newt-core 0.6.1

use serde::{Deserialize, Serialize};
use std::fmt;
use std::str::FromStr;
use uuid::Uuid;

/// Opaque session identifier — wraps a UUID v4.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(transparent)]
pub struct SessionId(Uuid);

impl SessionId {
    pub fn new() -> Self {
        Self(Uuid::new_v4())
    }

    pub fn from_uuid(uuid: Uuid) -> Self {
        Self(uuid)
    }

    pub fn as_uuid(&self) -> &Uuid {
        &self.0
    }
}

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

impl fmt::Display for SessionId {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.0.fmt(f)
    }
}

impl FromStr for SessionId {
    type Err = uuid::Error;
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        Uuid::from_str(s).map(Self)
    }
}

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

    #[test]
    fn generate_unique() {
        let a = SessionId::new();
        let b = SessionId::new();
        assert_ne!(a, b);
    }

    #[test]
    fn parse_roundtrip() {
        let id = SessionId::new();
        let s = id.to_string();
        let parsed: SessionId = s.parse().unwrap();
        assert_eq!(id, parsed);
    }

    #[test]
    fn display_is_uuid_format() {
        let id = SessionId::new();
        let s = id.to_string();
        assert_eq!(s.len(), 36);
        assert_eq!(s.as_bytes()[8], b'-');
        assert_eq!(s.as_bytes()[13], b'-');
        assert_eq!(s.as_bytes()[18], b'-');
        assert_eq!(s.as_bytes()[23], b'-');
    }

    #[test]
    fn invalid_string_rejected() {
        assert!("not-a-uuid".parse::<SessionId>().is_err());
    }

    #[test]
    fn serde_roundtrip() {
        let id = SessionId::new();
        let json = serde_json::to_string(&id).unwrap();
        let back: SessionId = serde_json::from_str(&json).unwrap();
        assert_eq!(id, back);
    }
}