use image::DynamicImage;

use crate::{
    layout::{
        Event, EventFn, EventModule, IdLike, PainterData, PixelRegion, TextureHandle, Vec2, Widget,
        WidgetInstance, WidgetLike, WidgetRef, WidgetUpdate,
    },
    util::{HashSet, Id},
};
use std::sync::mpsc::{Receiver, channel};

pub struct Ui {
    // TODO: make this at least pub(super)
    pub(crate) data: PainterData,
    root: Option<WidgetRef>,
    updates: HashSet<Id>,
    free: Vec<Id>,
    recv: Receiver<WidgetUpdate>,
    full_redraw: bool,
    resized: bool,
}

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

    pub fn add_widget<W: Widget>(&mut self, w: W) -> WidgetRef<W> {
        self.data.widgets.insert(w)
    }

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

    pub fn register_event<W, E: Event, Ctx: 'static>(
        &mut self,
        id: &WidgetRef<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;
    }

    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);
        }
    }

    pub fn update(&mut self) -> bool {
        for update in self.recv.try_iter() {
            match update {
                WidgetUpdate::Drop(id) => {
                    self.free.push(id);
                }
                WidgetUpdate::Mutate(id) => {
                    self.updates.insert(id);
                }
            }
        }
        if self.full_redraw {
            self.redraw_all();
            self.full_redraw = false;
            true
        } else if self.resized {
            self.resized = false;
            self.redraw_all();
            true
        } else if !self.updates.is_empty() {
            self.redraw_updates();
            true
        } else {
            false
        }
    }

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

    /// free any resources that don't have references anymore
    fn free(&mut self) {
        for id in self.free.drain(..) {
            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.updates.is_empty()
    }

    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<W>(&self, id: &impl IdLike<W>) -> 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 widget = &self.data.widgets.get(*id);
            if widget.get_label().as_str() == label {
                Some(inst)
            } else {
                None
            }
        })
    }
}

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