use anyhow::Result;
use ed25519_dalek::Signer;
use ed25519_dalek::SigningKey;
use tonic::metadata::AsciiMetadataValue;
use tonic::Request;

pub struct Key {
    pub sg_key: SigningKey,
    pub pubkey: String,
}

impl Key {
    pub fn new() -> Self {
        let sk = SigningKey::generate(&mut rand::rngs::OsRng);
        let pubkey = bs58::encode(sk.verifying_key().to_bytes()).into_string();
        Key { sg_key: sk, pubkey }
    }

    pub fn sign_request<T: std::fmt::Debug>(&self, req: T) -> Result<Request<T>> {
        let pubkey = self.pubkey.clone();
        let timestamp = chrono::Utc::now().to_rfc3339();
        let signature = self.try_sign_message(&format!("{timestamp}{req:?}"))?;
        let timestamp: AsciiMetadataValue = timestamp.parse()?;
        let pubkey: AsciiMetadataValue = pubkey.parse()?;
        let signature: AsciiMetadataValue = signature.parse()?;
        let mut req = Request::new(req);
        req.metadata_mut().insert("timestamp", timestamp);
        req.metadata_mut().insert("pubkey", pubkey);
        req.metadata_mut().insert("request-signature", signature);

        Ok(req)
    }

    pub fn try_sign_message(&self, message: &str) -> Result<String> {
        let key = self.sg_key.clone();
        Ok(bs58::encode(key.sign(message.as_bytes()).to_bytes()).into_string())
    }
}