package client

import (
	"context"
	"fmt"
	"log"

	"apskel-pos-be/config"

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

type FcmClient interface {
	SendMulticastNotification(ctx context.Context, tokens []string, title string, body string) error
}

type fcmClient struct {
	messagingClient *messaging.Client
}

func NewFcmClient(cfg *config.Firebase) FcmClient {
	if cfg == nil || cfg.GetCredentialsFile() == "" {
		log.Println("FCM: credentials file not configured, FCM client is disabled")
		return &fcmClient{messagingClient: nil}
	}

	opt := option.WithCredentialsFile(cfg.GetCredentialsFile())
	app, err := firebase.NewApp(context.Background(), nil, opt)
	if err != nil {
		log.Printf("FCM: failed to initialize Firebase app: %v", err)
		return &fcmClient{messagingClient: nil}
	}

	client, err := app.Messaging(context.Background())
	if err != nil {
		log.Printf("FCM: failed to create messaging client: %v", err)
		return &fcmClient{messagingClient: nil}
	}

	log.Println("FCM: client initialized successfully")
	return &fcmClient{messagingClient: client}
}

func (c *fcmClient) SendMulticastNotification(ctx context.Context, tokens []string, title string, body string) error {
	if c.messagingClient == nil {
		log.Println("FCM: client not initialized, skipping notification")
		return nil
	}

	if len(tokens) == 0 {
		return nil
	}

	message := &messaging.MulticastMessage{
		Notification: &messaging.Notification{
			Title: title,
			Body:  body,
		},
		Tokens: tokens,
		Android: &messaging.AndroidConfig{
			Priority: "high",
		},
	}

	response, err := c.messagingClient.SendMulticast(ctx, message)
	if err != nil {
		return fmt.Errorf("FCM: failed to send multicast notification: %w", err)
	}

	if response.FailureCount > 0 {
		log.Printf("FCM: %d tokens failed out of %d", response.FailureCount, len(tokens))
		for i, resp := range response.Responses {
			if !resp.Success {
				log.Printf("FCM: token[%d] failed: %v", i, resp.Error)
			}
		}
	}

	log.Printf("FCM: sent %d/%d notifications successfully", response.SuccessCount, len(tokens))
	return nil
}