/*
    wearechat - generic multiplayer game with voip
    Copyright (C) 2025 metamuffin

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as published by
    the Free Software Foundation, version 3 of the License only.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/
use crate::{
    camera::Camera, download::Downloader, interfaces::profiler::TimingProfiler,
    scene_prepare::ScenePreparer, scene_render::ScenePipeline, state::InputState, ui::UiRenderer,
};
use anyhow::{Result, anyhow};
use log::{info, warn};
use pollster::FutureExt;
use std::{
    mem::swap,
    sync::{Arc, Mutex},
    thread::{sleep, spawn},
    time::Duration,
};
use weareshared::tree::SceneTree;
use wgpu::{
    AdapterInfo, Backends, CommandEncoderDescriptor, Device, DeviceDescriptor, Extent3d, Features,
    Instance, InstanceDescriptor, Limits, MaintainBase, PowerPreference, Queue,
    RequestAdapterOptions, Surface, SurfaceConfiguration, TextureDescriptor, TextureDimension,
    TextureFormat, TextureUsages, TextureView, TextureViewDescriptor,
};
use winit::window::Window;

pub struct Renderer<'a> {
    surface: Surface<'a>,
    queue: Arc<Queue>,
    device: Arc<Device>,
    surface_configuration: SurfaceConfiguration,
    scene_pipeline: ScenePipeline,
    pub ui_renderer: UiRenderer,
    pub scene_prepare: Arc<ScenePreparer>,
    surface_needs_reconfigure: bool,
    depth: TextureView,
    pub timing: TimingProfiler,
    pub timing_submit: Arc<Mutex<TimingProfiler>>,
    pub adapter_info: Arc<AdapterInfo>,
}
impl<'a> Renderer<'a> {
    pub fn new(window: &'a Window, downloader: Arc<Downloader>) -> Result<Self> {
        info!("wgpu init");
        let instance = Instance::new(InstanceDescriptor {
            backends: Backends::all(),
            ..Default::default()
        });

        let surface = instance.create_surface(window)?;
        let adapter = instance
            .request_adapter(&RequestAdapterOptions {
                compatible_surface: Some(&surface),
                power_preference: PowerPreference::HighPerformance,
                ..Default::default()
            })
            .block_on()
            .ok_or(anyhow!("no adapter found"))?;

        let (device, queue) = adapter
            .request_device(
                &DeviceDescriptor {
                    required_features: Features::PUSH_CONSTANTS,
                    required_limits: Limits {
                        max_push_constant_size: 112,
                        max_vertex_buffers: 16,
                        ..Limits::default()
                    },
                    ..Default::default()
                },
                None,
            )
            .block_on()?;

        let surface_configuration = surface
            .get_default_config(&adapter, 256, 256)
            .ok_or(anyhow!("no default config"))?;

        surface.configure(&device, &surface_configuration);

        let device = Arc::new(device);
        let queue = Arc::new(queue);

        let (scene_pipeline, texture_bgl, material_bgl) =
            ScenePipeline::new(&device, surface_configuration.format);
        let scene_prepare = Arc::new(ScenePreparer::new(
            device.clone(),
            queue.clone(),
            texture_bgl,
            material_bgl,
        ));

        let ui_renderer =
            UiRenderer::new(device.clone(), queue.clone(), surface_configuration.format);

        let depth = device.create_texture(&TextureDescriptor {
            label: None,
            size: Extent3d {
                height: 256,
                width: 256,
                depth_or_array_layers: 1,
            },
            mip_level_count: 1,
            sample_count: 1,
            dimension: TextureDimension::D2,
            format: TextureFormat::Depth32Float,
            usage: TextureUsages::RENDER_ATTACHMENT,
            view_formats: &[],
        });
        let depth = depth.create_view(&TextureViewDescriptor::default());

        // TODO multithreading introduces double-loading some resources. fix that before increasing thread count
        for _ in 0..1 {
            let scene_prepare = scene_prepare.clone();
            let downloader = downloader.clone();
            spawn(move || {
                loop {
                    let ndone = scene_prepare.update(&downloader).unwrap();
                    if ndone == 0 {
                        sleep(Duration::from_millis(50));
                    }
                }
            });
        }

        let adapter_info = Arc::new(adapter.get_info());

        Ok(Self {
            scene_pipeline,
            scene_prepare,
            surface,
            adapter_info,
            depth,
            device,
            queue,
            surface_configuration,
            ui_renderer,
            surface_needs_reconfigure: false,
            timing: Default::default(),
            timing_submit: Default::default(),
        })
    }

    pub fn resize(&mut self, width: u32, height: u32) {
        self.surface_configuration.width = width;
        self.surface_configuration.height = height;
        self.surface
            .configure(&self.device, &self.surface_configuration);

        self.depth = self
            .device
            .create_texture(&TextureDescriptor {
                label: None,
                size: Extent3d {
                    height,
                    width,
                    depth_or_array_layers: 1,
                },
                mip_level_count: 1,
                sample_count: 1,
                dimension: TextureDimension::D2,
                format: TextureFormat::Depth32Float,
                usage: TextureUsages::RENDER_ATTACHMENT,
                view_formats: &[],
            })
            .create_view(&TextureViewDescriptor::default());
    }

    pub fn draw(
        &mut self,
        scene: &SceneTree,
        camera: &Camera,
        input_state: &mut InputState,
    ) -> Result<()> {
        self.timing.begin("prepare");
        if self.surface_needs_reconfigure {
            self.surface
                .configure(&self.device, &self.surface_configuration);
            self.surface_needs_reconfigure = false
        }
        let target = self.surface.get_current_texture()?;
        if target.suboptimal {
            warn!("suboptimal swapchain texture");
            self.surface_needs_reconfigure = true;
        }
        let target_view = target
            .texture
            .create_view(&TextureViewDescriptor::default());

        let mut commands = self
            .device
            .create_command_encoder(&CommandEncoderDescriptor { label: None });

        let projection = camera.to_matrix();

        self.timing.checkpoint("draw scene");
        self.scene_pipeline.draw(
            &mut commands,
            &target_view,
            &self.depth,
            scene,
            &self.scene_prepare.prefabs,
            projection,
        );

        self.timing.checkpoint("draw ui");
        self.ui_renderer.draw(
            &mut commands,
            &target_view,
            &self.depth,
            projection,
            input_state,
            &self.surface_configuration,
        );

        self.timing.checkpoint("submit");
        let i = self.queue.submit(Some(commands.finish()));
        self.timing.checkpoint("poll");
        self.device.poll(MaintainBase::WaitForSubmissionIndex(i));

        self.timing.checkpoint("present");
        target.present();

        self.timing.checkpoint("");

        let mut ts = self.timing_submit.lock().unwrap();
        swap(&mut *ts, &mut self.timing);

        Ok(())
    }
}