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use axum::http::StatusCode;
use axum::response::{IntoResponse, Response};
use miette::Diagnostic;

#[derive(Debug, thiserror::Error, Diagnostic)]
pub enum Error {
    #[error("io error: {0}")]
    #[diagnostic(code(docket::io))]
    Io(#[from] std::io::Error),

    #[error("database error: {0}")]
    #[diagnostic(code(docket::db))]
    Db(#[from] rusqlite::Error),

    #[error("jmap error: {0}")]
    #[diagnostic(code(docket::jmap))]
    Jmap(#[from] crate::jmap::JmapError),

    #[error("no user identity on the request")]
    #[diagnostic(code(docket::unauthenticated))]
    Unauthenticated,

    #[error("no such {0}")]
    #[diagnostic(code(docket::not_found))]
    NotFound(&'static str),

    #[error("{0}")]
    #[diagnostic(code(docket::forbidden))]
    Forbidden(&'static str),

    #[error("{0}")]
    #[diagnostic(code(docket::bad_request))]
    BadRequest(&'static str),
}

impl IntoResponse for Error {
    fn into_response(self) -> Response {
        let status = match self {
            Error::Io(_) | Error::Db(_) | Error::Jmap(_) => StatusCode::INTERNAL_SERVER_ERROR,
            Error::Unauthenticated => StatusCode::UNAUTHORIZED,
            Error::NotFound(_) => StatusCode::NOT_FOUND,
            Error::Forbidden(_) => StatusCode::FORBIDDEN,
            Error::BadRequest(_) => StatusCode::BAD_REQUEST,
        };
        // A 500 is Docket's fault, so it goes to Sentry as an issue;
        // the rest are the request's.
        if status.is_server_error() {
            tracing::error!(err = %self, "request failed");
        }
        (status, self.to_string()).into_response()
    }
}

impl Error {
    /// Whether a background job hitting this should try again rather
    /// than stop.
    pub fn is_retryable(&self) -> bool {
        match self {
            Error::Jmap(err) => err.is_retryable(),
            Error::Db(err) => matches!(
                err.sqlite_error_code(),
                Some(rusqlite::ErrorCode::DatabaseBusy | rusqlite::ErrorCode::DatabaseLocked)
            ),
            Error::Io(_)
            | Error::Unauthenticated
            | Error::NotFound(_)
            | Error::Forbidden(_)
            | Error::BadRequest(_) => false,
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn statuses() {
        let cases = [
            (Error::Io(std::io::Error::other("disk")), 500),
            (Error::Db(rusqlite::Error::QueryReturnedNoRows), 500),
            (
                Error::Jmap(crate::jmap::JmapError::NoMailAccount {
                    credential: "household".into(),
                }),
                500,
            ),
            (Error::Unauthenticated, 401),
            (Error::NotFound("thread"), 404),
            (Error::Forbidden("read-only"), 403),
            (Error::BadRequest("empty"), 400),
        ];
        for (err, status) in cases {
            assert_eq!(err.into_response().status().as_u16(), status);
        }
    }

    #[test]
    fn only_contention_and_transient_jmap_failures_retry() {
        let sqlite = |code| {
            Error::Db(rusqlite::Error::SqliteFailure(
                rusqlite::ffi::Error::new(code),
                None,
            ))
        };
        assert!(sqlite(rusqlite::ffi::SQLITE_BUSY).is_retryable());
        assert!(sqlite(rusqlite::ffi::SQLITE_LOCKED).is_retryable());
        assert!(!sqlite(rusqlite::ffi::SQLITE_CORRUPT).is_retryable());
        assert!(!Error::Db(rusqlite::Error::QueryReturnedNoRows).is_retryable());

        let method = |kind: &str| {
            Error::Jmap(crate::jmap::JmapError::Method {
                method: "Email/get",
                kind: kind.into(),
                description: None,
            })
        };
        assert!(method("serverUnavailable").is_retryable());
        assert!(!method("invalidArguments").is_retryable());

        for err in [
            Error::Io(std::io::Error::other("disk")),
            Error::Unauthenticated,
            Error::NotFound("thread"),
            Error::Forbidden("read-only"),
            Error::BadRequest("empty"),
        ] {
            assert!(!err.is_retryable(), "{err}");
        }
    }
}