Gravity Forms Recover Password Validation

gf_rp_validation.php

<?php
// remember, the hook suffix, should contain the form id!
add_filter( "gform_field_validation_2", 'wp_doin_validation_2', 10, 4 );

/**
 * Let's verify for the user email or username provided
 *
 * @return ARRAY_A
 */
function wp_doin_validation_2($result, $value, $form, $field) {

	$classes = explode( ' ', $field['cssClass'] );

	// let's assume it's all valid
	$result['is_valid'] = true;

	// lets check if the user with such a username is already in the database
	if ( in_array( 'user-email', $classes ) ) {

		// this means that the user has specified email
		if ( strpos( $value, '@' ) ) {
			$user_data = get_user_by( 'email', trim( $value ) );

			if ( empty( $user_data ) ) {
				$result['is_valid'] = false;
				$result['message'] = 'No such email in database.';
			}

			$allow = check_if_reset_is_allowed( $user_data->ID );
		} else {
			// let's verify the username existence
			$user_id = username_exists( $value );

			if ( !$user_id ) {
				// let's mark this field is invalid
				$result['is_valid'] = false;
				$result['message'] = 'No such user in database.';
			}

			$allow = check_if_reset_is_allowed( $user_id );
		}
	}

	// if the password change is not allowed return false
	if ( !$allow ) {
		// let's mark this field is invalid
		$result['is_valid'] = false;
		$result['message'] = 'Password change is not allowed.';
	}

	return $result;
}


/**
 * Utility to check if password reset is allowed based on user id.
 * 
 * @param INT $user_id
 * @return BOOL true / false
 */
function check_if_reset_is_allowed($user_id) {
	$allow = apply_filters( 'allow_password_reset', true, $user_id );

	if ( !$allow ) {
		return false;
	} elseif ( is_wp_error( $allow ) ) {
		return false;
	}

	return true;
}

In order to get the Email/Username Field, we should do :

$username_email_field_ID = 1;
	foreach ( $form['fields'] as $field ) {
		if($field->cssClass === 'user-email'){
			$username_email_field_ID = isset($field->id) ? $field->id : 0;
		}
	}
	// get the submitted value
	$email_or_username = $_POST['input_'.$username_email_field_ID];