Add framework composition runner

internal/framework/inputregistry/registry.go

@@ -0,0 +1,83 @@
+package inputregistry
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+
+	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
+)
+
+type Constructor func() (contracts.InputAdapter, error)
+
+type Registry struct {
+	constructors map[string]Constructor
+}
+
+func New() *Registry {
+	return &Registry{
+		constructors: make(map[string]Constructor),
+	}
+}
+
+func (r *Registry) Register(key string, constructor Constructor) error {
+	if r == nil {
+		return fmt.Errorf("input adapter registry must not be nil")
+	}
+
+	normalizedKey := strings.TrimSpace(key)
+	if normalizedKey == "" {
+		return fmt.Errorf("input adapter key must not be empty")
+	}
+	if constructor == nil {
+		return fmt.Errorf("input adapter constructor for %q must not be nil", normalizedKey)
+	}
+	if _, ok := r.constructors[normalizedKey]; ok {
+		return fmt.Errorf("input adapter %q is already registered", normalizedKey)
+	}
+
+	r.constructors[normalizedKey] = constructor
+	return nil
+}
+
+func (r *Registry) Build(key string) (contracts.InputAdapter, error) {
+	if r == nil {
+		return nil, fmt.Errorf("input adapter registry must not be nil")
+	}
+
+	normalizedKey := strings.TrimSpace(key)
+	if normalizedKey == "" {
+		return nil, fmt.Errorf("input adapter key must not be empty")
+	}
+
+	constructor, ok := r.constructors[normalizedKey]
+	if !ok {
+		return nil, fmt.Errorf("input adapter %q is not registered", normalizedKey)
+	}
+
+	adapter, err := constructor()
+	if err != nil {
+		return nil, fmt.Errorf("build input adapter %q: %w", normalizedKey, err)
+	}
+	if adapter == nil {
+		return nil, fmt.Errorf("input adapter %q constructor returned nil", normalizedKey)
+	}
+	if adapter.Key() != normalizedKey {
+		return nil, fmt.Errorf("input adapter %q returned key %q", normalizedKey, adapter.Key())
+	}
+
+	return adapter, nil
+}
+
+func (r *Registry) RegisteredKeys() []string {
+	if r == nil {
+		return nil
+	}
+
+	keys := make([]string, 0, len(r.constructors))
+	for key := range r.constructors {
+		keys = append(keys, key)
+	}
+	sort.Strings(keys)
+	return keys
+}