//! Utilities for dealing with proxy urls.

use crate::*;

/// Utility for dealing with proxy urls.
/// Proxy URLs are like super-urls... they need to be able to
/// compose a sub or base-transport url, while adding a new scheme and
/// a tls certificate digest, without shadowing any info.
///
/// We could do this by percent encoding the base-url into a
/// query string or path segment, but that is not very user-friendly looking.
///
/// Instead, we extract some info from the base-url into path
/// segments, and include everything else after a special path segment marker
/// `--`.
///
/// Optional extracted items (order matters):
///  - `h` - host: `/h/[host-name-here]`
///  - `p` - port: `/p/[port-here]`
///  - `u` - username: `/u/[user-name-here]`
///  - `w` - password: `/w/[password-here]`
#[derive(Debug, Display, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Deref, AsRef)]
#[display(fmt = "{}", full)]
pub struct ProxyUrl {
    #[deref]
    #[as_ref]
    full: url2::Url2,
    base: url2::Url2,
}

impl ProxyUrl {
    /// Create a new proxy url from a full url str.
    pub fn from_full(full: &str) -> KitsuneResult<Self> {
        macro_rules! err {
            ($h:literal) => {
                KitsuneError::from(format!(
                    "Invalid Proxy Url({}): {}: at: {}:{}",
                    $h,
                    full,
                    file!(),
                    line!()
                ))
            };
        }
        let full = url2::try_url2!("{}", full).map_err(|_| err!("parse"))?;
        let base_scheme = match full.path_segments() {
            None => return Err(err!("read scheme")),
            Some(mut s) => match s.next() {
                None => return Err(err!("read scheme")),
                Some(s) => s,
            },
        };
        let mut base = url2::url2!("{}://", base_scheme);
        {
            let mut path = full.path_segments().ok_or_else(|| err!("read base"))?;
            path.next();
            let mut found_base_path_marker = false;
            loop {
                let key = match path.next() {
                    None => break,
                    Some(key) => key,
                };
                if key == "--" {
                    found_base_path_marker = true;
                    continue;
                }
                if found_base_path_marker {
                    base.path_segments_mut()
                        .map_err(|_| err!("read marker"))?
                        .push(key);
                } else {
                    let val = match path.next() {
                        None => break,
                        Some(val) => val,
                    };
                    match key {
                        "h" => base.set_host(Some(val)).map_err(|_| err!("read host"))?,
                        "p" => base
                            .set_port(Some(val.parse().map_err(|_| err!("read port"))?))
                            .map_err(|_| err!("read port"))?,
                        "u" => base.set_username(val).map_err(|_| err!("read username"))?,
                        "w" => base
                            .set_password(Some(val))
                            .map_err(|_| err!("read password"))?,
                        _ => return Err(err!("read base")),
                    }
                }
            }
        }
        base.set_query(full.query());
        base.set_fragment(full.fragment());
        Ok(Self { full, base })
    }

    /// Create a new proxy url from a base + tls cert digest.
    pub fn new(base: &str, cert_digest: CertDigest) -> KitsuneResult<Self> {
        let base = url2::try_url2!("{}", base).map_err(KitsuneError::other)?;
        let tls = base64::encode_config(&cert_digest[..], base64::URL_SAFE_NO_PAD);
        let mut full = url2::url2!("kitsune-proxy://{}", tls);
        {
            let mut path = full
                .path_segments_mut()
                .map_err(|_| KitsuneError::from(""))?;
            path.push(base.scheme());
            if let Some(h) = base.host_str() {
                path.push("h");
                path.push(h);
            }
            if let Some(p) = base.port() {
                path.push("p");
                path.push(&format!("{}", p));
            }
            if !base.username().is_empty() {
                path.push("u");
                path.push(base.username());
            }
            if let Some(w) = base.password() {
                path.push("w");
                path.push(w);
            }
            path.push("--");
            if let Some(s) = base.path_segments() {
                for s in s {
                    path.push(s);
                }
            }
        }
        full.set_query(base.query());
        full.set_fragment(base.fragment());
        Ok(Self { full, base })
    }

    /// Extract the cert digest from the url
    pub fn digest(&self) -> CertDigest {
        let digest =
            base64::decode_config(self.full.host_str().unwrap(), base64::URL_SAFE_NO_PAD).unwrap();
        digest.into()
    }

    /// Get a short-hash / first six characters of tls digest for logging
    pub fn short(&self) -> &str {
        let h = self.full.host_str().unwrap();
        &h[..std::cmp::min(h.chars().count(), 6)]
    }

    /// Get the base url this proxy is addressable at.
    pub fn as_base(&self) -> &url2::Url2 {
        &self.base
    }

    /// Get the base url this proxy is addressable at as a &str reference.
    pub fn as_base_str(&self) -> &str {
        self.base.as_str()
    }

    /// Convert this proxy url instance into a base url.
    pub fn into_base(self) -> url2::Url2 {
        self.base
    }

    /// Get the full url referencing this proxy.
    pub fn as_full(&self) -> &url2::Url2 {
        &self.full
    }

    /// Get the full url referencing this proxy as a &str reference.
    pub fn as_full_str(&self) -> &str {
        self.full.as_str()
    }

    /// Convert this proxy url instance into a full url.
    pub fn into_full(self) -> url2::Url2 {
        self.full
    }

    /// Convert this proxy url instance into a (BaseUrl, FullUrl) tuple.
    pub fn into_inner(self) -> (url2::Url2, url2::Url2) {
        (self.base, self.full)
    }
}

macro_rules! q_from {
    ($($t1:ty => $t2:ty, | $i:ident | {$e:expr},)*) => {$(
        impl From<$t1> for $t2 {
            fn from($i: $t1) -> Self {
                $e
            }
        }
    )*};
}

q_from! {
       ProxyUrl => (url2::Url2, url2::Url2), |url| { url.into_inner() },
      &ProxyUrl => (url2::Url2, url2::Url2), |url| { url.clone().into_inner() },
       ProxyUrl => url2::Url2, |url| { url.into_full() },
      &ProxyUrl => url2::Url2, |url| { url.as_full().clone() },
         String => ProxyUrl, |url| { ProxyUrl::from_full(&url).unwrap() },
        &String => ProxyUrl, |url| { ProxyUrl::from_full(url).unwrap() },
           &str => ProxyUrl, |url| { ProxyUrl::from_full(url).unwrap() },
     url2::Url2 => ProxyUrl, |url| { ProxyUrl::from_full(url.as_str()).unwrap() },
    &url2::Url2 => ProxyUrl, |url| { ProxyUrl::from_full(url.as_str()).unwrap() },
}

impl AsRef<str> for ProxyUrl {
    fn as_ref(&self) -> &str {
        self.as_full_str()
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    const TEST_CERT: &str = "VlyCSmL5WRKUTOLmF9wF0oFy5Jqbxy0I9KPeXqB_9Z4";
    const TEST_FULL: &str = "kitsune-proxy://VlyCSmL5WRKUTOLmF9wF0oFy5Jqbxy0I9KPeXqB_9Z4/kitsune-quic/h/1.2.3.4/p/443/u/bob/w/pass/--/yada1/yada2?c=bla&t=EugO96mIgrCph7QMpqJkkI5BPY5GuIP7JcCshnwh8FY&j=bla#bla";
    const TEST_BASE: &str = "kitsune-quic://bob:pass@1.2.3.4:443/yada1/yada2?c=bla&t=EugO96mIgrCph7QMpqJkkI5BPY5GuIP7JcCshnwh8FY&j=bla#bla";

    #[test]
    fn proxy_url_from_full() {
        let u = ProxyUrl::from_full(TEST_FULL).unwrap();
        assert_eq!(TEST_FULL, u.as_full_str());
        assert_eq!(TEST_BASE, u.as_base_str());
    }

    #[test]
    fn proxy_url_from_base() {
        let cert_digest = base64::decode_config(TEST_CERT, base64::URL_SAFE_NO_PAD).unwrap();
        let u = ProxyUrl::new(TEST_BASE, cert_digest.into()).unwrap();
        assert_eq!(TEST_FULL, u.as_full_str());
        assert_eq!(TEST_BASE, u.as_base_str());
    }
}