package chat

import (
	"context"
	"fmt"
	"log/slog"
	"sync"
	"time"

	"trankilou.fr/lassistanoque/backend/internal/domain"
	"trankilou.fr/lassistanoque/backend/internal/service/tool"
)

type Service struct {
	repoUser        domain.UserRepository
	repoAgent       domain.AgentRepository
	repoProvider    domain.ProviderRepository
	repoChat        domain.ChatRepository
	llmEngine       domain.LLMEngine
	runningSessions map[string]*ChatSession
	toolService     *tool.Service
	mu              sync.Mutex
}

func NewService(
	repoUser domain.UserRepository,
	repoAgent domain.AgentRepository,
	repoProvider domain.ProviderRepository,
	repoChat domain.ChatRepository,
	llmEngine domain.LLMEngine,
	toolService *tool.Service,
) *Service {
	return &Service{
		repoUser:        repoUser,
		repoAgent:       repoAgent,
		repoProvider:    repoProvider,
		repoChat:        repoChat,
		llmEngine:       llmEngine,
		toolService:     toolService,
		runningSessions: make(map[string]*ChatSession),
	}
}

func (s *Service) NewChat(
	userID string,
	teamID string,
	agentID string,
) (*domain.Chat, error) {

	team, err := s.repoUser.FindTeam(userID, teamID)
	if err != nil {
		return nil, err
	}

	start := time.Now()

	chat := &domain.Chat{
		UserID:        userID,
		AgentID:       agentID,
		TeamID:        team.ID,
		StartDatetime: &start,
		Title:         "Nouvelle conversation",
	}

	chat, err = s.repoChat.CreateChat(userID, chat)
	if err != nil {
		return nil, err
	}

	return chat, nil

}

func (s *Service) AddChatMessage(
	ctx context.Context,
	userID string,
	teamID string,
	chatID string,
	agentID string,
	prompt string,
	params *domain.ChatParams,
) (*domain.Message, error) {

	team, err := s.repoUser.FindTeam(userID, teamID)
	if err != nil {
		return nil, err
	}

	var chatAgentID string
	if team.DefaultAgentID != nil {
		chatAgentID = *team.DefaultAgentID
	} else if agentID != "" {
		chatAgentID = agentID
	} else {
		return nil, fmt.Errorf("no agent defined")
	}

	agent, err := s.repoAgent.GetAgent(userID, team.ID, chatAgentID)
	if err != nil {
		return nil, err
	}

	chatProviderID := agent.DefaultProviderID
	chatModelID := agent.DefaultModelID
	if params != nil && params.ProviderID != "" {
		chatProviderID = params.ProviderID
	}
	if params != nil && params.ModelID != "" {
		chatModelID = params.ModelID
	}

	provider, err := s.repoProvider.GetProvider(userID, teamID, chatProviderID)
	if err != nil {
		return nil, err
	}

	message, err := s.repoChat.CreateChatMessage(userID, &domain.Message{
		ChatID:  chatID,
		TeamID:  teamID,
		Role:    string(domain.RoleUser),
		Content: prompt,
	})
	if err != nil {
		return nil, err
	}

	messages, err := s.repoChat.GetChatMessages(userID, teamID, chatID, true)
	if err != nil {
		return nil, err
	}

	var cb domain.StreamCallback
	if params != nil && params.OnChunk != nil {
		cb = params.OnChunk
	}

	s.runQuery(
		ctx,
		userID,
		teamID,
		chatID,
		agent,
		provider,
		chatModelID,
		messages,
		cb,
	)

	chat, _ := s.repoChat.GetChat(userID, teamID, chatID)
	chat.FreshTitle = false
	s.repoChat.UpdateChat(userID, chat)

	go s.RefreshTitles(provider, chatModelID, teamID)

	return message, nil
}

func (s *Service) ListChats(userID string, teamID string, page int) ([]*domain.Chat, error) {
	return s.repoChat.ListChats(userID, teamID, page)
}

func (s *Service) GetChat(userID string, teamID, chatID string) (*domain.Chat, error) {
	return s.repoChat.GetChat(userID, teamID, chatID)
}

func (s *Service) GetChatWithMessages(userID string, teamID, chatID string) (*domain.ChatWithMessages, error) {
	chat, err := s.repoChat.GetChat(userID, teamID, chatID)
	if err != nil {
		return nil, err
	}
	messages, err := s.repoChat.GetChatMessages(userID, teamID, chatID, false)
	if err != nil {
		return nil, err
	}

	return &domain.ChatWithMessages{
		Chat:     chat,
		Messages: messages,
	}, nil
}

func (s *Service) DeleteChat(userID string, teamID, chatID string) error {
	return s.repoChat.DeleteChat(userID, teamID, chatID)
}

func (s *Service) runQuery(
	ctx context.Context,
	userID string,
	teamID string,
	chatID string,
	agent *domain.Agent,
	provider *domain.Provider,
	modelID string,
	messages []*domain.Message,
	callback domain.StreamCallback,
) error {

	chatSession := &ChatSession{
		userID:      userID,
		teamID:      teamID,
		chatID:      chatID,
		agent:       agent,
		provider:    provider,
		modelID:     modelID,
		messages:    messages,
		llmEngine:   s.llmEngine,
		toolService: s.toolService,
		subscribers: make([]domain.StreamCallback, 0),
		repoChat:    s.repoChat,
	}

	if callback != nil {
		chatSession.subscribers = append(chatSession.subscribers, callback)
	}

	s.mu.Lock()
	s.runningSessions[chatID] = chatSession
	s.mu.Unlock()

	go func() {
		err := chatSession.run(ctx)
		if err != nil {
			slog.Info("chat session error", "error", err)
		}
		delete(s.runningSessions, chatID)
	}()

	return nil
}

func (s *Service) Subscribe(
	userID string,
	teamID string,
	chatID string,
	callback domain.StreamCallback,
) error {

	team, err := s.repoUser.FindTeam(userID, teamID)
	if err != nil {
		return err
	}

	_, err = s.repoChat.GetChat(userID, team.ID, chatID)
	if err != nil {
		return err
	}

	s.mu.Lock()

	if chat, ok := s.runningSessions[chatID]; ok {
		chat.subscribers = append(chat.subscribers, callback)
	}

	s.mu.Unlock()

	return nil
}