package service

import (
	"context"
	"log"
	"time"
)

// ExchangeRateScheduler handles scheduled fetching of exchange rates
type ExchangeRateScheduler struct {
	yunAPIClient *YunAPIClient
	interval     time.Duration
	stopChan     chan struct{}
}

// NewExchangeRateScheduler creates a new ExchangeRateScheduler
func NewExchangeRateScheduler(yunAPIClient *YunAPIClient, interval time.Duration) *ExchangeRateScheduler {
	return &ExchangeRateScheduler{
		yunAPIClient: yunAPIClient,
		interval:     interval,
		stopChan:     make(chan struct{}),
	}
}

// Start begins the scheduled fetching of exchange rates
// It fetches immediately on start, then every interval
func (s *ExchangeRateScheduler) Start(ctx context.Context) {
	log.Printf("[Scheduler] Starting exchange rate scheduler with interval: %v", s.interval)

	// Fetch immediately on start
	s.fetchRates()

	// Create ticker for periodic fetching
	ticker := time.NewTicker(s.interval)
	defer ticker.Stop()

	for {
		select {
		case <-ticker.C:
			s.fetchRates()
		case <-s.stopChan:
			log.Println("[Scheduler] Exchange rate scheduler stopped")
			return
		case <-ctx.Done():
			log.Println("[Scheduler] Exchange rate scheduler stopped due to context cancellation")
			return
		}
	}
}

// Stop stops the scheduler
func (s *ExchangeRateScheduler) Stop() {
	close(s.stopChan)
}

// fetchRates calls the YunAPI client to fetch and save rates
func (s *ExchangeRateScheduler) fetchRates() {
	log.Println("[Scheduler] Triggering exchange rate fetch...")
	if err := s.yunAPIClient.FetchAndSaveRates(); err != nil {
		log.Printf("[Scheduler] Error fetching exchange rates: %v", err)
	}
}