use std::fmt;

use axum::{
    extract::FromRequestParts,
    http::request::Parts,
    response::{IntoResponseParts, ResponseParts},
};
use axum_extra::extract::cookie::{Cookie, CookieJar};

use crate::token::Secret;

// The usage pattern here - receive the extractor as an argument, return it in
// the response - is heavily modelled after CookieJar's own intended usage.
#[derive(Clone)]
pub struct Identity {
    cookies: CookieJar,
}

impl fmt::Debug for Identity {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("IdentityCookie")
            .field("identity", &self.secret())
            .finish()
    }
}

impl Identity {
    const COOKIE_NAME: &str = "identity";

    // Creates a new, unpopulated identity token store.
    #[cfg(test)]
    pub fn new() -> Self {
        Self {
            cookies: CookieJar::new(),
        }
    }

    // Get the identity secret sent in the request, if any. If the identity
    // was not sent, or if it has previously been [clear]ed, then this will
    // return [None]. If the identity has previously been [set], then this
    // will return that secret, regardless of what the request originally
    // included.
    pub fn secret(&self) -> Option<Secret> {
        self.cookies
            .get(Self::COOKIE_NAME)
            .map(Cookie::value)
            .map(Secret::from)
    }

    // Positively set the identity secret, and ensure that it will be sent
    // back to the client when this extractor is included in a response.
    pub fn set(self, secret: impl Into<Secret>) -> Self {
        let secret = secret.into().reveal();
        let identity_cookie = Cookie::build((Self::COOKIE_NAME, secret))
            .http_only(true)
            .path("/")
            .permanent()
            .build();

        Self {
            cookies: self.cookies.add(identity_cookie),
        }
    }

    // Remove the identity secret and ensure that it will be cleared when this
    // extractor is included in a response.
    pub fn clear(self) -> Self {
        Self {
            cookies: self.cookies.remove(Self::COOKIE_NAME),
        }
    }
}

#[async_trait::async_trait]
impl<S> FromRequestParts<S> for Identity
where
    S: Send + Sync,
{
    type Rejection = <CookieJar as FromRequestParts<S>>::Rejection;

    async fn from_request_parts(parts: &mut Parts, state: &S) -> Result<Self, Self::Rejection> {
        let cookies = CookieJar::from_request_parts(parts, state).await?;
        Ok(Self { cookies })
    }
}

impl IntoResponseParts for Identity {
    type Error = <CookieJar as IntoResponseParts>::Error;

    fn into_response_parts(self, res: ResponseParts) -> Result<ResponseParts, Self::Error> {
        let Self { cookies } = self;
        cookies.into_response_parts(res)
    }
}