use std::cell::RefCell;
use std::rc::Rc;

use kahlo::{
    math::{PixelBox, PixelPoint, PixelSize},
    prelude::*,
};

use crate::layout::{self, LayoutNode, LayoutNodeAccess, LayoutTreeNode};
use crate::widget::Widget;
use crate::{component::Component, ui::UIHandle};
use crate::{
    input::{InputState, MouseButton},
    render::RenderTarget,
};

pub type RenderFormat = kahlo::formats::Bgr32;

#[derive(Debug)]
pub enum WindowEvent {
    CloseRequested,
    Resized,
}

pub trait WindowComponent: 'static + Sized + Component {
    fn map_window_event(&self, we: WindowEvent) -> Option<Self::Msg>;

    type RootWidget: Widget<Self>;
    fn root_widget(&self) -> &Self::RootWidget;
    fn root_widget_mut(&mut self) -> &mut Self::RootWidget;
}

pub(crate) struct WindowState<WC: WindowComponent> {
    render_generation: usize,
    wc: WC,
    root_node: LayoutNode,
    window: Rc<winit::window::Window>,
    events: Vec<WindowEvent>,
    istate: InputState,
    surface: softbuffer::Surface<Rc<winit::window::Window>, Rc<winit::window::Window>>,
    bitmap: RefCell<Option<kahlo::Bitmap<RenderFormat>>>,
}

impl<WC: WindowComponent> WindowState<WC> {
    fn redraw(&mut self, uih: &UIHandle) {
        let size = self.window.inner_size();
        // if size.width != self.surface.buffer_mut().unwrap().
        self.surface
            .resize(
                size.width.try_into().unwrap(),
                size.height.try_into().unwrap(),
            )
            .unwrap();
        let mut buf = self.surface.buffer_mut().unwrap();

        self.root_node.set_behaviour(layout::NodeBehaviour::Fixed {
            area: PixelBox::from_size(PixelSize::new(size.width as i32, size.height as i32)),
        });

        let layout = WindowLayoutHelper::new(&self.root_node, self.wc.root_widget().layout_node());

        let mut bitmap = self.bitmap.borrow_mut();
        if bitmap.as_ref().map(|v| v.size())
            != Some(PixelSize::new(size.width as i32, size.height as i32))
        {
            bitmap.take();
        }

        let bitmap = bitmap
            .get_or_insert_with(|| kahlo::Bitmap::new(size.width as usize, size.height as usize));

        let mut windowbuffer = kahlo::BitmapMut::<kahlo::formats::Bgr32>::new(
            unsafe {
                std::slice::from_raw_parts_mut(buf[..].as_mut_ptr() as *mut u8, buf.len() * 4)
            },
            size.width as usize,
            size.height as usize,
        );

        layout::recalculate(LayoutNodeAccess::new(&layout));
        // let before = std::time::Instant::now();

        // save the layout tree for later dumping
        let mut pre_render_dump = format!("render generation: {}\n", self.render_generation);
        {
            self.render_generation += 1;
            crate::layout::dump_node_tree(LayoutNodeAccess::new(&layout), &mut pre_render_dump);
        }

        let mut bmap = bitmap.as_mut();
        let mut render_target = RenderTarget::new(uih.theme(), &mut bmap);

        self.wc.root_widget().render(&mut render_target);
        windowbuffer.copy_from(
            bitmap,
            PixelBox::from_size(bitmap.size()),
            PixelPoint::zero(),
        );
        // let after = std::time::Instant::now();

        /*
        // put the render time on the screen
        // we're going to do this the very dumb way for now
        let render_time = format!(
            "time: {:.03}ms",
            (after - before).as_micros() as f32 / 1000.0
        );
        let (line, _) = uih.theme().make_line(render_time.as_str()).render_line();

        windowbuffer.fill_region_masked(
            &line,
            PixelBox::from_size(line.size()),
            PixelPoint::new(
                size.width as i32 - line.size().width,
                size.height as i32 - line.size().height,
            ),
            uih.theme().foreground,
            kahlo::colour::BlendMode::Simple,
        );*/

        // now put the pre-render layout dump on the window
        // again, we're doing this the dumb way
        /*let mut offset = 0;
        for text in pre_render_dump.split('\n') {
            if text.is_empty() {
                continue;
            }
            let line = uih.theme().make_line(text).render_line();

            windowbuffer.fill_region_masked(
                &line,
                PixelBox::from_size(line.size()),
                PixelPoint::new(0, offset),
                uih.theme().foreground,
                kahlo::colour::BlendMode::Simple,
            );

            offset += line.height() as i32 + 1;
        }*/

        buf.present().unwrap();
    }

    fn poll(&mut self, uih: &mut UIHandle) -> Vec<WC::ParentMsg> {
        let mut ret = vec![];
        for we in self.events.drain(..) {
            let mapped = self.wc.map_window_event(we);
            ret.extend(self.wc.process_all(mapped.into_iter()).into_iter());
        }

        let evts = self.wc.root_widget_mut().poll(uih, Some(&self.istate));
        ret.extend(self.wc.process_all(evts.into_iter()));

        self.istate.tick();

        ret
    }
}

pub(crate) trait WindowStateAccess {
    fn notify_resize(&self, new_size: PixelSize);
    fn push_event(&self, we: WindowEvent);
    fn redraw(&self, uih: &UIHandle);
    fn request_redraw(&self);
    fn update_mouse_pos(&self, pos: PixelPoint);
    fn update_mouse_button(&self, which: MouseButton, to: bool);
    fn update_text_input(&self, what: &str);
    fn push_keypress(&self, key: winit::keyboard::Key);
}

impl<WC: WindowComponent> WindowStateAccess for RefCell<WindowState<WC>> {
    fn notify_resize(&self, new_size: PixelSize) {
        if Some(new_size) != self.borrow().bitmap.borrow().as_ref().map(|v| v.size()) {
            self.borrow_mut().bitmap.take();
            self.borrow_mut()
                .wc
                .root_widget()
                .layout_node()
                .relayout_tree();
            self.borrow_mut()
                .wc
                .root_widget()
                .layout_node()
                .render_needed();
        }
    }
    fn push_event(&self, we: WindowEvent) {
        self.borrow_mut().events.push(we);
    }
    fn redraw(&self, uih: &UIHandle) {
        self.borrow_mut().redraw(uih);
    }
    fn request_redraw(&self) {
        self.borrow().window.request_redraw();
    }
    fn update_mouse_pos(&self, pos: PixelPoint) {
        self.borrow_mut().istate.mouse.pos = pos;
    }
    fn update_mouse_button(&self, which: MouseButton, to: bool) {
        let is = &mut self.borrow_mut().istate;
        is.mouse.buttons.set_button(which, to);
    }
    fn update_text_input(&self, what: &str) {
        let is = &mut self.borrow_mut().istate;
        is.set_text_input(what.into());
    }
    fn push_keypress(&self, key: winit::keyboard::Key) {
        let is = &mut self.borrow_mut().istate;
        is.keypress = Some(key);
    }
}

pub struct WindowBuilder<'r, 'l: 'r> {
    ui_handle: &'r mut UIHandle<'l>,
}

impl<'r, 'l: 'r> WindowBuilder<'r, 'l> {
    pub(crate) fn new(ui_handle: &'r mut UIHandle<'l>) -> Self {
        Self { ui_handle }
    }

    pub fn build<WC: WindowComponent>(self, wc: impl FnOnce(&mut UIHandle) -> WC) -> Window<WC> {
        let window = Rc::new(
            self.ui_handle
                .eloop
                .create_window(winit::window::WindowAttributes::default())
                .unwrap(),
        );
        let wid = window.id();

        let ctx = softbuffer::Context::new(window.clone()).unwrap();
        let surface = softbuffer::Surface::new(&ctx, window.clone()).unwrap();

        let wc = wc(self.ui_handle);
        let wstate = Rc::new(RefCell::new(WindowState {
            render_generation: 0,
            wc,
            root_node: LayoutNode::new(self.ui_handle.state.layout_cache.clone()),
            window,
            events: Default::default(),
            istate: InputState::default(),
            surface,
            bitmap: None.into(),
        }));

        self.ui_handle.state.window_states.insert(
            wid,
            Rc::downgrade(&(wstate.clone() as Rc<dyn WindowStateAccess>)),
        );

        Window { state: wstate }
    }
}

pub struct Window<WC: WindowComponent> {
    state: Rc<RefCell<WindowState<WC>>>,
}

impl<WC: WindowComponent> Window<WC> {
    pub fn poll(&mut self, uih: &mut UIHandle) -> Vec<WC::ParentMsg> {
        self.state.borrow_mut().poll(uih)
    }
}

struct WindowLayoutHelper<'l> {
    window_node: &'l LayoutNode,
    widget_node: LayoutNodeAccess<'l>,
}

impl<'l> WindowLayoutHelper<'l> {
    fn new(window: &'l LayoutNode, widget: LayoutNodeAccess<'l>) -> Self {
        Self {
            window_node: window,
            widget_node: widget,
        }
    }
}

impl<'l> LayoutTreeNode<()> for WindowLayoutHelper<'l> {
    fn current_node(&self) -> &LayoutNode {
        self.window_node
    }
    fn child(&self, ndx: usize) -> Option<LayoutNodeAccess<'_>> {
        if ndx == 0 {
            Some(self.widget_node)
        } else {
            None
        }
    }
    fn child_count(&self) -> usize {
        1
    }
}