// This file is part of Moonfire NVR, a security camera network video recorder.
// Copyright (C) 2021 The Moonfire NVR Authors; see AUTHORS and LICENSE.txt.
// SPDX-License-Identifier: GPL-v3.0-or-later WITH GPL-3.0-linking-exception.

//! Static file serving.

use http::{header, HeaderValue, Request};

use super::{internal_server_err, not_found, ResponseResult, Service};

impl Service {
    /// Serves a static file if possible.
    pub(super) async fn static_file(&self, req: Request<hyper::Body>) -> ResponseResult {
        let dir = self.ui_dir.clone().ok_or_else(|| {
            not_found("ui dir not configured or missing; no static files available.")
        })?;
        let static_req = match StaticFileRequest::parse(req.uri().path()) {
            None => return Err(not_found("static file not found")),
            Some(r) => r,
        };
        let f = dir.get(static_req.path, req.headers());
        let node = f.await.map_err(|e| {
            if e.kind() == std::io::ErrorKind::NotFound {
                not_found("no such static file")
            } else {
                internal_server_err(e)
            }
        })?;
        let mut hdrs = http::HeaderMap::new();
        node.add_encoding_headers(&mut hdrs);
        hdrs.insert(
            header::CACHE_CONTROL,
            HeaderValue::from_static(if static_req.immutable {
                // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control#Caching_static_assets
                "public, max-age=604800, immutable"
            } else {
                "public"
            }),
        );
        hdrs.insert(
            header::CONTENT_TYPE,
            HeaderValue::from_static(static_req.mime),
        );
        let e = node.into_file_entity(hdrs).map_err(internal_server_err)?;
        Ok(http_serve::serve(e, &req))
    }
}

#[derive(Debug, Eq, PartialEq)]
struct StaticFileRequest<'a> {
    path: &'a str,
    immutable: bool,
    mime: &'static str,
}

impl<'a> StaticFileRequest<'a> {
    fn parse(path: &'a str) -> Option<Self> {
        if !path.starts_with('/') || path == "/index.html" {
            return None;
        }

        let (path, immutable) = match &path[1..] {
            // These well-known URLs don't have content hashes in them, and
            // thus aren't immutable.
            "" => ("index.html", false),
            "robots.txt" => ("robots.txt", false),
            "site.webmanifest" => ("site.webmanifest", false),

            // Everything else is assumed to contain a hash and be immutable.
            p => (p, true),
        };

        let last_dot = match path.rfind('.') {
            None => return None,
            Some(d) => d,
        };
        let ext = &path[last_dot + 1..];
        let mime = match ext {
            "css" => "text/css",
            "html" => "text/html",
            "ico" => "image/x-icon",
            "js" | "map" => "text/javascript",
            "json" => "application/json",
            "png" => "image/png",
            "svg" => "image/svg+xml",
            "txt" => "text/plain",
            "webmanifest" => "application/manifest+json",
            "woff2" => "font/woff2",
            _ => return None,
        };

        Some(StaticFileRequest {
            path,
            immutable,
            mime,
        })
    }
}

#[cfg(test)]
mod tests {
    use db::testutil;

    use super::StaticFileRequest;

    #[test]
    fn static_file() {
        testutil::init();
        let r = StaticFileRequest::parse("/jquery-ui.b6d3d46c828800e78499.js").unwrap();
        assert_eq!(
            r,
            StaticFileRequest {
                path: "jquery-ui.b6d3d46c828800e78499.js",
                mime: "text/javascript",
                immutable: true,
            }
        );

        let r = StaticFileRequest::parse("/").unwrap();
        assert_eq!(
            r,
            StaticFileRequest {
                path: "index.html",
                mime: "text/html",
                immutable: false,
            }
        );
    }
}