//! C functions for interacting with [SPConnection]s
//!
//! prefix `sp_connection_`
//!
//! A connection to the display.
//!
//! # Examples
//!
//! ```C
//! CConnection connection = sp_connection_open("172.23.42.29:2342");
//! if (connection != NULL)
//!     sp_connection_send_command(connection, sp_command_clear());
//! ```

use servicepoint::{Connection, Packet, TypedCommand, UdpConnection};
use std::ffi::{c_char, CStr};

/// Creates a new instance of [SPConnection].
///
/// returns: NULL if connection fails, or connected instance
///
/// # Panics
///
/// - when `host` is null or an invalid host
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - the returned instance is freed in some way, either by using a consuming function or
///   by explicitly calling `sp_connection_free`.
#[no_mangle]
pub unsafe extern "C" fn sp_connection_open(
    host: *const c_char,
) -> *mut UdpConnection {
    assert!(!host.is_null());
    let host = unsafe { CStr::from_ptr(host) }
        .to_str()
        .expect("Bad encoding");
    let connection = match UdpConnection::open(host) {
        Err(_) => return std::ptr::null_mut(),
        Ok(value) => value,
    };

    Box::into_raw(Box::new(connection))
}

//#[no_mangle]
//pub unsafe extern "C" fn sp_connection_open_ipv4(
//    host: SocketAddrV4,
//) -> *mut SPConnection {
//    let connection = match servicepoint::UdpConnection::open(host) {
//        Err(_) => return std::ptr::null_mut(),
//        Ok(value) => value,
//    };
//
//    Box::into_raw(Box::new(SPConnection(connection)))
//}

// /// Creates a new instance of [SPUdpConnection] for testing that does not actually send anything.
// ///
// /// returns: a new instance. Will never return NULL.
// ///
// /// # Safety
// ///
// /// The caller has to make sure that:
// ///
// /// - the returned instance is freed in some way, either by using a consuming function or
// ///   by explicitly calling `sp_connection_free`.
// #[no_mangle]
// pub unsafe extern "C" fn sp_connection_fake() -> NonNull<SPUdpConnection> {
//     let result = Box::new(SPUdpConnection(servicepoint::Connection::Fake));
//     NonNull::from(Box::leak(result))
// }

/// Sends a [SPPacket] to the display using the [SPConnection].
///
/// The passed `packet` gets consumed.
///
/// returns: true in case of success
///
/// # Panics
///
/// - when `connection` is NULL
/// - when `packet` is NULL
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - `connection` points to a valid instance of [SPConnection]
/// - `packet` points to a valid instance of [SPPacket]
/// - `packet` is not used concurrently or after this call
#[no_mangle]
pub unsafe extern "C" fn sp_connection_send_packet(
    connection: *const UdpConnection,
    packet: *mut Packet,
) -> bool {
    assert!(!connection.is_null());
    assert!(!packet.is_null());
    let packet = unsafe { Box::from_raw(packet) };
    unsafe { (*connection).send(*packet) }.is_ok()
}

/// Sends a [SPCommand] to the display using the [SPConnection].
///
/// The passed `command` gets consumed.
///
/// returns: true in case of success
///
/// # Panics
///
/// - when `connection` is NULL
/// - when `command` is NULL
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - `connection` points to a valid instance of [SPConnection]
/// - `command` points to a valid instance of [SPPacket]
/// - `command` is not used concurrently or after this call
#[no_mangle]
pub unsafe extern "C" fn sp_connection_send_command(
    connection: *const UdpConnection,
    command: *mut TypedCommand,
) -> bool {
    assert!(!connection.is_null());
    assert!(!command.is_null());
    let command = *unsafe { Box::from_raw(command) };
    unsafe { (*connection).send(command) }.is_ok()
}

/// Closes and deallocates a [SPConnection].
///
/// # Panics
///
/// - when `connection` is NULL
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - `connection` points to a valid [SPConnection]
/// - `connection` is not used concurrently or after this call
#[no_mangle]
pub unsafe extern "C" fn sp_connection_free(connection: *mut UdpConnection) {
    assert!(!connection.is_null());
    _ = unsafe { Box::from_raw(connection) };
}