Refactor user validation

frontend/src/app/models/forms/default-validators.ts

@@ -0,0 +1,61 @@
+import { ValidationErrors, Validators } from '@angular/forms';
+
+// Match this with user entity in shared lib
+// (Security is not handled here, this is only for the user)
+
+function errorsToError(errors: ValidationErrors | null): string {
+  if (errors) {
+    const error = Object.keys(errors)[0];
+    return error;
+  }
+  return 'unkown';
+}
+
+export const UsernameValidators = [
+  Validators.required,
+  Validators.minLength(4),
+  Validators.maxLength(32),
+  Validators.pattern('^[a-zA-Z0-9]+$'),
+];
+
+export const CreateUsernameError = (
+  errors: ValidationErrors | null
+): string => {
+  const error = errorsToError(errors);
+  switch (error) {
+    case 'required':
+      return 'Username is required';
+    case 'minlength':
+      return 'Username is too short';
+    case 'maxlength':
+      return 'Username is too long';
+    case 'pattern':
+      return 'Username can only contain letters and numbers';
+    default:
+      return 'Invalid username';
+  }
+};
+
+export const PasswordValidators = [
+  Validators.required,
+  Validators.minLength(4),
+  Validators.maxLength(1024),
+];
+
+export const CreatePasswordError = (
+  errors: ValidationErrors | null
+): string => {
+  const error = errorsToError(errors);
+  switch (error) {
+    case 'required':
+      return 'Password is required';
+    case 'minlength':
+      return 'Password is too short';
+    case 'maxlength':
+      return 'Password is too long';
+    case 'compare':
+      return 'Password does not match';
+    default:
+      return 'Invalid password';
+  }
+};