use std::{collections::HashSet, num::NonZero, sync::Arc, thread, time::Duration};

use egui::{
    ahash::{HashMap, HashMapExt},
    Context, FontData, FontDefinitions, FontFamily, IconData, TextWrapMode, ViewportBuilder,
    ViewportCommand, ViewportId, ViewportInfo,
};
use gilrs::{EventType, Gilrs};
use winit::{
    application::ApplicationHandler,
    event::WindowEvent,
    event_loop::{ActiveEventLoop, EventLoopProxy},
    window::Window,
};

use crate::{
    controller::ControllerManager,
    emulator::{EmulatorClient, EmulatorCommand, SimId},
    input::MappingProvider,
    persistence::Persistence,
    window::{AboutWindow, AppWindow, GameWindow, InputWindow},
};

fn load_icon() -> anyhow::Result<IconData> {
    let bytes = include_bytes!("../assets/lemur-256x256.png");
    let img = image::load_from_memory_with_format(bytes, image::ImageFormat::Png)?;
    let rgba = img.into_rgba8();
    Ok(IconData {
        width: rgba.width(),
        height: rgba.height(),
        rgba: rgba.into_vec(),
    })
}

pub struct Application {
    icon: Option<Arc<IconData>>,
    client: EmulatorClient,
    proxy: EventLoopProxy<UserEvent>,
    mappings: MappingProvider,
    controllers: ControllerManager,
    persistence: Persistence,
    viewports: HashMap<ViewportId, Viewport>,
    focused: Option<ViewportId>,
}

impl Application {
    pub fn new(client: EmulatorClient, proxy: EventLoopProxy<UserEvent>) -> Self {
        let icon = load_icon().ok().map(Arc::new);
        let persistence = Persistence::new();
        let mappings = MappingProvider::new(persistence.clone());
        let controllers = ControllerManager::new(client.clone(), &mappings);
        {
            let mappings = mappings.clone();
            let proxy = proxy.clone();
            thread::spawn(|| process_gamepad_input(mappings, proxy));
        }
        Self {
            icon,
            client,
            proxy,
            mappings,
            controllers,
            persistence,
            viewports: HashMap::new(),
            focused: None,
        }
    }

    fn open(&mut self, event_loop: &ActiveEventLoop, window: Box<dyn AppWindow>) {
        let viewport_id = window.viewport_id();
        if self.viewports.contains_key(&viewport_id) {
            return;
        }
        self.viewports.insert(
            viewport_id,
            Viewport::new(event_loop, self.icon.clone(), window),
        );
    }
}

impl ApplicationHandler<UserEvent> for Application {
    fn resumed(&mut self, event_loop: &ActiveEventLoop) {
        let app = GameWindow::new(
            self.client.clone(),
            self.proxy.clone(),
            self.persistence.clone(),
            SimId::Player1,
        );
        let wrapper = Viewport::new(event_loop, self.icon.clone(), Box::new(app));
        self.focused = Some(wrapper.id());
        self.viewports.insert(wrapper.id(), wrapper);
    }

    fn window_event(
        &mut self,
        event_loop: &ActiveEventLoop,
        window_id: winit::window::WindowId,
        event: WindowEvent,
    ) {
        let Some(viewport) = self
            .viewports
            .values_mut()
            .find(|v| v.window.id() == window_id)
        else {
            return;
        };
        let viewport_id = viewport.id();
        match &event {
            WindowEvent::KeyboardInput { event, .. } => {
                self.controllers.handle_key_event(event);
                viewport.app.handle_key_event(event);
            }
            WindowEvent::Focused(new_focused) => {
                self.focused = new_focused.then_some(viewport_id);
            }
            _ => {}
        }
        let mut queue_redraw = false;
        let mut inactive_viewports = HashSet::new();
        match viewport.on_window_event(event) {
            Some(Action::Redraw) => {
                for viewport in self.viewports.values_mut() {
                    match viewport.redraw(event_loop) {
                        Some(Action::Redraw) => {
                            queue_redraw = true;
                        }
                        Some(Action::Close) => {
                            inactive_viewports.insert(viewport.id());
                        }
                        None => {}
                    }
                }
            }
            Some(Action::Close) => {
                inactive_viewports.insert(viewport_id);
            }
            None => {}
        }
        self.viewports
            .retain(|k, _| !inactive_viewports.contains(k));
        match self.viewports.get(&ViewportId::ROOT) {
            Some(viewport) => {
                if queue_redraw {
                    viewport.window.request_redraw();
                }
            }
            None => event_loop.exit(),
        }
    }

    fn device_event(
        &mut self,
        _event_loop: &ActiveEventLoop,
        _device_id: winit::event::DeviceId,
        event: winit::event::DeviceEvent,
    ) {
        if let winit::event::DeviceEvent::MouseMotion { delta } = event {
            let Some(viewport) = self
                .focused
                .as_ref()
                .and_then(|id| self.viewports.get_mut(id))
            else {
                return;
            };
            viewport.state.on_mouse_motion(delta);
        }
    }

    fn user_event(&mut self, event_loop: &ActiveEventLoop, event: UserEvent) {
        match event {
            UserEvent::GamepadEvent(event) => {
                self.controllers.handle_gamepad_event(&event);
                let Some(viewport) = self
                    .focused
                    .as_ref()
                    .and_then(|id| self.viewports.get_mut(id))
                else {
                    return;
                };
                viewport.app.handle_gamepad_event(&event);
            }
            UserEvent::OpenAbout => {
                let about = AboutWindow;
                self.open(event_loop, Box::new(about));
            }
            UserEvent::OpenInput => {
                let input = InputWindow::new(self.mappings.clone());
                self.open(event_loop, Box::new(input));
            }
            UserEvent::OpenPlayer2 => {
                let p2 = GameWindow::new(
                    self.client.clone(),
                    self.proxy.clone(),
                    self.persistence.clone(),
                    SimId::Player2,
                );
                self.open(event_loop, Box::new(p2));
            }
        }
    }

    fn about_to_wait(&mut self, _event_loop: &ActiveEventLoop) {
        if let Some(viewport) = self.viewports.get(&ViewportId::ROOT) {
            viewport.window.request_redraw();
        }
    }

    fn exiting(&mut self, _event_loop: &ActiveEventLoop) {
        let (sender, receiver) = oneshot::channel();
        if self.client.send_command(EmulatorCommand::Exit(sender)) {
            if let Err(err) = receiver.recv_timeout(Duration::from_secs(5)) {
                eprintln!("could not gracefully exit: {}", err);
            }
        }
    }
}

struct Viewport {
    painter: egui_wgpu::winit::Painter,
    ctx: Context,
    info: ViewportInfo,
    commands: Vec<ViewportCommand>,
    builder: ViewportBuilder,
    window: Arc<Window>,
    state: egui_winit::State,
    app: Box<dyn AppWindow>,
}
impl Viewport {
    pub fn new(
        event_loop: &ActiveEventLoop,
        icon: Option<Arc<IconData>>,
        mut app: Box<dyn AppWindow>,
    ) -> Self {
        let ctx = Context::default();
        let mut fonts = FontDefinitions::default();
        fonts.font_data.insert(
            "Selawik".into(),
            Arc::new(FontData::from_static(include_bytes!(
                "../assets/selawik.ttf"
            ))),
        );
        fonts
            .families
            .get_mut(&FontFamily::Proportional)
            .unwrap()
            .insert(0, "Selawik".into());
        ctx.set_fonts(fonts);
        ctx.style_mut(|s| {
            s.wrap_mode = Some(TextWrapMode::Extend);
            s.visuals.menu_rounding = Default::default();
        });
        egui_extras::install_image_loaders(&ctx);

        #[allow(unused_mut)]
        let mut wgpu_config = egui_wgpu::WgpuConfiguration {
            present_mode: wgpu::PresentMode::AutoNoVsync,
            ..egui_wgpu::WgpuConfiguration::default()
        };
        #[cfg(windows)]
        {
            if let egui_wgpu::WgpuSetup::CreateNew {
                supported_backends, ..
            } = &mut wgpu_config.wgpu_setup
            {
                *supported_backends -= wgpu::Backends::VULKAN;
            }
        }

        let mut painter =
            egui_wgpu::winit::Painter::new(ctx.clone(), wgpu_config, 1, None, false, true);

        let mut info = ViewportInfo::default();
        let mut builder = app.initial_viewport();
        if let Some(icon) = icon {
            builder = builder.with_icon(icon);
        }
        let (window, state) = create_window_and_state(&ctx, event_loop, &builder, &mut painter);
        egui_winit::update_viewport_info(&mut info, &ctx, &window, true);

        app.on_init(painter.render_state().as_ref().unwrap());
        Self {
            painter,
            ctx,
            info,
            commands: vec![],
            builder,
            window,
            state,
            app,
        }
    }

    pub fn id(&self) -> ViewportId {
        self.app.viewport_id()
    }

    pub fn on_window_event(&mut self, event: WindowEvent) -> Option<Action> {
        let response = self.state.on_window_event(&self.window, &event);
        egui_winit::update_viewport_info(
            &mut self.info,
            self.state.egui_ctx(),
            &self.window,
            false,
        );

        match event {
            WindowEvent::RedrawRequested => Some(Action::Redraw),
            WindowEvent::CloseRequested => Some(Action::Close),
            WindowEvent::Resized(size) => {
                let (Some(width), Some(height)) =
                    (NonZero::new(size.width), NonZero::new(size.height))
                else {
                    return None;
                };
                self.painter
                    .on_window_resized(ViewportId::ROOT, width, height);
                None
            }
            _ if response.repaint => Some(Action::Redraw),
            _ => None,
        }
    }

    fn redraw(&mut self, event_loop: &ActiveEventLoop) -> Option<Action> {
        let mut input = self.state.take_egui_input(&self.window);
        input.viewports = std::iter::once((ViewportId::ROOT, self.info.clone())).collect();
        let mut output = self.ctx.run(input, |ctx| {
            self.app.show(ctx);
        });
        let clipped_primitives = self.ctx.tessellate(output.shapes, output.pixels_per_point);
        self.painter.paint_and_update_textures(
            ViewportId::ROOT,
            output.pixels_per_point,
            [0.0, 0.0, 0.0, 0.0],
            &clipped_primitives,
            &output.textures_delta,
            vec![],
        );

        self.state
            .handle_platform_output(&self.window, output.platform_output);

        let Some(mut viewport_output) = output.viewport_output.remove(&ViewportId::ROOT) else {
            return Some(Action::Close);
        };

        let (mut deferred_commands, recreate) = self.builder.patch(viewport_output.builder);
        if recreate {
            let (window, state) =
                create_window_and_state(&self.ctx, event_loop, &self.builder, &mut self.painter);
            egui_winit::update_viewport_info(&mut self.info, &self.ctx, &window, true);
            self.window = window;
            self.state = state;
        }
        self.commands.append(&mut deferred_commands);
        self.commands.append(&mut viewport_output.commands);
        egui_winit::process_viewport_commands(
            &self.ctx,
            &mut self.info,
            std::mem::take(&mut self.commands),
            &self.window,
            &mut HashSet::default(),
        );

        if self.info.close_requested() {
            Some(Action::Close)
        } else {
            Some(Action::Redraw)
        }
    }
}

impl Drop for Viewport {
    fn drop(&mut self) {
        self.app.on_destroy();
    }
}

#[derive(Debug)]
pub enum UserEvent {
    GamepadEvent(gilrs::Event),
    OpenAbout,
    OpenInput,
    OpenPlayer2,
}

pub enum Action {
    Redraw,
    Close,
}

fn create_window_and_state(
    ctx: &Context,
    event_loop: &ActiveEventLoop,
    builder: &ViewportBuilder,
    painter: &mut egui_wgpu::winit::Painter,
) -> (Arc<Window>, egui_winit::State) {
    pollster::block_on(painter.set_window(ViewportId::ROOT, None)).unwrap();
    let window = Arc::new(egui_winit::create_window(ctx, event_loop, builder).unwrap());
    pollster::block_on(painter.set_window(ViewportId::ROOT, Some(window.clone()))).unwrap();
    let state = egui_winit::State::new(
        ctx.clone(),
        ViewportId::ROOT,
        event_loop,
        Some(window.scale_factor() as f32),
        event_loop.system_theme(),
        painter.max_texture_side(),
    );
    (window, state)
}

fn process_gamepad_input(mappings: MappingProvider, proxy: EventLoopProxy<UserEvent>) {
    let Ok(mut gilrs) = Gilrs::new() else {
        eprintln!("could not connect gamepad listener");
        return;
    };
    while let Some(event) = gilrs.next_event_blocking(None) {
        if event.event == EventType::Connected {
            let Some(gamepad) = gilrs.connected_gamepad(event.id) else {
                continue;
            };
            mappings.handle_gamepad_connect(&gamepad);
        }
        if event.event == EventType::Disconnected {
            mappings.handle_gamepad_disconnect(event.id);
        }
        if proxy.send_event(UserEvent::GamepadEvent(event)).is_err() {
            // main thread has closed! we done
            return;
        }
    }
}