use super::{error::EmulationError, EmulationHandle, InputEmulation};
use async_trait::async_trait;
use core_graphics::display::{CGDisplayBounds, CGMainDisplayID, CGPoint};
use core_graphics::event::{
    CGEvent, CGEventTapLocation, CGEventType, CGKeyCode, CGMouseButton, EventField, ScrollEventUnit,
};
use core_graphics::event_source::{CGEventSource, CGEventSourceStateID};
use input_event::{Event, KeyboardEvent, PointerEvent};
use keycode::{KeyMap, KeyMapping};
use std::ops::{Index, IndexMut};
use std::time::Duration;
use tokio::task::AbortHandle;

use super::error::MacOSEmulationCreationError;

const DEFAULT_REPEAT_DELAY: Duration = Duration::from_millis(500);
const DEFAULT_REPEAT_INTERVAL: Duration = Duration::from_millis(32);

pub struct MacOSEmulation {
    pub event_source: CGEventSource,
    repeat_task: Option<AbortHandle>,
    button_state: ButtonState,
}

struct ButtonState {
    left: bool,
    right: bool,
    center: bool,
}

impl Index<CGMouseButton> for ButtonState {
    type Output = bool;

    fn index(&self, index: CGMouseButton) -> &Self::Output {
        match index {
            CGMouseButton::Left => &self.left,
            CGMouseButton::Right => &self.right,
            CGMouseButton::Center => &self.center,
        }
    }
}

impl IndexMut<CGMouseButton> for ButtonState {
    fn index_mut(&mut self, index: CGMouseButton) -> &mut Self::Output {
        match index {
            CGMouseButton::Left => &mut self.left,
            CGMouseButton::Right => &mut self.right,
            CGMouseButton::Center => &mut self.center,
        }
    }
}

unsafe impl Send for MacOSEmulation {}

impl MacOSEmulation {
    pub fn new() -> Result<Self, MacOSEmulationCreationError> {
        let event_source = CGEventSource::new(CGEventSourceStateID::CombinedSessionState)
            .map_err(|_| MacOSEmulationCreationError::EventSourceCreation)?;
        let button_state = ButtonState {
            left: false,
            right: false,
            center: false,
        };
        Ok(Self {
            event_source,
            button_state,
            repeat_task: None,
        })
    }

    fn get_mouse_location(&self) -> Option<CGPoint> {
        let event: CGEvent = CGEvent::new(self.event_source.clone()).ok()?;
        Some(event.location())
    }

    async fn spawn_repeat_task(&mut self, key: u16) {
        // there can only be one repeating key and it's
        // always the last to be pressed
        self.kill_repeat_task();
        let event_source = self.event_source.clone();
        let repeat_task = tokio::task::spawn_local(async move {
            tokio::time::sleep(DEFAULT_REPEAT_DELAY).await;
            loop {
                key_event(event_source.clone(), key, 1);
                tokio::time::sleep(DEFAULT_REPEAT_INTERVAL).await;
            }
        });
        self.repeat_task = Some(repeat_task.abort_handle());
    }
    fn kill_repeat_task(&mut self) {
        if let Some(task) = self.repeat_task.take() {
            task.abort();
        }
    }
}

fn key_event(event_source: CGEventSource, key: u16, state: u8) {
    let event = match CGEvent::new_keyboard_event(event_source, key, state != 0) {
        Ok(e) => e,
        Err(_) => {
            log::warn!("unable to create key event");
            return;
        }
    };
    event.post(CGEventTapLocation::HID);
}

#[async_trait]
impl InputEmulation for MacOSEmulation {
    async fn consume(
        &mut self,
        event: Event,
        _handle: EmulationHandle,
    ) -> Result<(), EmulationError> {
        match event {
            Event::Pointer(pointer_event) => match pointer_event {
                PointerEvent::Motion { time: _, dx, dy } => {
                    // FIXME secondary displays?
                    let (min_x, min_y, max_x, max_y) = unsafe {
                        let display = CGMainDisplayID();
                        let bounds = CGDisplayBounds(display);
                        let min_x = bounds.origin.x;
                        let max_x = bounds.origin.x + bounds.size.width;
                        let min_y = bounds.origin.y;
                        let max_y = bounds.origin.y + bounds.size.height;
                        (min_x as f64, min_y as f64, max_x as f64, max_y as f64)
                    };
                    let mut mouse_location = match self.get_mouse_location() {
                        Some(l) => l,
                        None => {
                            log::warn!("could not get mouse location!");
                            return Ok(());
                        }
                    };

                    mouse_location.x = (mouse_location.x + dx).clamp(min_x, max_x - 1.);
                    mouse_location.y = (mouse_location.y + dy).clamp(min_y, max_y - 1.);

                    let mut event_type = CGEventType::MouseMoved;
                    if self.button_state.left {
                        event_type = CGEventType::LeftMouseDragged
                    } else if self.button_state.right {
                        event_type = CGEventType::RightMouseDragged
                    } else if self.button_state.center {
                        event_type = CGEventType::OtherMouseDragged
                    };
                    let event = match CGEvent::new_mouse_event(
                        self.event_source.clone(),
                        event_type,
                        mouse_location,
                        CGMouseButton::Left,
                    ) {
                        Ok(e) => e,
                        Err(_) => {
                            log::warn!("mouse event creation failed!");
                            return Ok(());
                        }
                    };
                    event.set_integer_value_field(EventField::MOUSE_EVENT_DELTA_X, dx as i64);
                    event.set_integer_value_field(EventField::MOUSE_EVENT_DELTA_Y, dy as i64);
                    event.post(CGEventTapLocation::HID);
                }
                PointerEvent::Button {
                    time: _,
                    button,
                    state,
                } => {
                    let (event_type, mouse_button) = match (button, state) {
                        (b, 1) if b == input_event::BTN_LEFT => {
                            (CGEventType::LeftMouseDown, CGMouseButton::Left)
                        }
                        (b, 0) if b == input_event::BTN_LEFT => {
                            (CGEventType::LeftMouseUp, CGMouseButton::Left)
                        }
                        (b, 1) if b == input_event::BTN_RIGHT => {
                            (CGEventType::RightMouseDown, CGMouseButton::Right)
                        }
                        (b, 0) if b == input_event::BTN_RIGHT => {
                            (CGEventType::RightMouseUp, CGMouseButton::Right)
                        }
                        (b, 1) if b == input_event::BTN_MIDDLE => {
                            (CGEventType::OtherMouseDown, CGMouseButton::Center)
                        }
                        (b, 0) if b == input_event::BTN_MIDDLE => {
                            (CGEventType::OtherMouseUp, CGMouseButton::Center)
                        }
                        _ => {
                            log::warn!("invalid button event: {button},{state}");
                            return Ok(());
                        }
                    };
                    // store button state
                    self.button_state[mouse_button] = state == 1;

                    let location = self.get_mouse_location().unwrap();
                    let event = match CGEvent::new_mouse_event(
                        self.event_source.clone(),
                        event_type,
                        location,
                        mouse_button,
                    ) {
                        Ok(e) => e,
                        Err(()) => {
                            log::warn!("mouse event creation failed!");
                            return Ok(());
                        }
                    };
                    event.post(CGEventTapLocation::HID);
                }
                PointerEvent::Axis {
                    time: _,
                    axis,
                    value,
                } => {
                    let value = value as i32;
                    let (count, wheel1, wheel2, wheel3) = match axis {
                        0 => (1, value, 0, 0), // 0 = vertical => 1 scroll wheel device (y axis)
                        1 => (2, 0, value, 0), // 1 = horizontal => 2 scroll wheel devices (y, x) -> (0, x)
                        _ => {
                            log::warn!("invalid scroll event: {axis}, {value}");
                            return Ok(());
                        }
                    };
                    let event = match CGEvent::new_scroll_event(
                        self.event_source.clone(),
                        ScrollEventUnit::PIXEL,
                        count,
                        wheel1,
                        wheel2,
                        wheel3,
                    ) {
                        Ok(e) => e,
                        Err(()) => {
                            log::warn!("scroll event creation failed!");
                            return Ok(());
                        }
                    };
                    event.post(CGEventTapLocation::HID);
                }
                PointerEvent::AxisDiscrete120 { axis, value } => {
                    let (count, wheel1, wheel2, wheel3) = match axis {
                        0 => (1, value, 0, 0), // 0 = vertical => 1 scroll wheel device (y axis)
                        1 => (2, 0, value, 0), // 1 = horizontal => 2 scroll wheel devices (y, x) -> (0, x)
                        _ => {
                            log::warn!("invalid scroll event: {axis}, {value}");
                            return Ok(());
                        }
                    };
                    let event = match CGEvent::new_scroll_event(
                        self.event_source.clone(),
                        ScrollEventUnit::PIXEL,
                        count,
                        wheel1,
                        wheel2,
                        wheel3,
                    ) {
                        Ok(e) => e,
                        Err(()) => {
                            log::warn!("scroll event creation failed!");
                            return Ok(());
                        }
                    };
                    event.post(CGEventTapLocation::HID);
                }
                PointerEvent::Frame { .. } => {}
            },
            Event::Keyboard(keyboard_event) => match keyboard_event {
                KeyboardEvent::Key {
                    time: _,
                    key,
                    state,
                } => {
                    let code = match KeyMap::from_key_mapping(KeyMapping::Evdev(key as u16)) {
                        Ok(k) => k.mac as CGKeyCode,
                        Err(_) => {
                            log::warn!("unable to map key event");
                            return Ok(());
                        }
                    };
                    match state {
                        // pressed
                        1 => self.spawn_repeat_task(code).await,
                        _ => self.kill_repeat_task(),
                    }
                    key_event(self.event_source.clone(), code, state)
                }
                KeyboardEvent::Modifiers { .. } => {}
            },
            _ => (),
        }
        // FIXME
        Ok(())
    }

    async fn create(&mut self, _handle: EmulationHandle) {}

    async fn destroy(&mut self, _handle: EmulationHandle) {}

    async fn terminate(&mut self) {}
}