//! This contains restricted message sets namespaced by link protocol version.

//!

//! In other words, each protocol version define sets of possible messages depending on the channel

//! type as in client or relay and initiator or responder.

//!

//! This module also defines [`MessageFilter`] which can be used to filter messages based on

//! specific details of the message such as direction, command, channel type and channel stage.

use bytes::{Bytes, BytesMut};

use tor_cell::chancell::{AnyChanCell, ChanCell, ChanMsg, codec, msg::AnyChanMsg};

use crate::{Error, channel::ChannelType};

/// Subprotocol LINK version 4.

///

/// Increases circuit ID width to 4 bytes.

pub(super) mod linkv4 {

    use bytes::{Bytes, BytesMut};

    use tor_cell::{

        chancell::{AnyChanCell, codec},

        restricted_msg,

    };

    use super::MessageStage;

    use crate::{

        Error,

        channel::{

            ChannelType,

            msg::{decode_as_any, encode_as_any},

        },

    };

    restricted_msg! {

        /// Handshake messages of a relay that initiates a connection. They are sent by the

        /// initiator and thus received by the responder.

        #[derive(Clone, Debug)]

        pub(super) enum HandshakeRelayInitiatorMsg: ChanMsg {

            Authenticate,

            Certs,

            Netinfo,

            Vpadding,

        }

    }

    restricted_msg! {

        /// Handshake messages of a relay that responds to a connection. They are received by the

        /// initiator and thus sent by the responder.

        #[derive(Clone, Debug)]

        pub(super) enum HandshakeRelayResponderMsg: ChanMsg {

            AuthChallenge,

            Certs,

            Netinfo,

            Vpadding,

        }

    }

    restricted_msg! {

        /// Handshake messages of a client that initiates a connection to a relay.

        ///

        /// The Versions message is not in this set as it is a special case as the very first cell

        /// being negotiated in order to learn the link protocol version.

        ///

        /// This MUST be a subset of HandshakeRelayResponderMsg because the relay responder doesn't

        /// know what the other side will send depending if it wants to authenticate or not.

        #[derive(Clone, Debug)]

        pub(super) enum HandshakeClientInitiatorMsg: ChanMsg {

            Netinfo,

            Vpadding,

        }

    }

    // From this point on, the C is "Client" and the R is "Relay" and the name indicate the

    // direction of messages. For example, C2R means client -> (to) relay.

    restricted_msg! {

        /// A channel message that we allow to be sent from a Client to a Relay on

        /// an open channel.

        #[derive(Clone, Debug)]

        pub(super) enum OpenChanMsgC2R: ChanMsg {

            // No Create*, it is obsolete (TAP).

            Create2,

            CreateFast,

            Destroy,

            Padding,

            Vpadding,

            // No PaddingNegotiate, it is v5+ only.

            Relay,

            RelayEarly,

        }

    }

    restricted_msg! {

        /// A channel message that we allow to be sent from a Relay to a Client on

        /// an open channel.

        ///

        /// (An Open channel here is one on which we have received a NETINFO cell.)

        #[derive(Clone, Debug)]

        pub(super) enum OpenChanMsgR2C : ChanMsg {

            // No Create*, we are not a client and it is obsolete (TAP).

            // No Created*, it is obsolete (TAP).

            CreatedFast,

            Created2,

            Relay,

            // No RelayEarly, only for client.

            Destroy,

            Padding,

            Vpadding,

        }

    }

    restricted_msg! {

        /// A channel message that we allow to be sent (bidirectionally) from a Relay to a Relay on

        /// an open channel.

        #[derive(Clone, Debug)]

        pub(super) enum OpenChanMsgR2R : ChanMsg {

            // No Vpadding, only sent during handshake.

            // No Create/Created, it is obsolete (TAP).

            CreateFast,

            CreatedFast,

            Create2,

            Created2,

            Destroy,

            Padding,

            Vpadding,

            Relay,

            RelayEarly,

            // No PaddingNegotiate, only client sends this.

            // No Versions, Certs, AuthChallenge, Authenticate, Netinfo: they are for handshakes.

            // No Authorize: it is reserved, but unused.

        }

    }

    /// Decode cell using the given channel type, message stage, codec and byte source.

    ///

    /// Returns both the cell and the bytes that the cell were decoded from.

        use ChannelType::*;

        use MessageStage::*;

            },

        };

    /// Encode a given cell which can contains any type of messages. It is filtered through its

    /// restricted message set at encoding time.

    ///

    /// Return an error if encoding fails or if cell is disallowed.

        use ChannelType::*;

        use MessageStage::*;

            },

        };

}

/// Subprotocol LINK version 5.

///

/// Adds support for padding and negotiation.

pub(super) mod linkv5 {

    use bytes::{Bytes, BytesMut};

    use tor_cell::{

        chancell::{AnyChanCell, codec},

        restricted_msg,

    };

    use super::MessageStage;

    use crate::{

        Error,

        channel::{

            ChannelType,

            msg::{decode_as_any, encode_as_any},

        },

    };

    restricted_msg! {

        /// Handshake messages of a relay that initiates a connection. They are sent by the

        /// initiator and thus received by the responder.

        #[derive(Clone,Debug)]

        pub(super) enum HandshakeRelayInitiatorMsg: ChanMsg {

            Authenticate,

            Certs,

            Netinfo,

            Vpadding,

        }

    }

    restricted_msg! {

        /// Handshake messages of a relay that responds to a connection. They are received by the

        /// initiator and thus sent by the responder.

        #[derive(Clone,Debug)]

        pub(super) enum HandshakeRelayResponderMsg: ChanMsg {

            AuthChallenge,

            Certs,

            Netinfo,

            Vpadding,

        }

    }

    restricted_msg! {

        /// Handshake messages of a client that initiates a connection to a relay.

        ///

        /// The Versions message is not in this set as it is a special case as the very first cell

        /// being negotiated in order to learn the link protocol version.

        #[derive(Clone,Debug)]

        pub(super) enum HandshakeClientInitiatorMsg: ChanMsg {

            Netinfo,

            Vpadding,

        }

    }

    // From this point on, the C is "Client" and the R is "Relay" and the name indicate the

    // direction of messages. For example, C2R means client -> (to) relay.

    restricted_msg! {

        /// A channel message that we allow to be sent from a Client to a Relay on

        /// an open channel.

        #[derive(Clone, Debug)]

        pub(super) enum OpenChanMsgC2R: ChanMsg {

            // No Create*, it is obsolete (TAP).

            Create2,

            CreateFast,

            Destroy,

            Padding,

            PaddingNegotiate,

            Vpadding,

            Relay,

            RelayEarly,

        }

    }

    restricted_msg! {

        /// A channel message that we allow to be sent from a Relay to a Client on

        /// an open channel.

        ///

        /// (An Open channel here is one on which we have received a NETINFO cell.)

        #[derive(Clone, Debug)]

        pub(super) enum OpenChanMsgR2C : ChanMsg {

            // No Create/d*, only clients and it is obsolete (TAP).

            CreatedFast,

            Created2,

            Destroy,

            Padding,

            Vpadding,

            Relay,

            // No PaddingNegotiate, only clients.

            // No Versions, Certs, AuthChallenge, Authenticate: they are for handshakes.

            // No Authorize: it is reserved, but unused.

        }

    }

    restricted_msg! {

        /// A channel message that we allow to be sent (bidirectionally) from a Relay to a Relay on

        /// an open channel.

        #[derive(Clone, Debug)]

        pub(super) enum OpenChanMsgR2R : ChanMsg {

            // No Create/Created, it is obsolete (TAP).

            CreateFast,

            CreatedFast,

            Create2,

            Created2,

            Destroy,

            Padding,

            Vpadding,

            // No Vpadding, only sent during handshake.

            Relay,

            RelayEarly,

            // No PaddingNegotiate, only client sends this.

            // No Versions, Certs, AuthChallenge, Authenticate, Netinfo: they are for handshakes.

            // No Authorize: it is reserved, but unused.

        }

    }

    /// Decode cell using the given channel type, message stage, codec and byte source.

    ///

    /// Returns both the cell and the bytes that the cell were decoded from.

        use ChannelType::*;

        use MessageStage::*;

            },

        };

    /// Encode a given cell which can contains any type of messages. It is filtered through its

    /// restricted message set at encoding time.

    ///

    /// Return an error if encoding fails or if cell is disallowed.

        use ChannelType::*;

        use MessageStage::*;

            },

        };

}

/// Helper function to decode a cell within a restricted msg set into an AnyChanCell.

///

/// The given stage is used to know which error to return.

///

/// Returns both the cell and the bytes that the cell were decoded from.

{

/// Helper function to encode an AnyChanCell cell that is within a restricted msg set R.

///

/// The given stage is used to know which error to return.

{

        }

    }

/// Channel protocol version negotiated.

#[derive(Copy, Clone, Debug)]

pub(super) enum LinkVersion {

    /// Version 4 that need to use linkv4:: messages.

    V4,

    /// Version 5 that need to use linkv5:: messages.

    V5,

}

impl LinkVersion {

    /// Return the value of this link version as a u16. Useful for lower level crates that require

    /// the value for which we can't export this enum.

        }

}

impl TryFrom<u16> for LinkVersion {

    type Error = Error;

            _ => {

            }

        })

}

/// What stage a channel can be of a negotiation. This is used in order to learn which restricted

/// message set we should be looking at.

///

/// Notice that we don't have the "New" stage and this is because we only learn the link protocol

/// version once we enter the Handshake stage.

pub(super) enum MessageStage {

    /// Handshaking as in the channel is working to become open.

    Handshake,

    /// Open as the channel is now open.

    Open,

}

impl MessageStage {

    /// Return an error using the given message for the right stage.

    ///

    /// Very useful helper that just select the right error type for the stage.

        }

}

/// A message filter object which is used to learn if a certain message is allowed or not on a

/// channel.

///

/// It is pinned to a link protocol version, a channel type and a channel message stage.

pub(super) struct MessageFilter {

    /// For what link protocol version this filter applies for.

    link_version: LinkVersion,

    /// For which channel type this filter applies for.

    channel_type: ChannelType,

    /// At which stage this filter applies for.

    stage: MessageStage,

}

impl MessageFilter {

    /// Constructor

    /// Return the [`ChannelType`] of this filter.

    /// Return the [`ChannelType`] of this filter as a mutable.

    /// Decode a cell from the given bytes for the right link version, channel type and message

    /// stage using the codec given.

    ///

    /// Returns both the cell and the bytes that the cell were decoded from.

        }

    /// Decode a cell from the given bytes for the right link version, channel type and message

    /// stage using the codec given.

            LinkVersion::V4 => {

            }

            LinkVersion::V5 => {

            }

        }

}