package client

import (
	"context"
	"fmt"

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

type FCMConfig interface {
	GetCredentialsFile() string
	GetProjectID() string
}

type FCMClient interface {
	SendNotification(ctx context.Context, token string, title string, body string, data map[string]string) error
	SendMulticastNotification(ctx context.Context, tokens []string, title string, body string, data map[string]string) error
	SendToTopic(ctx context.Context, topic string, title string, body string, data map[string]string) error
}

type fcmClient struct {
	messaging *messaging.Client
}

func NewFCMClient(cfg FCMConfig) (FCMClient, error) {
	ctx := context.Background()

	opt := option.WithCredentialsFile(cfg.GetCredentialsFile())

	app, err := firebase.NewApp(ctx, &firebase.Config{
		ProjectID: cfg.GetProjectID(),
	}, opt)
	if err != nil {
		return nil, fmt.Errorf("failed to initialize firebase app: %w", err)
	}

	msgClient, err := app.Messaging(ctx)
	if err != nil {
		return nil, fmt.Errorf("failed to initialize firebase messaging client: %w", err)
	}

	return &fcmClient{
		messaging: msgClient,
	}, nil
}

// SendNotification sends a push notification to a single device token.
func (f *fcmClient) SendNotification(ctx context.Context, token string, title string, body string, data map[string]string) error {
	message := &messaging.Message{
		Token: token,
		Notification: &messaging.Notification{
			Title: title,
			Body:  body,
		},
		Data: data,
		Android: &messaging.AndroidConfig{
			Priority: "high",
		},
		APNS: &messaging.APNSConfig{
			Payload: &messaging.APNSPayload{
				Aps: &messaging.Aps{
					Sound: "default",
				},
			},
		},
	}

	_, err := f.messaging.Send(ctx, message)
	if err != nil {
		return fmt.Errorf("failed to send FCM notification: %w", err)
	}

	return nil
}

// SendMulticastNotification sends a push notification to multiple device tokens.
func (f *fcmClient) SendMulticastNotification(ctx context.Context, tokens []string, title string, 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,
		Android: &messaging.AndroidConfig{
			Priority: "high",
		},
		APNS: &messaging.APNSConfig{
			Payload: &messaging.APNSPayload{
				Aps: &messaging.Aps{
					Sound: "default",
				},
			},
		},
	}

	batchResp, err := f.messaging.SendEachForMulticast(ctx, message)
	if err != nil {
		return fmt.Errorf("failed to send FCM multicast notification: %w", err)
	}

	if batchResp.FailureCount > 0 {
		return fmt.Errorf("FCM multicast: %d/%d messages failed to send", batchResp.FailureCount, len(tokens))
	}

	return nil
}

// SendToTopic sends a push notification to all devices subscribed to a topic.
func (f *fcmClient) SendToTopic(ctx context.Context, topic string, title string, body string, data map[string]string) error {
	message := &messaging.Message{
		Topic: topic,
		Notification: &messaging.Notification{
			Title: title,
			Body:  body,
		},
		Data: data,
		Android: &messaging.AndroidConfig{
			Priority: "high",
		},
		APNS: &messaging.APNSConfig{
			Payload: &messaging.APNSPayload{
				Aps: &messaging.Aps{
					Sound: "default",
				},
			},
		},
	}

	_, err := f.messaging.Send(ctx, message)
	if err != nil {
		return fmt.Errorf("failed to send FCM topic notification: %w", err)
	}

	return nil
}