dhan-rs 0.1.7

Unofficial Rust client library for the DhanHQ Broker API v2 — orders, market data, WebSocket feeds, and more
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//! Error types for the `dhan-rs` crate.
//!
//! All fallible operations in this crate return [`Result<T>`], which is an
//! alias for `std::result::Result<T, DhanError>`.
//!
//! [`DhanError`] covers:
//! - **API errors** — Structured error responses from DhanHQ (codes DH-901 to DH-910)
//! - **HTTP status errors** — Unexpected status codes with response body
//! - **HTTP transport errors** — Network, TLS, timeout failures
//! - **JSON errors** — Deserialization failures
//! - **WebSocket errors** — Connection and protocol errors
//! - **URL errors** — Malformed URL construction
//! - **Invalid arguments** — Client-side validation errors

use std::fmt;

/// Error response returned by the DhanHQ API.
#[derive(Debug, Clone, serde::Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ApiErrorBody {
    /// Category of the error (e.g. "Invalid Authentication").
    #[serde(default)]
    pub error_type: Option<String>,
    /// Dhan error code (e.g. "DH-901").
    #[serde(default)]
    pub error_code: Option<String>,
    /// Human-readable description of the error.
    #[serde(default)]
    pub error_message: Option<String>,
}

impl fmt::Display for ApiErrorBody {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(
            f,
            "[{}] {}: {}",
            self.error_code.as_deref().unwrap_or("UNKNOWN"),
            self.error_type.as_deref().unwrap_or("Unknown Error"),
            self.error_message.as_deref().unwrap_or("No message"),
        )
    }
}

/// All possible errors produced by the `dhan-rs` client.
#[derive(Debug, thiserror::Error)]
pub enum DhanError {
    /// An error response returned by the DhanHQ REST API.
    #[error("API error: {0}")]
    Api(ApiErrorBody),

    /// The server returned an unexpected HTTP status code.
    #[error("HTTP {status}: {body}")]
    HttpStatus {
        /// The HTTP status code.
        status: reqwest::StatusCode,
        /// The response body text.
        body: String,
    },

    /// A network or transport-level error from `reqwest`.
    #[error("HTTP request failed: {0}")]
    Http(#[from] reqwest::Error),

    /// Reading an HTTP response body failed after the server sent its status.
    #[error("HTTP response body read failed after {status}: {source}")]
    ResponseBody {
        /// Status received before the body read failed.
        status: reqwest::StatusCode,
        /// The underlying transport/body-read failure.
        #[source]
        source: reqwest::Error,
    },

    /// A credential cannot be represented safely as an HTTP header value.
    #[error("invalid HTTP header value: {0}")]
    InvalidHeaderValue(#[from] reqwest::header::InvalidHeaderValue),

    /// Failed to deserialize a JSON response body.
    #[error("JSON deserialization error: {0}")]
    Json(#[from] serde_json::Error),

    /// A WebSocket-level error (boxed to keep `Result<T>` small).
    #[error("WebSocket error: {0}")]
    WebSocket(Box<tokio_tungstenite::tungstenite::Error>),

    /// An error building or parsing a URL.
    #[error("URL error: {0}")]
    Url(#[from] url::ParseError),

    /// The caller provided an invalid argument.
    #[error("Invalid argument: {0}")]
    InvalidArgument(String),
}

impl From<tokio_tungstenite::tungstenite::Error> for DhanError {
    fn from(err: tokio_tungstenite::tungstenite::Error) -> Self {
        DhanError::WebSocket(Box::new(err))
    }
}

/// Convenience alias used throughout the crate.
pub type Result<T> = std::result::Result<T, DhanError>;