use std::marker::PhantomData;
use std::sync::Arc;

use chrono::prelude::*;
use lazy_static::lazy_static;
use rand::seq::SliceRandom;
use rand::thread_rng;
use regex::Regex;
use serde::de::DeserializeOwned;
use serde::{Deserialize, Serialize};
use serde_repr::{Deserialize_repr, Serialize_repr};

use crate::auth::Auth;
use crate::crypto::CipherParams;
use crate::error::*;
use crate::http::PaginatedRequestBuilder;
use crate::options::ClientOptions;
use crate::stats::Stats;
use crate::{http, json, presence, stats, Result};

pub const DEFAULT_FORMAT: Format = Format::MessagePack;

/// A client for the [Ably REST API].
///
/// [Ably REST API]: https://ably.com/documentation/rest-api
#[derive(Debug)]
pub(crate) struct RestInner {
    #[allow(dead_code)]
    pub channels: (),
    pub reqwest: reqwest::Client,
    pub opts: ClientOptions,
    pub url: reqwest::Url,
}

#[derive(Debug, Clone)]
pub struct Rest {
    pub(crate) inner: Arc<RestInner>,
}

impl Rest {
    pub fn auth(&self) -> Auth {
        Auth { rest: self }
    }

    pub fn channels(&self) -> Channels {
        Channels { rest: self }
    }

    pub fn options(&self) -> &ClientOptions {
        &self.inner.opts
    }

    pub fn new(key: &str) -> Result<Self> {
        ClientOptions::new(key).rest()
    }

    pub(crate) fn create(reqwest: reqwest::Client, opts: ClientOptions, url: reqwest::Url) -> Self {
        Self {
            inner: Arc::new(RestInner {
                reqwest,
                opts,
                url,
                channels: (),
            }),
        }
    }

    /// Start building a GET request to /stats.
    ///
    /// Returns a stats::RequestBuilder which is used to set parameters before
    /// sending the stats request.
    ///
    /// # Example
    ///
    /// ```
    /// # async fn run() -> ably::Result<()> {
    /// use ably::stats::Stats;
    ///
    /// let client = ably::Rest::from("<api_key>");
    ///
    /// let res = client
    ///     .stats()
    ///     .start("2021-09-09:15:00")
    ///     .end("2021-09-09:15:05")
    ///     .send()
    ///     .await?;
    ///
    /// let stats = res.items().await?;
    /// # Ok(())
    /// # }
    /// ```
    pub fn stats(&self) -> http::PaginatedRequestBuilder<stats::Stats> {
        self.paginated_request_with_options(http::Method::GET, "/stats", ())
    }

    /// Sends a GET request to /time and returns the server time in UTC.
    ///
    /// # Example
    ///
    /// ```
    /// # async fn run() -> ably::Result<()> {
    /// let client = ably::Rest::from("<api_key>");
    ///
    /// let time = client.time().await?;
    /// # Ok(())
    /// # }
    /// ```
    pub async fn time(&self) -> Result<DateTime<Utc>> {
        let mut res: Vec<i64> = self
            .request(http::Method::GET, "/time")
            .send()
            .await?
            .body()
            .await?;

        let time = res
            .pop()
            .ok_or_else(|| Error::new(ErrorCode::BadRequest, "Invalid response from /time"))?;

        Ok(Utc.timestamp_millis(time))
    }

    /// Start building a HTTP request to the Ably REST API.
    ///
    /// Returns a RequestBuilder which can be used to set query params, headers
    /// and the request body before sending the request.
    ///
    /// # Example
    ///
    /// ```
    /// # async fn run() -> ably::Result<()> {
    /// use ably::http::{HeaderMap,Method};
    ///
    /// let client = ably::Rest::from("<api_key>");
    ///
    /// let mut headers = HeaderMap::new();
    /// headers.insert("Foo", "Bar".parse().unwrap());
    ///
    /// let response = client
    ///     .request(Method::POST, "/some/custom/path")
    ///     .params(&[("key1", "val1"), ("key2", "val2")])
    ///     .body(r#"{"json":"body"}"#)
    ///     .headers(headers)
    ///     .send()
    ///     .await?;
    /// # Ok(())
    /// # }
    /// ```
    ///
    /// # Errors
    ///
    /// Returns an error if sending the request fails or if the resulting
    /// response is unsuccessful (i.e. the status code is not in the 200-299
    /// range).
    pub fn request(&self, method: http::Method, path: &str) -> http::RequestBuilder {
        let mut url = self.inner.url.clone();
        url.set_path(path);
        self.request_url(method, url)
    }

    pub(crate) fn request_url(
        &self,
        method: http::Method,
        url: impl reqwest::IntoUrl,
    ) -> http::RequestBuilder {
        http::RequestBuilder::new(
            self,
            self.inner.reqwest.request(method, url),
            self.inner.opts.format,
        )
    }

    /// Start building a paginated HTTP request to the Ably REST API.
    ///
    /// Returns a PaginatedRequestBuilder which can be used to set query
    /// params before sending the request.
    ///
    /// # Example
    ///
    /// ```
    /// # async fn run() -> ably::Result<()> {
    /// use futures::TryStreamExt;
    /// use ably::http::Method;
    ///
    /// let client = ably::Rest::from("<api_key>");
    ///
    /// let mut pages = client
    ///     .paginated_request::<String>(Method::GET, "/time")
    ///     .forwards()
    ///     .limit(1)
    ///     .pages();
    ///
    /// let page = pages.try_next().await?.expect("Expected a page");
    ///
    /// let items = page.items().await?;
    ///
    /// assert_eq!(items.len(), 1);
    /// # Ok(())
    /// # }
    /// ```
    ///
    /// # Errors
    ///
    /// Returns an error if sending the request fails or if the resulting
    /// response is unsuccessful (i.e. the status code is not in the 200-299
    /// range).
    pub fn paginated_request_with_options<'a, T: Decode + 'a>(
        &'a self,
        method: http::Method,
        path: &str,
        options: T::Options,
    ) -> http::PaginatedRequestBuilder<T> {
        http::PaginatedRequestBuilder::new(self.request(method, path), options)
    }

    pub fn paginated_request<'a, T: DeserializeOwned + Send + 'static>(
        &'a self,
        method: http::Method,
        path: &str,
    ) -> http::PaginatedRequestBuilder<DecodeRaw<T>> {
        self.paginated_request_with_options(method, path, ())
    }

    /// Send the given request, retrying against fallback hosts if it fails.
    pub(crate) async fn send(
        &self,
        req: reqwest::Request,
        authenticate: bool,
    ) -> Result<http::Response> {
        // Executing the request will consume it, so clone it first for a
        // potential retry later.
        let mut next_req = req.try_clone();

        // Execute the request, and return the response if it succeeds.
        let mut err = match self.execute(req, authenticate).await {
            Ok(res) => return Ok(res),
            Err(err) => err,
        };

        // Return the error if we're unable to retry against fallback hosts.
        if next_req.is_none() || !Self::is_retriable(&err) {
            return Err(err);
        }

        if self.inner.opts.fallback_hosts.is_empty() {
            return Err(err);
        }

        // Create a randomised list of fallback hosts if they're set.
        let mut hosts = self.inner.opts.fallback_hosts.clone();
        hosts.shuffle(&mut thread_rng());

        // Try sending the request to the fallback hosts, capped at
        // ClientOptions.httpMaxRetryCount.
        for host in hosts.iter().take(self.inner.opts.http_max_retry_count) {
            // Check we have a next request to send.
            let mut req = match next_req {
                Some(req) => req,
                None => break,
            };

            // Update the request host and prepare the next request.
            next_req = req.try_clone();
            req.url_mut().set_host(Some(host)).map_err(|err| {
                Error::new(
                    ErrorCode::BadRequest,
                    format!("invalid fallback host '{}': {}", host, err),
                )
            })?;

            // Execute the request, and return the response if it succeeds.
            err = match self.execute(req, authenticate).await {
                Ok(res) => return Ok(res),
                Err(err) => err,
            };

            // Continue only if the request can be retried.
            if !Self::is_retriable(&err) {
                break;
            }
        }

        Err(err)
    }

    async fn execute(
        &self,
        mut req: reqwest::Request,
        authenticate: bool,
    ) -> Result<http::Response> {
        if authenticate {
            self.auth().with_auth_headers(&mut req).await?;
        }

        let res = self.inner.reqwest.execute(req).await?;

        // Return the response if it was successful, otherwise try to decode a
        // JSON error from the response body, falling back to a generic error
        // if decoding fails.
        if res.status().is_success() {
            return Ok(http::Response::new(res));
        }

        let status_code: u32 = res.status().as_u16().into();
        Err(res
            .json::<WrappedError>()
            .await
            .map(|e| e.error)
            .unwrap_or_else(|err| {
                Error::with_status(
                    ErrorCode::InternalError,
                    status_code,
                    format!("Unexpected error: {}", err),
                )
            }))
    }

    /// Return whether a request can be retried based on the error which
    /// resulted from attempting to send it.
    fn is_retriable(err: &Error) -> bool {
        match err.status_code {
            Some(code) => (500..=504).contains(&code),
            None => true,
        }
    }
}

impl From<&str> for Rest {
    /// Returns a Rest client initialised with an API key or token contained
    /// in the given string.
    ///
    /// # Example
    ///
    /// ```
    /// // Initialise a Rest client with an API key.
    /// let client = ably::Rest::from("<api_key>");
    /// ```
    ///
    /// ```
    /// // Initialise a Rest client with a token.
    /// let client = ably::Rest::from("<token>");
    /// ```
    fn from(s: &str) -> Self {
        // unwrap the result since we're guaranteed to have a valid client when
        // it's initialised with an API key or token.
        ClientOptions::new(s).rest().unwrap()
    }
}

/// Options for publishing messages on a channel.
#[derive(Clone)]
pub struct ChannelOptions {
    pub(crate) cipher: Option<CipherParams>,
}

/// Start building a Channel to publish a message.
pub struct ChannelBuilder<'a> {
    rest: &'a Rest,
    name: String,
    cipher: Option<CipherParams>,
}

impl<'a> ChannelBuilder<'a> {
    fn new(rest: &'a Rest, name: String) -> Self {
        Self {
            rest,
            name,
            cipher: None,
        }
    }

    /// Set the channel cipher parameters.
    pub fn cipher(mut self, cipher: CipherParams) -> Self {
        self.cipher = Some(cipher);
        self
    }

    /// Build the Channel.
    pub fn get(self) -> Channel<'a> {
        let opts = Some(ChannelOptions {
            cipher: self.cipher,
        });

        Channel {
            name: self.name.clone(),
            rest: self.rest,
            presence: Presence::new(self.rest, self.name, opts.clone()),
            opts,
        }
    }
}

/// A collection of Channels.
#[derive(Clone, Debug)]
pub struct Channels<'a> {
    rest: &'a Rest,
}

impl<'a> Channels<'a> {
    pub fn new(rest: &'a Rest) -> Self {
        Self { rest }
    }

    /// Start building a Channel with the given name.
    pub fn name(&self, name: impl Into<String>) -> ChannelBuilder<'a> {
        ChannelBuilder::new(self.rest, name.into())
    }

    /// Build and return a Channel with the given name.
    pub fn get(&self, name: impl Into<String>) -> Channel<'a> {
        self.name(name).get()
    }
}

/// An Ably Channel to publish messages to or retrieve history or presence for.
pub struct Channel<'a> {
    pub name: String,
    pub presence: Presence<'a>,
    rest: &'a Rest,
    opts: Option<ChannelOptions>,
}

impl<'a> Channel<'a> {
    /// Start building a request to publish a message on the channel.
    pub fn publish(&self) -> PublishBuilder {
        let mut builder = PublishBuilder::new(self.rest, self.name.clone());

        if let Some(opts) = &self.opts {
            if let Some(cipher) = &opts.cipher {
                builder = builder.cipher(cipher.clone());
            }
        }

        builder
    }

    /// Start building a history request for the channel.
    ///
    /// Returns a history::RequestBuilder which is used to set parameters
    /// before sending the history request.
    pub fn history(&self) -> PaginatedRequestBuilder<Message> {
        self.rest.paginated_request_with_options(
            http::Method::GET,
            &format!("/channels/{}/history", self.name),
            self.opts.clone(),
        )
    }
}

pub struct Presence<'a> {
    rest: &'a Rest,
    name: String,
    opts: Option<ChannelOptions>,
}

impl<'a> Presence<'a> {
    fn new(rest: &'a Rest, name: String, opts: Option<ChannelOptions>) -> Self {
        Self { rest, name, opts }
    }

    /// Start building a presence request for the channel.
    pub fn get(&self) -> presence::RequestBuilder {
        let req = self.rest.paginated_request_with_options(
            http::Method::GET,
            &format!("/channels/{}/presence", self.name),
            self.opts.clone(),
        );
        presence::RequestBuilder::new(req)
    }

    /// Start building a presence history request for the channel.
    ///
    /// Returns a history::RequestBuilder which is used to set parameters
    /// before sending the history request.
    pub fn history(&self) -> PaginatedRequestBuilder<PresenceMessage> {
        self.rest.paginated_request_with_options(
            http::Method::GET,
            &format!("/channels/{}/presence/history", self.name),
            self.opts.clone(),
        )
    }
}

/// A request to publish a message to a channel.
pub struct PublishBuilder<'a> {
    req: http::RequestBuilder<'a>,
    msg: Result<Message>,
    format: Format,
    cipher: Option<CipherParams>,
}

impl<'a> PublishBuilder<'a> {
    fn new(rest: &'a Rest, channel: String) -> Self {
        let req = rest.request(
            http::Method::POST,
            &format!("/channels/{}/messages", channel),
        );

        Self {
            req,
            msg: Ok(Message::default()),
            format: rest.inner.opts.format,
            cipher: None,
        }
    }

    /// Set the message ID.
    pub fn id(mut self, id: impl Into<String>) -> Self {
        if let Ok(msg) = self.msg.as_mut() {
            msg.id = Some(id.into());
        }
        self
    }

    /// Set the message name.
    pub fn name(mut self, name: impl Into<String>) -> Self {
        if let Ok(msg) = self.msg.as_mut() {
            msg.name = Some(name.into());
        }
        self
    }

    /// Set the message data to the given string.
    pub fn string(mut self, data: impl Into<String>) -> Self {
        if let Ok(msg) = self.msg.as_mut() {
            msg.data = Data::String(data.into());
        }
        self
    }

    /// Set the message data to the JSON encoding of the given data.
    pub fn json(mut self, data: impl serde::Serialize) -> Self {
        if let Ok(msg) = self.msg.as_mut() {
            let data = data
                .serialize(serde_json::value::Serializer)
                .map(Into::into)
                .map_err(|err| {
                    Error::with_cause(
                        ErrorCode::InvalidMessageDataOrEncoding,
                        err,
                        "invalid message data",
                    )
                });

            match data {
                Ok(data) => {
                    msg.data = data;
                }
                Err(err) => self.msg = Err(err),
            }
        }
        self
    }

    /// Set the message data to the given binary data.
    pub fn binary(mut self, data: Vec<u8>) -> Self {
        if let Ok(msg) = self.msg.as_mut() {
            msg.data = data.into();
        }
        self
    }

    /// Set the message extras.
    pub fn extras(mut self, extras: json::Map) -> Self {
        if let Ok(msg) = self.msg.as_mut() {
            msg.extras = Some(extras);
        }
        self
    }

    /// Set the params to include in the publish request.
    pub fn params<T: Serialize + ?Sized>(mut self, params: &T) -> Self {
        self.req = self.req.params(params);
        self
    }

    /// Set the cipher to use to encrypt the message.
    pub fn cipher(mut self, cipher: CipherParams) -> Self {
        self.cipher = Some(cipher);
        self
    }

    /// Publish the message.
    pub async fn send(self) -> Result<()> {
        let mut msg = self.msg?;

        msg.encode(&self.format, self.cipher.as_ref())?;

        self.req.body(&msg).send().await.map(|_| ())
    }
}

/// Data is the payload of a message which can either be a utf-8 encoded
/// string, a JSON serializable object, or a binary array.
#[derive(Clone, Debug, Deserialize, PartialEq, Eq)]
#[serde(untagged)]
pub enum Data {
    String(String),
    JSON(serde_json::Value),
    Binary(serde_bytes::ByteBuf),
    None,
}

impl Data {
    fn is_none(&self) -> bool {
        matches!(self, Self::None)
    }
}

impl Serialize for Data {
    fn serialize<S>(&self, serializer: S) -> ::std::result::Result<S::Ok, S::Error>
    where
        S: serde::Serializer,
    {
        let s = match self {
            Self::String(s) => return s.serialize(serializer),
            Self::JSON(v) => serde_json::to_string(v).map_err(serde::ser::Error::custom)?,
            Self::Binary(v) => return v.serialize(serializer),
            Self::None => String::from(""),
        };
        s.serialize(serializer)
    }
}

impl Default for Data {
    fn default() -> Self {
        Self::None
    }
}

impl From<String> for Data {
    fn from(s: String) -> Self {
        Self::String(s)
    }
}

impl From<&str> for Data {
    fn from(s: &str) -> Self {
        Self::String(s.to_string())
    }
}

impl From<Vec<u8>> for Data {
    fn from(v: Vec<u8>) -> Self {
        Self::Binary(serde_bytes::ByteBuf::from(v))
    }
}

impl From<&[u8]> for Data {
    fn from(v: &[u8]) -> Self {
        Self::Binary(serde_bytes::ByteBuf::from(v))
    }
}

impl From<serde_json::Value> for Data {
    fn from(v: serde_json::Value) -> Self {
        Self::JSON(v)
    }
}

/// The encoding of a message, which is either unset or is a list of data
/// encodings separated by the '/' character.
#[derive(Debug, Deserialize, PartialEq, Eq, Serialize)]
#[serde(untagged)]
pub enum Encoding {
    None,
    Some(String),
}

impl Encoding {
    fn is_none(&self) -> bool {
        match self {
            Self::None => true,
            Self::Some(_) => false,
        }
    }

    /// Append the given encoding to the current list of encodings.
    fn push(&mut self, value: impl Into<String>) {
        *self = Self::Some(match self {
            Self::None => value.into(),
            Self::Some(s) => format!("{}/{}", s, value.into()),
        })
    }

    /// Pop the last encoding from the list of encodings, leaving the list
    /// unset if the popped encoding was the only one in the list.
    fn pop(&mut self) -> Option<String> {
        let mut encodings = match self {
            Self::Some(s) => s.split('/').collect::<Vec<&str>>(),
            Self::None => return None,
        };
        let last = encodings.pop()?.to_string();
        *self = if encodings.is_empty() {
            Self::None
        } else {
            Self::Some(encodings.join("/"))
        };
        Some(last)
    }
}

impl Default for Encoding {
    fn default() -> Self {
        Self::None
    }
}

/// A message which is published to a channel or returned by a history request.
#[derive(Default, Deserialize, Serialize)]
pub struct Message {
    #[serde(skip_serializing_if = "Option::is_none")]
    pub id: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub name: Option<String>,
    #[serde(skip_serializing_if = "Data::is_none")]
    pub data: Data,
    #[serde(default, skip_serializing_if = "Encoding::is_none")]
    pub encoding: Encoding,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub client_id: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub connection_id: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub extras: Option<json::Map>,
}

impl Message {
    /// Initialize a Message from the given JSON serialized data.
    pub fn from_encoded(v: json::Value, opts: Option<&ChannelOptions>) -> Result<Message> {
        let mut msg: Message = serde_json::from_value(v)?;

        // TODO fix unneeded conversion
        Message::decode(&mut msg, &opts.cloned());

        Ok(msg)
    }

    /// Encode the message ready to be sent in the body of a HTTP request.
    ///
    /// If the cipher is set, then use it to encrypt the message.
    pub fn encode(&mut self, format: &Format, cipher: Option<&CipherParams>) -> Result<()> {
        self.encode_with_iv(format, cipher, None)
    }

    pub(crate) fn encode_with_iv(
        &mut self,
        format: &Format,
        cipher: Option<&CipherParams>,
        iv: Option<Vec<u8>>,
    ) -> Result<()> {
        match &self.data {
            Data::String(data) => {
                if let Some(cipher) = cipher {
                    let data = data.as_bytes();
                    self.data = cipher.encrypt(iv, data)?.into();
                    self.encoding.push("utf-8");
                    self.encoding.push(cipher.encoding());
                }
            }
            Data::Binary(data) => {
                if let Some(cipher) = cipher {
                    self.data = cipher.encrypt(iv, data)?.into();
                    self.encoding.push(cipher.encoding());
                }
            }
            Data::JSON(data) => {
                let json_str = serde_json::to_string(data)?;

                if let Some(cipher) = cipher {
                    let data = json_str.as_bytes();
                    self.data = cipher.encrypt(iv, data)?.into();
                    self.encoding.push("json");
                    self.encoding.push("utf-8");
                    self.encoding.push(cipher.encoding());
                } else {
                    self.data = json_str.into();
                    self.encoding.push("json");
                }
            }
            Data::None => (),
        }

        // If we have binary data but JSON format, base64 encode the data.
        if let Data::Binary(data) = &self.data {
            if format.is_json() {
                self.data = base64::encode(data).into();
                self.encoding.push("base64");
            }
        };

        Ok(())
    }
}

#[derive(Deserialize, Serialize)]
#[serde(rename_all = "camelCase")]
pub struct PresenceMessage {
    pub action: PresenceAction,
    pub client_id: String,
    pub connection_id: String,
    #[serde(skip_serializing_if = "Data::is_none")]
    pub data: Data,
    #[serde(default, skip_serializing_if = "Encoding::is_none")]
    pub encoding: Encoding,
}

/// Iteratively decode the given data based on the given list of encodings.
fn decode(data: &mut Data, encoding: &mut Encoding, opts: Option<&ChannelOptions>) {
    while let Some(enc) = encoding.pop() {
        *data = match decode_once(data, &enc, opts) {
            Ok(data) => data,
            Err(_) => {
                encoding.push(enc);
                return;
            }
        }
    }
}

lazy_static! {
    /// A regular expression to split a data encoding into its format and params.
    static ref ENCODING_RE: Regex =
        Regex::new(r#"^(?P<format>[\-\w]+)(?:\+(?P<params>[\-\w]+))?"#).unwrap();
}

fn decode_once(data: &mut Data, encoding: &str, opts: Option<&ChannelOptions>) -> Result<Data> {
    let caps = ENCODING_RE
        .captures(encoding)
        .ok_or_else(|| Error::new(ErrorCode::InvalidHeader, "Invalid encoding"))?;
    let format = caps
        .name("format")
        .ok_or_else(|| Error::new(ErrorCode::InvalidHeader, "Invalid encoding; missing format"))?
        .as_str();

    match format {
        "utf-8" => match data {
            Data::String(s) => Ok(Data::String(s.to_string())),
            Data::Binary(data) => std::str::from_utf8(data)
                .map(Into::into)
                .map_err(Into::into),
            _ => Err(Error::new(
                ErrorCode::InvalidMessageDataOrEncoding,
                "invalid utf-8 message data",
            )),
        },
        "json" => match data {
            Data::String(s) => serde_json::from_str::<serde_json::Value>(s)
                .map(Into::into)
                .map_err(Into::into),
            _ => Err(Error::new(
                ErrorCode::InvalidMessageDataOrEncoding,
                "invalid JSON message data",
            )),
        },
        "base64" => match data {
            Data::String(s) => base64::decode(s).map(Into::into).map_err(Into::into),
            _ => Err(Error::new(
                ErrorCode::InvalidMessageDataOrEncoding,
                "invalid base64 message data",
            )),
        },
        "cipher" => match data {
            Data::Binary(ref mut data) => {
                let opts = opts.ok_or_else(|| {
                    Error::new(
                        ErrorCode::BadRequest,
                        "unable to decrypt message, no channel options",
                    )
                })?;
                let cipher = opts.cipher.as_ref().ok_or_else(|| {
                    Error::new(
                        ErrorCode::BadRequest,
                        "unable to decrypt message, no cipher params",
                    )
                })?;
                let params = caps.name("params").ok_or_else(|| {
                    Error::new(ErrorCode::InvalidHeader, "Invalid encoding; missing params")
                })?;
                if params.as_str() != cipher.algorithm() {
                    return Err(Error::new(
                        ErrorCode::BadRequest,
                        "unable to decrypt message, incompatible cipher params",
                    ));
                }
                cipher.decrypt(data).map(Into::into)
            }
            _ => Err(Error::new(
                ErrorCode::InvalidMessageDataOrEncoding,
                "invalid cipher message data",
            )),
        },
        _ => Err(Error::new(
            ErrorCode::InvalidMessageDataOrEncoding,
            "invalid message encoding",
        )),
    }
}

#[derive(Clone, Debug, Deserialize_repr, PartialEq, Eq, Serialize_repr)]
#[serde(untagged)]
#[repr(u8)]
pub enum PresenceAction {
    Absent,
    Present,
    Enter,
    Leave,
    Update,
}

#[derive(Copy, Clone, Debug)]
pub enum Format {
    MessagePack,
    JSON,
}

impl Format {
    fn is_json(&self) -> bool {
        match self {
            Self::MessagePack => false,
            Self::JSON => true,
        }
    }
}

pub struct DecodeRaw<T>(PhantomData<T>);

pub trait Decode {
    type Options: Clone + Send;
    type Item: DeserializeOwned + Send + 'static;
    fn decode(item: &mut Self::Item, options: &Self::Options);
}

impl Decode for Message {
    type Options = Option<ChannelOptions>;
    type Item = Self;

    fn decode(item: &mut Self::Item, options: &Self::Options) {
        crate::rest::decode(&mut item.data, &mut item.encoding, options.as_ref());
    }
}

impl Decode for Stats {
    type Options = ();
    type Item = Self;
    fn decode(_item: &mut Self::Item, _options: &Self::Options) {}
}

impl Decode for PresenceMessage {
    type Options = Option<ChannelOptions>;
    type Item = Self;

    fn decode(item: &mut Self::Item, options: &Self::Options) {
        crate::rest::decode(&mut item.data, &mut item.encoding, options.as_ref());
    }
}

impl<T: DeserializeOwned + 'static + Send> Decode for DecodeRaw<T> {
    type Options = ();
    type Item = T;
    fn decode(_item: &mut Self::Item, _options: &Self::Options) {}
}