#![warn(dead_code)]

use std::collections::HashMap;

use crate::{
    core::{
        events::Events,
        module::{Module, ModulesStack, RenderModule as ThreadLocalModule, RenderModulesStack},
    },
    modules::graphics::egui::{Gui, GuiConfig},
};
use anyhow::Result;
use flax::{Schedule, World};
use vulkano::device::DeviceFeatures;
use vulkano_util::{
    context::{VulkanoConfig, VulkanoContext},
    window::VulkanoWindows,
};
use winit::{event::{Event, WindowEvent}, window::WindowId};

#[allow(dead_code)]
pub struct App {
    name: String,
    modules: ModulesStack,
    thread_local_modules: RenderModulesStack,
    world: World,
    schedule: Schedule,
    events: Events,
    rx: flume::Receiver<AppEvent>,
    running: bool,
    event_cleanup_time: std::time::Duration,
    vk_context: VulkanoContext,
    vk_windows: VulkanoWindows,
    guis: HashMap<WindowId, Gui>,
}

impl App {
    pub fn new() -> Self {
        let mut events = Events::new();

        let (tx, rx) = flume::unbounded();
        events.subscribe_custom(tx);

        let schedule = Schedule::builder().build();

        let vk_config = VulkanoConfig {
            device_features: DeviceFeatures {
                dynamic_rendering: true,
                ..Default::default()
            },
            ..Default::default()
        };
        let vk_context = VulkanoContext::new(vk_config);
        let vk_windows = VulkanoWindows::default();

        Self {
            name: "Khors".into(),
            modules: ModulesStack::new(),
            thread_local_modules: RenderModulesStack::new(),
            world: World::new(),
            schedule,
            events,
            rx,
            running: false,
            event_cleanup_time: std::time::Duration::from_secs(60),
            vk_context,
            vk_windows,
            guis: HashMap::new(),
        }
    }

    pub fn run(&mut self) -> Result<()> {
        self.running = true;

        self.schedule.execute_par(&mut self.world).unwrap();

        let vk_context = &mut self.vk_context;
        let vk_windows = &mut self.vk_windows;
        let world = &mut self.world;
        let events = &mut self.events;
        let frame_time = std::time::Duration::from_millis(16);
        let guis = &mut self.guis;

        for module in self.modules.iter_mut() {
            module.on_update(world, events, frame_time)?;
        }

        for module in self.thread_local_modules.iter_mut() {
            module.on_update(guis, vk_context, vk_windows, world, events, frame_time)?;
        }

        self.handle_events();

        Ok(())
    }

    pub fn create_window<T>(&mut self, event_loop: &winit::event_loop::EventLoopWindowTarget<T>)
    where
        T: Clone + Send + Sync,
    {
        let window = self.vk_windows.create_window(
            event_loop,
            &self.vk_context,
            &vulkano_util::window::WindowDescriptor {
                title: self.name.clone(),
                present_mode: vulkano::swapchain::PresentMode::Fifo,
                ..Default::default()
            },
            |_| {},
        );

        let renderer = self.vk_windows.get_renderer(window).unwrap();
        let gui = Gui::new(
            event_loop,
            renderer.surface().clone(),
            renderer.graphics_queue().clone(),
            renderer.swapchain_format(),
            GuiConfig { is_overlay: true, allow_srgb_render_target: false, ..Default::default() },
        );

        self.guis.insert(window, gui);
    }

    pub fn process_event_loop<T>(
        &mut self,
        event: winit::event::Event<T>,
        _elwt: &winit::event_loop::EventLoopWindowTarget<T>,
    ) -> Result<bool>
    where
        T: Clone + Send + Sync,
    {
        match &event {
            Event::WindowEvent {
                event: WindowEvent::CloseRequested,
                ..
            } => {
                return Ok(true);
            }
            Event::WindowEvent {
                event: WindowEvent::Focused(_),
                ..
            } => self.events().send(event.clone()),
            Event::WindowEvent {
                event: WindowEvent::Resized(..) | WindowEvent::ScaleFactorChanged { .. },
                window_id,
            } => self
                .vk_windows
                .get_renderer_mut(*window_id)
                .unwrap()
                .resize(),
            Event::WindowEvent {
                event: WindowEvent::RedrawRequested,
                window_id,
            } => 'redraw: {
                // Tasks for redrawing:
                // 1. Update state based on events
                // 2. Compute & Render
                // 3. Reset input state
                // 4. Update time & title

                // The rendering part goes here:
                match self
                    .vk_windows
                    .get_renderer(*window_id)
                    .unwrap()
                    .window_size()
                {
                    [w, h] => {
                        // Skip this frame when minimized.
                        if w == 0.0 || h == 0.0 {
                            break 'redraw;
                        }
                    }
                }

                self.run()?;
            }
            Event::WindowEvent { window_id, event } => {
                let window = self.vk_windows.get_window(*window_id).unwrap();
                let gui = self.guis.get_mut(window_id).unwrap();
                gui.update(window, event);
            }
            Event::AboutToWait => {
                for (window_id, _) in self.vk_windows.iter() {
                    self.vk_windows
                        .get_window(*window_id)
                        .unwrap()
                        .request_redraw()
                }
            }
            _ => (),
        }
        Ok(false)
    }

    pub fn handle_events(&mut self) {
        for event in self.rx.try_iter() {
            match event {
                AppEvent::Exit => self.running = false,
            }
        }
    }

    #[allow(dead_code)]
    pub fn set_schedule(&mut self, schedule: Schedule) {
        self.schedule = schedule;
    }

    #[allow(dead_code)]
    pub fn world(&self) -> &World {
        &self.world
    }

    #[allow(dead_code)]
    pub fn world_mut(&mut self) -> &mut World {
        &mut self.world
    }

    pub fn events(&self) -> &Events {
        &self.events
    }

    #[allow(dead_code)]
    pub fn events_mut(&mut self) -> &mut Events {
        &mut self.events
    }

    /// Pushes a module from the provided init closure to to the top of the layer stack. The provided
    /// closure to construct the layer takes in the world and events.
    pub fn push_render_module<F, T>(&mut self, func: F)
    where
        F: FnOnce(
            &mut VulkanoContext,
            &mut VulkanoWindows,
            &mut Schedule,
            &mut World,
            &mut Events,
        ) -> T,
        T: 'static + ThreadLocalModule,
    {
        let module = func(
            &mut self.vk_context,
            &mut self.vk_windows,
            &mut self.schedule,
            &mut self.world,
            &mut self.events,
        );
        self.thread_local_modules.push(module);
    }

    /// Pushes a layer from the provided init closure to to the top of the layer stack. The provided
    /// closure to construct the layer takes in the world and events.
    pub fn push_module<F, T>(&mut self, func: F)
    where
        F: FnOnce(&mut Schedule, &mut World, &mut Events) -> T,
        T: 'static + Module,
    {
        let module = func(&mut self.schedule, &mut self.world, &mut self.events);
        self.modules.push(module);
    }

    /// Pushes a module from the provided init closure to to the top of the module stack. The provided
    /// closure to construct the module takes in the world and events, and may return an error which
    /// is propagated to the callee.
    #[allow(dead_code)]
    pub fn try_push_module<F, T, E>(&mut self, func: F) -> Result<(), E>
    where
        F: FnOnce(&mut World, &mut Events) -> Result<T, E>,
        T: 'static + Module,
    {
        let module = func(&mut self.world, &mut self.events)?;
        self.modules.push(module);
        Ok(())
    }

    /// Inserts a module from the provided init closure to to the top of the module stack. The provided
    /// closure to construct the module takes in the world and events.
    #[allow(dead_code)]
    pub fn insert_module<F, T>(&mut self, index: usize, func: F)
    where
        F: FnOnce(&mut World, &mut Events) -> T,
        T: 'static + Module,
    {
        let module = func(&mut self.world, &mut self.events);
        self.modules.insert(index, module);
    }

    /// Pushes a module from the provided init closure to to the top of the module stack. The provided
    /// closure to construct the module takes in the world and events, and may return an error which
    /// is propagated to the callee.
    #[allow(dead_code)]
    pub fn try_insert_module<F, T, E>(&mut self, index: usize, func: F) -> Result<(), E>
    where
        F: FnOnce(&mut World, &mut Events) -> Result<T, E>,
        T: 'static + Module,
    {
        let module = func(&mut self.world, &mut self.events)?;
        self.modules.insert(index, module);
        Ok(())
    }
}

#[derive(Debug, Clone, Copy, PartialEq)]
#[allow(dead_code)]
pub enum AppEvent {
    Exit,
}

impl Default for App {
    fn default() -> Self {
        Self::new()
    }
}