package chat

import (
	"errors"
	"strings"
)

var (
	ErrDependencyUnavailable = errors.New("dependency unavailable")
	ErrConversationNotFound  = errors.New("conversation not found")
	ErrPermissionDenied      = errors.New("permission denied")
	ErrInvalidMessage        = errors.New("invalid message")
)

type Service struct {
	repo *Repository
}

func NewService(repo *Repository) *Service {
	return &Service{repo: repo}
}

func (s *Service) ListConversations(principal Principal, page, pageSize int) (*PaginatedResult, error) {
	if s.repo == nil {
		return nil, ErrDependencyUnavailable
	}
	return s.repo.ListConversations(principal, page, pageSize)
}

func (s *Service) FindConversation(principal Principal, id uint64) (*ConversationDTO, error) {
	if s.repo == nil {
		return nil, ErrDependencyUnavailable
	}
	return s.repo.FindConversation(principal, id)
}

func (s *Service) FindOrderConversation(userID uint64, orderID uint64) (*ConversationDTO, error) {
	if s.repo == nil {
		return nil, ErrDependencyUnavailable
	}
	return s.repo.FindOrderConversation(userID, orderID)
}

func (s *Service) Messages(principal Principal, conversationID uint64, page, pageSize int) (*PaginatedResult, error) {
	if s.repo == nil {
		return nil, ErrDependencyUnavailable
	}
	return s.repo.Messages(principal, conversationID, page, pageSize)
}

func (s *Service) SendMessage(principal Principal, conversationID uint64, req SendMessageRequest) (*MessageDTO, error) {
	if s.repo == nil {
		return nil, ErrDependencyUnavailable
	}
	req.Content = strings.TrimSpace(req.Content)
	if conversationID == 0 || req.Content == "" {
		return nil, ErrInvalidMessage
	}
	if len([]rune(req.Content)) > 1000 {
		return nil, ErrInvalidMessage
	}
	return s.repo.SendMessage(principal, conversationID, req)
}

func (s *Service) MarkRead(principal Principal, conversationID uint64) error {
	if s.repo == nil {
		return ErrDependencyUnavailable
	}
	return s.repo.MarkRead(principal, conversationID)
}