Basic features done

lib/user.go

@@ -0,0 +1,82 @@
+package lib
+
+import (
+	"time"
+
+	"github.com/google/uuid"
+	"golang.org/x/crypto/bcrypt"
+)
+
+type User struct {
+	ID           int
+	Username     string
+	PasswordHash string
+}
+
+// hash password
+func HashPassword(password string) (string, error) {
+	bytes, err := bcrypt.GenerateFromPassword([]byte(password), 14)
+	return string(bytes), err
+}
+
+// check password
+func CheckPasswordHash(password, hash string) bool {
+	err := bcrypt.CompareHashAndPassword([]byte(hash), []byte(password))
+	return err == nil
+}
+
+// create new user
+func CreateUser(username, password string) error {
+	hash, err := HashPassword(password)
+	if err != nil {
+		return err
+	}
+	_, err = DB.Exec("INSERT INTO users (username, password_hash) VALUES (?, ?)", username, hash)
+	return err
+}
+
+// get user by name
+func GetUserByUsername(username string) (*User, error) {
+	row := DB.QueryRow("SELECT id, username, password_hash FROM users WHERE username = ?", username)
+	u := &User{}
+	err := row.Scan(&u.ID, &u.Username, &u.PasswordHash)
+	if err != nil {
+		return nil, err
+	}
+	return u, nil
+}
+
+// create session token
+func CreateSession(userID int) (string, error) {
+	sessionID := uuid.New().String()
+	expiresAt := time.Now().Add(24 * time.Hour)
+
+	_, err := DB.Exec("INSERT INTO sessions (id, user_id, expires_at) VALUES (?, ?, ?)", sessionID, userID, expiresAt)
+	if err != nil {
+		return "", err
+	}
+	return sessionID, nil
+}
+
+// get user from session
+func GetUserFromSession(sessionID string) (*User, error) {
+	row := DB.QueryRow(`
+		SELECT u.id, u.username, u.password_hash
+		FROM users u
+		JOIN sessions s ON u.id = s.user_id
+		WHERE s.id = ? AND s.expires_at > ?
+	`, sessionID, time.Now())
+
+	u := &User{}
+	err := row.Scan(&u.ID, &u.Username, &u.PasswordHash)
+	if err != nil {
+		return nil, err
+	}
+	return u, nil
+}
+
+// delete session
+func DeleteSession(sessionID string) error {
+	_, err := DB.Exec("DELETE FROM sessions WHERE id = ?", sessionID)
+	return err
+}