crypto-botters 0.6.0

//! A module for communicating with the [coincheck API](https://coincheck.com/ja/documents/exchange/api).
//! For example usages, see files in the examples/ directory.

use std::{
    marker::PhantomData,
    time::SystemTime,
};
use hmac::{Hmac, Mac};
use sha2::Sha256;
use serde::{de::DeserializeOwned, Serialize};
use serde_json::json;
use generic_api_client::{http::{*, header::HeaderValue}, websocket::*};
use crate::traits::*;

/// The type returned by [Client::request()].
pub type CoincheckRequestResult<T> = Result<T, CoincheckRequestError>;
pub type CoincheckRequestError = RequestError<&'static str, CoincheckHandlerError>;

/// Options that can be set when creating handlers
pub enum CoincheckOption {
    /// [Default] variant, does nothing
    Default,
    /// API key
    Key(String),
    /// Api secret
    Secret(String),
    /// Base url for HTTP requests
    HttpUrl(CoincheckHttpUrl),
    /// Whether [CoincheckRequestHandler] should perform authentication
    HttpAuth(bool),
    /// [RequestConfig] used when sending requests.
    /// `url_prefix` will be overridden by [HttpUrl](Self::HttpUrl) unless `HttpUrl` is [CoincheckHttpUrl::None].
    RequestConfig(RequestConfig),
    /// Base url for WebSocket connections
    WebSocketUrl(CoincheckWebSocketUrl),
    /// The channels to be subscribed by [WebSocketHandler].
    WebSocketChannels(Vec<String>),
    /// [WebSocketConfig] used for creating [WebSocketConnection]s
    /// `url_prefix` will be overridden by [WebSocketUrl](Self::WebSocketUrl) unless `WebSocketUrl` is [CoincheckWebSocketUrl::None].
    /// By default, ignore_duplicate_during_reconnection` is set to `true`.
    WebSocketConfig(WebSocketConfig),
}

/// A `struct` that represents a set of [CoincheckOption] s.
#[derive(Clone, Debug)]
pub struct CoincheckOptions {
    /// see [CoincheckOption::Key]
    pub key: Option<String>,
    /// see [CoincheckOption::Secret]
    pub secret: Option<String>,
    /// see [CoincheckOption::HttpUrl]
    pub http_url: CoincheckHttpUrl,
    /// see [CoincheckOption::HttpAuth]
    pub http_auth: bool,
    /// see [CoincheckOption::RequestConfig]
    pub request_config: RequestConfig,
    /// see [CoincheckOption::WebSocketUrl]
    pub websocket_url: CoincheckWebSocketUrl,
    /// see [CoincheckOption::WebSocketChannels]
    pub websocket_channels: Vec<String>,
    /// see [CoincheckOption::WebSocketConfig]
    pub websocket_config: WebSocketConfig,
}

/// A `enum` that represents the base url of the Coincheck HTTP API.
#[derive(Debug, Eq, PartialEq, Copy, Clone)]
pub enum CoincheckHttpUrl {
    /// `https://coincheck.com`
    Default,
    /// The url will not be modified by [CoincheckRequestHandler]
    None,
}

/// A `enum` that represents the base url of the Coincheck Realtime API
#[derive(Debug, Eq, PartialEq, Copy, Clone)]
#[non_exhaustive]
pub enum CoincheckWebSocketUrl {
    /// `wss://ws-api.coincheck.com/`
    Default,
    /// The url will not be modified by [CoincheckWebSocketHandler]
    None,
}

#[derive(Debug)]
pub enum CoincheckHandlerError {
    ApiError(serde_json::Value),
    RequestLimitExceeded(serde_json::Value),
    ParseError,
}

/// A `struct` that implements [RequestHandler]
pub struct CoincheckRequestHandler<'a, R: DeserializeOwned> {
    options: CoincheckOptions,
    _phantom: PhantomData<&'a R>,
}

/// A `struct` that implements [WebSocketHandler]
pub struct CoincheckWebSocketHandler {
    message_handler: Box<dyn FnMut(serde_json::Value) + Send>,
    options: CoincheckOptions,
}

impl<'a, B, R> RequestHandler<B> for CoincheckRequestHandler<'a, R>
where
    B: Serialize,
    R: DeserializeOwned,
{
    type Successful = R;
    type Unsuccessful = CoincheckHandlerError;
    type BuildError = &'static str;

    fn request_config(&self) -> RequestConfig {
        let mut config = self.options.request_config.clone();
        if self.options.http_url != CoincheckHttpUrl::None {
            config.url_prefix = self.options.http_url.as_str().to_owned();
        }
        config
    }

    fn build_request(&self, mut builder: RequestBuilder, request_body: &Option<B>, _: u8) -> Result<Request, Self::BuildError> {
        if let Some(body) = request_body {
            let encoded = serde_urlencoded::to_string(body).or(Err("could not serialize body as application/x-www-form-urlencoded"))?;
            builder = builder
                .header(header::CONTENT_TYPE, "application/x-www-form-urlencoded")
                .body(encoded);
        }

        let mut request = builder.build().or(Err("failed to build request"))?;

        if self.options.http_auth {
            // https://coincheck.com/ja/documents/exchange/api#auth
            let time = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap(); // always after the epoch
            let nonce = time.as_millis() as u64;

            let body = request.body()
                .and_then(|body| body.as_bytes())
                .map(String::from_utf8_lossy)
                .unwrap_or_default();

            let sign_contents = format!("{}{}{}", nonce, request.url(), body);

            let secret = self.options.secret.as_deref().ok_or("API secret not set")?;
            let mut hmac = Hmac::<Sha256>::new_from_slice(secret.as_bytes()).unwrap(); // hmac accepts key of any length

            hmac.update(sign_contents.as_bytes());
            let signature = hex::encode(hmac.finalize().into_bytes());

            let key = HeaderValue::from_str(self.options.key.as_deref().ok_or("API key not set")?).or(
                Err("invalid character in API key")
            )?;
            let headers = request.headers_mut();
            headers.insert("ACCESS-KEY", key);
            headers.insert("ACCESS-NONCE", HeaderValue::from(nonce));
            headers.insert("ACCESS-SIGNATURE", HeaderValue::from_str(&signature).unwrap()); // hex digits are valid
        }

        Ok(request)
    }

    fn handle_response(&self, status: StatusCode, _: HeaderMap, response_body: Bytes) -> Result<Self::Successful, Self::Unsuccessful> {
        if status.is_success() {
            serde_json::from_slice(&response_body).map_err(|error| {
                log::debug!("Failed to parse response due to an error: {}", error);
                CoincheckHandlerError::ParseError
            })
        } else {
            let error = match serde_json::from_slice(&response_body) {
                Ok(parsed_error) => {
                    if status == 429 {
                        CoincheckHandlerError::RequestLimitExceeded(parsed_error)
                    } else {
                        CoincheckHandlerError::ApiError(parsed_error)
                    }
                },
                Err(error) => {
                    log::debug!("Failed to parse error response due to an error: {}", error);
                    CoincheckHandlerError::ParseError
                }
            };
            Err(error)
        }
    }
}

impl WebSocketHandler for CoincheckWebSocketHandler {
    fn websocket_config(&self) -> WebSocketConfig {
        let mut config = self.options.websocket_config.clone();
        if self.options.websocket_url != CoincheckWebSocketUrl::None {
            config.url_prefix = self.options.websocket_url.as_str().to_owned();
        }
        config
    }

    fn handle_start(&mut self) -> Vec<WebSocketMessage> {
        self.options.websocket_channels.clone().into_iter().map(|channel| {
            WebSocketMessage::Text(json!({ "type": "subscribe", "channel": channel }).to_string())
        }).collect()
    }

    fn handle_message(&mut self, message: WebSocketMessage) -> Vec<WebSocketMessage> {
        match message {
            WebSocketMessage::Text(message) => {
                match serde_json::from_str(&message) {
                    Ok(message) => (self.message_handler)(message),
                    Err(_) => log::debug!("Invalid JSON message received"),
                };
            },
            WebSocketMessage::Binary(_) => log::debug!("Unexpected binary message received"),
            WebSocketMessage::Ping(_) | WebSocketMessage::Pong(_) => (),
        }
        vec![]
    }
}

impl CoincheckHttpUrl {
    /// The base URL that this variant represents.
    #[inline(always)]
    fn as_str(&self) -> &'static str {
        match self {
            Self::Default => "https://coincheck.com",
            Self::None => "",
        }
    }
}

impl CoincheckWebSocketUrl {
    /// The base URL that this variant represents.
    #[inline(always)]
    fn as_str(&self) -> &'static str {
        match self {
            Self::Default => "wss://ws-api.coincheck.com/",
            Self::None => "",
        }
    }
}

impl HandlerOptions for CoincheckOptions {
    type OptionItem = CoincheckOption;

    fn update(&mut self, option: Self::OptionItem) {
        match option {
            CoincheckOption::Default => (),
            CoincheckOption::Key(v) => self.key = Some(v),
            CoincheckOption::Secret(v) => self.secret = Some(v),
            CoincheckOption::HttpUrl(v) => self.http_url = v,
            CoincheckOption::HttpAuth(v) => self.http_auth = v,
            CoincheckOption::RequestConfig(v) => self.request_config = v,
            CoincheckOption::WebSocketUrl(v) => self.websocket_url = v,
            CoincheckOption::WebSocketChannels(v) => self.websocket_channels = v,
            CoincheckOption::WebSocketConfig(v) => self.websocket_config = v,
        }
    }
}

impl Default for CoincheckOptions {
    fn default() -> Self {
        let mut websocket_config = WebSocketConfig::new();
        websocket_config.ignore_duplicate_during_reconnection = true;
        Self {
            key: None,
            secret: None,
            http_url: CoincheckHttpUrl::Default,
            http_auth: false,
            request_config: RequestConfig::default(),
            websocket_url: CoincheckWebSocketUrl::Default,
            websocket_channels: vec![],
            websocket_config,
        }
    }
}

impl<'a, R, B> HttpOption<'a, R, B> for CoincheckOption
where
    R: DeserializeOwned + 'a,
    B: Serialize,
{
    type RequestHandler = CoincheckRequestHandler<'a, R>;

    #[inline(always)]
    fn request_handler(options: Self::Options) -> Self::RequestHandler {
        CoincheckRequestHandler::<'a, R> {
            options,
            _phantom: PhantomData,
        }
    }
}

impl<H: FnMut(serde_json::Value) + Send + 'static> WebSocketOption<H> for CoincheckOption {
    type WebSocketHandler = CoincheckWebSocketHandler;

    #[inline(always)]
    fn websocket_handler(handler: H, options: Self::Options) -> Self::WebSocketHandler {
        CoincheckWebSocketHandler {
            message_handler: Box::new(handler),
            options,
        }
    }
}

impl HandlerOption for CoincheckOption {
    type Options = CoincheckOptions;
}

impl Default for CoincheckOption {
    fn default() -> Self {
        Self::Default
    }
}