feat(lib): implement store interface

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

lib/store/decaymap.go

@@ -0,0 +1,61 @@
+package store
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/TecharoHQ/anubis/decaymap"
+)
+
+type decayMapStore struct {
+	store *decaymap.Impl[string, []byte]
+}
+
+func (d *decayMapStore) Delete(_ context.Context, key string) error {
+	if !d.store.Delete(key) {
+		return fmt.Errorf("%w: %q", ErrNotFound, key)
+	}
+
+	return nil
+}
+
+func (d *decayMapStore) Get(_ context.Context, key string) ([]byte, error) {
+	result, ok := d.store.Get(key)
+	if !ok {
+		return nil, fmt.Errorf("%w: %q", ErrNotFound, key)
+	}
+
+	return result, nil
+}
+
+func (d *decayMapStore) Set(_ context.Context, key string, value []byte, expiry time.Duration) error {
+	d.store.Set(key, value, expiry)
+	return nil
+}
+
+func (d *decayMapStore) cleanupThread(ctx context.Context) {
+	t := time.NewTicker(5 * time.Minute)
+	defer t.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-t.C:
+			d.store.Cleanup()
+		}
+	}
+}
+
+// NewDecayMapStore creates a simple in-memory store. This will not scale
+// to multiple Anubis instances.
+func NewDecayMapStore(ctx context.Context) Interface {
+	result := &decayMapStore{
+		store: decaymap.New[string, []byte](),
+	}
+
+	go result.cleanupThread(ctx)
+
+	return result
+}