use crate::prelude::*;
use std::{
    ops::{BitOr, Deref, DerefMut},
    rc::Rc,
};

#[derive(Clone, Copy, PartialEq)]
pub enum CursorButton {
    Left,
    Right,
    Middle,
}

#[derive(Clone, Copy, PartialEq)]
pub enum CursorSense {
    PressStart(CursorButton),
    Pressing(CursorButton),
    PressEnd(CursorButton),
    HoverStart,
    Hovering,
    HoverEnd,
    Scroll,
}

#[derive(Clone)]
pub struct CursorSenses(Vec<CursorSense>);

impl Event for CursorSenses {
    type Data<'a> = CursorData<'a>;
    type State = SensorState;
    fn should_run<'a>(&self, data: &Self::Data<'a>) -> Option<Self::Data<'a>> {
        if let Some(sense) = should_run(self, &data.cursor, data.hover) {
            let mut data = data.clone();
            data.sense = sense;
            Some(data)
        } else {
            None
        }
    }
}

impl CursorSense {
    pub fn click() -> Self {
        Self::PressStart(CursorButton::Left)
    }
    pub fn click_or_drag() -> CursorSenses {
        Self::click() | Self::Pressing(CursorButton::Left)
    }
    pub fn unclick() -> Self {
        Self::PressEnd(CursorButton::Left)
    }
    pub fn is_dragging(&self) -> bool {
        matches!(self, CursorSense::Pressing(CursorButton::Left))
    }
}

#[derive(Default, Clone)]
pub struct CursorState {
    pub pos: Vec2,
    pub exists: bool,
    pub buttons: CursorButtons,
    pub scroll_delta: Vec2,
}

#[derive(Default, Clone)]
pub struct CursorButtons {
    pub left: ActivationState,
    pub middle: ActivationState,
    pub right: ActivationState,
}

impl CursorButtons {
    pub fn select(&self, button: &CursorButton) -> &ActivationState {
        match button {
            CursorButton::Left => &self.left,
            CursorButton::Right => &self.right,
            CursorButton::Middle => &self.middle,
        }
    }

    pub fn end_frame(&mut self) {
        self.left.end_frame();
        self.middle.end_frame();
        self.right.end_frame();
    }

    pub fn iter(&self) -> impl Iterator<Item = (CursorButton, &ActivationState)> {
        [
            CursorButton::Left,
            CursorButton::Middle,
            CursorButton::Right,
        ]
        .into_iter()
        .map(|b| (b, self.select(&b)))
    }
}

impl CursorState {
    pub fn end_frame(&mut self) {
        self.buttons.end_frame();
        self.scroll_delta = Vec2::ZERO;
    }
}

#[derive(Debug, Clone, Copy, Default, PartialEq)]
pub enum ActivationState {
    Start,
    On,
    End,
    #[default]
    Off,
}

/// this and other similar stuff has a generic
/// because I kind of want to make CursorModule generic
/// or basically have some way to have custom senses
/// that depend on active widget positions
/// but I'm not sure how or if worth it
pub struct Sensor<Ctx: HasEvents, Data> {
    pub senses: CursorSenses,
    pub f: Rc<dyn EventFn<Ctx, Data>>,
}

pub type SenseShape = UiRegion;

#[derive(Default, Debug)]
pub struct SensorState {
    pub hover: ActivationState,
}

#[derive(Clone)]
pub struct CursorData<'a> {
    /// where this widget was hit
    pub pos: Vec2,
    pub size: Vec2,
    pub scroll_delta: Vec2,
    pub hover: ActivationState,
    pub cursor: CursorState,
    /// the first sense that triggered this
    pub sense: CursorSense,
    pub render: &'a UiRenderState,
}

pub trait SensorUi {
    fn run_sensors<Rsc: HasEvents>(
        &self,
        rsc: &mut Rsc,
        state: &mut Rsc::State,
        cursor: CursorState,
        window_size: Vec2,
    );
}

impl SensorUi for UiRenderState {
    fn run_sensors<Rsc: HasEvents>(
        &self,
        rsc: &mut Rsc,
        state: &mut Rsc::State,
        cursor: CursorState,
        window_size: Vec2,
    ) {
        // in order to remove this take, need to store active list in UiRenderState somehow
        // this would probably be done through a generic parameter that adds yet another rsc /
        // state like thing, but local to render state, and is passed to UiRsc events so you can
        // update it there?
        let mut active = std::mem::take(&mut rsc.events_mut().get_type::<CursorSense>().active);
        for layer in self.layers.indices().rev() {
            let mut sensed = false;
            for (id, sensor) in active.get_mut(&layer).into_flat_iter() {
                let shape = self.active.get(id).unwrap().region;
                let region = shape.to_px(window_size);
                let in_shape = cursor.exists && region.contains(cursor.pos);
                sensor.hover.update(in_shape);
                if sensor.hover == ActivationState::Off {
                    continue;
                }
                sensed = true;

                let cursor = cursor.clone();

                let data = CursorData {
                    pos: cursor.pos - region.top_left,
                    size: region.bot_right - region.top_left,
                    scroll_delta: cursor.scroll_delta,
                    hover: sensor.hover,
                    cursor,
                    // this does not have any meaning;
                    // might wanna set up Event to have a prepare stage
                    sense: CursorSense::Hovering,
                    render: self,
                };
                rsc.run_event::<CursorSense>(*id, data, state);
            }
            if sensed {
                break;
            }
        }
        rsc.events_mut().get_type::<CursorSense>().active = active;
    }
}

pub fn should_run(
    senses: &CursorSenses,
    cursor: &CursorState,
    hover: ActivationState,
) -> Option<CursorSense> {
    for sense in senses.iter() {
        if match sense {
            CursorSense::PressStart(button) => cursor.buttons.select(button).is_start(),
            CursorSense::Pressing(button) => cursor.buttons.select(button).is_on(),
            CursorSense::PressEnd(button) => cursor.buttons.select(button).is_end(),
            CursorSense::HoverStart => hover.is_start(),
            CursorSense::Hovering => hover.is_on(),
            CursorSense::HoverEnd => hover.is_end(),
            CursorSense::Scroll => cursor.scroll_delta != Vec2::ZERO,
        } {
            return Some(*sense);
        }
    }
    None
}

impl ActivationState {
    pub fn is_start(&self) -> bool {
        *self == Self::Start
    }
    pub fn is_on(&self) -> bool {
        *self == Self::Start || *self == Self::On
    }
    pub fn is_end(&self) -> bool {
        *self == Self::End
    }
    pub fn is_off(&self) -> bool {
        *self == Self::End || *self == Self::Off
    }
    pub fn update(&mut self, on: bool) {
        *self = match *self {
            Self::Start => match on {
                true => Self::On,
                false => Self::End,
            },
            Self::On => match on {
                true => Self::On,
                false => Self::End,
            },
            Self::End => match on {
                true => Self::Start,
                false => Self::Off,
            },
            Self::Off => match on {
                true => Self::Start,
                false => Self::Off,
            },
        }
    }

    pub fn end_frame(&mut self) {
        match self {
            Self::Start => *self = Self::On,
            Self::End => *self = Self::Off,
            _ => (),
        }
    }
}

impl EventLike for CursorSense {
    type Event = CursorSenses;
    fn into_event(self) -> Self::Event {
        self.into()
    }
}

impl Deref for CursorSenses {
    type Target = Vec<CursorSense>;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

impl DerefMut for CursorSenses {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.0
    }
}

impl From<CursorSense> for CursorSenses {
    fn from(val: CursorSense) -> Self {
        CursorSenses(vec![val])
    }
}

impl BitOr for CursorSense {
    type Output = CursorSenses;

    fn bitor(self, rhs: Self) -> Self::Output {
        CursorSenses(vec![self, rhs])
    }
}

impl BitOr<CursorSense> for CursorSenses {
    type Output = Self;

    fn bitor(mut self, rhs: CursorSense) -> Self::Output {
        self.0.push(rhs);
        self
    }
}