refactor

backend/src/utils/text.rs

@@ -0,0 +1,31 @@
+use crate::error::{AppError, AppResult};
+
+/// Normalizes an identifier-like user input by trimming, enforcing length, and validating characters.
+pub fn normalize_identifier<F>(
+    value: &str,
+    max_len: usize,
+    empty_message: &str,
+    length_message: &str,
+    invalid_message: Option<&str>,
+    mut validator: F,
+) -> AppResult<String>
+where
+    F: FnMut(char) -> bool,
+{
+    let trimmed = value.trim();
+    if trimmed.is_empty() {
+        return Err(AppError::bad_request(empty_message));
+    }
+
+    if trimmed.len() > max_len {
+        return Err(AppError::bad_request(length_message));
+    }
+
+    if let Some(msg) = invalid_message {
+        if !trimmed.chars().all(|ch| validator(ch)) {
+            return Err(AppError::bad_request(msg));
+        }
+    }
+
+    Ok(trimmed.to_string())
+}