use core::fmt::Debug;

#[cfg(all(doc, feature = "std"))]

use crate::KeyLogFile;

/// This trait represents the ability to do something useful

/// with key material, such as logging it to a file for debugging.

///

/// Naturally, secrets passed over the interface are *extremely*

/// sensitive and can break the security of past, present and

/// future sessions.

///

/// You'll likely want some interior mutability in your

/// implementation to make this useful.

///

/// See [`KeyLogFile`] that implements the standard

/// `SSLKEYLOGFILE` environment variable behaviour.

pub trait KeyLog: Debug + Send + Sync {

    /// Log the given `secret`.  `client_random` is provided for

    /// session identification.  `label` describes precisely what

    /// `secret` means:

    ///

    /// - `CLIENT_RANDOM`: `secret` is the master secret for a TLSv1.2 session.

    /// - `CLIENT_EARLY_TRAFFIC_SECRET`: `secret` encrypts early data

    ///   transmitted by a client

    /// - `SERVER_HANDSHAKE_TRAFFIC_SECRET`: `secret` encrypts

    ///   handshake messages from the server during a TLSv1.3 handshake.

    /// - `CLIENT_HANDSHAKE_TRAFFIC_SECRET`: `secret` encrypts

    ///   handshake messages from the client during a TLSv1.3 handshake.

    /// - `SERVER_TRAFFIC_SECRET_0`: `secret` encrypts post-handshake data

    ///   from the server in a TLSv1.3 session.

    /// - `CLIENT_TRAFFIC_SECRET_0`: `secret` encrypts post-handshake data

    ///   from the client in a TLSv1.3 session.

    /// - `EXPORTER_SECRET`: `secret` is the post-handshake exporter secret

    ///   in a TLSv1.3 session.

    ///

    /// These strings are selected to match the NSS key log format:

    /// <https://nss-crypto.org/reference/security/nss/legacy/key_log_format/index.html>

    fn log(&self, label: &str, client_random: &[u8], secret: &[u8]);

    /// Indicates whether the secret with label `label` will be logged.

    ///

    /// If `will_log` returns true then `log` will be called with the secret.

    /// Otherwise, `log` will not be called for the secret. This is a

    /// performance optimization.

    fn will_log(&self, _label: &str) -> bool {

        true

    }

}

/// KeyLog that does exactly nothing.

#[derive(Debug)]

pub struct NoKeyLog;

impl KeyLog for NoKeyLog {

    fn log(&self, _: &str, _: &[u8], _: &[u8]) {}

    #[inline]

    fn will_log(&self, _label: &str) -> bool {

        false

    }

}