/*
    This file is part of jellything (https://codeberg.org/metamuffin/jellything)
    which is licensed under the GNU Affero General Public License (version 3); see /COPYING.
    Copyright (C) 2025 metamuffin <metamuffin.org>
*/

use log::debug;
use rocket::{
    http::{Header, Status},
    response::{self, Responder},
    Request, Response,
};
use std::{
    hash::{DefaultHasher, Hash, Hasher},
    os::unix::fs::MetadataExt,
    path::Path,
};
use tokio::fs::File;

pub struct CacheControlFile(File, String);
impl CacheControlFile {
    pub async fn new_cachekey(p: &Path) -> anyhow::Result<Self> {
        let tag = p.file_name().unwrap().to_str().unwrap().to_owned();
        let f = File::open(p).await?;
        Ok(Self(f, tag))
    }
    pub async fn new_mtime(f: File) -> Self {
        let meta = f.metadata().await.unwrap();
        let modified = meta.mtime();
        let mut h = DefaultHasher::new();
        modified.hash(&mut h);
        let tag = format!("{:0>16x}", h.finish());
        Self(f, tag)
    }
}
impl<'r> Responder<'r, 'static> for CacheControlFile {
    fn respond_to(self, req: &'r Request<'_>) -> response::Result<'static> {
        let Self(file, tag) = self;
        if req.headers().get_one("if-none-match") == Some(&tag) {
            debug!("file cache: not modified");
            Response::build()
                .status(Status::NotModified)
                .header(Header::new("cache-control", "private"))
                .header(Header::new("etag", tag))
                .ok()
        } else {
            debug!("file cache: transfer");
            Response::build()
                .status(Status::Ok)
                .header(Header::new("cache-control", "private"))
                .header(Header::new("etag", tag))
                .streamed_body(file)
                .ok()
        }
    }
}