/// Per-message response context, threading the sender's identity from Matrix
/// through the tool loop and memory system.
#[derive(Debug, Clone)]
pub struct ResponseContext {
    /// Full Matrix user ID, e.g. `@sienna:sunbeam.pt`
    pub matrix_user_id: String,
    /// Derived portable ID, e.g. `sienna@sunbeam.pt`
    pub user_id: String,
    /// Display name if available
    pub display_name: Option<String>,
    /// Whether this message was sent in a DM
    pub is_dm: bool,
    /// Whether this message is a reply to Sol
    pub is_reply: bool,
    /// The room this message was sent in
    pub room_id: String,
}

/// Extract the localpart from a Matrix user ID.
///
/// `@sienna:sunbeam.pt` → `sienna`
pub fn localpart(matrix_user_id: &str) -> &str {
    let stripped = matrix_user_id.strip_prefix('@').unwrap_or(matrix_user_id);
    stripped.split(':').next().unwrap_or(stripped)
}

/// Derive a portable user ID from a Matrix user ID.
///
/// `@sienna:sunbeam.pt` → `sienna@sunbeam.pt`
pub fn derive_user_id(matrix_user_id: &str) -> String {
    let stripped = matrix_user_id.strip_prefix('@').unwrap_or(matrix_user_id);
    stripped.replacen(':', "@", 1)
}

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

    #[test]
    fn test_derive_user_id_standard() {
        assert_eq!(derive_user_id("@sienna:sunbeam.pt"), "sienna@sunbeam.pt");
    }

    #[test]
    fn test_derive_user_id_no_at_prefix() {
        assert_eq!(derive_user_id("sienna:sunbeam.pt"), "sienna@sunbeam.pt");
    }

    #[test]
    fn test_derive_user_id_complex() {
        assert_eq!(
            derive_user_id("@user.name:matrix.org"),
            "user.name@matrix.org"
        );
    }

    #[test]
    fn test_derive_user_id_only_first_colon() {
        assert_eq!(
            derive_user_id("@user:server:8448"),
            "user@server:8448"
        );
    }

    #[test]
    fn test_localpart_standard() {
        assert_eq!(localpart("@sienna:sunbeam.pt"), "sienna");
    }

    #[test]
    fn test_localpart_no_at_prefix() {
        assert_eq!(localpart("sienna:sunbeam.pt"), "sienna");
    }

    #[test]
    fn test_localpart_no_colon() {
        assert_eq!(localpart("@sienna"), "sienna");
    }

    #[test]
    fn test_localpart_complex() {
        assert_eq!(localpart("@user.name:matrix.org"), "user.name");
    }
}