use header::{Header, HeaderFormat};
use std::fmt;
use std::str::FromStr;
use header::parsing::{from_comma_delimited, fmt_comma_delimited};

pub use self::ConnectionOption::{KeepAlive, Close, ConnectionHeader};

/// The `Connection` header.
#[derive(Clone, PartialEq, Show)]
pub struct Connection(pub Vec<ConnectionOption>);

deref!(Connection => Vec<ConnectionOption>);

/// Values that can be in the `Connection` header.
#[derive(Clone, PartialEq, Show)]
pub enum ConnectionOption {
    /// The `keep-alive` connection value.
    KeepAlive,
    /// The `close` connection value.
    Close,
    /// Values in the Connection header that are supposed to be names of other Headers.
    ///
    /// > When a header field aside from Connection is used to supply control
    /// > information for or about the current connection, the sender MUST list
    /// > the corresponding field-name within the Connection header field.
    // TODO: it would be nice if these "Strings" could be stronger types, since
    // they are supposed to relate to other Header fields (which we have strong
    // types for).
    ConnectionHeader(String),
}

impl FromStr for ConnectionOption {
    fn from_str(s: &str) -> Option<ConnectionOption> {
        match s {
            "keep-alive" => Some(KeepAlive),
            "close" => Some(Close),
            s => Some(ConnectionHeader(s.to_string()))
        }
    }
}

impl fmt::String for ConnectionOption {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        write!(fmt, "{}", match *self {
            KeepAlive => "keep-alive",
            Close => "close",
            ConnectionHeader(ref s) => s.as_slice()
        })
    }
}

impl Header for Connection {
    fn header_name(_: Option<Connection>) -> &'static str {
        "Connection"
    }

    fn parse_header(raw: &[Vec<u8>]) -> Option<Connection> {
        from_comma_delimited(raw).map(|vec| Connection(vec))
    }
}

impl HeaderFormat for Connection {
    fn fmt_header(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        let Connection(ref parts) = *self;
        fmt_comma_delimited(fmt, &parts[])
    }
}

bench_header!(close, Connection, { vec![b"close".to_vec()] });
bench_header!(keep_alive, Connection, { vec![b"keep-alive".to_vec()] });
bench_header!(header, Connection, { vec![b"authorization".to_vec()] });