refactor: extract email validation and PII utils to common_utils crate (#72)

crates/common_utils/src/validation.rs

@@ -0,0 +1,102 @@
+//! Custom validations for some shared types.
+
+use error_stack::report;
+use once_cell::sync::Lazy;
+use regex::Regex;
+use router_env::logger;
+
+use crate::errors::{CustomResult, ValidationError};
+
+/// Performs a simple validation against a provided email address.
+pub fn validate_email(email: &str) -> CustomResult<(), ValidationError> {
+    #[deny(clippy::invalid_regex)]
+    static EMAIL_REGEX: Lazy<Option<Regex>> = Lazy::new(|| {
+        match Regex::new(
+            r"^(?i)[a-z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?(?:\.[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?)*$",
+        ) {
+            Ok(regex) => Some(regex),
+            Err(error) => {
+                logger::error!(?error);
+                None
+            }
+        }
+    });
+    let email_regex = match EMAIL_REGEX.as_ref() {
+        Some(regex) => Ok(regex),
+        None => Err(report!(ValidationError::InvalidValue {
+            message: "Invalid regex expression".into()
+        })),
+    }?;
+
+    const EMAIL_MAX_LENGTH: usize = 319;
+    if email.is_empty() || email.chars().count() > EMAIL_MAX_LENGTH {
+        return Err(report!(ValidationError::InvalidValue {
+            message: "Email address is either empty or exceeds maximum allowed length".into()
+        }));
+    }
+
+    if !email_regex.is_match(email) {
+        return Err(report!(ValidationError::InvalidValue {
+            message: "Invalid email address format".into()
+        }));
+    }
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use fake::{faker::internet::en::SafeEmail, Fake};
+    use proptest::{
+        prop_assert,
+        strategy::{Just, NewTree, Strategy},
+        test_runner::TestRunner,
+    };
+
+    use super::*;
+
+    #[derive(Debug)]
+    struct ValidEmail;
+
+    impl Strategy for ValidEmail {
+        type Tree = Just<String>;
+        type Value = String;
+
+        fn new_tree(&self, _runner: &mut TestRunner) -> NewTree<Self> {
+            Ok(Just(SafeEmail().fake()))
+        }
+    }
+
+    #[test]
+    fn test_validate_email() {
+        let result = validate_email("abc@example.com");
+        assert!(result.is_ok());
+
+        let result = validate_email("abc+123@example.com");
+        assert!(result.is_ok());
+
+        let result = validate_email("");
+        assert!(result.is_err());
+    }
+
+    proptest::proptest! {
+        /// Example of unit test
+        #[test]
+        fn proptest_valid_fake_email(email in ValidEmail) {
+            prop_assert!(validate_email(&email).is_ok());
+        }
+
+        /// Example of unit test
+        #[test]
+        fn proptest_invalid_data_email(email in "\\PC*") {
+            prop_assert!(validate_email(&email).is_err());
+        }
+
+        // TODO: make maybe unit test working
+        // minimal failing input: email = "+@a"
+        // #[test]
+        // fn proptest_invalid_email(email in "[.+]@(.+)") {
+        //     prop_assert!(validate_email(&email).is_err());
+        // }
+    }
+}