use crate::{
    layout::{
        Event, EventFn, EventModule, IdLike, PainterData, PixelRegion, TextureHandle, Widget,
        WidgetId, WidgetInstance, WidgetLike,
    },
    util::{Id, Vec2},
};
use image::DynamicImage;
use std::{
    any::{Any, TypeId},
    ops::{Index, IndexMut},
    sync::mpsc::{Receiver, Sender, channel},
};

pub struct Ui {
    // TODO: make this at least pub(super)
    pub data: PainterData,
    root: Option<WidgetId>,
    recv: Receiver<Id>,
    pub(super) send: Sender<Id>,
    full_redraw: bool,
    resized: bool,
}

impl Ui {
    pub fn add<W: Widget, Tag>(&mut self, w: impl WidgetLike<Tag, Widget = W>) -> WidgetId<W> {
        w.add(self)
    }

    /// useful for debugging
    pub fn set_label<W>(&mut self, id: &WidgetId<W>, label: String) {
        self.data.widgets.data_mut(&id.id()).unwrap().label = label;
    }

    pub fn label<W>(&self, id: &WidgetId<W>) -> &String {
        &self.data.widgets.data(&id.id()).unwrap().label
    }

    pub fn add_widget<W: Widget>(&mut self, w: W) -> WidgetId<W> {
        self.push(w)
    }

    pub fn push<W: Widget>(&mut self, w: W) -> WidgetId<W> {
        let id = self.new_id();
        self.data.widgets.insert(id.id(), w);
        id
    }

    pub fn set_root<Tag>(&mut self, w: impl WidgetLike<Tag>) {
        self.root = Some(w.add(self).any());
        self.full_redraw = true;
    }

    pub fn new() -> Self {
        Self::default()
    }

    pub fn get<I: IdLike>(&self, id: &I) -> Option<&I::Widget> {
        self.data.widgets.get(id)
    }

    pub fn get_mut<I: IdLike>(&mut self, id: &I) -> Option<&mut I::Widget> {
        self.data.widgets.get_mut(id)
    }

    fn new_id<W: Widget>(&mut self) -> WidgetId<W> {
        WidgetId::new(
            self.data.widgets.reserve(),
            TypeId::of::<W>(),
            self.send.clone(),
        )
    }

    pub fn add_texture(&mut self, image: DynamicImage) -> TextureHandle {
        self.data.textures.add(image)
    }

    pub fn register_event<W, E: Event, Ctx: 'static>(
        &mut self,
        id: &WidgetId<W>,
        event: E,
        f: impl EventFn<Ctx, E::Data>,
    ) {
        self.data
            .modules
            .get_mut::<E::Module<Ctx>>()
            .register(id.id(), event, f);
    }

    pub fn resize(&mut self, size: impl Into<Vec2>) {
        self.data.output_size = size.into();
        self.resized = true;
    }

    pub fn redraw_all(&mut self) {
        for (_, inst) in self.data.active.drain() {
            for m in self.data.modules.iter_mut() {
                m.on_undraw(&inst);
            }
        }
        // free before bc nothing should exist
        self.free();
        if let Some(root) = &self.root {
            self.data.draw(root.id());
        }
    }

    pub fn update(&mut self) {
        if self.full_redraw {
            self.redraw_all();
            self.full_redraw = false;
        } else if self.data.widgets.has_updates() {
            self.redraw_updates();
        }
        if self.resized {
            self.resized = false;
            self.redraw_all();
        }
    }

    fn redraw_updates(&mut self) {
        let mut updates = std::mem::take(&mut self.data.widgets.updates);
        self.data.redraw(&mut updates);
        self.data.widgets.updates = updates;
        self.free();
    }

    /// free any resources that don't have references anymore
    fn free(&mut self) {
        for id in self.recv.try_iter() {
            for m in self.data.modules.iter_mut() {
                m.on_remove(&id);
            }
            self.data.widgets.delete(id);
        }
        self.data.textures.free();
    }

    pub fn needs_redraw(&self) -> bool {
        self.full_redraw || self.data.widgets.has_updates()
    }

    pub fn num_widgets(&self) -> usize {
        self.data.widgets.len()
    }

    pub fn active_widgets(&self) -> usize {
        self.data.active.len()
    }

    pub fn debug_layers(&self) {
        for ((idx, depth), primitives) in self.data.layers.iter_depth() {
            let indent = " ".repeat(depth * 2);
            let len = primitives.instances().len();
            print!("{indent}{idx}: {len} primitives");
            if len >= 1 {
                print!(" ({})", primitives.instances()[0].binding);
            }
            println!();
        }
    }

    pub fn window_region(&self, id: &impl IdLike) -> Option<PixelRegion> {
        let region = self.data.active.get(&id.id())?.region;
        Some(region.to_px(self.data.output_size))
    }

    pub fn debug(&self, label: &str) -> impl Iterator<Item = &WidgetInstance> {
        self.data.active.iter().filter_map(move |(id, inst)| {
            let l = &self.data.widgets.label(id);
            if *l == label { Some(inst) } else { None }
        })
    }
}

impl<I: IdLike> Index<&I> for Ui {
    type Output = I::Widget;

    fn index(&self, id: &I) -> &Self::Output {
        self.get(id).unwrap()
    }
}

impl<I: IdLike> IndexMut<&I> for Ui {
    fn index_mut(&mut self, id: &I) -> &mut Self::Output {
        self.get_mut(id).unwrap()
    }
}

impl dyn Widget {
    pub fn as_any(&self) -> &dyn Any {
        self
    }

    pub fn as_any_mut(&mut self) -> &mut dyn Any {
        self
    }
}

impl Default for Ui {
    fn default() -> Self {
        let (send, recv) = channel();
        Self {
            data: PainterData::default(),
            root: Default::default(),
            full_redraw: false,
            send,
            recv,
            resized: false,
        }
    }
}