package enemyevents

import (
	"context"
	"fmt"

	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
	"gitea.maximumdirect.net/eric/notarius/internal/framework/pipeline"
	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd"
	sceneregistry "gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/scenedescriptions/registry"
	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/shared"
)

const (
	Key             = "dnd/enemy-events"
	mappingPolicy   = "dnd.enemy_events.extract_mapping.v1"
	sceneGatePolicy = "dnd.enemy_events.scene_gate.v1"
)

var requiredCapabilities = []string{
	"chunks",
	"source.transcript",
}

var providedCapabilities = []string{
	"dnd.enemy_events",
}

var _ contracts.Extractor[dnd.EnemyEventList] = (*Extractor)(nil)
var _ contracts.ManifestMetadataProvider = (*Extractor)(nil)
var _ pipeline.CheckpointFingerprintProvider = (*Extractor)(nil)

type Options struct{}

type Extractor struct {
	llm       contracts.StructuredLLMClient
	grounding *groundingResolver

	promptSHA         string
	responseSchemaSHA string
}

func New(llmClient contracts.StructuredLLMClient, _ Options, references ...contracts.ReferenceSet) (*Extractor, error) {
	if llmClient == nil {
		return nil, extractorErrorf("LLM client must not be nil")
	}
	if len(references) > 1 {
		return nil, extractorErrorf("at most one reference set may be supplied")
	}
	var referenceSet contracts.ReferenceSet
	if len(references) == 1 {
		referenceSet = references[0]
	}
	grounding, err := newGroundingResolver(referenceSet)
	if err != nil {
		return nil, extractorErrorf("prepare grounding: %w", err)
	}
	promptSHA, err := promptAssetMetadata()
	if err != nil {
		return nil, extractorErrorf("load prompt metadata: %w", err)
	}
	responseSchema, err := loadResponseSchema()
	if err != nil {
		return nil, extractorErrorf("load response schema: %w", err)
	}
	return &Extractor{
		llm:               llmClient,
		grounding:         grounding,
		promptSHA:         promptSHA,
		responseSchemaSHA: responseSchema.SHA256,
	}, nil
}

func (e *Extractor) Key() string { return Key }

func (e *Extractor) ReferenceSlots() []contracts.ReferenceSlot { return referenceSlots() }

func (e *Extractor) ManifestMetadata() map[string]any {
	if e == nil {
		return nil
	}
	return map[string]any{
		"prompt_id":               PromptID,
		"prompt_version":          SchemaVersion,
		"prompt_sha256":           e.promptSHA,
		"mapping_policy":          mappingPolicy,
		"scene_gate_policy":       sceneGatePolicy,
		"response_schema_key":     string(ResponseSchemaKey),
		"response_schema_id":      ResponseSchemaID,
		"response_schema_name":    ResponseSchemaName,
		"response_schema_version": SchemaVersion,
		"response_schema_sha256":  e.responseSchemaSHA,
	}
}

func (e *Extractor) CheckpointFingerprints() []pipeline.CheckpointFingerprint {
	if e == nil {
		return nil
	}
	return []pipeline.CheckpointFingerprint{
		{Name: "prompt", Value: e.promptSHA},
		{Name: "response_schema", Value: e.responseSchemaSHA},
		{Name: "mapping_policy", Value: mappingPolicy},
		{Name: "scene_gate_policy", Value: sceneGatePolicy},
	}
}

func (e *Extractor) Extract(ctx context.Context, req contracts.TypedExtractionRequest) (contracts.TypedExtractionResult[dnd.EnemyEventList], error) {
	if e == nil {
		return contracts.TypedExtractionResult[dnd.EnemyEventList]{}, extractorErrorf("extractor must not be nil")
	}
	if e.llm == nil {
		return contracts.TypedExtractionResult[dnd.EnemyEventList]{}, extractorErrorf("LLM client must not be nil")
	}
	if e.grounding == nil {
		return contracts.TypedExtractionResult[dnd.EnemyEventList]{}, extractorErrorf("grounding resolver must not be nil")
	}
	sourceInput, err := shared.PrepareChunkExtraction(ctx, req)
	if err != nil {
		return contracts.TypedExtractionResult[dnd.EnemyEventList]{}, extractorErrorf("%w", err)
	}
	match, err := e.grounding.SceneMatch(req.References, req.Chunk)
	if err != nil {
		return contracts.TypedExtractionResult[dnd.EnemyEventList]{}, extractorErrorf("resolve scene eligibility: %w", err)
	}
	switch match.State {
	case sceneregistry.MatchExact:
		if match.Kind != dnd.SceneKindCombat {
			return emptyResult(), nil
		}
	case sceneregistry.MatchMissing, sceneregistry.MatchMismatched:
		return unavailableSceneResult(), nil
	default:
		return contracts.TypedExtractionResult[dnd.EnemyEventList]{}, extractorErrorf("unsupported scene eligibility match state %q", match.State)
	}
	grounding, err := e.grounding.Resolve(req.References)
	if err != nil {
		return contracts.TypedExtractionResult[dnd.EnemyEventList]{}, extractorErrorf("resolve enemy-event grounding: %w", err)
	}
	inputs := shared.PromptInputs(sourceInput, req.References)
	for name, input := range grounding.PromptInputs() {
		inputs[name] = input
	}
	var response extractionResponse
	if _, err := e.llm.CompleteStructured(ctx, contracts.StructuredCompletionRequest{
		StageName:     Key,
		PromptID:      PromptID,
		PromptVersion: SchemaVersion,
		ProfileID:     req.LLMProfile,
		SessionID:     req.SessionID,
		Inputs:        inputs,
	}, &response); err != nil {
		return contracts.TypedExtractionResult[dnd.EnemyEventList]{}, extractorErrorf("complete structured output: %w", err)
	}
	return contracts.TypedExtractionResult[dnd.EnemyEventList]{
		Value: canonicalEnemyEventList(response, shared.NewSourceRefOrder(req.Source), req.Source.ID),
	}, nil
}

func emptyResult() contracts.TypedExtractionResult[dnd.EnemyEventList] {
	return contracts.TypedExtractionResult[dnd.EnemyEventList]{Value: dnd.EnemyEventList{Events: []dnd.EnemyEvent{}}}
}

func unavailableSceneResult() contracts.TypedExtractionResult[dnd.EnemyEventList] {
	result := emptyResult()
	result.Warnings = []contracts.Warning{{
		Scope:      SceneDescriptionReferenceSlot,
		ReasonCode: "scene_classification_unavailable",
		Message:    "No exact scene classification was available; enemy-event extraction was skipped.",
	}}
	return result
}

func ModuleSpec() pipeline.ModuleSpec {
	return pipeline.ModuleSpec{
		Key:            Key,
		Stage:          pipeline.StageExtract,
		ExecutionClass: contracts.ExecutionClassLLMBacked,
		Requires:       append([]string(nil), requiredCapabilities...),
		Provides:       append([]string(nil), providedCapabilities...),
		ArtifactKind:   dnd.EnemyEventListKind,
		ReferenceSlots: referenceSlots(),
	}
}

func Register(registry *pipeline.ExtractorRegistry) error {
	return pipeline.RegisterExtractorBuilder(registry, ModuleSpec(), validateOptions, func(request pipeline.BuildRequest) (contracts.Extractor[dnd.EnemyEventList], error) {
		options, err := DecodeOptions(request.Options)
		if err != nil {
			return nil, err
		}
		return New(request.Dependencies.LLM, options, request.References)
	})
}

func validateOptions(options map[string]any) error {
	_, err := DecodeOptions(options)
	return err
}

func DecodeOptions(options map[string]any) (Options, error) {
	if err := pipeline.RejectUnknownOptions(options); err != nil {
		return Options{}, extractorErrorf("%w", err)
	}
	return Options{}, nil
}

func extractorErrorf(format string, args ...any) error {
	return fmt.Errorf("dnd enemy events extractor: "+format, args...)
}