salvo_core 0.56.0

Salvo is a powerful web framework that can make your work easier.
Documentation 
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//! [`Catcher`] is the default implement [`Handler`] for catch page error.
//!
//! A web application can specify several different Catchers to handle errors.
//!
//! They can be set via the `with_catchers` function of `Server`:
//!
//! # Example
//!
//! ```
//! # use salvo_core::prelude::*;
//! # use salvo_core::catcher::Catcher;
//!
//! #[handler]
//! async fn handle404(&self, _req: &Request, _depot: &Depot, res: &mut Response, ctrl: &mut FlowCtrl) {
//!     if let Some(StatusCode::NOT_FOUND) = res.status_code {
//!         res.render("Custom 404 Error Page");
//!         ctrl.skip_rest();
//!     }
//! }
//!
//! #[tokio::main]
//! async fn main() {
//!     Service::new(Router::new()).catcher(Catcher::default().hoop(handle404));
//! }
//! ```
//!
//! When there is an error in the website request result, first try to set the error page
//! through the [`Catcher`] set by the user. If the [`Catcher`] catches the error,
//! it will return `true`.
//!
//! If your custom catchers does not capture this error, then the system uses
//! [`write_error_default`] to capture processing errors and send the default error page.

use std::borrow::Cow;
use std::sync::Arc;

use async_trait::async_trait;
use bytes::Bytes;
use mime::Mime;
use once_cell::sync::Lazy;
use serde::Serialize;

use crate::handler::{Handler, WhenHoop};
use crate::http::{guess_accept_mime, header, Request, ResBody, Response, StatusCode, StatusError};
use crate::{Depot, FlowCtrl};

static SUPPORTED_FORMATS: Lazy<Vec<mime::Name>> = Lazy::new(|| vec![mime::JSON, mime::HTML, mime::XML, mime::PLAIN]);
const EMPTY_CAUSE_MSG: &str = "There is no more detailed explanation.";
const SALVO_LINK: &str = r#"<a href="https://salvo.rs" target="_blank">salvo</a>"#;

#[inline]
fn status_error_html(code: StatusCode, name: &str, brief: &str, cause: Option<&str>, footer: Option<&str>) -> String {
    format!(
        r#"<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width">
    <title>{0}: {1}</title>
    <style>
    :root {{
        --bg-color: #fff;
        --text-color: #222;
    }}
    body {{
        background: var(--bg-color);
        color: var(--text-color);
        text-align: center;
    }}
    pre {{ text-align: left; padding: 0 1rem; }}
    footer{{text-align:center;}}
    @media (prefers-color-scheme: dark) {{
        :root {{
            --bg-color: #222;
            --text-color: #ddd;
        }}
        a:link {{ color: red; }}
        a:visited {{ color: #a8aeff; }}
        a:hover {{color: #a8aeff;}}
        a:active {{color: #a8aeff;}}
    }}
    </style>
</head>
<body>
    <div><h1>{0}: {1}</h1><h3>{2}</h3><pre>{3}</pre><hr><footer>{4}</footer></div>
</body>
</html>"#,
        code.as_u16(),
        name,
        brief,
        cause.unwrap_or(EMPTY_CAUSE_MSG),
        footer.unwrap_or(SALVO_LINK)
    )
}
#[inline]
fn status_error_json(code: StatusCode, name: &str, brief: &str, cause: Option<&str>) -> String {
    #[derive(Serialize)]
    struct Data<'a> {
        error: Error<'a>,
    }
    #[derive(Serialize)]
    struct Error<'a> {
        code: u16,
        name: &'a str,
        brief: &'a str,
        cause: &'a str,
    }
    let data = Data {
        error: Error {
            code: code.as_u16(),
            name,
            brief,
            cause: cause.unwrap_or(EMPTY_CAUSE_MSG),
        },
    };
    serde_json::to_string(&data).unwrap()
}
#[inline]
fn status_error_plain(code: StatusCode, name: &str, brief: &str, cause: Option<&str>) -> String {
    format!(
        "code: {}\n\nname: {}\n\nbrief: {}\n\ncause: {}",
        code.as_u16(),
        name,
        brief,
        cause.unwrap_or(EMPTY_CAUSE_MSG)
    )
}
#[inline]
fn status_error_xml(code: StatusCode, name: &str, brief: &str, cause: Option<&str>) -> String {
    #[derive(Serialize)]
    struct Data<'a> {
        code: u16,
        name: &'a str,
        brief: &'a str,
        cause: &'a str,
    }

    let data = Data {
        code: code.as_u16(),
        name,
        brief,
        cause: cause.unwrap_or(EMPTY_CAUSE_MSG),
    };
    serde_xml_rs::to_string(&data).unwrap()
}
/// Create bytes from `StatusError`.
#[inline]
pub fn status_error_bytes(err: &StatusError, prefer_format: &Mime, footer: Option<&str>) -> (Mime, Bytes) {
    let format = if !SUPPORTED_FORMATS.contains(&prefer_format.subtype()) {
        "text/html".parse().unwrap()
    } else {
        prefer_format.clone()
    };
    #[cfg(debug_assertions)]
    let cause = err.cause.as_ref().map(|e| format!("{:#?}", e.as_ref()));
    #[cfg(not(debug_assertions))]
    let cause: Option<String> = None;
    let content = match format.subtype().as_ref() {
        "plain" => status_error_plain(err.code, &err.name, &err.brief, cause.as_deref()),
        "json" => status_error_json(err.code, &err.name, &err.brief, cause.as_deref()),
        "xml" => status_error_xml(err.code, &err.name, &err.brief, cause.as_deref()),
        _ => status_error_html(err.code, &err.name, &err.brief, cause.as_deref(), footer),
    };
    (format, Bytes::from(content))
}

/// Default implementation of [`Catcher`].
///
/// If http status is error, and user is not set custom catcher to catch them,
/// `write_error_default` will used to catch them.
///
/// `Catcher` supports sending error pages in `XML`, `JSON`, `HTML`, `Text` formats.
pub struct Catcher {
    goal: Arc<dyn Handler>,
    hoops: Vec<Arc<dyn Handler>>,
}
impl Default for Catcher {
    fn default() -> Self {
        Catcher {
            goal: Arc::new(DefaultGoal::new()),
            hoops: vec![],
        }
    }
}
impl Catcher {
    /// Create new `Catcher`.
    pub fn new<H: Into<Arc<dyn Handler>>>(goal: H) -> Self {
        Catcher {
            goal: goal.into(),
            hoops: vec![],
        }
    }

    /// Get current catcher's middlewares reference.
    #[inline]
    pub fn hoops(&self) -> &Vec<Arc<dyn Handler>> {
        &self.hoops
    }
    /// Get current catcher's middlewares mutable reference.
    #[inline]
    pub fn hoops_mut(&mut self) -> &mut Vec<Arc<dyn Handler>> {
        &mut self.hoops
    }

    /// Add a handler as middleware, it will run the handler in current router or it's descendants
    /// handle the request.
    #[inline]
    pub fn hoop<H: Handler>(mut self, hoop: H) -> Self {
        self.hoops.push(Arc::new(hoop));
        self
    }

    /// Add a handler as middleware, it will run the handler in current router or it's descendants
    /// handle the request. This middleware only effective when the filter return true.
    #[inline]
    pub fn hoop_when<H, F>(mut self, hoop: H, filter: F) -> Self
    where
        H: Handler,
        F: Fn(&Request, &Depot) -> bool + Send + Sync + 'static,
    {
        self.hoops.push(Arc::new(WhenHoop { inner: hoop, filter }));
        self
    }

    /// Catch error and send error page.
    pub async fn catch(&self, req: &mut Request, depot: &mut Depot, res: &mut Response) {
        let mut ctrl = FlowCtrl::new(self.hoops.iter().chain([&self.goal]).cloned().collect());
        ctrl.call_next(req, depot, res).await;
    }
}

impl<H> From<H> for Catcher
where
    H: Into<Arc<dyn Handler>>,
{
    fn from(goal: H) -> Self {
        Catcher::new(goal)
    }
}

/// Default [`Handler`] for [`Catcher`].
///
/// If http status is error, and user is not set custom catcher to catch them,
/// `write_error_default` will used to catch them.
///
/// `Catcher` supports sending error pages in `XML`, `JSON`, `HTML`, `Text` formats.
#[derive(Default)]
pub struct DefaultGoal {
    footer: Option<Cow<'static, str>>,
}
impl DefaultGoal {
    /// Create new `Catcher`.
    pub fn new() -> Self {
        DefaultGoal { footer: None }
    }
    /// Create with footer.
    #[inline]
    pub fn with_footer(footer: impl Into<Cow<'static, str>>) -> Self {
        Self::new().footer(footer)
    }

    /// Set footer.
    pub fn footer(mut self, footer: impl Into<Cow<'static, str>>) -> Self {
        self.footer = Some(footer.into());
        self
    }
}
#[async_trait]
impl Handler for DefaultGoal {
    async fn handle(&self, req: &mut Request, _depot: &mut Depot, res: &mut Response, _ctrl: &mut FlowCtrl) {
        let status = res.status_code.unwrap_or(StatusCode::NOT_FOUND);
        if (status.is_server_error() || status.is_client_error()) && (res.body.is_none() || res.body.is_error()) {
            write_error_default(req, res, self.footer.as_deref());
        }
    }
}

#[doc(hidden)]
pub fn write_error_default(req: &Request, res: &mut Response, footer: Option<&str>) {
    let format = guess_accept_mime(req, None);
    let (format, data) = if let ResBody::Error(body) = &res.body {
        status_error_bytes(body, &format, footer)
    } else {
        let status = res.status_code.unwrap_or(StatusCode::NOT_FOUND);
        status_error_bytes(&StatusError::from_code(status).unwrap(), &format, footer)
    };
    res.headers_mut()
        .insert(header::CONTENT_TYPE, format.to_string().parse().unwrap());
    res.write_body(data).ok();
}

#[cfg(test)]
mod tests {
    use crate::prelude::*;
    use crate::test::{ResponseExt, TestClient};

    use super::*;

    struct CustomError;
    #[async_trait]
    impl Writer for CustomError {
        async fn write(mut self, _req: &mut Request, _depot: &mut Depot, res: &mut Response) {
            res.status_code = Some(StatusCode::INTERNAL_SERVER_ERROR);
            res.render("custom error");
        }
    }

    #[handler]
    async fn handle404(&self, _req: &Request, _depot: &Depot, res: &mut Response, ctrl: &mut FlowCtrl) {
        if let Some(StatusCode::NOT_FOUND) = res.status_code {
            res.render("Custom 404 Error Page");
            ctrl.skip_rest();
        }
    }

    #[tokio::test]
    async fn test_handle_error() {
        #[handler]
        async fn handle_custom() -> Result<(), CustomError> {
            Err(CustomError)
        }
        let router = Router::new().push(Router::with_path("custom").get(handle_custom));
        let service = Service::new(router);

        async fn access(service: &Service, name: &str) -> String {
            TestClient::get(format!("http://127.0.0.1:5800/{}", name))
                .send(service)
                .await
                .take_string()
                .await
                .unwrap()
        }

        assert_eq!(access(&service, "custom").await, "custom error");
    }

    #[tokio::test]
    async fn test_custom_catcher() {
        #[handler]
        async fn hello() -> &'static str {
            "Hello World"
        }
        let router = Router::new().get(hello);
        let service = Service::new(router).catcher(Catcher::default().hoop(handle404));

        async fn access(service: &Service, name: &str) -> String {
            TestClient::get(format!("http://127.0.0.1:5800/{}", name))
                .send(service)
                .await
                .take_string()
                .await
                .unwrap()
        }

        assert_eq!(access(&service, "notfound").await, "Custom 404 Error Page");
    }
}