package sync

import (
	"bytes"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"mime/multipart"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"time"

	"rrbec_server/internal/models"
	"rrbec_server/internal/repository"

	"github.com/google/uuid"
)

type Syncer struct {
	repo         *repository.Repository
	djangoURL    string
	masterUser   string
	masterPass   string
	accessToken  string
	refreshToken string
}

func NewSyncer(repo *repository.Repository, djangoURL, masterUser, masterPass string) *Syncer {
	return &Syncer{
		repo:       repo,
		djangoURL:  djangoURL,
		masterUser: masterUser,
		masterPass: masterPass,
	}
}

func (s *Syncer) Start() {
	go func() {
		// 1. Login to Django
		token, err := s.LoginToDjango()
		if err != nil {
			log.Printf("Initial Django login failed: %v", err)
		} else {
			s.masterPass = token // Use token for future requests

			// 2. Load Last Sync ID
			lastID := s.repo.GetLastSyncID()
			if lastID == 0 {
				log.Println("Database is empty or fresh. Starting initial sync...")
				s.InitialSync()
			}
		}

		// 3. Sync Loop (Bidirectional)
		for {
			log.Println("Sync cycle started...")
			s.processChangeLog() // Cloud -> Local
			s.pushLocalChanges() // Local -> Cloud
			time.Sleep(5 * time.Second)
		}
	}()
}

func (s *Syncer) ensureValidToken() {
	if s.accessToken == "" {
		token, err := s.LoginToDjango()
		if err != nil {
			log.Printf("Failed to login: %v", err)
			return
		}
		s.accessToken = token
	}
}

func (s *Syncer) ensureValidTokenWithRefresh() {
	s.ensureValidToken()
	if s.refreshToken == "" {
		return
	}

	resp := s.fetchFromDjangoRaw("products")
	if s.IsTokenExpired(resp) {
		if err := s.RefreshAccessToken(); err != nil {
			log.Printf("Token refresh failed, trying full login: %v", err)
			s.accessToken = ""
			s.ensureValidToken()
		}
	}
}

func (s *Syncer) LoginToDjango() (string, error) {
	url := fmt.Sprintf("%s/api/v1/token/", s.djangoURL)
	loginData := map[string]string{
		"username": s.masterUser,
		"password": s.masterPass,
	}

	jsonData, _ := json.Marshal(loginData)
	resp, err := http.Post(url, "application/json", bytes.NewBuffer(jsonData))
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return "", fmt.Errorf("login failed with status: %d", resp.StatusCode)
	}

	var result struct {
		Access  string `json:"access"`
		Refresh string `json:"refresh"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return "", err
	}

	s.accessToken = result.Access
	s.refreshToken = result.Refresh

	return result.Access, nil
}

func (s *Syncer) RefreshAccessToken() error {
	url := fmt.Sprintf("%s/api/v1/token/refresh/", s.djangoURL)
	refreshData := map[string]string{
		"refresh": s.refreshToken,
	}

	jsonData, _ := json.Marshal(refreshData)
	resp, err := http.Post(url, "application/json", bytes.NewBuffer(jsonData))
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		log.Printf("Token refresh failed: %s", string(body))
		return fmt.Errorf("refresh failed with status: %d", resp.StatusCode)
	}

	var result struct {
		Access string `json:"access"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return err
	}

	s.accessToken = result.Access
	log.Println("Token refreshed successfully")
	return nil
}

func (s *Syncer) IsTokenExpired(responseBody []byte) bool {
	var errResp struct {
		Code string `json:"code"`
	}
	if json.Unmarshal(responseBody, &errResp) == nil {
		return errResp.Code == "token_not_valid" || strings.Contains(string(responseBody), "token_not_valid")
	}
	return false
}

func (s *Syncer) InitialSync() {
	// Sync Products
	var products []models.Product
	s.fetchFromDjango("products", &products)
	for _, p := range products {
		p.Sincronizado = true
		if p.UUID == "" {
			p.UUID = uuid.New().String()
		}
		s.repo.SaveProduct(&p)
	}

	// Sync Clients
	var clients []models.Client
	s.fetchFromDjango("clients", &clients)
	for _, c := range clients {
		c.Sincronizado = true
		if c.UUID == "" {
			c.UUID = uuid.New().String()
		}
		s.repo.SaveClient(&c)
	}

	// Sync Mesas
	var mesas []models.Mesa
	s.fetchFromDjango("mesas", &mesas)
	for _, m := range mesas {
		m.Sincronizado = true
		if m.UUID == "" {
			m.UUID = uuid.New().String()
		}
		s.repo.SaveMesa(&m)
	}

	// Sync Users
	var users []models.User
	s.fetchFromDjango("users", &users)
	for _, u := range users {
		u.Sincronizado = true
		if u.UUID == "" {
			u.UUID = uuid.New().String()
		}
		s.repo.SaveUser(&u)
	}

	// Sync Categories
	var categories []models.Category
	s.fetchFromDjango("categories", &categories)
	for _, cat := range categories {
		cat.Sincronizado = true
		if cat.UUID == "" {
			cat.UUID = uuid.New().String()
		}
		s.repo.SaveCategory(&cat)
	}

	// Sync Payment Types
	var paymentTypes []models.TypePay
	s.fetchFromDjango("payment-types", &paymentTypes)
	for _, tp := range paymentTypes {
		tp.Sincronizado = true
		if tp.UUID == "" {
			tp.UUID = uuid.New().String()
		}
		s.repo.SaveTypePay(&tp)
	}

	// Sync Comandas
	var comandas []models.Comanda
	s.fetchFromDjango("comandas", &comandas)
	for _, co := range comandas {
		co.Sincronizado = true
		if co.UUID == "" {
			co.UUID = uuid.New().String()
		}
		s.repo.SaveComanda(&co)

		// Sync nested items from the serializer
		for _, item := range co.Items {
			item.Sincronizado = true
			if item.UUID == "" {
				item.UUID = uuid.New().String()
			}
			s.repo.SaveProductComanda(&item)
		}
	}

	// Sync Comanda Items
	var items []models.ProductComanda
	s.fetchFromDjango("items-comanda", &items)
	for _, it := range items {
		it.Sincronizado = true
		if it.UUID == "" {
			it.UUID = uuid.New().String()
		}
		s.repo.SaveProductComanda(&it)
	}

	// Sync Orders
	var orders []models.Order
	s.fetchFromDjango("orders", &orders)
	for _, o := range orders {
		o.Sincronizado = true
		if o.UUID == "" {
			o.UUID = uuid.New().String()
		}
		s.repo.SaveOrder(&o)
	}

	// Sync Payments
	var payments []models.Payment
	s.fetchFromDjango("payments", &payments)
	for _, pay := range payments {
		pay.Sincronizado = true
		if pay.UUID == "" {
			pay.UUID = uuid.New().String()
		}
		s.repo.SavePayment(&pay)
	}

	log.Println("Initial sync completed successfully.")
}

func (s *Syncer) fetchFromDjango(endpoint string, target interface{}) {
	endpoint = strings.Trim(endpoint, "/")

	url := ""
	if strings.Contains(endpoint, "?") {
		url = fmt.Sprintf("%s/api/v1/%s", s.djangoURL, endpoint)
	} else {
		url = fmt.Sprintf("%s/api/v1/%s/", s.djangoURL, endpoint)
	}

	token := s.accessToken
	if token == "" {
		token = s.masterPass
	}

	req, _ := http.NewRequest("GET", url, nil)
	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token))

	client := &http.Client{Timeout: 30 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		log.Printf("Failed to fetch %s: %v", endpoint, err)
		return
	}
	defer resp.Body.Close()

	bodyBytes, _ := io.ReadAll(resp.Body)

	if err := json.Unmarshal(bodyBytes, target); err != nil {
		var paginated struct {
			Results json.RawMessage `json:"results"`
		}
		if err2 := json.Unmarshal(bodyBytes, &paginated); err2 == nil && paginated.Results != nil {
			if err3 := json.Unmarshal(paginated.Results, target); err3 != nil {
				log.Printf("Failed to decode paginated %s: %v", endpoint, err3)
			}
		} else {
			log.Printf("Failed to decode %s: %v", endpoint, err)
		}
	}

	log.Printf("Synchronized %s from cloud", endpoint)
}

func (s *Syncer) fetchFromDjangoRaw(endpoint string) []byte {
	endpoint = strings.Trim(endpoint, "/")

	url := ""
	if strings.Contains(endpoint, "?") {
		url = fmt.Sprintf("%s/api/v1/%s", s.djangoURL, endpoint)
	} else {
		url = fmt.Sprintf("%s/api/v1/%s/", s.djangoURL, endpoint)
	}

	token := s.accessToken
	if token == "" {
		token = s.masterPass
	}

	req, _ := http.NewRequest("GET", url, nil)
	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token))

	client := &http.Client{Timeout: 30 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		log.Printf("Failed to fetch %s: %v", endpoint, err)
		return nil
	}
	defer resp.Body.Close()

	bodyBytes, _ := io.ReadAll(resp.Body)

	if s.IsTokenExpired(bodyBytes) {
		log.Printf("Token expired, refreshing...")
		if err := s.RefreshAccessToken(); err != nil {
			log.Printf("Token refresh failed: %v", err)
		} else {
			return s.fetchFromDjangoRaw(endpoint)
		}
	}

	log.Printf("DEBUG: Raw response for %s: %s", endpoint, string(bodyBytes))
	return bodyBytes
}

func (s *Syncer) processChangeLog() {
	lastID := s.repo.GetLastSyncID()
	url := fmt.Sprintf("sync?since_id=%d", lastID)

	var changes []models.ChangeLog
	respBody := s.fetchFromDjangoRaw(url)
	if respBody != nil {
		if err := json.Unmarshal(respBody, &changes); err != nil {
			log.Printf("ERROR: Failed to parse changelog: %v", err)
			return
		}
	}

	log.Printf("DEBUG: Received %d changes from Django", len(changes))

	if len(changes) == 0 {
		return
	}

	maxID := lastID
	for _, change := range changes {
		log.Printf("Processing change %s for %s (ID: %d)", change.Action, change.ModelName, change.ObjectID)

		if change.Action == "SAVE" {
			s.fetchAndSaveObject(change.ModelName, change.ObjectID)
		} else if change.Action == "DELETE" {
			s.repo.DeleteByID(change.ModelName, change.ObjectID)
		}

		if change.ID > maxID {
			maxID = change.ID
		}
	}

	s.repo.SaveLastSyncID(maxID)
}

func (s *Syncer) fetchAndSaveObject(modelName string, id uint) {
	endpoint := ""
	switch modelName {
	case "Product":
		endpoint = "products"
	case "Comanda":
		endpoint = "comandas"
	case "ProductComanda":
		endpoint = "items-comanda"
	case "Order":
		endpoint = "orders"
	case "Client":
		endpoint = "clients"
	case "Categories":
		endpoint = "categories"
	case "Mesa":
		endpoint = "mesas"
	case "Payments":
		endpoint = "payments"
	default:
		return
	}

	url := fmt.Sprintf("%s/%d", endpoint, id)

	// Create temporary instance based on modelName
	switch modelName {
	case "Comanda":
		var obj models.Comanda
		s.fetchFromDjango(url, &obj)
		if obj.UUID == "" {
			var local models.Comanda
			if err := s.repo.GetComandaToSync(obj.ID, &local); err == nil {
				obj.UUID = local.UUID
			}
			if obj.UUID == "" {
				obj.UUID = uuid.New().String()
			}
		}
		obj.Sincronizado = true
		s.repo.SaveComanda(&obj)
	case "Product":
		var obj models.Product
		s.fetchFromDjango(url, &obj)
		if obj.UUID == "" {
			var local models.Product
			if err := s.repo.GetProductToSync(obj.ID, &local); err == nil {
				obj.UUID = local.UUID
			}
			if obj.UUID == "" {
				obj.UUID = uuid.New().String()
			}
		}
		obj.Sincronizado = true
		s.repo.SaveProduct(&obj)
	case "ProductComanda":
		var obj models.ProductComanda
		s.fetchFromDjango(url, &obj)
		if obj.UUID == "" {
			var local models.ProductComanda
			if err := s.repo.GetItemToSync(obj.ID, &local); err == nil {
				obj.UUID = local.UUID
			}
			if obj.UUID == "" {
				obj.UUID = uuid.New().String()
			}
		}
		obj.Sincronizado = true
		s.repo.SaveProductComanda(&obj)
	case "Order":
		var obj models.Order
		s.fetchFromDjango(url, &obj)
		if obj.UUID == "" {
			var local models.Order
			if err := s.repo.GetOrderToSync(obj.ID, &local); err == nil {
				obj.UUID = local.UUID
			}
			if obj.UUID == "" {
				obj.UUID = uuid.New().String()
			}
		}
		obj.Sincronizado = true
		s.repo.SaveOrder(&obj)
	case "Client":
		var obj models.Client
		s.fetchFromDjango(url, &obj)
		if obj.UUID == "" {
			obj.UUID = uuid.New().String()
		}
		obj.Sincronizado = true
		s.repo.SaveClient(&obj)
	case "Categories":
		var obj models.Category
		s.fetchFromDjango(url, &obj)
		if obj.UUID == "" {
			obj.UUID = uuid.New().String()
		}
		obj.Sincronizado = true
		s.repo.SaveCategory(&obj)
	case "Mesa":
		var obj models.Mesa
		s.fetchFromDjango(url, &obj)
		if obj.UUID == "" {
			obj.UUID = uuid.New().String()
		}
		obj.Sincronizado = true
		s.repo.SaveMesa(&obj)
	case "Payments":
		var obj models.Payment
		s.fetchFromDjango(url, &obj)
		if obj.UUID == "" {
			var local models.Payment
			if err := s.repo.GetPaymentToSync(obj.ID, &local); err == nil {
				obj.UUID = local.UUID
			}
			if obj.UUID == "" {
				obj.UUID = uuid.New().String()
			}
		}
		obj.Sincronizado = true
		s.repo.SavePayment(&obj)
	}
}

func (s *Syncer) pushLocalChanges() {
	// 1. Sync Comandas
	comandas, err := s.repo.GetUnsyncedComandas()
	if err == nil && len(comandas) > 0 {
		for _, c := range comandas {
			if c.MesaID == 0 {
				log.Printf("SKIP: Comanda %d has mesa 0. Correct data required.", c.ID)
				continue
			}

			// Capture local ID before we might change it
			oldID := c.ID
			comandaName := c.Name
			if comandaName == "" {
				comandaName = fmt.Sprintf("Comanda %d", oldID)
			}

			payload := map[string]interface{}{
				"mesa":   c.MesaID,
				"client": c.ClientID,
				"user":   c.UserID,
				"status": c.Status,
				"name":   comandaName,
				"uuid":   c.UUID,
			}

			// Try PATCH first
			endpoint := fmt.Sprintf("comandas/%d", c.ID)
			respBody, err := s.sendRequest("PATCH", endpoint, payload)
			if err != nil && strings.Contains(err.Error(), "status: 404") {
				respBody, err = s.sendRequest("POST", "comandas", payload)
			}

			if err == nil {
				var created models.Comanda
				json.Unmarshal(respBody, &created)

				// CRITICAL: Update local ID and children safely
				if created.ID != 0 && created.ID != oldID {
					s.repo.SafeChangeID("comandas", oldID, created.ID)
					// Update items that were pointing to the old ID
					s.repo.UpdateFK("product_comandas", "comanda_id", oldID, created.ID)
					s.repo.UpdateFK("orders", "id_comanda", oldID, created.ID)
					s.repo.UpdateFK("payments", "comanda_id", oldID, created.ID)
				}

				s.repo.MarkAsSynced(&models.Comanda{}, created.ID)
				log.Printf("SUCCESS: Pushed Comanda %d (now %d) to cloud", oldID, created.ID)
			} else {
				log.Printf("ERROR pushing Comanda %d: %v", oldID, err)
			}
		}
	}

	// 2. Sync Items
	items, err := s.repo.GetUnsyncedItems()
	if err == nil && len(items) > 0 {
		for _, it := range items {
			oldID := it.ID
			payload := map[string]interface{}{
				"comanda":   it.ComandaID,
				"product":   it.ProductID,
				"applicant": it.Applicant,
				"uuid":      it.UUID,
			}

			endpoint := fmt.Sprintf("items-comanda/%d", it.ID)
			respBody, err := s.sendRequest("PATCH", endpoint, payload)
			if err != nil && strings.Contains(err.Error(), "status: 404") {
				respBody, err = s.sendRequest("POST", "items-comanda", payload)
			}

			if err == nil {
				var created models.ProductComanda
				json.Unmarshal(respBody, &created)
				if created.ID != 0 && created.ID != oldID {
					s.repo.SafeChangeID("product_comandas", oldID, created.ID)
					s.repo.UpdateFK("orders", "product_comanda_id", oldID, created.ID)
				}
				s.repo.MarkAsSynced(&models.ProductComanda{}, created.ID)
				log.Printf("SUCCESS: Pushed Item %d (now %d) to cloud", oldID, created.ID)
			} else {
				log.Printf("ERROR pushing Item %d: %v", oldID, err)
			}
		}
	}

	// 3. Sync Orders
	orders, err := s.repo.GetUnsyncedOrders()
	if err == nil && len(orders) > 0 {
		for _, o := range orders {
			oldID := o.ID
			payload := map[string]interface{}{
				"productComanda": o.ProductComandaID,
				"id_product":     o.ProductID,
				"id_comanda":     o.ComandaID,
				"obs":            o.Obs,
				"uuid":           o.UUID,
			}

			// Optional: mapping timestamps if they exist
			if !o.Queue.IsZero() {
				payload["queue"] = o.Queue
			}
			if o.Preparing != nil {
				payload["preparing"] = o.Preparing
			}
			if o.Finished != nil {
				payload["finished"] = o.Finished
			}
			if o.Delivered != nil {
				payload["delivered"] = o.Delivered
			}
			if o.Canceled != nil {
				payload["canceled"] = o.Canceled
			}

			endpoint := fmt.Sprintf("orders/%d", o.ID)
			respBody, err := s.sendRequest("PATCH", endpoint, payload)
			if err != nil && strings.Contains(err.Error(), "status: 404") {
				respBody, err = s.sendRequest("POST", "orders", payload)
			}

			if err == nil {
				var created models.Order
				json.Unmarshal(respBody, &created)
				if created.ID != 0 && created.ID != oldID {
					s.repo.SafeChangeID("orders", oldID, created.ID)
				}
				s.repo.MarkAsSynced(&models.Order{}, created.ID)
				log.Printf("SUCCESS: Pushed Order %d (now %d) to cloud", oldID, created.ID)
			} else {
				log.Printf("ERROR pushing Order %d: %v", oldID, err)
			}
		}
	}

	// 4. Sync Payments
	payments, err := s.repo.GetUnsyncedPayments()
	if err == nil && len(payments) > 0 {
		for _, p := range payments {
			if p.TypePayID == 0 {
				log.Printf("SKIP: Payment %d has invalid type_pay 0.", p.ID)
				s.repo.MarkAsSynced(&models.Payment{}, p.ID)
				continue
			}

			oldID := p.ID
			payload := map[string]interface{}{
				"value":       p.Value,
				"type_pay":    p.TypePayID,
				"comanda":     p.ComandaID,
				"description": p.Description,
				"datetime":    p.DateTime,
				"uuid":        p.UUID,
			}
			if p.ClientID != nil {
				payload["client"] = *p.ClientID
			}

			endpoint := fmt.Sprintf("payments/%d", p.ID)
			respBody, err := s.sendRequest("PATCH", endpoint, payload)
			if err != nil && strings.Contains(err.Error(), "status: 404") {
				respBody, err = s.sendRequest("POST", "payments", payload)
			}

			if err == nil {
				var created models.Payment
				json.Unmarshal(respBody, &created)
				if created.ID != 0 && created.ID != oldID {
					s.repo.SafeChangeID("payments", oldID, created.ID)
				}
				s.repo.MarkAsSynced(&models.Payment{}, created.ID)
				log.Printf("SUCCESS: Pushed Payment %d (now %d) to cloud", oldID, created.ID)
			} else {
				log.Printf("ERROR pushing Payment %d: %v", oldID, err)
			}
		}
	}

	// 5. Sync Products
	products, err := s.repo.GetUnsyncedProducts()
	if err == nil && len(products) > 0 {
		for _, p := range products {
			oldID := p.ID
			payload := map[string]interface{}{
				"name":        p.Name,
				"description": p.Description,
				"image":       p.Image,
				"price":       p.Price,
				"quantity":    p.Quantity,
				"category":    p.CategoryID,
				"cuisine":     p.Cuisine,
				"active":      p.Active,
				"uuid":        p.UUID,
			}
			if p.UnitOfMeasure != nil {
				payload["unit_of_measure"] = *p.UnitOfMeasure
			}

			endpoint := fmt.Sprintf("products/%d", p.ID)
			respBody, err := s.sendMultipartRequest("PATCH", endpoint, payload)
			if err != nil && strings.Contains(err.Error(), "status: 404") {
				respBody, err = s.sendMultipartRequest("POST", "products", payload)
			}

			if err == nil {
				var created models.Product
				json.Unmarshal(respBody, &created)
				if created.ID != 0 && created.ID != oldID {
					s.repo.SafeChangeID("products", oldID, created.ID)
				}
				s.repo.MarkAsSynced(&models.Product{}, created.ID)
				log.Printf("SUCCESS: Pushed Product %d (now %d) to cloud", oldID, created.ID)
			} else {
				log.Printf("ERROR pushing Product %d: %v", oldID, err)
			}
		}
	}
}

func (s *Syncer) sendRequest(method, endpoint string, data interface{}) ([]byte, error) {
	url := fmt.Sprintf("%s/api/v1/%s/", s.djangoURL, endpoint)
	jsonData, _ := json.Marshal(data)

	token := s.accessToken
	if token == "" {
		token = s.masterPass
	}

	req, _ := http.NewRequest(method, url, bytes.NewBuffer(jsonData))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token))

	client := &http.Client{Timeout: 10 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	respBody, _ := io.ReadAll(resp.Body)

	if resp.StatusCode == 401 || strings.Contains(string(respBody), "token_not_valid") {
		log.Printf("Token expired during %s %s, refreshing...", method, endpoint)
		if err := s.RefreshAccessToken(); err != nil {
			return nil, fmt.Errorf("token refresh failed: %w", err)
		}
		return s.sendRequest(method, endpoint, data)
	}

	if resp.StatusCode >= 200 && resp.StatusCode < 300 {
		return respBody, nil
	}
	return nil, fmt.Errorf("django returned status: %d | Response: %s", resp.StatusCode, string(respBody))
}

func (s *Syncer) sendMultipartRequest(method, endpoint string, data map[string]interface{}) ([]byte, error) {
	urlStr := fmt.Sprintf("%s/api/v1/%s/", s.djangoURL, endpoint)
	var b bytes.Buffer
	w := multipart.NewWriter(&b)

	for key, val := range data {
		if key == "image" {
			imageStr, ok := val.(string)
			if !ok || imageStr == "" {
				continue // Skip empty image
			}

			// If it's an existing URL, don't re-upload it
			if strings.HasPrefix(imageStr, "http") || strings.HasPrefix(imageStr, "/media/") || strings.HasPrefix(imageStr, "/images/") {
				continue
			}

			// Base64
			if strings.HasPrefix(imageStr, "data:image") {
				parts := strings.Split(imageStr, ",")
				if len(parts) == 2 {
					decoded, err := base64.StdEncoding.DecodeString(parts[1])
					if err == nil {
						fw, _ := w.CreateFormFile(key, "upload.jpg")
						fw.Write(decoded)
					}
				}
				continue
			}

			// Local file
			fileContent, err := os.ReadFile(imageStr)
			if err == nil {
				fw, _ := w.CreateFormFile(key, filepath.Base(imageStr))
				fw.Write(fileContent)
			}
		} else {
			// standard text field
			w.WriteField(key, fmt.Sprintf("%v", val))
		}
	}
	w.Close()

	token := s.accessToken
	if token == "" {
		token = s.masterPass
	}

	req, _ := http.NewRequest(method, urlStr, &b)
	req.Header.Set("Content-Type", w.FormDataContentType())
	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token))

	client := &http.Client{Timeout: 15 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	respBody, _ := io.ReadAll(resp.Body)

	if resp.StatusCode == 401 || strings.Contains(string(respBody), "token_not_valid") {
		log.Printf("Token expired during %s %s, refreshing...", method, urlStr)
		if err := s.RefreshAccessToken(); err != nil {
			return nil, fmt.Errorf("token refresh failed: %w", err)
		}
		return s.sendMultipartRequest(method, endpoint, data)
	}

	if resp.StatusCode >= 200 && resp.StatusCode < 300 {
		return respBody, nil
	}
	return nil, fmt.Errorf("django returned status: %d | Response: %s", resp.StatusCode, string(respBody))
}

func (s *Syncer) syncUsers() {
	// Optional: logic for background sync of users if needed
}