use antigravity to rewrite all your code to migrate from flat files to relational database. YOLO

server/user.go

@@ -1,11 +1,11 @@
 package main
 
 import (
+	"database/sql"
 	"encoding/json"
 	"fmt"
 	"net/http"
 	"os"
-	"sync"
 	"time"
 )
 
@@ -16,104 +16,38 @@ type User struct {
 	CreatedAt    time.Time `json:"created_at"`
 }
 
-type UserRegistry struct {
-	Users map[string]*User `json:"users"` // Map of FitbitUserID -> User
-	mu    sync.RWMutex
-}
-
-var userRegistry *UserRegistry
-
-// InitUserRegistry loads or creates the user registry
-func InitUserRegistry() {
-	userRegistry = &UserRegistry{
-		Users: make(map[string]*User),
-	}
-	userRegistry.Load()
-}
-
-// Load reads the user registry from disk
-func (ur *UserRegistry) Load() error {
-	ur.mu.Lock()
-	defer ur.mu.Unlock()
-
-	data, err := os.ReadFile("data/users.json")
+// GetUser retrieves a user by Fitbit user ID from the database
+func GetUser(fitbitUserID string) (*User, error) {
+	var user User
+	err := db.QueryRow("SELECT fitbit_user_id, display_name, avatar_url, created_at FROM users WHERE fitbit_user_id = ?", fitbitUserID).
+		Scan(&user.FitbitUserID, &user.DisplayName, &user.AvatarURL, &user.CreatedAt)
 	if err != nil {
-		if os.IsNotExist(err) {
-			return nil // First run, no users yet
+		if err == sql.ErrNoRows {
+			return nil, nil
 		}
-		return err
+		return nil, err
 	}
-
-	return json.Unmarshal(data, ur)
+	return &user, nil
 }
 
-// Save writes the user registry to disk
-func (ur *UserRegistry) Save() error {
-	ur.mu.RLock()
-	defer ur.mu.RUnlock()
-	return ur.saveUnlocked()
-}
-
-// saveUnlocked writes the user registry to disk without locking (caller must hold lock)
-func (ur *UserRegistry) saveUnlocked() error {
-	if err := os.MkdirAll("data", 0755); err != nil {
-		return err
-	}
-
-	data, err := json.MarshalIndent(ur, "", "  ")
+// CreateOrUpdateUser adds or updates a user in the database
+func CreateOrUpdateUser(fitbitUserID, displayName, avatarURL string) (*User, error) {
+	_, err := db.Exec(`
+		INSERT INTO users (fitbit_user_id, display_name, avatar_url, created_at)
+		VALUES (?, ?, ?, NOW())
+		ON DUPLICATE KEY UPDATE display_name = ?, avatar_url = ?
+	`, fitbitUserID, displayName, avatarURL, displayName, avatarURL)
 	if err != nil {
-		return err
-	}
-
-	return os.WriteFile("data/users.json", data, 0644)
-}
-
-// GetUser retrieves a user by Fitbit user ID
-func (ur *UserRegistry) GetUser(fitbitUserID string) (*User, bool) {
-	ur.mu.RLock()
-	defer ur.mu.RUnlock()
-
-	user, exists := ur.Users[fitbitUserID]
-	return user, exists
-}
-
-// CreateOrUpdateUser adds or updates a user in the registry
-func (ur *UserRegistry) CreateOrUpdateUser(fitbitUserID, displayName, avatarURL string) (*User, error) {
-	ur.mu.Lock()
-	defer ur.mu.Unlock()
-
-	user, exists := ur.Users[fitbitUserID]
-	if exists {
-		// Update existing user
-		user.DisplayName = displayName
-		user.AvatarURL = avatarURL
-	} else {
-		// Create new user
-		user = &User{
-			FitbitUserID: fitbitUserID,
-			DisplayName:  displayName,
-			AvatarURL:    avatarURL,
-			CreatedAt:    time.Now(),
-		}
-		ur.Users[fitbitUserID] = user
-	}
-
-	// Save without locking (we already have the lock)
-	if err := ur.saveUnlocked(); err != nil {
 		return nil, err
 	}
 
-	// Create user directory
-	userDir := fmt.Sprintf("data/users/%s", fitbitUserID)
+	// Create user directory for KML files
+	userDir := fmt.Sprintf("data/users/%s/kml", fitbitUserID)
 	if err := os.MkdirAll(userDir, 0755); err != nil {
 		return nil, err
 	}
-	kmlDir := fmt.Sprintf("data/users/%s/kml", fitbitUserID)
-	if err := os.MkdirAll(kmlDir, 0755); err != nil {
-		return nil, err
-	}
 
-	return user, nil
+	return GetUser(fitbitUserID)
 }
 
 // FetchFitbitUserProfile fetches the user's profile from Fitbit API