//! Deterministic extraction of shipment identifiers from free text.
//!
//! Pulled out as its own unit (rather than a method on `DocumentRetriever`)
//! purely so it's testable without spinning up a Qdrant connection.

use regex::Regex;

pub struct ReferenceExtractor {
    booking_reference_re: Regex,
    container_number_re: Regex,
}

impl ReferenceExtractor {
    pub fn new() -> Self {
        Self {
            booking_reference_re: Regex::new(r"\bMSL-[A-Z0-9]{7}\b").expect("valid regex"),
            container_number_re: Regex::new(r"\b[A-Z]{4}\d{7}\b").expect("valid regex"),
        }
    }

    /// Preferred over asking the LLM to do this: it's cheap, exact, and
    /// never hallucinates a reference that wasn't actually typed.
    pub fn extract(&self, query: &str) -> Option<String> {
        let upper = query.to_uppercase();
        self.booking_reference_re
            .find(&upper)
            .or_else(|| self.container_number_re.find(&upper))
            .map(|m| m.as_str().to_string())
    }
}

impl Default for ReferenceExtractor {
    fn default() -> Self {
        Self::new()
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn extracts_booking_reference_case_insensitively() {
        let r = ReferenceExtractor::new();
        assert_eq!(
            r.extract("where is msl-4b7k921 right now?"),
            Some("MSL-4B7K921".to_string())
        );
    }

    #[test]
    fn extracts_container_number() {
        let r = ReferenceExtractor::new();
        assert_eq!(
            r.extract("container MSCU1234567 status please"),
            Some("MSCU1234567".to_string())
        );
    }

    #[test]
    fn returns_none_when_no_reference_present() {
        let r = ReferenceExtractor::new();
        assert_eq!(r.extract("what are your office hours?"), None);
    }
}