// SPDX-License-Identifier: AGPL-3.0-only

//! Session-level concepts describing the relationship between a client and the server it is playing against.

/// Which kind of server a client session is running against.
///
/// Deliberately not part of the wire protocol. The client already knows the answer without asking: it either spawned a server in-process or dialled a socket. A server-declared field would be redundant at best and spoofable at worst, so the value is constructed client-side from facts the client already holds.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ServerKind {
    /// The server runs in this process, backing single-player.
    Integrated,
    /// The server is a separate process reached over the network.
    Dedicated {
        /// Whether the server's address is off this machine. Decided from the `SocketAddr` the client dialled, not from anything the server says.
        remote: bool,
    },
}

impl ServerKind {
    /// Classifies a dedicated server from the address the client dialled.
    ///
    /// A loopback address means the process is on this machine (a locally hosted server), which is distinct from an integrated one: it is still a separate process reached over a socket.
    #[must_use]
    pub const fn dedicated(addr: std::net::SocketAddr) -> Self {
        Self::Dedicated {
            remote: !addr.ip().is_loopback(),
        }
    }

    /// Returns a short human-readable label for the session's server kind.
    #[must_use]
    pub const fn label(self) -> &'static str {
        match self {
            Self::Integrated => "integrated",
            Self::Dedicated { remote: false } => "dedicated (local)",
            Self::Dedicated { remote: true } => "dedicated (remote)",
        }
    }
}

#[cfg(test)]
#[path = "tests/session.rs"]
mod tests;