use response::{Outcome, Responder};
use http::hyper::{header, FreshHyperResponse, StatusCode};
use outcome::IntoOutcome;

/// An empty redirect response to a given URL.
///
/// This type simplifies returning a redirect response to the client.
#[derive(Debug)]
pub struct Redirect(StatusCode, String);

impl Redirect {
    /// Construct a temporary "see other" (303) redirect response. This is the
    /// typical response when redirecting a user to another page. This type of
    /// redirect indicates that the client should look elsewhere, but always via
    /// a `GET` request, for a given resource.
    ///
    /// # Examples
    ///
    /// ```rust
    /// use rocket::response::Redirect;
    ///
    /// let redirect = Redirect::to("/other_url");
    /// ```
    pub fn to(uri: &str) -> Redirect {
        Redirect(StatusCode::SeeOther, String::from(uri))
    }

    /// Construct a "temporary" (307) redirect response. This response instructs
    /// the client to reissue the current request to a different URL,
    /// maintaining the contents of the request identically. This means that,
    /// for example, a `POST` request will be resent, contents included, to the
    /// requested URL.
    ///
    /// # Examples
    ///
    /// ```rust
    /// use rocket::response::Redirect;
    ///
    /// let redirect = Redirect::temporary("/other_url");
    /// ```
    pub fn temporary(uri: &str) -> Redirect {
        Redirect(StatusCode::TemporaryRedirect, String::from(uri))
    }

    /// Construct a "permanent" (308) redirect response. This redirect must only
    /// be used for permanent redirects as it is cached by clients. This
    /// response instructs the client to reissue requests tot he current URL to
    /// a different URL, now and in the future, maintaining the contents of the
    /// request identically. This means that, for example, a `POST` request will
    /// be resent, contents included, to the requested URL.
    ///
    /// # Examples
    ///
    /// ```rust
    /// use rocket::response::Redirect;
    ///
    /// let redirect = Redirect::permanent("/other_url");
    /// ```
    pub fn permanent(uri: &str) -> Redirect {
        Redirect(StatusCode::PermanentRedirect, String::from(uri))
    }

    /// Construct a temporary "found" (302) redirect response. This response
    /// instructs the client to reissue the current request to a different URL,
    /// ideally maintaining the contents of the request identically.
    /// Unfortunately, different clients may respond differently to this type of
    /// redirect, so `303` or `307` redirects, which disambiguate, are
    /// preferred.
    ///
    /// # Examples
    ///
    /// ```rust
    /// use rocket::response::Redirect;
    ///
    /// let redirect = Redirect::found("/other_url");
    /// ```
    pub fn found(uri: &str) -> Redirect {
        Redirect(StatusCode::Found, String::from(uri))
    }

    /// Construct a permanent "moved" (301) redirect response. This response
    /// should only be used for permanent redirects as it can be cached by
    /// browsers. Because different clients may respond differently to this type
    /// of redirect, a `308` redirect, which disambiguates, is preferred.
    ///
    /// # Examples
    ///
    /// ```rust
    /// use rocket::response::Redirect;
    ///
    /// let redirect = Redirect::moved("/other_url");
    /// ```
    pub fn moved(uri: &str) -> Redirect {
        Redirect(StatusCode::MovedPermanently, String::from(uri))
    }
}

/// Constructs a response with the appropriate status code and the given URL in
/// the `Location` header field. The body of the response is empty. This
/// responder does not fail.
impl<'a> Responder for Redirect {
    fn respond<'b>(&mut self, mut res: FreshHyperResponse<'b>) -> Outcome<'b> {
        res.headers_mut().set(header::ContentLength(0));
        res.headers_mut().set(header::Location(self.1.clone()));
        *(res.status_mut()) = self.0;
        res.send(b"").into_outcome()
    }
}