v_exchanges_adapters 0.18.1

// A module for communicating with the MEXC API (https://mexcdevelop.github.io/apidocs/spot/en/)

use std::{collections::HashSet, marker::PhantomData, str::FromStr, time::SystemTime};

use ahash::AHashSet;
use eyre::eyre;
use generics::{ConstructAuthError, UrlError};
use hmac::{Hmac, KeyInit as _, Mac};
use jiff::{SignedDuration, Timestamp};
use secrecy::{ExposeSecret as _, SecretString};
use serde::{Deserialize, Serialize, de::DeserializeOwned};
use sha2::Sha256;
use url::Url;
use v_exchanges_api_generics::{http::*, ws::*};

use crate::traits::*;

/// Options that can be set when creating handlers
#[derive(Debug, Default)]
pub enum MexcOption {
	/// Does nothing
	#[default]
	Default,
	/// API key
	Pubkey(String),
	/// Api secret
	Secret(SecretString),
	/// Whether to make all requests to the testnet
	Testnet(bool),
	/// Base url for HTTP requests
	HttpUrl(MexcHttpUrl),
	/// Authentication type for HTTP requests
	HttpAuth(MexcAuth),
	/// receive window parameter used for requests
	RecvWindow(std::time::Duration),
	/// Base url for Ws connections
	WsUrl(MexcWsUrl),
	/// WsConfig used for creating WsConnections
	WsConfig(WsConfig),
	/// Topics to subscribe to on Ws connections
	WsTopics(Vec<String>),
}
/// A struct that represents a set of MexcOptions
#[derive(Clone, derive_more::Debug, Default)]
pub struct MexcOptions {
	/// see [MexcOption::Key]
	pub pubkey: Option<String>,
	/// see [MexcOption::Secret]
	#[debug("[REDACTED]")]
	pub secret: Option<SecretString>,
	/// see [MexcOption::Testnet]
	pub testnet: bool,
	/// see [MexcOption::HttpUrl]
	pub http_url: MexcHttpUrl,
	/// see [MexcOption::HttpAuth]
	pub http_auth: MexcAuth,
	/// see [MexcOption::RecvWindow]
	pub recv_window: Option<std::time::Duration>,
	/// see [MexcOption::WsUrl]
	pub ws_url: MexcWsUrl,
	/// see [MexcOption::WsConfig]
	pub ws_config: WsConfig,
	/// see [MexcOption::WsTopics]
	pub ws_topics: AHashSet<String>,
}
/// Enum that represents the base url of the MEXC REST API
#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
#[non_exhaustive]
pub enum MexcHttpUrl {
	Spot,
	Futures,
	#[default]
	None,
}
#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
pub enum MexcAuth {
	Sign,
	Key,
	#[default]
	None,
}
#[derive(Debug, Deserialize, Serialize)]
pub struct MexcError {
	pub code: MexcErrorCode,
	#[serde(alias = "message")]
	pub msg: String,
}
#[non_exhaustive]
#[derive(Clone, Copy, Debug, Deserialize, PartialEq, Serialize)]
#[serde(from = "i32", into = "i32")]
pub enum MexcErrorCode {
	// Auth
	Unauthorized(i32),
	InvalidApiKey(i32),
	InvalidSignature(i32),
	ApiKeyExpired(i32),
	SignatureNotValid(i32),

	// Rate limiting
	TooManyRequests(i32),

	// General
	BadSymbol(i32),
	PermissionDenied(i32),

	Other(i32),
}
impl MexcErrorCode {
	fn as_i32(self) -> i32 {
		match self {
			Self::Unauthorized(c)
			| Self::InvalidApiKey(c)
			| Self::InvalidSignature(c)
			| Self::ApiKeyExpired(c)
			| Self::SignatureNotValid(c)
			| Self::TooManyRequests(c)
			| Self::BadSymbol(c)
			| Self::PermissionDenied(c)
			| Self::Other(c) => c,
		}
	}
}

/// A struct that implements RequestHandler
pub struct MexcRequestHandler<'a, R: DeserializeOwned> {
	options: MexcOptions,
	_phantom: PhantomData<&'a R>,
}
/// A struct that implements [WsHandler]
#[derive(Debug, derive_new::new)]
pub struct MexcWsHandler {
	options: MexcOptions,
}
/// Enum that represents the base url of the MEXC Ws API
#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
#[non_exhaustive]
pub enum MexcWsUrl {
	Spot,
	Futures,
	#[default]
	None,
}
static MAX_RECV_WINDOW: std::time::Duration = std::time::Duration::from_millis(60000); // as of (2025/01/18)

impl EndpointUrl for MexcHttpUrl {
	fn url_mainnet(&self) -> Url {
		match self {
			Self::Spot => Url::parse("https://api.mexc.com").unwrap(),
			Self::Futures => Url::parse("https://contract.mexc.com").unwrap(),
			Self::None => Url::parse("").unwrap(),
		}
	}

	fn url_testnet(&self) -> Option<Url> {
		match self {
			Self::Spot => Some(Url::parse("https://api-testnet.mexc.com").unwrap()),
			Self::Futures => Some(Url::parse("https://contract-testnet.mexc.com").unwrap()),
			Self::None => Some(Url::parse("").unwrap()),
		}
	}
}

/// Envelope used by MEXC futures API, which returns errors with HTTP 200
#[derive(Deserialize)]
struct MexcEnvelope {
	success: bool,
	code: i32,
	#[serde(default)]
	message: String,
}

impl From<MexcError> for ApiError {
	fn from(e: MexcError) -> Self {
		use v_exchanges_api_generics::http::AuthError;
		match e.code {
			MexcErrorCode::ApiKeyExpired(_) => AuthError::KeyExpired { msg: e.msg }.into(),
			MexcErrorCode::Unauthorized(_) | MexcErrorCode::InvalidApiKey(_) | MexcErrorCode::InvalidSignature(_) | MexcErrorCode::SignatureNotValid(_) =>
				AuthError::Unauthorized { msg: e.msg }.into(),
			_ => ApiError::Other(eyre!("MEXC API error {}: {}", e.code.as_i32(), e.msg)),
		}
	}
}

impl From<i32> for MexcErrorCode {
	fn from(code: i32) -> Self {
		match code {
			602 => Self::Unauthorized(code),
			10001 => Self::InvalidApiKey(code),
			140002 => Self::InvalidSignature(code),
			402 | 700001 => Self::ApiKeyExpired(code),
			700002 => Self::SignatureNotValid(code),
			700007 | 700013 => Self::InvalidSignature(code),
			70011 => Self::PermissionDenied(code),
			10007 => Self::BadSymbol(code),
			code => Self::Other(code),
		}
	}
}

impl From<MexcErrorCode> for i32 {
	fn from(code: MexcErrorCode) -> Self {
		code.as_i32()
	}
}

impl<B, R> RequestHandler<B> for MexcRequestHandler<'_, R>
where
	B: Serialize,
	R: DeserializeOwned,
{
	type Successful = R;

	fn base_url(&self, is_test: bool) -> Result<Url, UrlError> {
		match is_test {
			true => self.options.http_url.url_testnet().ok_or_else(|| UrlError::MissingTestnet(self.options.http_url.url_mainnet())),
			false => Ok(self.options.http_url.url_mainnet()),
		}
	}

	#[tracing::instrument(skip_all, fields(?builder))]
	fn build_request(&self, mut builder: RequestBuilder, request_body: &Option<B>, _: u8) -> Result<Request, BuildError> {
		if let Some(body) = request_body {
			let encoded = serde_urlencoded::to_string(body)?;
			builder = builder.header(header::CONTENT_TYPE, "application/x-www-form-urlencoded").body(encoded);
			//builder = builder.header(header::CONTENT_TYPE, "application/json");
		}

		if self.options.http_auth != MexcAuth::None {
			let pubkey = self.options.pubkey.as_deref().ok_or(ConstructAuthError::new_missing_pubkey())?;
			builder = builder.header("ApiKey", pubkey);

			let time = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap();
			let timestamp = time.as_millis();
			builder = builder.header("Request-Time", timestamp.to_string());

			if let Some(recv_window) = self.options.recv_window {
				builder = builder.header("Recv-Window", (recv_window.as_millis() as u64).to_string());
			}

			if self.options.http_auth == MexcAuth::Sign {
				let secret = self.options.secret.as_ref().map(|s| s.expose_secret()).ok_or(ConstructAuthError::new_missing_secret())?;
				let mut hmac = Hmac::<Sha256>::new_from_slice(secret.as_bytes()).unwrap();

				let mut request = builder.build().expect("My understanding is that this doesn't fail on client, so fail fast for dev");
				let param_string = if request.method() == Method::GET || request.method() == Method::DELETE {
					if let Some(body) = request_body { serde_urlencoded::to_string(body)? } else { String::new() }
				} else {
					// For POST, use body as JSON string
					String::from_utf8(request.body().and_then(|body| body.as_bytes()).unwrap_or_default().to_vec()).unwrap_or_default()
				};

				let signature_base = format!("{pubkey}{timestamp}{param_string}");
				hmac.update(signature_base.as_bytes());
				let signature = hex::encode(hmac.finalize().into_bytes());
				request.headers_mut().insert("Signature", signature.parse().unwrap());

				return Ok(request);
			}
		}
		Ok(builder.build().expect("Don't expect this to be reached by client. Same reasoning - fail fast for dev"))
	}

	fn handle_response(&self, status: StatusCode, headers: HeaderMap, response_body: Bytes) -> Result<Self::Successful, HandleError> {
		if status.is_success() {
			// MEXC futures API returns errors with HTTP 200 but `"success": false` in the body
			if let Ok(envelope) = serde_json::from_slice::<MexcEnvelope>(&response_body)
				&& !envelope.success
			{
				let api_error = MexcError {
					code: envelope.code.into(),
					msg: envelope.message,
				};
				return Err(ApiError::from(api_error).into());
			}
			serde_json::from_slice(&response_body).map_err(|error| {
				let response_str = v_utils::utils::truncate_msg(String::from_utf8_lossy(&response_body));
				HandleError::Parse(eyre!("Failed to parse response: {error}\nResponse body: {response_str}"))
			})
		} else {
			if status == 401 {
				use v_exchanges_api_generics::http::AuthError;
				let msg = match std::str::from_utf8(&response_body) {
					Ok(s) if !s.is_empty() => s.to_string(),
					_ => "HTTP 401 Unauthorized".to_string(),
				};
				return Err(ApiError::Auth(AuthError::Unauthorized { msg }).into());
			}
			//Q: does MEXC even have this, or am I just blindly copying from Binance?
			if status == 429 {
				let retry_after_sec = if let Some(value) = headers.get("Retry-After") {
					if let Ok(string) = value.to_str() {
						if let Ok(retry_after) = u32::from_str(string) {
							Some(retry_after)
						} else {
							tracing::debug!("Invalid number in Retry-After header");
							None
						}
					} else {
						tracing::debug!("Non-ASCII character in Retry-After header");
						None
					}
				} else {
					None
				};
				let e = match retry_after_sec {
					Some(s) => {
						let until = Some(Timestamp::now() + SignedDuration::from_secs(s as i64));
						ApiError::from(IpError::Timeout { until }).into()
					}
					None => eyre!("Could't interpret Retry-After header").into(),
				};
				return Err(e);
			}

			let api_error: MexcError = match serde_json::from_slice(&response_body) {
				Ok(parsed) => parsed,
				Err(error) => {
					let response_str = v_utils::utils::truncate_msg(String::from_utf8_lossy(&response_body));
					return Err(HandleError::Parse(eyre!("Failed to parse error response: {error}\nResponse body: {response_str}")));
				}
			};
			Err(ApiError::from(api_error).into())
		}
	}
}

// Ws stuff {{{
impl WsHandler for MexcWsHandler {
	fn config(&self) -> Result<WsConfig, UrlError> {
		let mut config = self.options.ws_config.clone();
		if self.options.ws_url != MexcWsUrl::None {
			config.base_url = match self.options.testnet {
				true => Some(self.options.ws_url.url_testnet().ok_or_else(|| UrlError::MissingTestnet(self.options.ws_url.url_mainnet()))?),
				false => Some(self.options.ws_url.url_mainnet()),
			}
		}
		config.topics = config.topics.union(&self.options.ws_topics).cloned().collect();
		Ok(config)
	}

	fn handle_jrpc(&mut self, _jrpc: serde_json::Value) -> Result<ResponseOrContent, WsError> {
		todo!();
	}

	fn handle_subscribe(&mut self, _topics: AHashSet<Topic>) -> Result<Vec<generics::tokio_tungstenite::tungstenite::Message>, WsError> {
		todo!()
	}
}
impl EndpointUrl for MexcWsUrl {
	fn url_mainnet(&self) -> Url {
		match self {
			Self::Spot => Url::parse("wss://stream.mexc.com/ws").unwrap(),
			Self::Futures => Url::parse("wss://contract.mexc.com/ws").unwrap(),
			Self::None => Url::parse("").unwrap(),
		}
	}

	fn url_testnet(&self) -> Option<Url> {
		match self {
			Self::Spot => Some(Url::parse("wss://stream-testnet.mexc.com/ws").unwrap()),
			Self::Futures => Some(Url::parse("wss://contract-testnet.mexc.com/ws").unwrap()),
			Self::None => None,
		}
	}
}
impl WsOption for MexcOption {
	type WsHandler = MexcWsHandler;

	fn ws_handler(options: Self::Options) -> Self::WsHandler {
		MexcWsHandler::new(options)
	}
}
//,}}}

impl HandlerOptions for MexcOptions {
	type OptionItem = MexcOption;

	fn update(&mut self, option: Self::OptionItem) {
		match option {
			MexcOption::Default => (),
			MexcOption::Pubkey(v) => self.pubkey = Some(v),
			MexcOption::Secret(v) => self.secret = Some(v),
			MexcOption::Testnet(v) => self.testnet = v,
			MexcOption::HttpUrl(v) => self.http_url = v,
			MexcOption::HttpAuth(v) => self.http_auth = v,
			MexcOption::RecvWindow(v) =>
				if v > MAX_RECV_WINDOW {
					tracing::warn!("recvWindow is too large, overwriting with maximum value of {MAX_RECV_WINDOW:?}");
					self.recv_window = Some(MAX_RECV_WINDOW);
				} else {
					self.recv_window = Some(v);
				},
			MexcOption::WsUrl(v) => self.ws_url = v,
			MexcOption::WsConfig(v) => self.ws_config = v,
			MexcOption::WsTopics(v) => self.ws_topics = v.into_iter().collect(),
		}
	}

	fn is_authenticated(&self) -> bool {
		self.pubkey.is_some() // some end points are satisfied with just the key, and it's really difficult to provide only a key without a secret from the clientside, so assume intent if it's missing.
	}
}

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

	fn request_handler(options: Self::Options) -> Self::RequestHandler {
		MexcRequestHandler::<'a, R> { options, _phantom: PhantomData }
	}
}

impl HandlerOption for MexcOption {
	type Options = MexcOptions;
}