package services

import (
	"bytes"
	"encoding/json"
	"fmt"
	"net/http"
	"os"
	"time"
)

// FCMService handles Firebase Cloud Messaging
type FCMService struct {
	serverKey string
	projectID string
	client    *http.Client
}

// NewFCMService creates a new FCM service
func NewFCMService() *FCMService {
	serverKey := os.Getenv("FCM_SERVER_KEY")
	projectID := os.Getenv("FCM_PROJECT_ID")

	if serverKey == "" && projectID == "" {
		// Return nil if not configured - notifications will still work without push
		return nil
	}

	return &FCMService{
		serverKey: serverKey,
		projectID: projectID,
		client: &http.Client{
			Timeout: 10 * time.Second,
		},
	}
}

// FCMMessage represents an FCM push message
type FCMMessage struct {
	To           string            `json:"to,omitempty"`
	Notification FCMNotification   `json:"notification"`
	Data         map[string]string `json:"data,omitempty"`
	Priority     string            `json:"priority"`
}

type FCMNotification struct {
	Title string `json:"title"`
	Body  string `json:"body"`
	Icon  string `json:"icon,omitempty"`
	Badge string `json:"badge,omitempty"`
}

// Send sends a push notification to a device
func (s *FCMService) Send(token, title, body string, data map[string]string) error {
	if s == nil || s.serverKey == "" {
		// FCM not configured, skip silently
		return nil
	}

	message := FCMMessage{
		To: token,
		Notification: FCMNotification{
			Title: title,
			Body:  body,
			Icon:  "/icon-192x192.png",
		},
		Data:     data,
		Priority: "high",
	}

	jsonData, err := json.Marshal(message)
	if err != nil {
		return err
	}

	req, err := http.NewRequest("POST", "https://fcm.googleapis.com/fcm/send", bytes.NewBuffer(jsonData))
	if err != nil {
		return err
	}

	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", "key="+s.serverKey)

	resp, err := s.client.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("FCM returned status %d", resp.StatusCode)
	}

	return nil
}

// SendMulticast sends to multiple devices
func (s *FCMService) SendMulticast(tokens []string, title, body string, data map[string]string) []error {
	var errors []error
	for _, token := range tokens {
		if err := s.Send(token, title, body, data); err != nil {
			errors = append(errors, err)
		}
	}
	return errors
}