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use crate::{AccountCache, CertCache};
use async_trait::async_trait;
use base64::engine::general_purpose::URL_SAFE_NO_PAD;
use base64::Engine;
use ring::digest::{Context, SHA256};
use std::io::ErrorKind;
use std::path::Path;
use tokio::fs;

pub struct DirCache<P: AsRef<Path> + Send + Sync> {
    inner: P,
}

impl<P: AsRef<Path> + Send + Sync> DirCache<P> {
    pub fn new(dir: P) -> Self {
        Self { inner: dir }
    }
    async fn read_if_exist(
        &self,
        file: impl AsRef<Path>,
    ) -> Result<Option<Vec<u8>>, std::io::Error> {
        let path = self.inner.as_ref().join(file);
        match fs::read(path).await {
            Ok(content) => Ok(Some(content)),
            Err(err) => match err.kind() {
                ErrorKind::NotFound => Ok(None),
                _ => Err(err),
            },
        }
    }
    async fn write(
        &self,
        file: impl AsRef<Path>,
        contents: impl AsRef<[u8]>,
    ) -> Result<(), std::io::Error> {
        fs::create_dir_all(&self.inner).await?;
        let path = self.inner.as_ref().join(file);
        fs::write(path, contents).await
    }

    fn cached_account_file_name(contact: &[String], directory_url: impl AsRef<str>) -> String {
        let mut ctx = Context::new(&SHA256);
        for el in contact {
            ctx.update(el.as_ref());
            ctx.update(&[0])
        }
        ctx.update(directory_url.as_ref().as_bytes());
        let hash = URL_SAFE_NO_PAD.encode(ctx.finish());
        format!("cached_account_{}", hash)
    }
    fn cached_cert_file_name(domains: &[String], directory_url: impl AsRef<str>) -> String {
        let mut ctx = Context::new(&SHA256);
        for domain in domains {
            ctx.update(domain.as_ref());
            ctx.update(&[0])
        }
        ctx.update(directory_url.as_ref().as_bytes());
        let hash = URL_SAFE_NO_PAD.encode(ctx.finish());
        format!("cached_cert_{}", hash)
    }
}

#[async_trait]
impl<P: AsRef<Path> + Send + Sync> CertCache for DirCache<P> {
    type EC = std::io::Error;
    async fn load_cert(
        &self,
        domains: &[String],
        directory_url: &str,
    ) -> Result<Option<Vec<u8>>, Self::EC> {
        let file_name = Self::cached_cert_file_name(domains, directory_url);
        self.read_if_exist(file_name).await
    }
    async fn store_cert(
        &self,
        domains: &[String],
        directory_url: &str,
        cert: &[u8],
    ) -> Result<(), Self::EC> {
        let file_name = Self::cached_cert_file_name(domains, directory_url);
        self.write(file_name, cert).await
    }
}

#[async_trait]
impl<P: AsRef<Path> + Send + Sync> AccountCache for DirCache<P> {
    type EA = std::io::Error;
    async fn load_account(
        &self,
        contact: &[String],
        directory_url: &str,
    ) -> Result<Option<Vec<u8>>, Self::EA> {
        let file_name = Self::cached_account_file_name(contact, directory_url);
        self.read_if_exist(file_name).await
    }

    async fn store_account(
        &self,
        contact: &[String],
        directory_url: &str,
        account: &[u8],
    ) -> Result<(), Self::EA> {
        let file_name = Self::cached_account_file_name(contact, directory_url);
        self.write(file_name, account).await
    }
}