use std::collections::HashSet;

fn process_local_part(s: &str) -> String {
    match s.find('+') {
        Some(plus_index) => &s[0..plus_index],
        None => s,
    }
    .replace('.', "")
}

#[cfg(test)]
mod process_local_part_tests {
    use super::process_local_part;

    #[test]
    fn processing_works() {
        let result = process_local_part("a.b+c");
        assert_eq!(result, "ab");
    }

    #[test]
    fn processing_without_plus_works() {
        let result = process_local_part("a.b");
        assert_eq!(result, "ab");
    }
}

pub fn num_unique_emails(emails: Vec<String>) -> i32 {
    let mut unique_emails = HashSet::new();

    for email in emails.iter() {
        let parts: Vec<&str> = email.split('@').collect();
        unique_emails.insert(format!("{}@{}", process_local_part(parts[0]), parts[1]));
    }

    unique_emails.len() as i32
}

#[cfg(test)]
mod num_unique_emails_tests {
    use super::num_unique_emails;

    #[test]
    fn num_unique_emails_is_correct() {
        let result = num_unique_emails(
            [
                "test.email+alex@leetcode.com",
                "test.e.mail+bob.cathy@leetcode.com",
                "testemail+david@lee.tcode.com",
            ]
            .iter()
            .map(|s| s.to_string())
            .collect(),
        );
        assert_eq!(result, 2)
    }
}