use {
    crate::{
        backend::InputDeviceId,
        ifs::wl_seat::SeatId,
        it::test_error::{TestError, TestResult},
        utils::stack::Stack,
    },
    isnt::std_1::primitive::IsntConstPtrExt,
    jay_config::{
        _private::{
            bincode_ops,
            ipc::{ClientMessage, Response, ServerMessage},
            ConfigEntry, VERSION,
        },
        input::{InputDevice, Seat},
        Direction,
    },
    std::{cell::Cell, ops::Deref, ptr, rc::Rc},
};

pub static TEST_CONFIG_ENTRY: ConfigEntry = ConfigEntry {
    version: VERSION,
    init,
    unref,
    handle_msg,
};

#[thread_local]
static mut CONFIG: *const TestConfig = ptr::null();

pub fn with_test_config<T, F>(f: F) -> T
where
    F: FnOnce(Rc<TestConfig>) -> T,
{
    unsafe {
        let tc = Rc::new(TestConfig {
            srv: Cell::new(None),
            responses: Default::default(),
        });
        let old = CONFIG;
        CONFIG = tc.deref();
        let res = f(tc.clone());
        CONFIG = old;
        res
    }
}

unsafe extern "C" fn init(
    srv_data: *const u8,
    srv_unref: unsafe extern "C" fn(data: *const u8),
    srv_handler: unsafe extern "C" fn(data: *const u8, msg: *const u8, size: usize),
    _msg: *const u8,
    _size: usize,
) -> *const u8 {
    let tc = CONFIG;
    assert!(tc.is_not_null());
    Rc::increment_strong_count(tc);
    {
        let tc = &*tc;
        tc.srv.set(Some(ServerData {
            srv_data,
            srv_unref,
            srv_handler,
        }));
    }
    tc.cast()
}

unsafe extern "C" fn unref(data: *const u8) {
    Rc::decrement_strong_count(data.cast::<TestConfig>());
}

unsafe extern "C" fn handle_msg(data: *const u8, msg: *const u8, size: usize) {
    let tc = &*data.cast::<TestConfig>();
    let msg = std::slice::from_raw_parts(msg, size);
    let res = bincode::decode_from_slice::<ServerMessage, _>(msg, bincode_ops());
    let (msg, _) = match res {
        Ok(msg) => msg,
        Err(e) => {
            log::error!("could not deserialize message: {}", e);
            return;
        }
    };
    match msg {
        ServerMessage::Configure { .. } => {}
        ServerMessage::Response { response } => {
            tc.responses.push(response);
        }
        ServerMessage::InvokeShortcut { .. } => {}
        ServerMessage::NewInputDevice { .. } => {}
        ServerMessage::DelInputDevice { .. } => {}
        ServerMessage::ConnectorConnect { .. } => {}
        ServerMessage::ConnectorDisconnect { .. } => {}
        ServerMessage::NewConnector { .. } => {}
        ServerMessage::DelConnector { .. } => {}
        ServerMessage::TimerExpired { .. } => {}
        ServerMessage::GraphicsInitialized => {}
        ServerMessage::Clear => tc.clear(),
    }
}

#[derive(Copy, Clone)]
struct ServerData {
    srv_data: *const u8,
    srv_unref: unsafe extern "C" fn(data: *const u8),
    srv_handler: unsafe extern "C" fn(data: *const u8, msg: *const u8, size: usize),
}

pub struct TestConfig {
    srv: Cell<Option<ServerData>>,
    responses: Stack<Response>,
}

macro_rules! get_response {
    ($res:expr, $ty:ident { $($field:ident),+ }) => {
        let ($($field,)+) = match $res {
            Response::$ty { $($field,)+ } => ($($field,)+),
            _ => {
                bail!("Server did not send a response to a {} request", stringify!($ty));
            }
        };
    }
}

impl TestConfig {
    fn send(&self, msg: ClientMessage) -> Result<(), TestError> {
        self.send_(&msg)
    }

    fn send_(&self, msg: &ClientMessage) -> Result<(), TestError> {
        let srv = match self.srv.get() {
            Some(srv) => srv,
            _ => bail!("srv not set"),
        };
        let mut buf = vec![];
        bincode::encode_into_std_write(msg, &mut buf, bincode_ops()).unwrap();
        unsafe {
            (srv.srv_handler)(srv.srv_data, buf.as_ptr(), buf.len());
        }
        Ok(())
    }

    fn send_with_reply(&self, msg: ClientMessage) -> Result<Response, TestError> {
        self.send_(&msg)?;
        match self.responses.pop() {
            Some(r) => Ok(r),
            _ => bail!("Compositor did not send a response to {:?}", msg),
        }
    }

    pub fn quit(&self) -> Result<(), TestError> {
        self.send(ClientMessage::Quit)
    }

    pub fn get_seat(&self, name: &str) -> Result<SeatId, TestError> {
        let reply = self.send_with_reply(ClientMessage::GetSeat { name })?;
        get_response!(reply, GetSeat { seat });
        Ok(SeatId::from_raw(seat.0 as _))
    }

    pub fn show_workspace(&self, seat: SeatId, name: &str) -> Result<(), TestError> {
        let reply = self.send_with_reply(ClientMessage::GetWorkspace { name })?;
        get_response!(reply, GetWorkspace { workspace });
        self.send(ClientMessage::ShowWorkspace {
            seat: Seat(seat.raw() as _),
            workspace,
        })
    }

    pub fn set_input_device_seat(&self, id: InputDeviceId, seat: SeatId) -> Result<(), TestError> {
        self.send(ClientMessage::SetSeat {
            device: InputDevice(id.raw() as _),
            seat: Seat(seat.raw() as _),
        })
    }

    pub fn focus(&self, seat: SeatId, direction: Direction) -> TestResult {
        self.send(ClientMessage::Focus {
            seat: Seat(seat.raw() as _),
            direction,
        })
    }

    fn clear(&self) {
        unsafe {
            if let Some(srv) = self.srv.take() {
                (srv.srv_unref)(srv.srv_data);
            }
        }
    }
}

impl Drop for TestConfig {
    fn drop(&mut self) {
        self.clear();
    }
}