use crate::prelude::*;

use std::ops::{BitOr, Deref, DerefMut};

use crate::{
    layout::{UiModule, UiRegion, Vec2},
    util::{HashMap, Id},
};

pub trait CursorCtx {
    fn cursor_state(&self) -> &CursorState;
}

pub enum Button {
    Left,
    Right,
    Middle,
}

pub enum Sense {
    PressStart(Button),
    Pressing(Button),
    PressEnd(Button),
    HoverStart,
    Hovering,
    HoverEnd,
}

pub struct Senses(Vec<Sense>);

impl Sense {
    pub fn click() -> Self {
        Self::PressStart(Button::Left)
    }
    pub fn unclick() -> Self {
        Self::PressEnd(Button::Left)
    }
}

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

#[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();
    }
}

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

pub struct Sensor<Ctx> {
    pub senses: Senses,
    pub f: Box<dyn SenseFn<Ctx>>,
}

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

pub struct SenseData {
    pub cursor: Vec2,
    pub size: Vec2,
}

pub trait SenseFn<Ctx>: FnMut(&mut Ctx, SenseData) + 'static {}
impl<F: FnMut(&mut Ctx, SenseData) + 'static, Ctx> SenseFn<Ctx> for F {}

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

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

    fn on_undraw(&mut self, inst: &WidgetInstance) {
        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);
    }
}

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

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

        // TODO: temp, need to actually make reverse
        let mut layer_idxs = Vec::new();
        for (i, _) in layers.iter_mut() {
            layer_idxs.push(i);
        }

        for l in &layer_idxs {
            let Some(list) = module.active.get_mut(l) else {
                continue;
            };
            let mut ran = false;
            for (id, shape) in list.iter() {
                let group = module.map.get_mut(id).unwrap();
                let region = shape.to_screen(window_size);
                let in_shape = cursor.exists && region.contains(cursor.pos);
                group.hover.update(in_shape);
                if group.hover == ActivationState::Off {
                    continue;
                }

                for sensor in &mut group.sensors {
                    if should_run(&sensor.senses, &cursor.buttons, group.hover) {
                        ran = true;
                        let sctx = SenseData {
                            cursor: cursor.pos - region.top_left,
                            size: region.bot_right - region.top_left,
                        };
                        (sensor.f)(ctx, sctx);
                    }
                }
            }
            if ran {
                break;
            }
        }

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

pub fn should_run(senses: &Senses, cursor: &CursorButtons, hover: ActivationState) -> bool {
    for sense in senses.iter() {
        if match sense {
            Sense::PressStart(button) => cursor.select(button).is_start(),
            Sense::Pressing(button) => cursor.select(button).is_on(),
            Sense::PressEnd(button) => cursor.select(button).is_end(),
            Sense::HoverStart => hover.is_start(),
            Sense::Hovering => hover.is_on(),
            Sense::HoverEnd => hover.is_end(),
        } {
            return true;
        }
    }
    false
}

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<Ctx: 'static> Event<Ctx> for Senses {
    type Module = SensorModule<Ctx>;
    type Data = SenseData;
}

impl<Ctx: 'static> EventModule<Ctx, Senses> for SensorModule<Ctx> {
    fn register(&mut self, id: Id, senses: Senses, f: impl EventFn<Ctx, SenseData>) {
        self.map.entry(id).or_default().sensors.push(Sensor {
            senses,
            f: Box::new(f),
        });
    }
}

impl<Ctx: 'static> Event<Ctx> for Sense {
    type Module = SensorModule<Ctx>;
    type Data = SenseData;
}

impl<Ctx: 'static> EventModule<Ctx, Sense> for SensorModule<Ctx> {
    fn register(&mut self, id: Id, sense: Sense, f: impl EventFn<Ctx, SenseData>) {
        // TODO: does not add to active if currently active
        self.map.entry(id).or_default().sensors.push(Sensor {
            senses: sense.into(),
            f: Box::new(f),
        });
    }
}

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

impl Deref for Senses {
    type Target = Vec<Sense>;

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

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

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

impl BitOr for Sense {
    type Output = Senses;

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

impl BitOr<Sense> for Senses {
    type Output = Self;

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

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