)
+	}
+	dsn := fmt.Sprintf("file:%s?_pragma=journal_mode(WAL)&_pragma=busy_timeout(5000)",
+		filepath.Join(dataDir, "games.db"))
+	db, err := sql.Open("sqlite", dsn)
+	if err != nil {
+		return nil, err
+	}
+	// modernc.org/sqlite is happiest with a single writer connection.
+	db.SetMaxOpenConns(1)
+	if _, err := db.Exec(`
+		CREATE TABLE IF NOT EXISTS games (
+			id         TEXT PRIMARY KEY,
+			code       TEXT NOT NULL UNIQUE,
+			state      TEXT NOT NULL,
+			created_at INTEGER NOT NULL,
+			updated_at INTEGER NOT NULL
+		);
+	`); err != nil {
+		db.Close()
+		return nil, fmt.Errorf("init schema: %w", err)
+	}
+	return &Store{db: db}, nil
+}
+
+func (s *Store) Close() error { return s.db.Close() }
+
+// Save upserts the full game state.
+func (s *Store) Save(g *game.Game) error {
+	blob, err := json.Marshal(g)
+	if err != nil {
+		return err
+	}
+	now := time.Now().UnixMilli()
+	_, err = s.db.Exec(`
+		INSERT INTO games (id, code, state, created_at, updated_at)
+		VALUES (?, ?, ?, ?, ?)
+		ON CONFLICT(id) DO UPDATE SET state = excluded.state, updated_at = excluded.updated_at
+	`, g.ID, g.Code, string(blob), now, now)
+	return err
+}
+
+// Load fetches a game by ID.
+func (s *Store) Load(id string) (*game.Game, error) {
+	return s.loadWhere(`id = ?`, id)
+}
+
+// LoadByCode fetches a game by its join code.
+func (s *Store) LoadByCode(code string) (*game.Game, error) {
+	return s.loadWhere(`code = ?`, code)
+}
+
+func (s *Store) loadWhere(cond string, arg any) (*game.Game, error) {
+	var blob string
+	err := s.db.QueryRow(`SELECT state FROM games WHERE `+cond, arg).Scan(&blob)
+	if errors.Is(err, sql.ErrNoRows) {
+		return nil, ErrNotFound
+	}
+	if err != nil {
+		return nil, err
+	}
+	var g game.Game
+	if err := json.Unmarshal([]byte(blob), &g); err != nil {
+		return nil, fmt.Errorf("corrupt game state %v: %w", arg, err)
+	}
+	return &g, nil
+}