use base64::{Engine, engine::general_purpose::URL_SAFE};
use p256::ecdsa::VerifyingKey;
use serde::Serialize;

use crate::event::{Instant, Sequenced};

#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize)]
#[serde(tag = "event", rename_all = "snake_case")]
pub enum Event {
    Changed(Changed),
}

impl Sequenced for Event {
    fn instant(&self) -> Instant {
        match self {
            Self::Changed(event) => event.instant(),
        }
    }
}

#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize)]
pub struct Changed {
    #[serde(flatten)]
    pub instant: Instant,
    #[serde(serialize_with = "as_vapid_key")]
    pub key: VerifyingKey,
}

impl From<Changed> for Event {
    fn from(event: Changed) -> Self {
        Self::Changed(event)
    }
}

impl Sequenced for Changed {
    fn instant(&self) -> Instant {
        self.instant
    }
}

fn as_vapid_key<S>(key: &VerifyingKey, serializer: S) -> Result<S::Ok, S::Error>
where
    S: serde::Serializer,
{
    let key = key.to_sec1_bytes();
    let key = URL_SAFE.encode(key);
    key.serialize(serializer)
}