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//! `Error` response for the [`HTTP tracker`](crate::servers::http).
//!
//! Data structures and logic to build the error responses.
//!
//! From the [BEP 03. The `BitTorrent` Protocol Specification](https://www.bittorrent.org/beps/bep_0003.html):
//!
//! _"Tracker responses are bencoded dictionaries. If a tracker response has a
//! key failure reason, then that maps to a human readable string which explains
//! why the query failed, and no other keys are required."_
//!
//! > **NOTICE**: error responses are bencoded and always have a `200 OK` status
//!  code. The official `BitTorrent` specification does not specify the status
//! code.
use axum::http::StatusCode;
use axum::response::{IntoResponse, Response};
use serde::{self, Serialize};

/// `Error` response for the [`HTTP tracker`](crate::servers::http).
#[derive(Serialize, Debug, PartialEq)]
pub struct Error {
    /// Human readable string which explains why the request failed.
    #[serde(rename = "failure reason")]
    pub failure_reason: String,
}

impl Error {
    /// Returns the bencoded representation of the `Error` struct.
    ///
    /// ```rust
    /// use torrust_tracker::servers::http::v1::responses::error::Error;
    ///
    /// let err = Error {
    ///    failure_reason: "error message".to_owned(),
    /// };
    ///
    /// // cspell:disable-next-line
    /// assert_eq!(err.write(), "d14:failure reason13:error messagee");
    /// ```
    ///
    /// # Panics
    ///
    /// It would panic if the `Error` struct contained an inappropriate field
    /// type.
    #[must_use]
    pub fn write(&self) -> String {
        serde_bencode::to_string(&self).unwrap()
    }
}

impl IntoResponse for Error {
    fn into_response(self) -> Response {
        (StatusCode::OK, self.write()).into_response()
    }
}

#[cfg(test)]
mod tests {

    use super::Error;

    #[test]
    fn http_tracker_errors_can_be_bencoded() {
        let err = Error {
            failure_reason: "error message".to_owned(),
        };

        assert_eq!(err.write(), "d14:failure reason13:error messagee"); // cspell:disable-line
    }
}