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use thiserror::Error;
/// A structured error code returned by the Fynd RPC API.
///
/// Mapped from the raw string `code` field in
/// [`fynd_rpc_types::ErrorResponse`].
#[derive(Debug, Clone, PartialEq, Eq)]
#[non_exhaustive]
pub enum ErrorCode {
/// The request was malformed or contained invalid parameters.
///
/// Server codes: `BAD_REQUEST`, `INVALID_ORDER`.
BadRequest,
/// No swap route exists between the requested token pair.
///
/// Server code: `NO_ROUTE_FOUND`.
NoRouteFound,
/// A route exists but available pool liquidity is too shallow for the requested amount.
///
/// Server code: `INSUFFICIENT_LIQUIDITY`.
InsufficientLiquidity,
/// The solver timed out before returning a route. Retrying may succeed.
///
/// Server code: `TIMEOUT`.
SolveTimeout,
/// The server is temporarily unavailable (overloaded, queue full, stale data, or not yet
/// initialised). Retrying after a short backoff should succeed.
///
/// Server codes: `QUEUE_FULL`, `SERVICE_OVERLOADED`, `STALE_DATA`, `NOT_READY`.
ServiceUnavailable,
/// The server encountered an internal error processing the request. Not retryable.
///
/// Server codes: `ALGORITHM_ERROR`, `INTERNAL_ERROR`, `FAILED_ENCODING`.
ServerError,
/// The requested endpoint does not exist. Indicates a client misconfiguration.
///
/// Server code: `NOT_FOUND`.
NotFound,
/// A truly unrecognised server error code. The raw string is preserved for debugging.
Unknown(String),
}
impl ErrorCode {
/// Map a raw server error code string to a typed [`ErrorCode`].
///
/// Unknown codes are wrapped in [`ErrorCode::Unknown`] rather than panicking.
pub fn from_server_code(code: &str) -> Self {
match code {
"BAD_REQUEST" | "INVALID_ORDER" => Self::BadRequest,
"NO_ROUTE_FOUND" => Self::NoRouteFound,
"INSUFFICIENT_LIQUIDITY" => Self::InsufficientLiquidity,
"TIMEOUT" => Self::SolveTimeout,
"QUEUE_FULL" | "SERVICE_OVERLOADED" | "STALE_DATA" | "NOT_READY" => {
Self::ServiceUnavailable
}
"ALGORITHM_ERROR" | "INTERNAL_ERROR" | "FAILED_ENCODING" | "PRICE_CHECK_FAILED" => {
Self::ServerError
}
"NOT_FOUND" => Self::NotFound,
other => Self::Unknown(other.to_string()),
}
}
/// Returns `true` if this error code indicates that the request is safe to retry.
///
/// Only [`SolveTimeout`](Self::SolveTimeout) and
/// [`ServiceUnavailable`](Self::ServiceUnavailable) are retryable; all other codes
/// represent permanent failures.
pub fn is_retryable(&self) -> bool {
matches!(self, Self::SolveTimeout | Self::ServiceUnavailable)
}
}
/// Errors that can be returned by [`FyndClient`](crate::FyndClient) methods.
#[derive(Debug, Error)]
pub enum FyndError {
/// An HTTP-level error from the underlying `reqwest` client (network failure, timeout, etc.).
///
/// HTTP errors are always considered retryable.
#[error("HTTP error: {0}")]
Http(#[from] reqwest::Error),
/// An error returned by the Ethereum JSON-RPC provider (e.g. during nonce/fee estimation or
/// transaction submission).
#[error("provider error: {0}")]
Provider(#[from] alloy::transports::RpcError<alloy::transports::TransportErrorKind>),
/// A structured error response from the Fynd RPC API. Check `code` to distinguish permanent
/// failures (e.g. `NoRouteFound`) from transient ones (e.g. `SolveTimeout`).
#[error("API error ({code:?}): {message}")]
Api {
/// The structured error code identifying the failure kind.
code: ErrorCode,
/// The human-readable error message returned by the server.
message: String,
},
/// Malformed or unexpected data in the API response (e.g. an address with the wrong byte
/// length, an unrecognised enum variant).
#[error("protocol error: {0}")]
Protocol(String),
/// A `eth_call` simulation of the swap transaction reverted. The message contains the
/// revert reason when available.
#[error("simulation failed: {0}")]
SimulationFailed(String),
/// An on-chain transaction was mined but reverted. The message contains the revert reason
/// decoded from replaying the transaction via `eth_call`.
#[error("transaction reverted: {0}")]
TransactionReverted(String),
/// Invalid client configuration (e.g. unparseable URL, missing sender address).
#[error("configuration error: {0}")]
Config(String),
}
impl FyndError {
/// Returns `true` if the operation that produced this error can safely be retried.
///
/// HTTP errors and certain API error codes are retryable. Protocol, config, and simulation
/// errors are not.
pub fn is_retryable(&self) -> bool {
match self {
Self::Http(_) => true,
Self::Api { code, .. } => code.is_retryable(),
_ => false,
}
}
/// Returns `true` if this error represents an on-chain transaction revert.
pub fn is_revert(&self) -> bool {
matches!(self, Self::TransactionReverted(_))
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn error_code_from_known_server_codes() {
assert_eq!(ErrorCode::from_server_code("BAD_REQUEST"), ErrorCode::BadRequest);
assert_eq!(ErrorCode::from_server_code("NO_ROUTE_FOUND"), ErrorCode::NoRouteFound);
assert_eq!(
ErrorCode::from_server_code("INSUFFICIENT_LIQUIDITY"),
ErrorCode::InsufficientLiquidity
);
assert_eq!(ErrorCode::from_server_code("INVALID_ORDER"), ErrorCode::BadRequest);
assert_eq!(ErrorCode::from_server_code("TIMEOUT"), ErrorCode::SolveTimeout);
assert_eq!(ErrorCode::from_server_code("QUEUE_FULL"), ErrorCode::ServiceUnavailable);
assert_eq!(
ErrorCode::from_server_code("SERVICE_OVERLOADED"),
ErrorCode::ServiceUnavailable
);
assert_eq!(ErrorCode::from_server_code("STALE_DATA"), ErrorCode::ServiceUnavailable);
assert_eq!(ErrorCode::from_server_code("NOT_READY"), ErrorCode::ServiceUnavailable);
}
#[test]
fn error_code_server_error_for_server_fault_codes() {
assert_eq!(ErrorCode::from_server_code("ALGORITHM_ERROR"), ErrorCode::ServerError);
assert_eq!(ErrorCode::from_server_code("INTERNAL_ERROR"), ErrorCode::ServerError);
assert_eq!(ErrorCode::from_server_code("FAILED_ENCODING"), ErrorCode::ServerError);
}
#[test]
fn error_code_not_found_for_not_found_code() {
assert_eq!(ErrorCode::from_server_code("NOT_FOUND"), ErrorCode::NotFound);
}
#[test]
fn error_code_unknown_for_unrecognised_codes() {
assert!(matches!(ErrorCode::from_server_code("WHATEVER"), ErrorCode::Unknown(_)));
assert!(matches!(ErrorCode::from_server_code("SOME_FUTURE_CODE"), ErrorCode::Unknown(_)));
}
#[test]
fn is_retryable_true_for_retryable_codes() {
assert!(
FyndError::Api { code: ErrorCode::SolveTimeout, message: String::new() }.is_retryable()
);
assert!(FyndError::Api { code: ErrorCode::ServiceUnavailable, message: String::new() }
.is_retryable());
}
#[test]
fn is_retryable_false_for_non_retryable_errors() {
assert!(
!FyndError::Api { code: ErrorCode::BadRequest, message: String::new() }.is_retryable()
);
assert!(!FyndError::Api { code: ErrorCode::NoRouteFound, message: String::new() }
.is_retryable());
assert!(!FyndError::Protocol("bad data".into()).is_retryable());
assert!(!FyndError::Config("missing sender".into()).is_retryable());
}
}