package telegram

import (
	"context"
	"fmt"
	"log/slog"
)

type Service struct {
	repo   Repository
	sender Sender
	logger *slog.Logger
}

func NewService(repo Repository, sender Sender, logger *slog.Logger) *Service {
	return &Service{repo: repo, sender: sender, logger: logger}
}

func (s *Service) Get(ctx context.Context) (*Settings, error) {
	return s.repo.Get(ctx)
}

// Update persists the settings. botToken == "" means "leave the currently
// stored token untouched" -- the admin never has to re-type the secret just
// to flip a checkbox, and the API never has to echo it back.
func (s *Service) Update(ctx context.Context, enabled bool, botToken, chatID string, notifyNewOrder, notifyStatusChange bool) (*Settings, error) {
	settings := &Settings{
		Enabled:            enabled,
		BotToken:           botToken,
		ChatID:             chatID,
		NotifyNewOrder:     notifyNewOrder,
		NotifyStatusChange: notifyStatusChange,
	}
	if err := s.repo.Update(ctx, settings); err != nil {
		return nil, err
	}
	return s.repo.Get(ctx)
}

func (s *Service) SendTestMessage(ctx context.Context) error {
	settings, err := s.repo.Get(ctx)
	if err != nil {
		return err
	}
	if settings.BotToken == "" || settings.ChatID == "" {
		return fmt.Errorf("bot token and chat id must be configured before testing")
	}
	return s.sender.Send(ctx, settings.BotToken, settings.ChatID, "Test notification: your Telegram integration is working.")
}

// NotifyNewOrder implements orders.OrderNotifier. It never returns an error
// to the caller: a broken/misconfigured Telegram integration must not
// prevent a customer's order from being created, so failures are only
// logged.
func (s *Service) NotifyNewOrder(ctx context.Context, summary string) {
	s.notify(ctx, func(st *Settings) bool { return st.NotifyNewOrder }, summary)
}

func (s *Service) NotifyOrderStatusChange(ctx context.Context, summary string) {
	s.notify(ctx, func(st *Settings) bool { return st.NotifyStatusChange }, summary)
}

func (s *Service) notify(ctx context.Context, shouldSend func(*Settings) bool, text string) {
	settings, err := s.repo.Get(ctx)
	if err != nil {
		s.logger.Error("telegram: failed to load settings", "error", err)
		return
	}
	if !settings.Enabled || !shouldSend(settings) {
		return
	}
	if err := s.sender.Send(ctx, settings.BotToken, settings.ChatID, text); err != nil {
		s.logger.Error("telegram: failed to send notification", "error", err)
	}
}