feat(lib): implement store interface

Signed-off-by: Xe Iaso <me@xeiaso.net>

lib/store/memory/memory.go

@@ -0,0 +1,75 @@
+package memory
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"github.com/TecharoHQ/anubis/decaymap"
+	"github.com/TecharoHQ/anubis/lib/store"
+)
+
+type factory struct{}
+
+func (factory) Build(ctx context.Context, _ json.RawMessage) (store.Interface, error) {
+	return New(ctx), nil
+}
+
+func (factory) Valid(json.RawMessage) error { return nil }
+
+func init() {
+	store.Register("memory", factory{})
+}
+
+type impl struct {
+	store *decaymap.Impl[string, []byte]
+}
+
+func (i *impl) Delete(_ context.Context, key string) error {
+	if !i.store.Delete(key) {
+		return fmt.Errorf("%w: %q", store.ErrNotFound, key)
+	}
+
+	return nil
+}
+
+func (i *impl) Get(_ context.Context, key string) ([]byte, error) {
+	result, ok := i.store.Get(key)
+	if !ok {
+		return nil, fmt.Errorf("%w: %q", store.ErrNotFound, key)
+	}
+
+	return result, nil
+}
+
+func (i *impl) Set(_ context.Context, key string, value []byte, expiry time.Duration) error {
+	i.store.Set(key, value, expiry)
+	return nil
+}
+
+func (i *impl) cleanupThread(ctx context.Context) {
+	t := time.NewTicker(5 * time.Minute)
+	defer t.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-t.C:
+			i.store.Cleanup()
+		}
+	}
+}
+
+// NewDecayMapStore creates a simple in-memory store. This will not scale
+// to multiple Anubis instances.
+func New(ctx context.Context) store.Interface {
+	result := &impl{
+		store: decaymap.New[string, []byte](),
+	}
+
+	go result.cleanupThread(ctx)
+
+	return result
+}