//! Message types used in the Arti's RPC protocol.

//

// TODO: This could become a more zero-copy-friendly with some effort, but it's

// not really sure if it's needed.

mod invalid;

use serde::{Deserialize, Serialize};

use tor_rpcbase as rpc;

/// An identifier for a Request within the context of a Session.

///

/// Multiple inflight requests can share the same `RequestId`,

/// but doing so may make Arti's responses ambiguous.

#[derive(Debug, Eq, PartialEq, Hash, Clone, Serialize, Deserialize)]

#[serde(untagged)]

pub(crate) enum RequestId {

    /// A client-provided string.

    //

    // (We use Box<str> to save a word here, since these don't have to be

    // mutable ever.)

    Str(Box<str>),

    /// A client-provided integer.

    ///

    /// [I-JSON] says that we don't have to handle any integer that can't be

    /// represented as an `f64`, but we do anyway.  This won't confuse clients,

    /// since we won't send them any integer that they didn't send us first.

    ///

    /// [I-JSON]: https://www.rfc-editor.org/rfc/rfc7493

    Int(i64),

}

/// Metadata associated with a single Request.

//

// NOTE: When adding new fields to this type, make sure that `Default` gives

// the correct value for an absent metadata.

#[derive(Debug, Clone, Serialize, Deserialize, Default)]

pub(crate) struct ReqMeta {

    /// If true, the client will accept intermediate Updates other than the

    /// final Request or Response.

    #[serde(default)]

    pub(crate) updates: bool,

    /// A list of features which must be implemented in order to understand the request.

    /// If any feature in this list is not available, the request must be rejected.

    #[serde(default)]

    pub(crate) require: Vec<String>,

}

/// A single Request received from an RPC client.

#[derive(Debug, Deserialize)]

pub(crate) struct Request {

    /// The client's identifier for this request.

    ///

    /// We'll use this to link all responses to this request.

    pub(crate) id: RequestId,

    /// The object to receive this request.

    pub(crate) obj: rpc::ObjectId,

    /// Any metadata to explain how this request is handled.

    #[serde(default)]

    pub(crate) meta: ReqMeta,

    /// The method to actually execute.

    ///

    /// Using "flatten" here will make it expand to "method" and "params".

    #[serde(flatten)]

    pub(crate) method: Box<dyn rpc::DeserMethod>,

}

/// A request that may or may not be valid.

///

/// If it invalid, it contains information that can be used to construct an error.

#[derive(Debug, serde::Deserialize)]

#[serde(untagged)]

pub(crate) enum FlexibleRequest {

    /// A valid request.

    Valid(Request),

    /// An invalid request.

    Invalid(invalid::InvalidRequest),

    // TODO RPC: Right now `InvalidRequest` should handle any Json Object,

    // but we might additionally want to parse any Json _Value_

    // (and reject it without killing the connection).

    // If we do, we ought to add a third variant here.

    //

    // Without this change, our implementation will be slightly more willing to close connections

    // than the spec requires:

    // The spec says we need to kill a connection on anything that can't be parsed as Json;

    // we kill a connection on anything that can't be parsed as a Json _Object_.

}

/// A Response to send to an RPC client.

#[derive(Debug, Serialize)]

pub(crate) struct BoxedResponse {

    /// An ID for the request that we're responding to.

    ///

    /// This is always present on a response to every valid request; it is also

    /// present on responses to invalid requests if we could discern what their

    /// `id` field was. We only omit it when the request id was indeterminate.

    /// If we do that, we close the connection immediately afterwards.

    #[serde(skip_serializing_if = "Option::is_none")]

    pub(crate) id: Option<RequestId>,

    /// The body  that we're sending.

    #[serde(flatten)]

    pub(crate) body: ResponseBody,

}

impl BoxedResponse {

    /// Construct a BoxedResponse from an error that can be converted into an

    /// RpcError.

}

/// The body of a response for an RPC client.

#[derive(Serialize)]

pub(crate) enum ResponseBody {

    /// The request has failed; no more responses will be sent in reply to it.

    #[serde(rename = "error")]

    Error(Box<rpc::RpcError>),

    /// The request has succeeded; no more responses will be sent in reply to

    /// it.

    ///

    /// Note that in the spec, this is called a "result": we don't propagate

    /// that terminology into Rust, where `Result` has a different meaning.

    #[serde(rename = "result")]

    Success(Box<dyn erased_serde::Serialize + Send>),

    /// The request included the `updates` flag to increment that incremental

    /// progress information is acceptable.

    #[serde(rename = "update")]

    Update(Box<dyn erased_serde::Serialize + Send>),

}

impl ResponseBody {

    /// Return true if this body type indicates that no future responses will be

    /// sent for this request.

        }

}

impl From<rpc::RpcError> for ResponseBody {

}

impl std::fmt::Debug for ResponseBody {

        }

}

#[cfg(test)]

mod test {

    // @@ begin test lint list maintained by maint/add_warning @@

    #![allow(clippy::bool_assert_comparison)]

    #![allow(clippy::clone_on_copy)]

    #![allow(clippy::dbg_macro)]

    #![allow(clippy::mixed_attributes_style)]

    #![allow(clippy::print_stderr)]

    #![allow(clippy::print_stdout)]

    #![allow(clippy::single_char_pattern)]

    #![allow(clippy::unwrap_used)]

    #![allow(clippy::unchecked_duration_subtraction)]

    #![allow(clippy::useless_vec)]

    #![allow(clippy::needless_pass_by_value)]

    //! <!-- @@ end test lint list maintained by maint/add_warning @@ -->

    use super::*;

    use derive_deftly::Deftly;

    use tor_rpcbase::templates::*;

    /// Assert that two arguments have the same output from `std::fmt::Debug`.

    ///

    /// This can be handy for testing for some notion of equality on objects

    /// that implement `Debug` but not `PartialEq`.

    macro_rules! assert_dbg_eq {

        ($a:expr, $b:expr) => {

            assert_eq!(format!("{:?}", $a), format!("{:?}", $b));

        };

    }

    // TODO RPC: note that the existence of this method type can potentially

    // leak into our real RPC engine when we're compiled with `test` enabled!

    // We should consider how bad this is, and maybe use a real method instead.

    #[derive(Debug, serde::Deserialize, Deftly)]

    #[derive_deftly(DynMethod)]

    #[deftly(rpc(method_name = "x-test:dummy"))]

    struct DummyMethod {

        #[serde(default)]

        #[allow(dead_code)]

        stuff: u64,

    }

    impl rpc::RpcMethod for DummyMethod {

        type Output = DummyResponse;

        type Update = rpc::NoUpdates;

    }

    #[derive(Serialize)]

    struct DummyResponse {

        hello: i64,

        world: String,

    }

    #[test]

    fn valid_requests() {

        let parse_request = |s| match serde_json::from_str::<FlexibleRequest>(s) {

            Ok(FlexibleRequest::Valid(req)) => req,

            other => panic!("{:?}", other),

        };

        let r =

            parse_request(r#"{"id": 7, "obj": "hello", "method": "x-test:dummy", "params": {} }"#);

        assert_dbg_eq!(

            r,

            Request {

                id: RequestId::Int(7),

                obj: rpc::ObjectId::from("hello"),

                meta: ReqMeta::default(),

                method: Box::new(DummyMethod { stuff: 0 })

            }

        );

    }

    #[test]

    fn invalid_requests() {

        use crate::err::RequestParseError as RPE;

        fn parsing_error(s: &str) -> RPE {

            match serde_json::from_str::<FlexibleRequest>(s) {

                Ok(FlexibleRequest::Invalid(req)) => req.error(),

                x => panic!("Didn't expect {:?}", x),

            }

        }

        macro_rules! expect_err {

            ($p:pat, $e:expr) => {

                let err = parsing_error($e);

                assert!(matches!(err, $p), "Unexpected error type {:?}", err);

            };

        }

        expect_err!(

            RPE::IdMissing,

            r#"{ "obj": "hello", "method": "x-test:dummy", "params": {} }"#

        );

        expect_err!(

            RPE::IdType,

            r#"{ "id": {}, "obj": "hello", "method": "x-test:dummy", "params": {} }"#

        );

        expect_err!(

            RPE::ObjMissing,

            r#"{ "id": 3, "method": "x-test:dummy", "params": {} }"#

        );

        expect_err!(

            RPE::ObjType,

            r#"{ "id": 3, "obj": 9, "method": "x-test:dummy", "params": {} }"#

        );

        expect_err!(

            RPE::MethodMissing,

            r#"{ "id": 3, "obj": "hello",  "params": {} }"#

        );

        expect_err!(

            RPE::MethodType,

            r#"{ "id": 3, "obj": "hello", "method": [], "params": {} }"#

        );

        expect_err!(

            RPE::MetaType,

            r#"{ "id": 3, "obj": "hello", "meta": 7, "method": "x-test:dummy", "params": {} }"#

        );

        expect_err!(

            RPE::MetaType,

            r#"{ "id": 3, "obj": "hello", "meta": { "updates": 3}, "method": "x-test:dummy", "params": {} }"#

        );

        expect_err!(

            RPE::NoSuchMethod,

            r#"{ "id": 3, "obj": "hello", "method": "arti:this-is-not-a-method", "params": {} }"#

        );

        expect_err!(

            RPE::MissingParams,

            r#"{ "id": 3, "obj": "hello", "method": "x-test:dummy" }"#

        );

        expect_err!(

            RPE::ParamType,

            r#"{ "id": 3, "obj": "hello", "method": "x-test:dummy", "params": 7 }"#

        );

    }

    #[test]

    fn fmt_replies() {

        let resp = BoxedResponse {

            id: Some(RequestId::Int(7)),

            body: ResponseBody::Success(Box::new(DummyResponse {

                hello: 99,

                world: "foo".into(),

            })),

        };

        let s = serde_json::to_string(&resp).unwrap();

        // NOTE: This is a bit fragile for a test, since nothing in serde or

        // serde_json guarantees that the fields will be serialized in this

        // exact order.

        assert_eq!(s, r#"{"id":7,"result":{"hello":99,"world":"foo"}}"#);

        let resp = BoxedResponse {

            id: None,

            body: ResponseBody::Error(Box::new(rpc::RpcError::from(

                crate::err::RequestParseError::IdMissing,

            ))),

        };

        let s = serde_json::to_string(&resp).unwrap();

        // NOTE: as above.

        assert_eq!(

            s,

            r#"{"error":{"message":"Request did not have any `id` field.","code":-32600,"kinds":["rpc:InvalidRequest"]}}"#

        );

    }

}