// SPDX-License-Identifier: GPL-3.0-only

use crate::state::State;
use smithay::{
    backend::input::{Device, DeviceCapability, InputBackend, InputEvent},
    desktop::{layer_map_for_output, Space},
    reexports::wayland_server::{protocol::wl_surface::WlSurface, Display},
    utils::{Logical, Point},
    wayland::{
        data_device::set_data_device_focus,
        output::Output,
        seat::{CursorImageStatus, FilterResult, Keysym, Seat, XkbConfig},
        shell::wlr_layer::Layer as WlrLayer,
        SERIAL_COUNTER,
    },
};
use std::{cell::RefCell, collections::HashMap};

pub struct ActiveOutput(pub RefCell<Output>);

pub struct Devices(RefCell<HashMap<String, Vec<DeviceCapability>>>);

impl Devices {
    fn new() -> Devices {
        Devices(RefCell::new(HashMap::new()))
    }

    fn add_device<D: Device>(&self, device: &D) -> Vec<DeviceCapability> {
        let id = device.id();
        let mut map = self.0.borrow_mut();
        let caps = [DeviceCapability::Keyboard, DeviceCapability::Pointer]
            .iter()
            .cloned()
            .filter(|c| device.has_capability(*c))
            .collect::<Vec<_>>();
        let new_caps = caps
            .iter()
            .cloned()
            .filter(|c| map.values().flatten().all(|has| *c != *has))
            .collect::<Vec<_>>();
        map.insert(id, caps);
        new_caps
    }

    pub fn has_device<D: Device>(&self, device: &D) -> bool {
        self.0.borrow().contains_key(&device.id())
    }

    fn remove_device<D: Device>(&self, device: &D) -> Vec<DeviceCapability> {
        let id = device.id();
        let mut map = self.0.borrow_mut();
        map.remove(&id)
            .unwrap_or(Vec::new())
            .into_iter()
            .filter(|c| map.values().flatten().all(|has| *c != *has))
            .collect()
    }
}

pub fn add_seat(display: &mut Display, name: String) -> Seat {
    let (seat, _) = Seat::new(display, name, None);
    let userdata = seat.user_data();
    userdata.insert_if_missing(|| Devices::new());
    userdata.insert_if_missing(|| RefCell::new(CursorImageStatus::Hidden));
    userdata.insert_if_missing(|| Vec::<Keysym>::new());
    seat
}

pub fn active_output(seat: &Seat, state: &State) -> Output {
    seat.user_data()
        .get::<ActiveOutput>()
        .map(|x| x.0.borrow().clone())
        .unwrap_or_else(|| {
            state
                .spaces
                .outputs()
                .next()
                .cloned()
                .expect("Backend has no outputs?")
        })
}

pub fn set_active_output(seat: &Seat, output: &Output) {
    if !seat
        .user_data()
        .insert_if_missing(|| ActiveOutput(RefCell::new(output.clone())))
    {
        *seat
            .user_data()
            .get::<ActiveOutput>()
            .unwrap()
            .0
            .borrow_mut() = output.clone();
    }
}

impl State {
    pub fn process_input_event<B: InputBackend>(&mut self, event: InputEvent<B>) {
        use smithay::backend::input::Event;

        match event {
            InputEvent::DeviceAdded { device } => {
                let seat = &mut self.last_active_seat;
                let userdata = seat.user_data();
                let devices = userdata.get::<Devices>().unwrap();
                for cap in devices.add_device(&device) {
                    match cap {
                        DeviceCapability::Keyboard => {
                            let _ =
                                seat.add_keyboard(XkbConfig::default(), 200, 25, |seat, focus| {
                                    set_data_device_focus(
                                        seat,
                                        focus.and_then(|s| s.as_ref().client()),
                                    )
                                });
                        }
                        DeviceCapability::Pointer => {
                            let output = self
                                .spaces
                                .outputs()
                                .next()
                                .expect("Backend initialized without output")
                                .clone();
                            seat.user_data()
                                .insert_if_missing(|| ActiveOutput(RefCell::new(output)));
                            let owned_seat = seat.clone();
                            seat.add_pointer(move |status| {
                                *owned_seat
                                    .user_data()
                                    .get::<RefCell<CursorImageStatus>>()
                                    .unwrap()
                                    .borrow_mut() = status;
                            });
                        }
                        _ => {}
                    }
                }
            }
            InputEvent::DeviceRemoved { device } => {
                for seat in &mut self.seats {
                    let userdata = seat.user_data();
                    let devices = userdata.get::<Devices>().unwrap();
                    if devices.has_device(&device) {
                        for cap in devices.remove_device(&device) {
                            match cap {
                                DeviceCapability::Keyboard => {
                                    seat.remove_keyboard();
                                }
                                DeviceCapability::Pointer => {
                                    seat.remove_pointer();
                                }
                                _ => {}
                            }
                        }
                        break;
                    }
                }
            }
            InputEvent::Keyboard { event, .. } => {
                use smithay::backend::input::KeyboardKeyEvent;

                let device = event.device();
                for seat in self.seats.clone().iter() {
                    let userdata = seat.user_data();
                    let devices = userdata.get::<Devices>().unwrap();
                    if devices.has_device(&device) {
                        let keycode = event.key_code();
                        let state = event.state();
                        slog_scope::trace!("key"; "keycode" => keycode, "state" => format!("{:?}", state));

                        let serial = SERIAL_COUNTER.next_serial();
                        let time = Event::time(&event);
                        seat.get_keyboard().unwrap().input::<(), _>(
                            keycode,
                            state,
                            serial,
                            time,
                            |modifiers, handle| {
                                // here we can handle global shortcuts and the like
                                let _ = (modifiers, handle);
                                FilterResult::Forward
                            },
                        );
                        break;
                    }
                }
            }
            InputEvent::PointerMotion { event, .. } => {
                use smithay::backend::input::PointerMotionEvent;

                let device = event.device();
                for seat in self.seats.clone().iter() {
                    let userdata = seat.user_data();
                    let devices = userdata.get::<Devices>().unwrap();
                    if devices.has_device(&device) {
                        let current_output = active_output(seat, &self);

                        let mut position = seat.get_pointer().unwrap().current_location();
                        position += event.delta();

                        let output = self
                            .spaces
                            .outputs()
                            .find(|output| {
                                self.spaces
                                    .output_geometry(output)
                                    .to_f64()
                                    .contains(position)
                            })
                            .cloned()
                            .unwrap_or(current_output.clone());
                        if output != current_output {
                            set_active_output(seat, &output);
                        }
                        let output_geometry = self.spaces.output_geometry(&output);

                        position.x = 0.0f64
                            .max(position.x)
                            .min((output_geometry.loc.x + output_geometry.size.w) as f64);
                        position.y = 0.0f64
                            .max(position.y)
                            .min((output_geometry.loc.y + output_geometry.size.h) as f64);

                        let serial = SERIAL_COUNTER.next_serial();
                        let space = self.spaces.active_space_mut(&output);
                        let under = State::surface_under(position, &output, space);
                        handle_window_movement(under.as_ref().map(|(s, _)| s), space);
                        seat.get_pointer()
                            .unwrap()
                            .motion(position, under, serial, event.time());

                        break;
                    }
                }
            }
            InputEvent::PointerMotionAbsolute { event, .. } => {
                use smithay::backend::input::PointerMotionAbsoluteEvent;

                let device = event.device();
                for seat in self.seats.clone().iter() {
                    let userdata = seat.user_data();
                    let devices = userdata.get::<Devices>().unwrap();
                    if devices.has_device(&device) {
                        let output = active_output(seat, &self);
                        let geometry = self.spaces.output_geometry(&output);
                        let space = self.spaces.active_space_mut(&output);
                        let position =
                            geometry.loc.to_f64() + event.position_transformed(geometry.size);
                        let serial = SERIAL_COUNTER.next_serial();
                        let under = State::surface_under(position, &output, space);
                        handle_window_movement(under.as_ref().map(|(s, _)| s), space);
                        seat.get_pointer()
                            .unwrap()
                            .motion(position, under, serial, event.time());
                        break;
                    }
                }
            }
            InputEvent::PointerButton { event, .. } => {
                use smithay::{
                    backend::input::{ButtonState, PointerButtonEvent},
                    reexports::wayland_server::protocol::wl_pointer,
                };

                let device = event.device();
                for seat in self.seats.clone().iter() {
                    let userdata = seat.user_data();
                    let devices = userdata.get::<Devices>().unwrap();
                    if devices.has_device(&device) {
                        let serial = SERIAL_COUNTER.next_serial();
                        let button = event.button_code();
                        let state = match event.state() {
                            ButtonState::Pressed => {
                                // change the keyboard focus unless the pointer is grabbed
                                if !seat.get_pointer().unwrap().is_grabbed() {
                                    let output = active_output(seat, &self);
                                    let mut pos = seat.get_pointer().unwrap().current_location();
                                    let output_geo = self.spaces.output_geometry(&output);
                                    let space = self.spaces.active_space_mut(&output);
                                    let layers = layer_map_for_output(&output);
                                    pos -= output_geo.loc.to_f64();
                                    let mut under = None;

                                    if let Some(layer) = layers
                                        .layer_under(WlrLayer::Overlay, pos)
                                        .or_else(|| layers.layer_under(WlrLayer::Top, pos))
                                    {
                                        if layer.can_receive_keyboard_focus() {
                                            let layer_loc = layers.layer_geometry(layer).loc;
                                            under = layer
                                                .surface_under(pos - layer_loc.to_f64())
                                                .map(|(s, _)| s);
                                        }
                                    } else if let Some(window) = space.window_under(pos).cloned() {
                                        let window_loc =
                                            space.window_geometry(&window).unwrap().loc;
                                        under = window
                                            .surface_under(pos - window_loc.to_f64())
                                            .map(|(s, _)| s);
                                        space.raise_window(&window);
                                    } else if let Some(layer) = layers
                                        .layer_under(WlrLayer::Bottom, pos)
                                        .or_else(|| layers.layer_under(WlrLayer::Background, pos))
                                    {
                                        if layer.can_receive_keyboard_focus() {
                                            let layer_loc = layers.layer_geometry(layer).loc;
                                            under = layer
                                                .surface_under(pos - layer_loc.to_f64())
                                                .map(|(s, _)| s);
                                        }
                                    };

                                    if let Some(keyboard) = seat.get_keyboard() {
                                        keyboard.set_focus(under.as_ref(), serial);
                                    }
                                }
                                wl_pointer::ButtonState::Pressed
                            }
                            ButtonState::Released => wl_pointer::ButtonState::Released,
                        };
                        seat.get_pointer()
                            .unwrap()
                            .button(button, state, serial, event.time());
                        break;
                    }
                }
            }
            InputEvent::PointerAxis { event, .. } => {
                use smithay::{
                    backend::input::{Axis, AxisSource, PointerAxisEvent},
                    reexports::wayland_server::protocol::wl_pointer,
                    wayland::seat::AxisFrame,
                };

                let device = event.device();
                for seat in self.seats.clone().iter() {
                    let userdata = seat.user_data();
                    let devices = userdata.get::<Devices>().unwrap();
                    if devices.has_device(&device) {
                        let source = match event.source() {
                            AxisSource::Continuous => wl_pointer::AxisSource::Continuous,
                            AxisSource::Finger => wl_pointer::AxisSource::Finger,
                            AxisSource::Wheel | AxisSource::WheelTilt => {
                                wl_pointer::AxisSource::Wheel
                            }
                        };
                        let horizontal_amount =
                            event.amount(Axis::Horizontal).unwrap_or_else(|| {
                                event.amount_discrete(Axis::Horizontal).unwrap() * 3.0
                            });
                        let vertical_amount = event.amount(Axis::Vertical).unwrap_or_else(|| {
                            event.amount_discrete(Axis::Vertical).unwrap() * 3.0
                        });
                        let horizontal_amount_discrete = event.amount_discrete(Axis::Horizontal);
                        let vertical_amount_discrete = event.amount_discrete(Axis::Vertical);

                        {
                            let mut frame = AxisFrame::new(event.time()).source(source);
                            if horizontal_amount != 0.0 {
                                frame = frame
                                    .value(wl_pointer::Axis::HorizontalScroll, horizontal_amount);
                                if let Some(discrete) = horizontal_amount_discrete {
                                    frame = frame.discrete(
                                        wl_pointer::Axis::HorizontalScroll,
                                        discrete as i32,
                                    );
                                }
                            } else if source == wl_pointer::AxisSource::Finger {
                                frame = frame.stop(wl_pointer::Axis::HorizontalScroll);
                            }
                            if vertical_amount != 0.0 {
                                frame =
                                    frame.value(wl_pointer::Axis::VerticalScroll, vertical_amount);
                                if let Some(discrete) = vertical_amount_discrete {
                                    frame = frame.discrete(
                                        wl_pointer::Axis::VerticalScroll,
                                        discrete as i32,
                                    );
                                }
                            } else if source == wl_pointer::AxisSource::Finger {
                                frame = frame.stop(wl_pointer::Axis::VerticalScroll);
                            }
                            seat.get_pointer().unwrap().axis(frame);
                        }
                        break;
                    }
                }
            }
            _ => { /* TODO e.g. tablet or touch events */ }
        }
    }

    pub fn surface_under(
        pos: Point<f64, Logical>,
        output: &Output,
        space: &Space,
    ) -> Option<(WlSurface, Point<i32, Logical>)> {
        let layers = layer_map_for_output(output);
        let output_geo = space.output_geometry(output).unwrap();

        if let Some(layer) = layers
            .layer_under(WlrLayer::Overlay, pos)
            .or_else(|| layers.layer_under(WlrLayer::Top, pos))
        {
            let layer_loc = layers.layer_geometry(layer).loc;
            layer
                .surface_under(pos - output_geo.loc.to_f64() - layer_loc.to_f64())
                .map(|(s, loc)| (s, loc + layer_loc))
        } else if let Some(window) = space.window_under(pos) {
            let window_loc = space.window_geometry(window).unwrap().loc;
            window
                .surface_under(pos - window_loc.to_f64())
                .map(|(s, loc)| (s, loc + window_loc))
        } else if let Some(layer) = layers
            .layer_under(WlrLayer::Bottom, pos)
            .or_else(|| layers.layer_under(WlrLayer::Background, pos))
        {
            let layer_loc = layers.layer_geometry(layer).loc;
            layer
                .surface_under(pos - output_geo.loc.to_f64() - layer_loc.to_f64())
                .map(|(s, loc)| (s, loc + layer_loc))
        } else {
            None
        }
    }
}

pub fn handle_window_movement(surface: Option<&WlSurface>, space: &mut Space) {
    if let Some(surface) = surface {
        if let Some(window) = space.window_for_surface(&surface).cloned() {
            if let Some(new_position) =
                crate::shell::grabs::MoveSurfaceGrab::apply_move_state(&window)
            {
                space.map_window(&window, new_position);
            }
        }
    }
}