//! Translate relay information from the formats used in the onion service

//! protocol into `CircTarget`s that we can use for building circuits.

//!

//! (Later this will include support for INTRODUCE2 messages too.)

use tor_error::{into_internal, HasRetryTime, RetryTime};

use tor_linkspec::{

    decode::Strictness, verbatim::VerbatimLinkSpecCircTarget, CircTarget, EncodedLinkSpec,

    OwnedChanTargetBuilder, OwnedCircTarget,

};

use tor_llcrypto::pk::curve25519;

use tor_netdir::NetDir;

use tor_netdoc::doc::hsdesc::IntroPointDesc;

/// Helper: create a [`CircTarget`] from its component parts as provided by

/// another party on the network.

///

/// This function is used to build a `CircTarget` from an `IntroPointDesc` (for

/// extending to an introduction point).  Later, it can also be used to build a

/// CircTarget from an `Introduce2` message (for extending to a rendezvous

/// point).

//

// TODO (#1223): This function is very similar to a block of code in

// `tor-hsservice`.  Can/should we unify them?

    // Decode the link specifiers and use them to find out what we can about

    // this relay.

    // Look up the relay in the directory, to see:

    //    1) if it is flatly impossible,

    //    2) what subprotocols we should assume it implements.

        }

    };

/// Construct a [`CircTarget`] from a provided [`IntroPointDesc`].

///

/// Onion service clients use this function to convert an `IntroPointDesc` in

/// the onion service descriptor into a form that they can use when building a

/// circuit to an introduction point.

///

/// The `netdir` argument is used to fill in missing information about the

/// target relay, and to make sure that the target relay's identities are not

/// inconsistent with the rest of the network.

/// We were given unusable information about an introduction point or rendezvous

/// point.

//

// This is returned by `ipt_to_circtarget`.  It will also be used for rendezvous

// points when we implement the HS server side.

// At that point, this module will need to move to a crate where it can be used

// by the HS server code.

#[derive(Clone, Debug, thiserror::Error)]

#[non_exhaustive]

pub enum InvalidTarget {

    /// The provided link specifiers included some that, when we tried to parse

    /// them, proved to be malformed.

    #[error("Malformed channel target information provided")]

    UnparseableChanTargetInfo(#[from] tor_bytes::Error),

    /// The provided link specifiers were inconsistent with one another, or missing

    /// key information.

    #[error("Invalid channel target information provided")]

    InvalidChanTargetInfo(#[from] tor_linkspec::decode::ChanTargetDecodeError),

    /// The provided relay identities (in the link specifiers) described a relay

    /// which, according to the network directory, cannot possibly exist.

    #[error("Impossible combination of relay identities")]

    ImpossibleRelayIds(#[from] tor_netdir::RelayLookupError),

    /// An internal error occurred.

    #[error("{0}")]

    Bug(#[from] tor_error::Bug),

}

/// When to maybe retry *with the same inputs* that generated this error.

///

/// When returned from `ipt_to_circtarget`, that means this is when to retry

/// the *same introduction point* for the *same hidden service*.

///

/// "The same introduction point" means one with precisely the same set of identities

/// and link specifiers.

//

// Note about correctness, and introduction point identity:

//

// We use this as part of HasRetryTime for FailedAttemptError.

// HasRetryTime for FailedAttemptError is used for selecting which intro point to retry.

// Our introduction point experiences are recorded according to *one* relay identity,

// not the complete set.

//

// Nevertheless, this is correct, because: we only select from, and record experiences for,

// *usable* introduction points.  An InvalidTarget error is detected early enough

// to avoid regarding the introduction point as usable at all.  So we never use

// this RetryTime impl, here, to choose between introduction points.

impl HasRetryTime for InvalidTarget {

        use InvalidTarget as IT;

        use RetryTime as RT;

        }

}