use super::Endpoint;
use std::error::Error;

pub trait Reader<E: Endpoint>: Send + Sync {
    type Error: Error;

    fn read(&self, buf: &mut [u8]) -> Result<(usize, E), Self::Error>;
}

pub trait Writer<E: Endpoint>: Send + Sync + Clone + 'static {
    type Error: Error;

    fn write(&self, buf: &[u8], dst: &E) -> Result<(), Self::Error>;
}

pub trait Bind: Send + Sync + 'static {
    type Error: Error;
    type Endpoint: Endpoint;

    /* Until Rust gets type equality constraints these have to be generic */
    type Writer: Writer<Self::Endpoint>;
    type Reader: Reader<Self::Endpoint>;
}

/// On platforms where fwmark can be set and the
/// implementation can bind to a new port during later configuration (UAPI support),
/// this type provides the ability to set the fwmark and close the socket (by dropping the instance)
pub trait Owner: Send {
    type Error: Error;

    fn get_port(&self) -> u16;

    fn get_fwmark(&self) -> Option<u32>;

    fn set_fwmark(&mut self, value: Option<u32>) -> Option<Self::Error>;
}

/// On some platforms the application can itself bind to a socket.
/// This enables configuration using the UAPI interface.
pub trait Platform: Bind {
    type Owner: Owner;

    /// Bind to a new port, returning the reader/writer and
    /// an associated instance of the owner type, which closes the UDP socket upon "drop"
    /// and enables configuration of the fwmark value.
    fn bind(port: u16) -> Result<(Vec<Self::Reader>, Self::Writer, Self::Owner), Self::Error>;
}