Add --no-register flag and register-account CLI

Author: https://github.com/REUSS-dev

server/internal/auth/store.go

@@ -0,0 +1,103 @@
+package auth
+
+import (
+	"database/sql"
+	"errors"
+	"fmt"
+	"time"
+
+	"golang.org/x/crypto/bcrypt"
+)
+
+var (
+	ErrUserExists   = errors.New("username already taken")
+	ErrInvalidCreds = errors.New("invalid username or password")
+)
+
+type AuthUser struct {
+	ID       int64
+	Username string
+}
+
+type AuthStore struct {
+	db *sql.DB
+}
+
+func NewAuthStore(db *sql.DB) (*AuthStore, error) {
+	_, err := db.Exec(`
+		CREATE TABLE IF NOT EXISTS auth_users (
+			id         INTEGER PRIMARY KEY AUTOINCREMENT,
+			username   TEXT    NOT NULL UNIQUE,
+			password   BLOB   NOT NULL,
+			created_at TEXT    NOT NULL
+		)
+	`)
+	if err != nil {
+		return nil, fmt.Errorf("create auth_users table: %w", err)
+	}
+	return &AuthStore{db: db}, nil
+}
+
+func (s *AuthStore) CreateUser(username, password string) (AuthUser, error) {
+	hash, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
+	if err != nil {
+		return AuthUser{}, fmt.Errorf("hash password: %w", err)
+	}
+
+	res, err := s.db.Exec(
+		`INSERT INTO auth_users (username, password, created_at) VALUES (?, ?, ?)`,
+		username, hash, time.Now().UTC().Format(time.RFC3339),
+	)
+	if err != nil {
+		if isUniqueViolation(err) {
+			return AuthUser{}, ErrUserExists
+		}
+		return AuthUser{}, fmt.Errorf("insert user: %w", err)
+	}
+
+	id, _ := res.LastInsertId()
+	return AuthUser{ID: id, Username: username}, nil
+}
+
+func (s *AuthStore) VerifyUser(username, password string) (AuthUser, error) {
+	var id int64
+	var hash []byte
+	err := s.db.QueryRow(
+		`SELECT id, password FROM auth_users WHERE username = ?`, username,
+	).Scan(&id, &hash)
+	if err != nil {
+		return AuthUser{}, ErrInvalidCreds
+	}
+
+	if err := bcrypt.CompareHashAndPassword(hash, []byte(password)); err != nil {
+		return AuthUser{}, ErrInvalidCreds
+	}
+
+	return AuthUser{ID: id, Username: username}, nil
+}
+
+func (s *AuthStore) UserExists(username string) bool {
+	var n int
+	err := s.db.QueryRow(`SELECT 1 FROM auth_users WHERE username = ?`, username).Scan(&n)
+	return err == nil
+}
+
+func isUniqueViolation(err error) bool {
+	return err != nil && (errors.Is(err, sql.ErrNoRows) ||
+		// modernc.org/sqlite returns error strings containing "UNIQUE constraint failed"
+		fmt.Sprintf("%v", err) == fmt.Sprintf("%v", err) &&
+			contains(err.Error(), "UNIQUE constraint failed"))
+}
+
+func contains(s, substr string) bool {
+	return len(s) >= len(substr) && searchStr(s, substr)
+}
+
+func searchStr(s, sub string) bool {
+	for i := 0; i <= len(s)-len(sub); i++ {
+		if s[i:i+len(sub)] == sub {
+			return true
+		}
+	}
+	return false
+}