package pipeline

import (
	"fmt"
	"reflect"
	"strings"

	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
)

type LegacyRawNormalizerConstructor func() (contracts.LegacyRawNormalizer, error)

type NormalizerRegistry struct {
	legacyConstructors map[string]LegacyRawNormalizerConstructor
	legacySpecs        map[string]ModuleSpec
	typedEntries       map[artifactVariantKey]typedNormalizerEntry
}

type typedNormalizerEntry struct {
	spec        ModuleSpec
	valueType   reflect.Type
	constructor func() (any, error)
}

func NewNormalizerRegistry() *NormalizerRegistry {
	return &NormalizerRegistry{
		legacyConstructors: make(map[string]LegacyRawNormalizerConstructor),
		legacySpecs:        make(map[string]ModuleSpec),
		typedEntries:       make(map[artifactVariantKey]typedNormalizerEntry),
	}
}

func (r *NormalizerRegistry) RegisterLegacyRaw(key string, constructor LegacyRawNormalizerConstructor) error {
	return r.RegisterLegacyRawWithSpec(defaultModuleSpec(key, StageNormalize), constructor)
}

func (r *NormalizerRegistry) RegisterLegacyRawWithSpec(spec ModuleSpec, constructor LegacyRawNormalizerConstructor) error {
	if r == nil {
		return fmt.Errorf("normalizer registry must not be nil")
	}
	normalizedSpec := normalizeModuleSpec(spec)
	if err := validateModuleSpec("normalizer", StageNormalize, normalizedSpec); err != nil {
		return err
	}
	if normalizedSpec.ArtifactKind != "" {
		return fmt.Errorf("legacy raw normalizer %q must not declare an artifact kind", normalizedSpec.Key)
	}
	if constructor == nil {
		return fmt.Errorf("normalizer constructor for %q must not be nil", normalizedSpec.Key)
	}
	if _, ok := r.legacyConstructors[normalizedSpec.Key]; ok {
		return fmt.Errorf("legacy raw normalizer %q is already registered", normalizedSpec.Key)
	}
	if r.legacyConstructors == nil {
		r.legacyConstructors = make(map[string]LegacyRawNormalizerConstructor)
	}
	if r.legacySpecs == nil {
		r.legacySpecs = make(map[string]ModuleSpec)
	}
	r.legacyConstructors[normalizedSpec.Key] = constructor
	r.legacySpecs[normalizedSpec.Key] = cloneModuleSpec(normalizedSpec)
	return nil
}

func RegisterNormalizer[T any](registry *NormalizerRegistry, spec ModuleSpec, constructor func() (contracts.Normalizer[T], error)) error {
	if registry == nil {
		return fmt.Errorf("normalizer registry must not be nil")
	}
	normalizedSpec := normalizeModuleSpec(spec)
	if err := validateModuleSpec("normalizer", StageNormalize, normalizedSpec); err != nil {
		return err
	}
	if normalizedSpec.ArtifactKind == "" {
		return fmt.Errorf("typed normalizer %q artifact kind must not be empty", normalizedSpec.Key)
	}
	if constructor == nil {
		return fmt.Errorf("normalizer constructor for %q must not be nil", normalizedSpec.Key)
	}
	key := artifactVariantKey{module: normalizedSpec.Key, kind: normalizedSpec.ArtifactKind}
	if _, ok := registry.typedEntries[key]; ok {
		return fmt.Errorf("normalizer %q variant for artifact kind %q is already registered", key.module, key.kind)
	}
	if registry.typedEntries == nil {
		registry.typedEntries = make(map[artifactVariantKey]typedNormalizerEntry)
	}
	registry.typedEntries[key] = typedNormalizerEntry{
		spec:      cloneModuleSpec(normalizedSpec),
		valueType: reflect.TypeFor[T](),
		constructor: func() (any, error) {
			return constructor()
		},
	}
	return nil
}

func (r *NormalizerRegistry) BuildLegacyRaw(key string) (contracts.LegacyRawNormalizer, error) {
	if r == nil {
		return nil, fmt.Errorf("normalizer registry must not be nil")
	}
	normalizedKey := strings.TrimSpace(key)
	if normalizedKey == "" {
		return nil, fmt.Errorf("normalizer key must not be empty")
	}
	constructor, ok := r.legacyConstructors[normalizedKey]
	if !ok {
		return nil, fmt.Errorf("legacy raw normalizer %q is not registered", normalizedKey)
	}
	normalizer, err := constructor()
	if err != nil {
		return nil, fmt.Errorf("build normalizer %q: %w", normalizedKey, err)
	}
	if normalizer == nil {
		return nil, fmt.Errorf("normalizer %q constructor returned nil", normalizedKey)
	}
	if normalizer.Key() != normalizedKey {
		return nil, fmt.Errorf("normalizer %q returned key %q", normalizedKey, normalizer.Key())
	}
	return normalizer, nil
}

func (r *NormalizerRegistry) Spec(key string) (ModuleSpec, bool) {
	if r == nil {
		return ModuleSpec{}, false
	}
	spec, ok := r.legacySpecs[strings.TrimSpace(key)]
	if !ok {
		return ModuleSpec{}, false
	}
	return cloneModuleSpec(spec), true
}

func (r *NormalizerRegistry) typedEntry(key string, kind contracts.ArtifactKind) (typedNormalizerEntry, bool) {
	if r == nil {
		return typedNormalizerEntry{}, false
	}
	entry, ok := r.typedEntries[artifactVariantKey{module: strings.TrimSpace(key), kind: normalizeArtifactKind(kind)}]
	return entry, ok
}

func (r *NormalizerRegistry) registeredKinds(key string) []contracts.ArtifactKind {
	if r == nil {
		return nil
	}
	module := strings.TrimSpace(key)
	kinds := make([]contracts.ArtifactKind, 0)
	for variant := range r.typedEntries {
		if variant.module == module {
			kinds = append(kinds, variant.kind)
		}
	}
	sortArtifactKinds(kinds)
	return kinds
}

func (r *NormalizerRegistry) RegisteredKeys() []string {
	if r == nil {
		return nil
	}
	keys := make(map[string]struct{}, len(r.legacySpecs)+len(r.typedEntries))
	for key := range r.legacySpecs {
		keys[key] = struct{}{}
	}
	for key := range r.typedEntries {
		keys[key.module] = struct{}{}
	}
	return sortedRegistryKeys(keys)
}