jae-blog/src/error.rs

use std::fmt::Display;

use askama_axum::Template;
use axum::http::StatusCode;
use axum::response::{IntoResponse, Response};
use thiserror::Error;

#[derive(Debug)]
#[repr(transparent)]
pub struct FronmaError(fronma::error::Error);

impl std::error::Error for FronmaError {}

impl Display for FronmaError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_str("failed to parse front matter: ")?;
        match &self.0 {
            fronma::error::Error::MissingBeginningLine => f.write_str("missing beginning line"),
            fronma::error::Error::MissingEndingLine => f.write_str("missing ending line"),
            fronma::error::Error::SerdeYaml(yaml_error) => write!(f, "{}", yaml_error),
        }
    }
}

#[derive(Error, Debug)]
#[allow(clippy::enum_variant_names)]
pub enum PostError {
    #[error(transparent)]
    IoError(#[from] std::io::Error),
    #[error(transparent)]
    AskamaError(#[from] askama::Error),
    #[error(transparent)]
    ParseError(#[from] FronmaError),
    #[error("post {0:?} not found")]
    NotFound(String),
}

impl From<fronma::error::Error> for PostError {
    fn from(value: fronma::error::Error) -> Self {
        Self::ParseError(FronmaError(value))
    }
}

impl IntoResponse for PostError {
    fn into_response(self) -> axum::response::Response {
        (StatusCode::INTERNAL_SERVER_ERROR, self.to_string()).into_response()
    }
}

pub type AppResult<T> = Result<T, AppError>;

#[derive(Error, Debug)]
pub enum AppError {
    #[error("failed to fetch post: {0}")]
    PostError(#[from] PostError),
    #[error("rss is disabled")]
    RssDisabled,
    #[error(transparent)]
    UrlError(#[from] url::ParseError),
}

impl From<std::io::Error> for AppError {
    #[inline(always)]
    fn from(value: std::io::Error) -> Self {
        Self::PostError(PostError::IoError(value))
    }
}

#[derive(Template)]
#[template(path = "error.html")]
struct ErrorTemplate {
    error: String,
}

impl IntoResponse for AppError {
    fn into_response(self) -> Response {
        let status_code = match &self {
            AppError::PostError(err) => match err {
                PostError::NotFound(_) => StatusCode::NOT_FOUND,
                _ => StatusCode::INTERNAL_SERVER_ERROR,
            },
            AppError::RssDisabled => StatusCode::FORBIDDEN,
            AppError::UrlError(_) => StatusCode::INTERNAL_SERVER_ERROR,
        };
        (
            status_code,
            ErrorTemplate {
                error: self.to_string(),
            },
        )
            .into_response()
    }
}