mod ui;

use std::sync::Arc;

use fxhash::FxHashMap;
use winit::window::Window;

use crate::{
    Config, Diagnostics, Input,
    camera::Camera,
    config::{CELLS_IN_CHUNK, CHUNK_SIZE},
    renderer::ui::draw_egui,
    sim::{cell::materials::MaterialId, cell_sim::world::World, rb_sim::RbSimManager},
};

// TODO derive from shared chunk config
const CHUNK_SLOTS: usize = 11 * 200;
const RB_ENTITY_SLOTS: usize = 64;
const CELL_SLOTS: usize = CHUNK_SLOTS + RB_ENTITY_SLOTS;

#[repr(C)]
#[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
struct Instance {
    centre: [f32; 2],
    cos_sin: [f32; 2],
    half_size: [f32; 2],
    dims: [u32; 2],
    cell_offset: u32,
    _padding: u32,
}

fn srgb_to_linear(channel: u8) -> f32 {
    let channel = channel as f32 / 255.0;
    if channel <= 0.04045 {
        channel / 12.92
    } else {
        ((channel + 0.055) / 1.055).powf(2.4)
    }
}

pub struct RendererState {
    window: Arc<Window>,
    surface: wgpu::Surface<'static>,
    device: wgpu::Device,
    queue: wgpu::Queue,
    config: wgpu::SurfaceConfiguration,
    is_surface_configured: bool,

    // egui
    egui_context: egui::Context,
    // TODO remove pub
    pub egui_state: egui_winit::State,
    egui_renderer: egui_wgpu::Renderer,

    // world pixels
    pixels_pipeline: wgpu::RenderPipeline,
    camera_uniform_buffer: wgpu::Buffer,
    instance_buffer: wgpu::Buffer,
    cell_buffer: wgpu::Buffer,
    pixels_bind_group: wgpu::BindGroup,

    renderer_rb_entities: FxHashMap<u32, usize>,
}

impl RendererState {
    // https://sotrh.github.io/learn-wgpu/beginner/tutorial1-window
    pub async fn new(window: Arc<Window>) -> Self {
        let size = window.inner_size();
        println!("Got window! ({}x{})", size.width, size.height);

        let instance = wgpu::Instance::default();
        let surface = instance.create_surface(window.clone()).unwrap();

        let adapter = instance
            .request_adapter(&wgpu::RequestAdapterOptions {
                compatible_surface: Some(&surface),
                ..wgpu::RequestAdapterOptions::default()
            })
            .await
            .unwrap();

        println!(
            "Initialized adapter, using GPU '{}'",
            adapter.get_info().name
        );

        let (device, queue) = adapter
            .request_device(&wgpu::DeviceDescriptor {
                required_features: wgpu::Features::default() | wgpu::Features::IMMEDIATES,
                required_limits: wgpu::Limits {
                    max_immediate_size: 16,
                    ..wgpu::Limits::defaults()
                },
                ..wgpu::DeviceDescriptor::default()
            })
            .await
            .unwrap();

        device.on_uncaptured_error(Arc::new(|err| panic!("{err}")));

        let surface_caps = surface.get_capabilities(&adapter);
        let surface_format = surface_caps
            .formats
            .iter()
            .find(|f| f.is_srgb())
            .copied()
            .unwrap_or(surface_caps.formats[0]);

        let config = wgpu::SurfaceConfiguration {
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
            format: surface_format,
            width: size.width,
            height: size.height,
            present_mode: wgpu::PresentMode::AutoVsync,
            alpha_mode: surface_caps.alpha_modes[0],
            view_formats: vec![],
            desired_maximum_frame_latency: 2,
        };

        let egui_context = egui::Context::default();
        let egui_state = egui_winit::State::new(
            egui_context.clone(),
            egui_context.viewport_id(),
            &window,
            None,
            None,
            None,
        );
        let egui_renderer = egui_wgpu::Renderer::new(&device, surface_format, {
            egui_wgpu::RendererOptions {
                msaa_samples: 1,
                ..egui_wgpu::RendererOptions::default()
            }
        });

        let pixels_bind_group_layout =
            device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                label: None,
                entries: &[
                    // camera uniform
                    wgpu::BindGroupLayoutEntry {
                        ty: wgpu::BindingType::Buffer {
                            ty: wgpu::BufferBindingType::Uniform,
                            has_dynamic_offset: false,
                            min_binding_size: None,
                        },
                        binding: 0,
                        count: None,
                        visibility: wgpu::ShaderStages::VERTEX,
                    },
                    // palette
                    wgpu::BindGroupLayoutEntry {
                        ty: wgpu::BindingType::Buffer {
                            ty: wgpu::BufferBindingType::Storage { read_only: true },
                            has_dynamic_offset: false,
                            min_binding_size: None,
                        },
                        binding: 1,
                        count: None,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                    },
                    // instance buffer
                    wgpu::BindGroupLayoutEntry {
                        ty: wgpu::BindingType::Buffer {
                            ty: wgpu::BufferBindingType::Storage { read_only: true },
                            has_dynamic_offset: false,
                            min_binding_size: None,
                        },
                        binding: 2,
                        count: None,
                        visibility: wgpu::ShaderStages::VERTEX | wgpu::ShaderStages::FRAGMENT,
                    },
                    // cells
                    wgpu::BindGroupLayoutEntry {
                        ty: wgpu::BindingType::Buffer {
                            ty: wgpu::BufferBindingType::Storage { read_only: true },
                            has_dynamic_offset: false,
                            min_binding_size: None,
                        },
                        binding: 3,
                        count: None,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                    },
                ],
            });

        let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("Shader"),
            source: wgpu::ShaderSource::Wgsl(include_str!("../shader/shader.wgsl").into()),
        });

        let pixels_pipeline_layout =
            device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
                label: None,
                immediate_size: 0,
                bind_group_layouts: &[Some(&pixels_bind_group_layout)],
            });

        let pixels_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: None,
            layout: Some(&pixels_pipeline_layout),
            vertex: wgpu::VertexState {
                module: &shader,
                entry_point: Some("vs_main"),
                buffers: &[],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            fragment: Some(wgpu::FragmentState {
                module: &shader,
                entry_point: Some("fs_main"),
                targets: &[Some(wgpu::ColorTargetState {
                    format: config.format,
                    blend: Some(wgpu::BlendState::ALPHA_BLENDING),
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            primitive: wgpu::PrimitiveState {
                topology: wgpu::PrimitiveTopology::TriangleStrip,
                strip_index_format: None,
                front_face: wgpu::FrontFace::Ccw,
                cull_mode: None,
                polygon_mode: wgpu::PolygonMode::Fill,
                unclipped_depth: false,
                conservative: false,
            },
            depth_stencil: None,
            multisample: wgpu::MultisampleState::default(),
            multiview_mask: None,
            cache: None,
        });

        let camera_uniform_buffer = device.create_buffer(&wgpu::BufferDescriptor {
            label: Some("Camera uniform buffer"),
            size: 16,
            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
            mapped_at_creation: false,
        });

        let mut palette = [0.0f32; MaterialId::ALL.len() * 4];
        for material in MaterialId::ALL {
            let def = material.def();
            let i = material as usize * 4;
            palette[i] = srgb_to_linear(def.color.0);
            palette[i + 1] = srgb_to_linear(def.color.1);
            palette[i + 2] = srgb_to_linear(def.color.2);
            palette[i + 3] = def.color.3 as f32 / 255.0;
        }

        let palette_buffer = device.create_buffer(&wgpu::BufferDescriptor {
            label: Some("Palette buffer"),
            size: size_of_val(&palette) as u64,
            usage: wgpu::BufferUsages::STORAGE | wgpu::BufferUsages::COPY_DST,
            mapped_at_creation: false,
        });

        queue.write_buffer(&palette_buffer, 0, bytemuck::cast_slice(&palette));

        let instance_buffer = device.create_buffer(&wgpu::BufferDescriptor {
            label: Some("Instance buffer"),
            size: (CELL_SLOTS * size_of::<Instance>()) as u64,
            usage: wgpu::BufferUsages::STORAGE | wgpu::BufferUsages::COPY_DST,
            mapped_at_creation: false,
        });

        let cell_buffer = device.create_buffer(&wgpu::BufferDescriptor {
            label: Some("Cell buffer"),
            size: (CELL_SLOTS * CELLS_IN_CHUNK) as u64,
            usage: wgpu::BufferUsages::STORAGE | wgpu::BufferUsages::COPY_DST,
            mapped_at_creation: false,
        });

        let pixels_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            label: None,
            layout: &pixels_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: camera_uniform_buffer.as_entire_binding(),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: palette_buffer.as_entire_binding(),
                },
                wgpu::BindGroupEntry {
                    binding: 2,
                    resource: instance_buffer.as_entire_binding(),
                },
                wgpu::BindGroupEntry {
                    binding: 3,
                    resource: cell_buffer.as_entire_binding(),
                },
            ],
        });

        RendererState {
            window,
            surface,
            device,
            queue,
            config,
            is_surface_configured: false,

            egui_context,
            egui_state,
            egui_renderer,

            pixels_pipeline,
            camera_uniform_buffer,
            instance_buffer,
            cell_buffer,
            pixels_bind_group,

            renderer_rb_entities: FxHashMap::default(),
        }
    }

    pub fn resize(&mut self, width: u32, height: u32) {
        if width > 0 && height > 0 {
            self.config.width = width;
            self.config.height = height;
            self.surface.configure(&self.device, &self.config);
            self.is_surface_configured = true;
        }
    }

    pub fn render(
        &mut self,
        world: &mut World,
        rb_sim_manager: &RbSimManager,
        camera: &mut Camera,
        config: &mut Config,
        diagnostics: &Diagnostics,
        input: &Input,
    ) {
        puffin::profile_function!();

        self.window.request_redraw();

        if !self.is_surface_configured {
            return;
        }

        let output = {
            puffin::profile_scope!("Get current surface texture");
            match self.surface.get_current_texture() {
                wgpu::CurrentSurfaceTexture::Success(surface_texture) => surface_texture,
                wgpu::CurrentSurfaceTexture::Suboptimal(surface_texture) => surface_texture,
                wgpu::CurrentSurfaceTexture::Timeout
                | wgpu::CurrentSurfaceTexture::Occluded
                | wgpu::CurrentSurfaceTexture::Validation => {
                    // Skip this frame
                    return;
                }
                wgpu::CurrentSurfaceTexture::Outdated => {
                    self.surface.configure(&self.device, &self.config);
                    return;
                }
                wgpu::CurrentSurfaceTexture::Lost => {
                    panic!("Lost device?");
                }
            }
        };

        let view = output
            .texture
            .create_view(&wgpu::TextureViewDescriptor::default());

        let mut encoder = self
            .device
            .create_command_encoder(&wgpu::CommandEncoderDescriptor {
                label: Some("Render Encoder"),
            });

        let raw_input = self.egui_state.take_egui_input(&self.window);
        let full_output = self.egui_context.run_ui(raw_input, |ui| {
            let right_panel = egui::Panel::right(egui::Id::new("right_panel"));
            right_panel
                .resizable(false)
                // TODO collapse button
                .show_collapsible(ui, &mut true, |panel_ui| {
                    draw_egui(panel_ui, config, camera, diagnostics, input, world)
                });
        });

        self.egui_state
            .handle_platform_output(&self.window, full_output.platform_output);

        let clipped_primitives = self
            .egui_context
            .tessellate(full_output.shapes, full_output.pixels_per_point);

        let pixels_per_point = full_output.pixels_per_point;

        let size = self.window.inner_size();
        let screen_descriptor = egui_wgpu::ScreenDescriptor {
            size_in_pixels: [size.width, size.height],
            pixels_per_point,
        };

        for (id, delta) in &full_output.textures_delta.set {
            self.egui_renderer
                .update_texture(&self.device, &self.queue, *id, delta);
        }

        self.egui_renderer.update_buffers(
            &self.device,
            &self.queue,
            &mut encoder,
            &clipped_primitives,
            &screen_descriptor,
        );

        // write the camera buffer
        self.queue.write_buffer(
            &self.camera_uniform_buffer,
            0,
            bytemuck::bytes_of(&camera.to_uniform()),
        );

        let mut cell_buffer: [u8; CELLS_IN_CHUNK] = [0; CELLS_IN_CHUNK];
        let mut instances: Vec<Instance> = Vec::new();

        {
            puffin::profile_scope!("Upload chunk cells");
            for &idx in world.chunk_position_to_chunk_idx.values() {
                let chunk = &mut world.chunks[idx];
                if !chunk.needs_texture_update {
                    continue;
                }
                chunk.needs_texture_update = false;

                for (byte, cell) in cell_buffer.iter_mut().zip(chunk.cells.iter()) {
                    *byte = cell.material as u8;
                }

                self.queue.write_buffer(
                    &self.cell_buffer,
                    (idx * CELLS_IN_CHUNK) as u64,
                    &cell_buffer,
                );
            }
        }

        {
            puffin::profile_scope!("Upload entity cells");
            for entity in rb_sim_manager.rb_entities.values() {
                // TODO add "needs texture update"?
                for (byte, cell) in cell_buffer.iter_mut().zip(entity.cells.iter()) {
                    *byte = cell.material as u8;
                }

                let next_slot = CHUNK_SLOTS + self.renderer_rb_entities.len();
                let slot = *self
                    .renderer_rb_entities
                    .entry(entity.id)
                    .or_insert(next_slot);

                self.queue.write_buffer(
                    &self.cell_buffer,
                    (slot * CELLS_IN_CHUNK) as u64,
                    &cell_buffer,
                );
            }
        }

        {
            puffin::profile_scope!("Build instances");
            let (xl, xu, yl, yu) = camera.viewport_bounds_world();
            let ((cxl, cyl), _) = World::split_game_position(xl.floor() as i32, yl.floor() as i32);
            let ((cxu, cyu), _) = World::split_game_position(xu.floor() as i32, yu.floor() as i32);

            let half_size = [CHUNK_SIZE as f32 / 2.0, CHUNK_SIZE as f32 / 2.0];
            let dims = [CHUNK_SIZE as u32, CHUNK_SIZE as u32];

            for cx in cxl..=cxu {
                for cy in cyl..=cyu {
                    if let Some(idx) = world.chunk_position_to_chunk_idx.get(&(cx, cy)) {
                        instances.push(Instance {
                            centre: [
                                (cx * CHUNK_SIZE) as f32 + half_size[0],
                                (cy * CHUNK_SIZE) as f32 + half_size[1],
                            ],
                            cos_sin: [1.0, 0.0],
                            half_size,
                            dims,
                            cell_offset: (idx * CELLS_IN_CHUNK) as u32,
                            _padding: 0,
                        });
                    }
                }
            }

            for (id, slot) in &self.renderer_rb_entities {
                if let Some((x, y, cos, sin)) = rb_sim_manager.get_rb_entity_transform(*id) {
                    instances.push(Instance {
                        centre: [x, y],
                        cos_sin: [cos, sin],
                        half_size,
                        dims,
                        cell_offset: (slot * CELLS_IN_CHUNK) as u32,
                        _padding: 0,
                    });
                }
            }

            self.queue
                .write_buffer(&self.instance_buffer, 0, bytemuck::cast_slice(&instances));
        }

        {
            puffin::profile_scope!("Main render pass");
            let mut render_pass: wgpu::RenderPass<'_> =
                encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                    label: Some("Render Pass"),
                    color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                        view: &view,
                        resolve_target: None,
                        depth_slice: None,
                        ops: wgpu::Operations {
                            load: wgpu::LoadOp::Clear(wgpu::Color {
                                r: 0.0,
                                g: 0.0,
                                b: 0.0,
                                a: 1.0,
                            }),
                            store: wgpu::StoreOp::Store,
                        },
                    })],
                    depth_stencil_attachment: None,
                    occlusion_query_set: None,
                    timestamp_writes: None,
                    multiview_mask: None,
                });

            render_pass.set_pipeline(&self.pixels_pipeline);
            render_pass.set_bind_group(0, &self.pixels_bind_group, &[]);
            render_pass.draw(0..4, 0..instances.len() as u32);
        }

        {
            puffin::profile_scope!("Egui render pass");
            let mut egui_pass = encoder
                .begin_render_pass(&wgpu::RenderPassDescriptor {
                    label: Some("egui pass"),
                    color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                        view: &view,
                        resolve_target: None,
                        depth_slice: None,
                        ops: wgpu::Operations {
                            load: wgpu::LoadOp::Load,
                            store: wgpu::StoreOp::Store,
                        },
                    })],
                    depth_stencil_attachment: None,
                    timestamp_writes: None,
                    occlusion_query_set: None,
                    multiview_mask: None,
                })
                .forget_lifetime();

            self.egui_renderer
                .render(&mut egui_pass, &clipped_primitives, &screen_descriptor);
        }

        {
            puffin::profile_scope!("Submit queue and present");
            self.queue.submit(std::iter::once(encoder.finish()));
            output.present();
        }
    }
}