use std::convert::{From, TryFrom};
use std::fmt;
use std::str::FromStr;

use serde_with::{DeserializeFromStr, SerializeDisplay};

#[derive(Debug, Clone, PartialEq, DeserializeFromStr, SerializeDisplay)]
/// DER-encoded ASN.1 in either PKCS#8, PKCS#1, or Sec1 format, like rustls::PrivateKey.
pub struct PrivateKey(Vec<u8>);

impl PrivateKey {
    #[allow(clippy::new_without_default)]
    pub fn new() -> PrivateKey {
        acme2::gen_rsa_private_key(4096)
            .expect("RSA private key generated")
            .as_ref()
            .try_into()
            .expect("RSA private key converted to internal representation")
    }
}

impl FromStr for PrivateKey {
    type Err = pem::PemError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        Ok(PrivateKey(pem::parse(s)?.into_contents()))
    }
}

impl fmt::Display for PrivateKey {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        pem::Pem::new("PRIVATE KEY", self.0.clone()).fmt(f)
    }
}

impl TryFrom<&openssl::pkey::PKeyRef<openssl::pkey::Private>> for PrivateKey {
    type Error = openssl::error::ErrorStack;

    fn try_from(k: &openssl::pkey::PKeyRef<openssl::pkey::Private>) -> Result<Self, Self::Error> {
        Ok(PrivateKey(k.private_key_to_der()?))
    }
}

impl TryFrom<&PrivateKey> for openssl::pkey::PKey<openssl::pkey::Private> {
    type Error = openssl::error::ErrorStack;

    fn try_from(k: &PrivateKey) -> Result<Self, Self::Error> {
        openssl::pkey::PKey::private_key_from_der(&k.0)
    }
}

impl From<PrivateKey> for rustls::PrivateKey {
    fn from(k: PrivateKey) -> Self {
        rustls::PrivateKey(k.0)
    }
}