package spells

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"strings"

	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
	"gitea.maximumdirect.net/eric/notarius/internal/framework/pipeline"
	"gitea.maximumdirect.net/eric/notarius/internal/modules/sharedassets/dnd"
)

const Key = "dnd/spells"
const ArtifactType = "dnd.spell_cast"
const SchemaVersion = "v1"

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

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

var referenceSlotDescriptions = dnd.ReferenceSlotDescriptions{
	Glossary: "Optional campaign glossary reference material used only for disambiguation.",
	Party:    "Optional party roster reference material used only for disambiguation.",
	Players:  "Optional player list reference material used only for disambiguation.",
	Roster:   "Deprecated alias for party roster reference material used only for disambiguation.",
}

var _ contracts.Extractor = (*Extractor)(nil)

type Extractor struct{}

func New() *Extractor {
	return &Extractor{}
}

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

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

func (e *Extractor) ManifestMetadata() map[string]any {
	promptSHA, err := scriptoriumPromptMetadata()
	if err != nil {
		promptSHA = ""
	}
	metadata := map[string]any{
		"prompt_id":            PromptID,
		"prompt_version":       SchemaVersion,
		"prompt_sha256":        promptSHA,
		"response_schema_key":  string(ResponseSchemaKey),
		"response_schema_id":   ResponseSchemaID,
		"response_schema_name": ResponseSchemaName,
	}
	if schema, err := loadResponseSchema(); err == nil {
		metadata["response_schema_version"] = schema.Version
		metadata["response_schema_sha256"] = schema.SHA256
	}
	return metadata
}

func (e *Extractor) Extract(ctx context.Context, req contracts.ExtractionRequest) (contracts.ExtractionResult, error) {
	if e == nil {
		return contracts.ExtractionResult{}, extractorErrorf("extractor must not be nil")
	}
	if ctx == nil {
		return contracts.ExtractionResult{}, extractorErrorf("context must not be nil")
	}
	if err := ctx.Err(); err != nil {
		return contracts.ExtractionResult{}, extractorErrorf("context error before extraction: %w", err)
	}
	if req.Source == nil {
		return contracts.ExtractionResult{}, extractorErrorf("source must not be nil")
	}
	if req.Chunk == nil {
		return contracts.ExtractionResult{}, extractorErrorf("chunk must not be nil")
	}
	if len(req.Chunk.Units) == 0 {
		return contracts.ExtractionResult{}, extractorErrorf("chunk %q units must not be empty", req.Chunk.ID)
	}
	if req.LLMClient == nil {
		return contracts.ExtractionResult{}, extractorErrorf("LLM client must not be nil")
	}
	sourceInput, err := chunkSourceInput(req)
	if err != nil {
		return contracts.ExtractionResult{}, err
	}

	var response extractionResponse
	completion, err := req.LLMClient.CompleteStructured(ctx, contracts.StructuredCompletionRequest{
		StageName:     Key,
		PromptID:      PromptID,
		PromptVersion: SchemaVersion,
		ProfileID:     req.LLMProfile,
		SessionID:     req.SessionID,
		Inputs:        dnd.PromptInputs(sourceInput, req.References),
	}, &response)
	if err != nil {
		return contracts.ExtractionResult{}, extractorErrorf("complete structured output: %w", err)
	}
	content := append([]byte(nil), completion.Content...)
	if len(strings.TrimSpace(string(content))) == 0 {
		var err error
		content, err = json.Marshal(response)
		if err != nil {
			return contracts.ExtractionResult{}, extractorErrorf("marshal raw output: %w", err)
		}
	}
	return contracts.ExtractionResult{
		Output: contracts.ExtractOutput{
			Schema: contracts.ResponseSchema{
				ID:      ResponseSchemaID,
				Name:    ResponseSchemaName,
				Version: SchemaVersion,
			},
			Payload: contracts.RawPayload{
				Content:   content,
				MediaType: "application/json",
				Metadata: map[string]any{
					"spell_cast_count": len(response.SpellCasts),
				},
			},
		},
	}, nil
}

func chunkSourceInput(req contracts.ExtractionRequest) (contracts.LLMInputMaterial, error) {
	material := req.SourceInput.Clone()
	if len(material.Content) == 0 {
		material = contracts.NewLLMInputMaterial("source", req.Chunk.MediaType, req.Chunk.Content, "", "")
	}
	if !bytes.Equal(material.Content, req.Chunk.Content) {
		return contracts.LLMInputMaterial{}, extractorErrorf("source input must match chunk %q content", req.Chunk.ID)
	}
	if material.Name == "" {
		material.Name = "source"
	}
	if material.MediaType == "" {
		material.MediaType = req.Chunk.MediaType
	}
	if material.SizeBytes == 0 {
		material.SizeBytes = int64(len(material.Content))
	}
	return material, nil
}

func ModuleSpec() pipeline.ModuleSpec {
	return pipeline.ModuleSpec{
		Key:            Key,
		Stage:          pipeline.StageExtract,
		Requires:       append([]string(nil), requiredCapabilities...),
		Provides:       append([]string(nil), providedCapabilities...),
		ReferenceSlots: dnd.ReferenceSlots(referenceSlotDescriptions),
	}
}

func Register(registry *pipeline.ExtractorRegistry) error {
	return registry.RegisterWithSpec(ModuleSpec(), func() (contracts.Extractor, error) {
		return New(), nil
	})
}

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