use input::{Event};
use input::event::{EventTrait, KeyboardEvent, PointerEvent};
use input::event::keyboard::{KeyboardEventTrait, KeyState};
use input::event::pointer::{Axis, ButtonState, PointerButtonEvent, PointerMotionAbsoluteEvent, PointerMotionEvent, PointerScrollContinuousEvent, PointerScrollEvent, PointerScrollFingerEvent, PointerScrollWheelEvent};

use crate::input::events::{KvmButtonState, KvmEvent, KvmEventTrait};
use crate::input::events::keyboard::KvmKeyboardEvent;
use crate::input::events::pointer::{KvmPointerButtonEvent, KvmPointerEvent, KvmPointerEventTrait, KvmPointerMotionAbsoluteEvent, KvmPointerMotionRelativeEvent, KvmPointerScrollEvent};
use crate::input::mappings::MappingError::{UnknownEvent, UnsupportedEvent};

#[derive(Debug)]
pub enum MappingError {
    UnsupportedEvent(Event),
    UnknownEvent(Event),
}

pub trait FromLibinputEvent<T>
    where Self: Sized, T: EventTrait {
    fn from_libinput(t: T) -> Result<Self, MappingError>;
}

impl FromLibinputEvent<Event> for KvmEvent {
    fn from_libinput(event: Event) -> Result<Self, MappingError> {
        match event {
            Event::Keyboard(event) => get_event::<KeyboardEvent, KvmKeyboardEvent>(event),
            Event::Pointer(event) => get_event::<PointerEvent, KvmPointerEvent>(event),
            _ => Err(UnsupportedEvent(event))
        }
    }
}

fn get_event<T, U>(event: T) -> Result<KvmEvent, MappingError>
    where T: EventTrait, U: FromLibinputEvent<T> + KvmEventTrait {
    Ok(U::from_libinput(event)?.into_kvm_event())
}

impl FromLibinputEvent<KeyboardEvent> for KvmKeyboardEvent {
    fn from_libinput(event: KeyboardEvent) -> Result<Self, MappingError> {
        let key_code = event.key();
        let state = KvmButtonState::from_key_state(event.key_state());

        Ok(KvmKeyboardEvent { key_code, state })
    }
}

impl FromLibinputEvent<PointerEvent> for KvmPointerEvent {
    fn from_libinput(event: PointerEvent) -> Result<Self, MappingError> {
        #[allow(deprecated)]
        match event {
            PointerEvent::Motion(event) => get_pointer_event::<PointerMotionEvent, KvmPointerMotionRelativeEvent>(event),
            PointerEvent::MotionAbsolute(event) => get_pointer_event::<PointerMotionAbsoluteEvent, KvmPointerMotionAbsoluteEvent>(event),
            PointerEvent::Button(event) => get_pointer_event::<PointerButtonEvent, KvmPointerButtonEvent>(event),
            PointerEvent::ScrollWheel(event) => get_pointer_event::<PointerScrollWheelEvent, KvmPointerScrollEvent>(event),
            PointerEvent::ScrollFinger(event) => get_pointer_event::<PointerScrollFingerEvent, KvmPointerScrollEvent>(event),
            PointerEvent::ScrollContinuous(event) => get_pointer_event::<PointerScrollContinuousEvent, KvmPointerScrollEvent>(event),
            PointerEvent::Axis(event) => Err(UnsupportedEvent(event.into_event())),
            _ => Err(UnknownEvent(event.into_event()))
        }
    }
}

fn get_pointer_event<T, U>(event: T) -> Result<KvmPointerEvent, MappingError>
    where T: EventTrait, U: FromLibinputEvent<T> + KvmPointerEventTrait {
    Ok(U::from_libinput(event)?.into_kvm_pointer_event())
}

impl FromLibinputEvent<PointerMotionEvent> for KvmPointerMotionRelativeEvent {
    fn from_libinput(event: PointerMotionEvent) -> Result<Self, MappingError> {
        Ok(KvmPointerMotionRelativeEvent {
            dx: event.dx(),
            dx_unaccelerated: event.dx_unaccelerated(),
            dy: event.dy(),
            dy_unaccelerated: event.dy_unaccelerated(),
        })
    }
}

impl FromLibinputEvent<PointerMotionAbsoluteEvent> for KvmPointerMotionAbsoluteEvent {
    fn from_libinput(event: PointerMotionAbsoluteEvent) -> Result<Self, MappingError> {
        Ok(KvmPointerMotionAbsoluteEvent {
            x: event.absolute_x_transformed(1920),
            x_mm: event.absolute_x(),
            y: event.absolute_y_transformed(1080),
            y_mm: event.absolute_y(),
        })
    }
}

impl FromLibinputEvent<PointerButtonEvent> for KvmPointerButtonEvent {
    fn from_libinput(event: PointerButtonEvent) -> Result<Self, MappingError> {
        let button = event.button();
        let state = KvmButtonState::from_button_state(event.button_state());

        Ok(KvmPointerButtonEvent { button, state })
    }
}

impl<T> FromLibinputEvent<T> for KvmPointerScrollEvent
    where T: EventTrait + PointerScrollEvent {
    fn from_libinput(event: T) -> Result<Self, MappingError> {
        fn get_axis_value<T>(event: &T, axis: Axis) -> f64
            where T: PointerScrollEvent {
            if event.has_axis(axis) {
                return event.scroll_value(axis);
            }

            0f64
        }

        let horizontal_scroll_value = get_axis_value(&event, Axis::Horizontal);
        let vertical_scroll_value = get_axis_value(&event, Axis::Vertical);

        Ok(KvmPointerScrollEvent {
            horizontal_scroll_value,
            vertical_scroll_value,
        })
    }
}

impl KvmButtonState {
    pub fn from_key_state(state: KeyState) -> Self {
        match state {
            KeyState::Released => Self::Released,
            KeyState::Pressed => Self::Pressed,
        }
    }

    pub fn from_button_state(state: ButtonState) -> Self {
        match state {
            ButtonState::Released => Self::Released,
            ButtonState::Pressed => Self::Pressed,
        }
    }
}