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



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

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

pub struct CursorSenses(Vec<CursorSense>);

impl CursorSense {
    pub fn click() -> Self {
        Self::PressStart(Button::Left)
    }
    pub fn click_or_drag() -> CursorSenses {
        Self::click() | Self::Pressing(Button::Left)
    }
    pub fn unclick() -> Self {
        Self::PressEnd(Button::Left)
    }
    pub fn is_dragging(&self) -> bool {
        matches!(self, CursorSense::Pressing(Button::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: &Button) -> &ActivationState {
        match button {
            Button::Left => &self.left,
            Button::Right => &self.right,
            Button::Middle => &self.middle,
        }
    }

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

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, Data> {
    pub senses: CursorSenses,
    pub f: Rc<dyn EventFn<Ctx, Data>>,
}

pub type SensorMap<Ctx, Data> = HashMap<Id, SensorGroup<Ctx, Data>>;
pub type SenseShape = UiRegion;
pub struct SensorGroup<Ctx, Data> {
    pub hover: ActivationState,
    pub sensors: Vec<Sensor<Ctx, Data>>,
}

#[derive(Clone)]
pub struct CursorData {
    pub cursor: Vec2,
    pub size: Vec2,
    pub scroll_delta: Vec2,
    /// the (first) sense that triggered this event
    /// the senses are checked in order
    pub sense: CursorSense,
}

pub struct CursorModule<Ctx> {
    map: SensorMap<Ctx, CursorData>,
    active: HashMap<usize, HashMap<Id, SenseShape>>,
}

impl<Ctx: 'static> UiModule for CursorModule<Ctx> {
    fn on_draw(&mut self, inst: &ActiveData) {
        if self.map.contains_key(&inst.id) {
            self.active
                .entry(inst.layer)
                .or_default()
                .insert(inst.id, inst.region);
        }
    }

    fn on_undraw(&mut self, inst: &ActiveData) {
        if let Some(layer) = self.active.get_mut(&inst.layer) {
            layer.remove(&inst.id);
        }
    }

    fn on_remove(&mut self, id: &Id) {
        self.map.remove(id);
        for layer in self.active.values_mut() {
            layer.remove(id);
        }
    }

    fn on_move(&mut self, inst: &ActiveData) {
        if let Some(map) = self.active.get_mut(&inst.layer)
            && let Some(region) = map.get_mut(&inst.id)
        {
            *region = inst.region;
        }
    }
}

impl<Ctx> CursorModule<Ctx> {
    pub fn merge(&mut self, other: Self) {
        for (id, group) in other.map {
            for sensor in group.sensors {
                self.map.entry(id).or_default().sensors.push(sensor);
            }
        }
    }
}

pub trait SensorUi {
    fn run_sensors<Ctx: 'static>(&mut self, ctx: &mut Ctx, cursor: &CursorState, window_size: Vec2);
}

impl SensorUi for Ui {
    fn run_sensors<Ctx: 'static>(
        &mut self,
        ctx: &mut Ctx,
        cursor: &CursorState,
        window_size: Vec2,
    ) {
        CursorModule::<Ctx>::run(self, ctx, cursor, window_size);
    }
}

impl<Ctx: 'static> CursorModule<Ctx> {
    pub fn run(ui: &mut Ui, ctx: &mut Ctx, cursor: &CursorState, window_size: Vec2) {
        let layers = std::mem::take(&mut ui.data.layers);
        let mut module = std::mem::take(ui.data.modules.get_mut::<Self>());

        for i in layers.indices().rev() {
            let Some(list) = module.active.get_mut(&i) else {
                continue;
            };
            let mut sensed = false;
            for (id, shape) in list.iter() {
                let group = module.map.get_mut(id).unwrap();
                let region = shape.to_px(window_size);
                let in_shape = cursor.exists && region.contains(cursor.pos);
                group.hover.update(in_shape);
                if group.hover == ActivationState::Off {
                    continue;
                }
                sensed = true;

                for sensor in &mut group.sensors {
                    if let Some(sense) = should_run(&sensor.senses, cursor, group.hover) {
                        let data = CursorData {
                            cursor: cursor.pos - region.top_left,
                            size: region.bot_right - region.top_left,
                            scroll_delta: cursor.scroll_delta,
                            sense,
                        };
                        (sensor.f)(EventCtx {
                            ui,
                            state: ctx,
                            data,
                        });
                    }
                }
            }
            if sensed {
                break;
            }
        }

        let ui_mod = ui.data.modules.get_mut::<Self>();
        std::mem::swap(ui_mod, &mut module);
        ui_mod.merge(module);
        ui.data.layers = layers;
    }
}

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 Event for CursorSenses {
    type Module<Ctx: 'static> = CursorModule<Ctx>;
    type Data = CursorData;
}

impl Event for CursorSense {
    type Module<Ctx: 'static> = CursorModule<Ctx>;
    type Data = CursorData;
}

impl<E: Event<Data = <CursorSenses as Event>::Data> + Into<CursorSenses>, Ctx: 'static>
    EventModule<E, Ctx> for CursorModule<Ctx>
{
    fn register(&mut self, id: Id, senses: E, f: impl EventFn<Ctx, <E as Event>::Data>) {
        // TODO: does not add to active if currently active
        self.map.entry(id).or_default().sensors.push(Sensor {
            senses: senses.into(),
            f: Rc::new(f),
        });
    }

    fn run<'a>(
        &self,
        id: &Id,
        event: E,
    ) -> Option<impl Fn(EventCtx<Ctx, <E as Event>::Data>) + use<'a, E, Ctx>> {
        let senses = event.into();
        if let Some(group) = self.map.get(id) {
            let fs: Vec<_> = group
                .sensors
                .iter()
                .filter_map(|sensor| {
                    if sensor.senses.iter().any(|s| senses.contains(s)) {
                        Some(sensor.f.clone())
                    } else {
                        None
                    }
                })
                .collect();
            Some(move |ctx: EventCtx<Ctx, CursorData>| {
                for f in &fs {
                    f(EventCtx {
                        state: ctx.state,
                        ui: ctx.ui,
                        data: ctx.data.clone(),
                    });
                }
            })
        } else {
            None
        }
    }
}

impl<Ctx, Data> Default for SensorGroup<Ctx, Data> {
    fn default() -> Self {
        Self {
            hover: Default::default(),
            sensors: Default::default(),
        }
    }
}

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
    }
}

impl<Ctx> Default for CursorModule<Ctx> {
    fn default() -> Self {
        Self {
            map: Default::default(),
            active: Default::default(),
        }
    }
}