Consolidate the architecture plan into fewer packages

internal/framework/pipeline/extractor_registry.go

@@ -0,0 +1,83 @@
+package pipeline
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+
+	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
+)
+
+type ExtractorConstructor func() (contracts.Extractor, error)
+
+type ExtractorRegistry struct {
+	constructors map[string]ExtractorConstructor
+}
+
+func NewExtractorRegistry() *ExtractorRegistry {
+	return &ExtractorRegistry{
+		constructors: make(map[string]ExtractorConstructor),
+	}
+}
+
+func (r *ExtractorRegistry) Register(key string, constructor ExtractorConstructor) error {
+	if r == nil {
+		return fmt.Errorf("extractor registry must not be nil")
+	}
+
+	normalizedKey := strings.TrimSpace(key)
+	if normalizedKey == "" {
+		return fmt.Errorf("extractor key must not be empty")
+	}
+	if constructor == nil {
+		return fmt.Errorf("extractor constructor for %q must not be nil", normalizedKey)
+	}
+	if _, ok := r.constructors[normalizedKey]; ok {
+		return fmt.Errorf("extractor %q is already registered", normalizedKey)
+	}
+
+	r.constructors[normalizedKey] = constructor
+	return nil
+}
+
+func (r *ExtractorRegistry) Build(key string) (contracts.Extractor, error) {
+	if r == nil {
+		return nil, fmt.Errorf("extractor registry must not be nil")
+	}
+
+	normalizedKey := strings.TrimSpace(key)
+	if normalizedKey == "" {
+		return nil, fmt.Errorf("extractor key must not be empty")
+	}
+
+	constructor, ok := r.constructors[normalizedKey]
+	if !ok {
+		return nil, fmt.Errorf("extractor %q is not registered", normalizedKey)
+	}
+
+	extractor, err := constructor()
+	if err != nil {
+		return nil, fmt.Errorf("build extractor %q: %w", normalizedKey, err)
+	}
+	if extractor == nil {
+		return nil, fmt.Errorf("extractor %q constructor returned nil", normalizedKey)
+	}
+	if extractor.Key() != normalizedKey {
+		return nil, fmt.Errorf("extractor %q returned key %q", normalizedKey, extractor.Key())
+	}
+
+	return extractor, nil
+}
+
+func (r *ExtractorRegistry) 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
+}