//! `GET /_matrix/client/*/rooms/{roomId}/messages`

pub mod v3 {
    //! `/v3/` ([spec])
    //!
    //! [spec]: https://spec.matrix.org/v1.2/client-server-api/#get_matrixclientv3roomsroomidmessages

    use js_int::{uint, UInt};
    use ruma_common::{
        api::ruma_api,
        events::{AnyRoomEvent, AnyStateEvent},
        serde::Raw,
        RoomId,
    };
    use serde::{Deserialize, Serialize};

    use crate::filter::{IncomingRoomEventFilter, RoomEventFilter};

    ruma_api! {
        metadata: {
            description: "Get message events for a room.",
            method: GET,
            name: "get_message_events",
            r0_path: "/_matrix/client/r0/rooms/:room_id/messages",
            stable_path: "/_matrix/client/v3/rooms/:room_id/messages",
            rate_limited: false,
            authentication: AccessToken,
            added: 1.0,
        }

        request: {
            /// The room to get events from.
            #[ruma_api(path)]
            pub room_id: &'a RoomId,

            /// The token to start returning events from.
            ///
            /// This token can be obtained from a `prev_batch` token returned for each room by the
            /// sync endpoint, or from a `start` or `end` token returned by a previous request to
            /// this endpoint.
            ///
            /// If this is `None`, the server will return messages from the start or end of the
            /// history visible to the user, depending on the value of [`dir`][Self::dir].
            ///
            /// *Note: This field is marked required in v1.2 of the specification, but that is
            /// changing, most likely as part of v1.3. To frontload the breaking change, this field
            /// is optional already even though v1.2 is the latest version at the time of writing.
            /// The specification change can be found [here].*
            ///
            /// [here]: https://github.com/matrix-org/matrix-spec/pull/1002
            #[ruma_api(query)]
            pub from: Option<&'a str>,

            /// The token to stop returning events at.
            ///
            /// This token can be obtained from a `prev_batch` token returned for each room by the
            /// sync endpoint, or from a `start` or `end` token returned by a previous request to
            /// this endpoint.
            #[serde(skip_serializing_if = "Option::is_none")]
            #[ruma_api(query)]
            pub to: Option<&'a str>,

            /// The direction to return events from.
            #[ruma_api(query)]
            pub dir: Direction,

            /// The maximum number of events to return.
            ///
            /// Default: `10`.
            #[ruma_api(query)]
            #[serde(default = "default_limit", skip_serializing_if = "is_default_limit")]
            pub limit: UInt,

            /// A [`RoomEventFilter`] to filter returned events with.
            #[ruma_api(query)]
            #[serde(
                with = "ruma_common::serde::json_string",
                default,
                skip_serializing_if = "RoomEventFilter::is_empty"
            )]
            pub filter: RoomEventFilter<'a>,
        }

        #[derive(Default)]
        response: {
            /// The token the pagination starts from.
            pub start: String,

            /// The token the pagination ends at.
            #[serde(skip_serializing_if = "Option::is_none")]
            pub end: Option<String>,

            /// A list of room events.
            #[serde(default)]
            pub chunk: Vec<Raw<AnyRoomEvent>>,

            /// A list of state events relevant to showing the `chunk`.
            #[serde(default, skip_serializing_if = "Vec::is_empty")]
            pub state: Vec<Raw<AnyStateEvent>>,
        }

        error: crate::Error
    }

    impl<'a> Request<'a> {
        /// Creates a new `Request` with the given parameters.
        ///
        /// All other parameters will be defaulted.
        pub fn new(room_id: &'a RoomId, from: &'a str, dir: Direction) -> Self {
            Self {
                room_id,
                from: Some(from),
                to: None,
                dir,
                limit: default_limit(),
                filter: RoomEventFilter::default(),
            }
        }

        /// Creates a new `Request` with the given room ID and from token, and `dir` set to
        /// `Backward`.
        pub fn backward(room_id: &'a RoomId, from: &'a str) -> Self {
            Self::new(room_id, from, Direction::Backward)
        }

        /// Creates a new `Request` with the given room ID and from token, and `dir` set to
        /// `Forward`.
        pub fn forward(room_id: &'a RoomId, from: &'a str) -> Self {
            Self::new(room_id, from, Direction::Forward)
        }

        /// Creates a new `Request` to fetch messages from the very start of the available history
        /// for a given room.
        pub fn from_start(room_id: &'a RoomId) -> Self {
            Self {
                room_id,
                from: None,
                to: None,
                dir: Direction::Forward,
                limit: default_limit(),
                filter: RoomEventFilter::default(),
            }
        }

        /// Creates a new `Request` to fetch messages from the very end of the available history for
        /// a given room.
        pub fn from_end(room_id: &'a RoomId) -> Self {
            Self {
                room_id,
                from: None,
                to: None,
                dir: Direction::Backward,
                limit: default_limit(),
                filter: RoomEventFilter::default(),
            }
        }
    }

    impl Response {
        /// Creates an empty `Response`.
        pub fn new() -> Self {
            Default::default()
        }
    }

    fn default_limit() -> UInt {
        uint!(10)
    }

    #[allow(clippy::trivially_copy_pass_by_ref)]
    fn is_default_limit(val: &UInt) -> bool {
        *val == default_limit()
    }

    /// The direction to return events from.
    #[derive(Clone, Debug, Deserialize, Serialize)]
    #[allow(clippy::exhaustive_enums)]
    pub enum Direction {
        /// Return events backwards in time from the requested `from` token.
        #[serde(rename = "b")]
        Backward,

        /// Return events forwards in time from the requested `from` token.
        #[serde(rename = "f")]
        Forward,
    }

    #[cfg(all(test, feature = "client"))]
    mod tests {
        use js_int::uint;
        use ruma_common::{
            api::{MatrixVersion, OutgoingRequest, SendAccessToken},
            room_id,
        };

        use super::{Direction, Request};
        use crate::filter::{LazyLoadOptions, RoomEventFilter};

        #[test]
        fn serialize_some_room_event_filter() {
            let room_id = room_id!("!roomid:example.org");
            let rooms = &[room_id.to_owned()];
            let filter = RoomEventFilter {
                lazy_load_options: LazyLoadOptions::Enabled { include_redundant_members: true },
                rooms: Some(rooms),
                not_rooms: &[
                    room_id!("!room:example.org").to_owned(),
                    room_id!("!room2:example.org").to_owned(),
                    room_id!("!room3:example.org").to_owned(),
                ],
                not_types: &["type".into()],
                ..Default::default()
            };
            let req = Request {
                room_id,
                from: Some("token"),
                to: Some("token2"),
                dir: Direction::Backward,
                limit: uint!(0),
                filter,
            };

            let request: http::Request<Vec<u8>> = req
                .try_into_http_request(
                    "https://homeserver.tld",
                    SendAccessToken::IfRequired("auth_tok"),
                    &[MatrixVersion::V1_1],
                )
                .unwrap();
            assert_eq!(
            "from=token\
             &to=token2\
             &dir=b\
             &limit=0\
             &filter=%7B%22not_types%22%3A%5B%22type%22%5D%2C%22not_rooms%22%3A%5B%22%21room%3Aexample.org%22%2C%22%21room2%3Aexample.org%22%2C%22%21room3%3Aexample.org%22%5D%2C%22rooms%22%3A%5B%22%21roomid%3Aexample.org%22%5D%2C%22lazy_load_members%22%3Atrue%2C%22include_redundant_members%22%3Atrue%7D",
            request.uri().query().unwrap()
        );
        }

        #[test]
        fn serialize_default_room_event_filter() {
            let room_id = room_id!("!roomid:example.org");
            let req = Request {
                room_id,
                from: Some("token"),
                to: Some("token2"),
                dir: Direction::Backward,
                limit: uint!(0),
                filter: RoomEventFilter::default(),
            };

            let request = req
                .try_into_http_request::<Vec<u8>>(
                    "https://homeserver.tld",
                    SendAccessToken::IfRequired("auth_tok"),
                    &[MatrixVersion::V1_1],
                )
                .unwrap();
            assert_eq!("from=token&to=token2&dir=b&limit=0", request.uri().query().unwrap(),);
        }
    }
}