package service

import (
	"context"
	"errors"

	"knowlege-lsxd/internal/logger"
	"knowlege-lsxd/internal/models/chat"
	"knowlege-lsxd/internal/models/embedding"
	"knowlege-lsxd/internal/models/rerank"
	"knowlege-lsxd/internal/models/utils/ollama"
	"knowlege-lsxd/internal/types"
	"knowlege-lsxd/internal/types/interfaces"
)

// ErrModelNotFound is returned when a model cannot be found in the repository
var ErrModelNotFound = errors.New("model not found")

// modelService implements the model service interface
type modelService struct {
	repo          interfaces.ModelRepository
	ollamaService *ollama.OllamaService
}

// NewModelService creates a new model service instance
func NewModelService(repo interfaces.ModelRepository, ollamaService *ollama.OllamaService) interfaces.ModelService {
	return &modelService{
		repo:          repo,
		ollamaService: ollamaService,
	}
}

// CreateModel creates a new model in the repository
// For local models, it initiates an asynchronous download process
// Remote models are immediately set to active status
func (s *modelService) CreateModel(ctx context.Context, model *types.Model) error {
	logger.Info(ctx, "Start creating model")
	logger.Infof(ctx, "Creating model: %s, type: %s, source: %s", model.Name, model.Type, model.Source)

	// Handle remote models (e.g., OpenAI, Azure)
	if model.Source == types.ModelSourceRemote {
		logger.Info(ctx, "Remote model detected, setting status to active")
		model.Status = types.ModelStatusActive

		logger.Info(ctx, "Saving remote model to repository")
		err := s.repo.Create(ctx, model)
		if err != nil {
			logger.ErrorWithFields(ctx, err, map[string]interface{}{
				"model_name": model.Name,
				"model_type": model.Type,
			})
			return err
		}

		logger.Infof(ctx, "Remote model created successfully: %s", model.ID)
		return nil
	}

	// Handle local models (e.g., Ollama)
	logger.Info(ctx, "Local model detected, setting status to downloading")
	model.Status = types.ModelStatusDownloading

	logger.Info(ctx, "Saving local model to repository")
	err := s.repo.Create(ctx, model)
	if err != nil {
		logger.ErrorWithFields(ctx, err, map[string]interface{}{
			"model_name": model.Name,
			"model_type": model.Type,
		})
		return err
	}

	// Start asynchronous model download
	logger.Infof(ctx, "Starting background download for model: %s", model.Name)
	newCtx := logger.CloneContext(ctx)
	go func() {
		logger.Info(newCtx, "Background download started")
		err := s.ollamaService.PullModel(newCtx, model.Name)
		if err != nil {
			logger.ErrorWithFields(newCtx, err, map[string]interface{}{
				"model_name": model.Name,
			})
			model.Status = types.ModelStatusDownloadFailed
		} else {
			logger.Infof(newCtx, "Model download completed successfully: %s", model.Name)
			model.Status = types.ModelStatusActive
		}
		logger.Infof(newCtx, "Updating model status to: %s", model.Status)
		s.repo.Update(newCtx, model)
	}()

	logger.Infof(ctx, "Model creation initiated successfully: %s", model.ID)
	return nil
}

// GetModelByID retrieves a model by its ID
// Returns an error if the model is not found or is in a non-active state
func (s *modelService) GetModelByID(ctx context.Context, id string) (*types.Model, error) {
	logger.Info(ctx, "Start getting model by ID")
	logger.Infof(ctx, "Getting model with ID: %s", id)

	tenantID := ctx.Value(types.TenantIDContextKey).(uint)
	logger.Infof(ctx, "Tenant ID: %d", tenantID)

	// Fetch model from repository
	model, err := s.repo.GetByID(ctx, tenantID, id)
	if err != nil {
		logger.ErrorWithFields(ctx, err, map[string]interface{}{
			"model_id":  id,
			"tenant_id": tenantID,
		})
		return nil, err
	}

	// Check if model exists
	if model == nil {
		logger.Error(ctx, "Model not found")
		return nil, ErrModelNotFound
	}

	logger.Infof(ctx, "Model found, name: %s, status: %s", model.Name, model.Status)

	// Check model status
	if model.Status == types.ModelStatusActive {
		logger.Info(ctx, "Model is active and ready to use")
		return model, nil
	}

	if model.Status == types.ModelStatusDownloading {
		logger.Warn(ctx, "Model is currently downloading")
		return nil, errors.New("model is currently downloading")
	}

	if model.Status == types.ModelStatusDownloadFailed {
		logger.Error(ctx, "Model download failed")
		return nil, errors.New("model download failed")
	}

	logger.Error(ctx, "Model status is abnormal")
	return nil, errors.New("abnormal model status")
}

// ListModels returns all models belonging to the tenant
func (s *modelService) ListModels(ctx context.Context) ([]*types.Model, error) {
	logger.Info(ctx, "Start listing models")

	tenantID := ctx.Value(types.TenantIDContextKey).(uint)
	logger.Infof(ctx, "Listing models for tenant ID: %d", tenantID)

	// List models from repository with no additional filters
	models, err := s.repo.List(ctx, tenantID, "", "")
	if err != nil {
		logger.ErrorWithFields(ctx, err, map[string]interface{}{
			"tenant_id": tenantID,
		})
		return nil, err
	}

	logger.Infof(ctx, "Retrieved %d models successfully", len(models))
	return models, nil
}

// UpdateModel updates an existing model in the repository
func (s *modelService) UpdateModel(ctx context.Context, model *types.Model) error {
	logger.Info(ctx, "Start updating model")
	logger.Infof(ctx, "Updating model ID: %s, name: %s", model.ID, model.Name)

	// Update model in repository
	err := s.repo.Update(ctx, model)
	if err != nil {
		logger.ErrorWithFields(ctx, err, map[string]interface{}{
			"model_id":   model.ID,
			"model_name": model.Name,
		})
		return err
	}

	logger.Infof(ctx, "Model updated successfully: %s", model.ID)
	return nil
}

// DeleteModel removes a model from the repository
func (s *modelService) DeleteModel(ctx context.Context, id string) error {
	logger.Info(ctx, "Start deleting model")
	logger.Infof(ctx, "Deleting model ID: %s", id)

	tenantID := ctx.Value(types.TenantIDContextKey).(uint)
	logger.Infof(ctx, "Tenant ID: %d", tenantID)

	// Delete model from repository
	err := s.repo.Delete(ctx, tenantID, id)
	if err != nil {
		logger.ErrorWithFields(ctx, err, map[string]interface{}{
			"model_id":  id,
			"tenant_id": tenantID,
		})
		return err
	}

	logger.Infof(ctx, "Model deleted successfully: %s", id)
	return nil
}

// GetEmbeddingModel retrieves and initializes an embedding model instance
// Takes a model ID and returns an Embedder interface implementation
func (s *modelService) GetEmbeddingModel(ctx context.Context, modelId string) (embedding.Embedder, error) {
	logger.Info(ctx, "Start getting embedding model")
	logger.Infof(ctx, "Getting embedding model with ID: %s", modelId)

	// Get the model details
	model, err := s.GetModelByID(ctx, modelId)
	if err != nil {
		logger.ErrorWithFields(ctx, err, map[string]interface{}{
			"model_id": modelId,
		})
		return nil, err
	}

	logger.Info(ctx, "Creating embedder instance")
	logger.Infof(ctx, "Model name: %s, source: %s", model.Name, model.Source)

	// Initialize the embedder with model configuration
	embedder, err := embedding.NewEmbedder(embedding.Config{
		Source:               model.Source,
		BaseURL:              model.Parameters.BaseURL,
		APIKey:               model.Parameters.APIKey,
		ModelID:              model.ID,
		ModelName:            model.Name,
		Dimensions:           model.Parameters.EmbeddingParameters.Dimension,
		TruncatePromptTokens: model.Parameters.EmbeddingParameters.TruncatePromptTokens,
	})
	if err != nil {
		logger.ErrorWithFields(ctx, err, map[string]interface{}{
			"model_id":   model.ID,
			"model_name": model.Name,
		})
		return nil, err
	}

	logger.Info(ctx, "Embedding model initialized successfully")
	return embedder, nil
}

// GetRerankModel retrieves and initializes a reranking model instance
// Takes a model ID and returns a Reranker interface implementation
func (s *modelService) GetRerankModel(ctx context.Context, modelId string) (rerank.Reranker, error) {
	logger.Info(ctx, "Start getting rerank model")
	logger.Infof(ctx, "Getting rerank model with ID: %s", modelId)

	// Get the model details
	model, err := s.GetModelByID(ctx, modelId)
	if err != nil {
		logger.ErrorWithFields(ctx, err, map[string]interface{}{
			"model_id": modelId,
		})
		return nil, err
	}

	logger.Info(ctx, "Creating reranker instance")
	logger.Infof(ctx, "Model name: %s, source: %s", model.Name, model.Source)

	// Initialize the reranker with model configuration
	reranker, err := rerank.NewReranker(&rerank.RerankerConfig{
		ModelID:   model.ID,
		APIKey:    model.Parameters.APIKey,
		BaseURL:   model.Parameters.BaseURL,
		ModelName: model.Name,
		Source:    model.Source,
	})
	if err != nil {
		logger.ErrorWithFields(ctx, err, map[string]interface{}{
			"model_id":   model.ID,
			"model_name": model.Name,
		})
		return nil, err
	}

	logger.Info(ctx, "Rerank model initialized successfully")
	return reranker, nil
}

// GetChatModel retrieves and initializes a chat model instance
// Takes a model ID and returns a Chat interface implementation
func (s *modelService) GetChatModel(ctx context.Context, modelId string) (chat.Chat, error) {
	logger.Info(ctx, "Start getting chat model")
	logger.Infof(ctx, "Getting chat model with ID: %s", modelId)

	tenantID := ctx.Value(types.TenantIDContextKey).(uint)
	logger.Infof(ctx, "Tenant ID: %d", tenantID)

	// Get the model directly from repository to avoid status checks
	model, err := s.repo.GetByID(ctx, tenantID, modelId)
	if err != nil {
		logger.ErrorWithFields(ctx, err, map[string]interface{}{
			"model_id":  modelId,
			"tenant_id": tenantID,
		})
		return nil, err
	}

	if model == nil {
		logger.Error(ctx, "Chat model not found")
		return nil, ErrModelNotFound
	}

	logger.Info(ctx, "Creating chat model instance")
	logger.Infof(ctx, "Model name: %s, source: %s", model.Name, model.Source)

	// Initialize the chat model with model configuration
	chatModel, err := chat.NewChat(&chat.ChatConfig{
		ModelID:   model.ID,
		APIKey:    model.Parameters.APIKey,
		BaseURL:   model.Parameters.BaseURL,
		ModelName: model.Name,
		Source:    model.Source,
	})
	if err != nil {
		logger.ErrorWithFields(ctx, err, map[string]interface{}{
			"model_id":   model.ID,
			"model_name": model.Name,
		})
		return nil, err
	}

	logger.Info(ctx, "Chat model initialized successfully")
	return chatModel, nil
}