package notifications

import (
	"context"
	"fmt"
	"log"

	firebase "firebase.google.com/go/v4"
	"firebase.google.com/go/v4/messaging"
	"google.golang.org/api/option"
)

type FCMService struct {
	app    *firebase.App
	client *messaging.Client
}

func NewFCMService(serviceAccountJSON []byte) (*FCMService, error) {
	ctx := context.Background()
	opt := option.WithCredentialsJSON(serviceAccountJSON)
	
	app, err := firebase.NewApp(ctx, nil, opt)
	if err != nil {
		return nil, fmt.Errorf("error initializing firebase app: %w", err)
	}

	client, err := app.Messaging(ctx)
	if err != nil {
		return nil, fmt.Errorf("error getting messaging client: %w", err)
	}

	return &FCMService{
		app:    app,
		client: client,
	}, nil
}

func (s *FCMService) SendPush(ctx context.Context, token, title, body string, data map[string]string) error {
	message := &messaging.Message{
		Token: token,
		Notification: &messaging.Notification{
			Title: title,
			Body:  body,
		},
		Data: data,
	}

	response, err := s.client.Send(ctx, message)
	if err != nil {
		return fmt.Errorf("error sending fcm message: %w", err)
	}

	log.Printf("Successfully sent fcm message: %s", response)
	return nil
}

func (s *FCMService) SendMulticast(ctx context.Context, tokens []string, title, body string, data map[string]string) error {
	if len(tokens) == 0 {
		return nil
	}

	message := &messaging.MulticastMessage{
		Tokens: tokens,
		Notification: &messaging.Notification{
			Title: title,
			Body:  body,
		},
		Data: data,
	}

	br, err := s.client.SendEachForMulticast(ctx, message)
	if err != nil {
		return fmt.Errorf("error sending multicast message: %w", err)
	}

	log.Printf("Multicast results: %d successes, %d failures", br.SuccessCount, br.FailureCount)
	return nil
}