package service

// NoteService provides business logic for contact notes.
// Reference: Chatwoot app/controllers/api/v1/accounts/contacts/notes_controller.rb

import (
	"errors"

	"github.com/gochat/gochat/internal/model"
	"github.com/gochat/gochat/internal/repository"
)

var (
	ErrNoteNotFound      = errors.New("note not found")
	ErrNoteContentEmpty  = errors.New("note content is required")
	ErrNoteAccountMismatch = errors.New("note does not belong to the account")
)

// NoteService handles CRUD operations for contact notes.
type NoteService struct {
	noteRepo *repository.NoteRepo
}

// NewNoteService creates a new NoteService instance.
func NewNoteService(noteRepo *repository.NoteRepo) *NoteService {
	return &NoteService{noteRepo: noteRepo}
}

// List returns all notes for a contact in an account, ordered latest first.
// Reference: Chatwoot `def index; @notes = @contact.notes.latest.includes(:user); end`
func (s *NoteService) List(accountID, contactID uint) ([]model.Note, error) {
	return s.noteRepo.ListByContact(accountID, contactID)
}

// Get returns a single note by ID.
// Reference: Chatwoot `def show; end`
func (s *NoteService) Get(accountID, contactID, noteID uint) (*model.Note, error) {
	note, err := s.noteRepo.GetByID(accountID, contactID, noteID)
	if err != nil {
		return nil, ErrNoteNotFound
	}
	return note, nil
}

// Create creates a new note for a contact.
// Reference: Chatwoot `def create; @note = @contact.notes.create!(note_params); end`
// note_params merges contact_id and current_user.id
func (s *NoteService) Create(accountID, contactID uint, userID uint, content string) (*model.Note, error) {
	if content == "" {
		return nil, ErrNoteContentEmpty
	}
	note := &model.Note{
		Content:   content,
		AccountID: accountID,
		ContactID: contactID,
		UserID:    &userID,
	}
	return s.noteRepo.CreateNote(note)
}

// Update updates an existing note's content.
// Reference: Chatwoot `def update; @note.update(note_params); end`
func (s *NoteService) Update(accountID, contactID, noteID uint, content string) (*model.Note, error) {
	if content == "" {
		return nil, ErrNoteContentEmpty
	}
	note, err := s.noteRepo.GetByID(accountID, contactID, noteID)
	if err != nil {
		return nil, ErrNoteNotFound
	}
	note.Content = content
	return s.noteRepo.Update(note)
}

// Delete removes a note.
// Reference: Chatwoot `def destroy; @note.destroy!; head :ok; end`
// Chatwoot returns 200 OK on destroy, not 204 NoContent.
func (s *NoteService) Delete(accountID, contactID, noteID uint) error {
	err := s.noteRepo.Delete(accountID, contactID, noteID)
	if err != nil {
		return ErrNoteNotFound
	}
	return nil
}