package service

import (
	"context"
	"errors"

	"github.com/gochat/gochat/internal/model"
	"github.com/gochat/gochat/internal/repository"
	applogger "github.com/gochat/gochat/pkg/logger"
)

// DraftMessageService implements business logic for DraftMessage operations.
// Reference: Chatwoot app/controllers/api/v1/conversations/draft_messages_controller.rb
type DraftMessageService struct {
	repo             *repository.DraftMessageRepo
	conversationRepo *repository.ConversationRepo
}

// NewDraftMessageService creates a new DraftMessage service.
func NewDraftMessageService(repo *repository.DraftMessageRepo, conversationRepo *repository.ConversationRepo) *DraftMessageService {
	return &DraftMessageService{repo: repo, conversationRepo: conversationRepo}
}

// Ready reports whether the service has its repository configured.
func (s *DraftMessageService) Ready() bool {
	return s != nil && s.repo != nil
}

// List retrieves all draft messages for a conversation, optionally filtered by user.
func (s *DraftMessageService) List(ctx context.Context, accountID, conversationID, userID uint) ([]model.DraftMessage, error) {
	// Verify conversation belongs to the account
	if _, err := s.conversationRepo.FindByAccountAndID(ctx, accountID, conversationID); err != nil {
		return nil, err
	}
	return s.repo.FindByConversationID(ctx, conversationID, userID)
}

// Create creates a new draft message.
func (s *DraftMessageService) Create(ctx context.Context, accountID, conversationID, userID uint, content string) (*model.DraftMessage, error) {
	// Verify conversation belongs to the account
	if _, err := s.conversationRepo.FindByAccountAndID(ctx, accountID, conversationID); err != nil {
		return nil, err
	}

	draft := &model.DraftMessage{
		ConversationID: conversationID,
		UserID:         userID,
		Content:        content,
	}

	if err := s.repo.Create(ctx, draft); err != nil {
		applogger.L().Errorf("Failed to create draft message for conversation %d: %v", conversationID, err)
		return nil, err
	}

	return draft, nil
}

// Get retrieves a draft message by ID.
func (s *DraftMessageService) Get(ctx context.Context, id uint) (*model.DraftMessage, error) {
	return s.repo.FindByID(ctx, id)
}

// Update updates an existing draft message.
func (s *DraftMessageService) Update(ctx context.Context, id uint, content string) (*model.DraftMessage, error) {
	draft, err := s.repo.FindByID(ctx, id)
	if err != nil {
		return nil, err
	}

	draft.Content = content
	if err := s.repo.Update(ctx, draft); err != nil {
		applogger.L().Errorf("Failed to update draft message %d: %v", id, err)
		return nil, err
	}

	return draft, nil
}

// Delete deletes a draft message.
func (s *DraftMessageService) Delete(ctx context.Context, id uint) error {
	// Verify draft exists before deleting
	draft, err := s.repo.FindByID(ctx, id)
	if err != nil {
		applogger.L().Errorf("Draft message %d not found for deletion: %v", id, err)
		return err
	}
	if draft == nil {
		return errors.New("draft message not found")
	}
	if err := s.repo.Delete(ctx, id); err != nil {
		applogger.L().Errorf("Failed to delete draft message %d: %v", id, err)
		return err
	}
	return nil
}

// Search searches draft messages by content for an account using LIKE query.
func (s *DraftMessageService) Search(ctx context.Context, accountID uint, query string) ([]model.DraftMessage, error) {
	if query == "" {
		return nil, errors.New("search query must not be empty")
	}
	return s.repo.SearchByContent(ctx, accountID, query)
}

// Count returns the total number of draft messages for an account.
func (s *DraftMessageService) Count(ctx context.Context, accountID uint) (int64, error) {
	return s.repo.CountByAccount(ctx, accountID)
}