use std::{process::Command, sync::atomic::Ordering};

#[cfg(feature = "udev")]
use crate::udev::UdevData;
#[cfg(feature = "winit")]
use crate::winit::WinitData;
use crate::AnvilState;

use smithay::{
    backend::input::{
        self, Event, InputBackend, InputEvent, KeyState, KeyboardKeyEvent, PointerAxisEvent,
        PointerButtonEvent,
    },
    reexports::wayland_server::protocol::wl_pointer,
    wayland::{
        seat::{keysyms as xkb, AxisFrame, Keysym, ModifiersState},
        SERIAL_COUNTER as SCOUNTER,
    },
};

#[cfg(feature = "winit")]
use smithay::backend::input::PointerMotionAbsoluteEvent;

#[cfg(feature = "udev")]
use smithay::backend::{input::PointerMotionEvent, session::Session};

impl<Backend> AnvilState<Backend> {
    fn keyboard_key_to_action<B: InputBackend>(&mut self, evt: B::KeyboardKeyEvent) -> KeyAction {
        let keycode = evt.key_code();
        let state = evt.state();
        debug!(self.log, "key"; "keycode" => keycode, "state" => format!("{:?}", state));
        let serial = SCOUNTER.next_serial();
        let log = &self.log;
        let time = Event::time(&evt);
        let mut action = KeyAction::None;
        let suppressed_keys = &mut self.suppressed_keys;
        self.keyboard
            .input(keycode, state, serial, time, |modifiers, keysym| {
                debug!(log, "keysym";
                    "state" => format!("{:?}", state),
                    "mods" => format!("{:?}", modifiers),
                    "keysym" => ::xkbcommon::xkb::keysym_get_name(keysym)
                );

                // If the key is pressed and triggered a action
                // we will not forward the key to the client.
                // Additionally add the key to the suppressed keys
                // so that we can decide on a release if the key
                // should be forwarded to the client or not.
                if let KeyState::Pressed = state {
                    action = process_keyboard_shortcut(*modifiers, keysym);

                    // forward to client only if action == KeyAction::Forward
                    let forward = matches!(action, KeyAction::Forward);

                    if !forward {
                        suppressed_keys.push(keysym);
                    }

                    forward
                } else {
                    let suppressed = suppressed_keys.contains(&keysym);

                    if suppressed {
                        suppressed_keys.retain(|k| *k != keysym);
                    }

                    !suppressed
                }
            });
        action
    }

    fn on_pointer_button<B: InputBackend>(&mut self, evt: B::PointerButtonEvent) {
        let serial = SCOUNTER.next_serial();
        let button = match evt.button() {
            input::MouseButton::Left => 0x110,
            input::MouseButton::Right => 0x111,
            input::MouseButton::Middle => 0x112,
            input::MouseButton::Other(b) => b as u32,
        };
        let state = match evt.state() {
            input::MouseButtonState::Pressed => {
                // change the keyboard focus unless the pointer is grabbed
                if !self.pointer.is_grabbed() {
                    let under = self
                        .window_map
                        .borrow_mut()
                        .get_surface_and_bring_to_top(self.pointer_location);
                    self.keyboard
                        .set_focus(under.as_ref().map(|&(ref s, _)| s), serial);
                }
                wl_pointer::ButtonState::Pressed
            }
            input::MouseButtonState::Released => wl_pointer::ButtonState::Released,
        };
        self.pointer.button(button, state, serial, evt.time());
    }

    fn on_pointer_axis<B: InputBackend>(&mut self, evt: B::PointerAxisEvent) {
        let source = match evt.source() {
            input::AxisSource::Continuous => wl_pointer::AxisSource::Continuous,
            input::AxisSource::Finger => wl_pointer::AxisSource::Finger,
            input::AxisSource::Wheel | input::AxisSource::WheelTilt => wl_pointer::AxisSource::Wheel,
        };
        let horizontal_amount = evt
            .amount(input::Axis::Horizontal)
            .unwrap_or_else(|| evt.amount_discrete(input::Axis::Horizontal).unwrap() * 3.0);
        let vertical_amount = evt
            .amount(input::Axis::Vertical)
            .unwrap_or_else(|| evt.amount_discrete(input::Axis::Vertical).unwrap() * 3.0);
        let horizontal_amount_discrete = evt.amount_discrete(input::Axis::Horizontal);
        let vertical_amount_discrete = evt.amount_discrete(input::Axis::Vertical);

        {
            let mut frame = AxisFrame::new(evt.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);
            }
            self.pointer.axis(frame);
        }
    }
}

#[cfg(feature = "winit")]
impl AnvilState<WinitData> {
    pub fn process_input_event<B: InputBackend>(&mut self, event: InputEvent<B>) {
        match event {
            InputEvent::Keyboard { event, .. } => match self.keyboard_key_to_action::<B>(event) {
                KeyAction::None | KeyAction::Forward => {}
                KeyAction::Quit => {
                    info!(self.log, "Quitting.");
                    self.running.store(false, Ordering::SeqCst);
                }
                KeyAction::Run(cmd) => {
                    info!(self.log, "Starting program"; "cmd" => cmd.clone());
                    if let Err(e) = Command::new(&cmd).spawn() {
                        error!(self.log,
                            "Failed to start program";
                            "cmd" => cmd,
                            "err" => format!("{:?}", e)
                        );
                    }
                }
                action => {
                    warn!(self.log, "Key action {:?} unsupported on winit backend.", action);
                }
            },
            InputEvent::PointerMotionAbsolute { event, .. } => self.on_pointer_move_absolute::<B>(event),
            InputEvent::PointerButton { event, .. } => self.on_pointer_button::<B>(event),
            InputEvent::PointerAxis { event, .. } => self.on_pointer_axis::<B>(event),
            _ => {
                // other events are not handled in anvil (yet)
            }
        }
    }

    fn on_pointer_move_absolute<B: InputBackend>(&mut self, evt: B::PointerMotionAbsoluteEvent) {
        // different cases depending on the context:
        let (x, y) = evt.position();
        self.pointer_location = (x, y);
        let serial = SCOUNTER.next_serial();
        let under = self.window_map.borrow().get_surface_under((x as f64, y as f64));
        self.pointer.motion((x, y), under, serial, evt.time());
    }
}

#[cfg(feature = "udev")]
impl AnvilState<UdevData> {
    pub fn process_input_event<B: InputBackend>(&mut self, event: InputEvent<B>) {
        match event {
            InputEvent::Keyboard { event, .. } => match self.keyboard_key_to_action::<B>(event) {
                KeyAction::None | KeyAction::Forward => {}
                KeyAction::Quit => {
                    info!(self.log, "Quitting.");
                    self.running.store(false, Ordering::SeqCst);
                }
                #[cfg(feature = "udev")]
                KeyAction::VtSwitch(vt) => {
                    info!(self.log, "Trying to switch to vt {}", vt);
                    if let Err(err) = self.backend_data.session.change_vt(vt) {
                        error!(self.log, "Error switching to vt {}: {}", vt, err);
                    }
                }
                KeyAction::Run(cmd) => {
                    info!(self.log, "Starting program"; "cmd" => cmd.clone());
                    if let Err(e) = Command::new(&cmd).spawn() {
                        error!(self.log,
                            "Failed to start program";
                            "cmd" => cmd,
                            "err" => format!("{:?}", e)
                        );
                    }
                }
                KeyAction::Screen(num) => {
                    if let Some(output) = self.backend_data.output_map.get(num) {
                        let x = self
                            .backend_data
                            .output_map
                            .iter()
                            .take(num)
                            .fold(0, |acc, output| acc + output.size.0)
                            as f64
                            + (output.size.0 as f64 / 2.0);
                        let y = output.size.1 as f64 / 2.0;
                        self.pointer_location = (x as f64, y as f64)
                    }
                }
            },
            InputEvent::PointerMotion { event, .. } => self.on_pointer_move::<B>(event),
            InputEvent::PointerButton { event, .. } => self.on_pointer_button::<B>(event),
            InputEvent::PointerAxis { event, .. } => self.on_pointer_axis::<B>(event),
            _ => {
                // other events are not handled in anvil (yet)
            }
        }
    }

    fn on_pointer_move<B: InputBackend>(&mut self, evt: B::PointerMotionEvent) {
        let (x, y) = (evt.delta_x(), evt.delta_y());
        let serial = SCOUNTER.next_serial();
        self.pointer_location.0 += x as f64;
        self.pointer_location.1 += y as f64;

        // clamp to screen limits
        // this event is never generated by winit
        self.pointer_location = self.clamp_coords(self.pointer_location);

        let under = self.window_map.borrow().get_surface_under(self.pointer_location);
        self.pointer
            .motion(self.pointer_location, under, serial, evt.time());
    }

    fn clamp_coords(&self, pos: (f64, f64)) -> (f64, f64) {
        if self.backend_data.output_map.is_empty() {
            return pos;
        }

        let (mut x, mut y) = pos;
        // max_x is the sum of the width of all outputs
        let max_x = self
            .backend_data
            .output_map
            .iter()
            .fold(0u32, |acc, output| acc + output.size.0);
        x = x.max(0.0).min(max_x as f64);

        // max y depends on the current output
        let max_y = self.current_output_size(x).1;
        y = y.max(0.0).min(max_y as f64);

        (x, y)
    }

    fn current_output_idx(&self, x: f64) -> usize {
        self.backend_data
            .output_map
            .iter()
            // map each output to their x position
            .scan(0u32, |acc, output| {
                let curr_x = *acc;
                *acc += output.size.0;
                Some(curr_x)
            })
            // get an index
            .enumerate()
            // find the first one with a greater x
            .find(|(_idx, x_pos)| *x_pos as f64 > x)
            // the previous output is the one we are on
            .map(|(idx, _)| idx - 1)
            .unwrap_or(self.backend_data.output_map.len() - 1)
    }

    fn current_output_size(&self, x: f64) -> (u32, u32) {
        self.backend_data.output_map[self.current_output_idx(x)].size
    }
}

/// Possible results of a keyboard action
#[derive(Debug)]
enum KeyAction {
    /// Quit the compositor
    Quit,
    /// Trigger a vt-switch
    VtSwitch(i32),
    /// run a command
    Run(String),
    /// Switch the current screen
    Screen(usize),
    /// Forward the key to the client
    Forward,
    /// Do nothing more
    None,
}

fn process_keyboard_shortcut(modifiers: ModifiersState, keysym: Keysym) -> KeyAction {
    if modifiers.ctrl && modifiers.alt && keysym == xkb::KEY_BackSpace
        || modifiers.logo && keysym == xkb::KEY_q
    {
        // ctrl+alt+backspace = quit
        // logo + q = quit
        KeyAction::Quit
    } else if (xkb::KEY_XF86Switch_VT_1..=xkb::KEY_XF86Switch_VT_12).contains(&keysym) {
        // VTSwicth
        KeyAction::VtSwitch((keysym - xkb::KEY_XF86Switch_VT_1 + 1) as i32)
    } else if modifiers.logo && keysym == xkb::KEY_Return {
        // run terminal
        KeyAction::Run("weston-terminal".into())
    } else if modifiers.logo && keysym >= xkb::KEY_1 && keysym <= xkb::KEY_9 {
        KeyAction::Screen((keysym - xkb::KEY_1) as usize)
    } else {
        KeyAction::Forward
    }
}