use imgui::*;
use imgui_wgpu::{Renderer, RendererConfig};
use imgui_winit_support::WinitPlatform;
use pollster::block_on;
use std::{sync::Arc, time::Instant};
use wgpu::util::DeviceExt as _;
#[cfg(target_os = "windows")]
use winit::platform::windows::{CornerPreference, WindowAttributesExtWindows as _};
use winit::{
    application::ApplicationHandler,
    dpi::{LogicalSize, PhysicalSize},
    event::{Event, WindowEvent},
    event_loop::ActiveEventLoop,
    window::Window,
};

use crate::{
    controller::ControllerState,
    emulator::{EmulatorClient, EmulatorCommand},
    renderer::GameRenderer,
};

struct ImguiState {
    context: imgui::Context,
    platform: WinitPlatform,
    renderer: Renderer,
    clear_color: wgpu::Color,
    last_frame: Instant,
    last_cursor: Option<MouseCursor>,
}

struct AppWindow {
    device: wgpu::Device,
    queue: Arc<wgpu::Queue>,
    window: Arc<Window>,
    surface_desc: wgpu::SurfaceConfiguration,
    surface: wgpu::Surface<'static>,
    hidpi_factor: f64,
    pipeline: wgpu::RenderPipeline,
    bind_group: wgpu::BindGroup,
    imgui: Option<ImguiState>,
}

impl AppWindow {
    fn setup_gpu(event_loop: &ActiveEventLoop, client: &EmulatorClient) -> Self {
        let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
            backends: wgpu::Backends::PRIMARY,
            ..Default::default()
        });

        let window = {
            let size = LogicalSize::new(384, 244);

            let attributes = Window::default_attributes()
                .with_inner_size(size)
                .with_title("Shrooms VB");
            #[cfg(target_os = "windows")]
            let attributes = attributes.with_corner_preference(CornerPreference::DoNotRound);
            Arc::new(event_loop.create_window(attributes).unwrap())
        };

        let size = window.inner_size();
        let hidpi_factor = window.scale_factor();
        let surface = instance.create_surface(window.clone()).unwrap();

        let adapter = block_on(instance.request_adapter(&wgpu::RequestAdapterOptions {
            power_preference: wgpu::PowerPreference::HighPerformance,
            compatible_surface: Some(&surface),
            force_fallback_adapter: false,
        }))
        .unwrap();

        let (device, queue) =
            block_on(adapter.request_device(&wgpu::DeviceDescriptor::default(), None)).unwrap();
        let queue = Arc::new(queue);
        let eyes = Arc::new(GameRenderer::create_texture(&device, "eye"));
        client.send_command(EmulatorCommand::SetRenderer(GameRenderer {
            queue: queue.clone(),
            eyes: eyes.clone(),
        }));
        let eyes = eyes.create_view(&wgpu::TextureViewDescriptor::default());
        let sampler = device.create_sampler(&wgpu::SamplerDescriptor::default());
        let colors = Colors {
            left: [1.0, 0.0, 0.0, 1.0],
            right: [0.0, 0.7734375, 0.9375, 1.0],
        };
        let color_buf = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
            label: Some("colors"),
            contents: bytemuck::bytes_of(&colors),
            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
        });
        let texture_bind_group_layout =
            device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                label: Some("texture bind group layout"),
                entries: &[
                    wgpu::BindGroupLayoutEntry {
                        binding: 0,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Texture {
                            sample_type: wgpu::TextureSampleType::Float { filterable: true },
                            view_dimension: wgpu::TextureViewDimension::D2,
                            multisampled: false,
                        },
                        count: None,
                    },
                    wgpu::BindGroupLayoutEntry {
                        binding: 1,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
                        count: None,
                    },
                    wgpu::BindGroupLayoutEntry {
                        binding: 2,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Buffer {
                            ty: wgpu::BufferBindingType::Uniform,
                            has_dynamic_offset: false,
                            min_binding_size: None,
                        },
                        count: None,
                    },
                ],
            });
        let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            label: Some("bind group"),
            layout: &texture_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&eyes),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&sampler),
                },
                wgpu::BindGroupEntry {
                    binding: 2,
                    resource: color_buf.as_entire_binding(),
                },
            ],
        });

        // Set up swap chain
        let surface_desc = wgpu::SurfaceConfiguration {
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
            format: wgpu::TextureFormat::Bgra8UnormSrgb,
            width: size.width,
            height: size.height,
            present_mode: wgpu::PresentMode::Fifo,
            desired_maximum_frame_latency: 2,
            alpha_mode: wgpu::CompositeAlphaMode::Auto,
            view_formats: vec![wgpu::TextureFormat::Bgra8Unorm],
        };

        surface.configure(&device, &surface_desc);

        let shader = device.create_shader_module(wgpu::include_wgsl!("anaglyph.wgsl"));
        let render_pipeline_layout =
            device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
                label: Some("render pipeline layout"),
                bind_group_layouts: &[&texture_bind_group_layout],
                push_constant_ranges: &[],
            });
        let render_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("render pipeline"),
            layout: Some(&render_pipeline_layout),
            vertex: wgpu::VertexState {
                module: &shader,
                entry_point: "vs_main",
                buffers: &[],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            fragment: Some(wgpu::FragmentState {
                module: &shader,
                entry_point: "fs_main",
                targets: &[Some(wgpu::ColorTargetState {
                    format: wgpu::TextureFormat::Bgra8UnormSrgb,
                    blend: Some(wgpu::BlendState::REPLACE),
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            primitive: wgpu::PrimitiveState {
                topology: wgpu::PrimitiveTopology::TriangleList,
                strip_index_format: None,
                front_face: wgpu::FrontFace::Ccw,
                cull_mode: Some(wgpu::Face::Back),
                polygon_mode: wgpu::PolygonMode::Fill,
                unclipped_depth: false,
                conservative: false,
            },
            depth_stencil: None,
            multisample: wgpu::MultisampleState {
                count: 1,
                mask: !0,
                alpha_to_coverage_enabled: false,
            },
            multiview: None,
            cache: None,
        });

        let imgui = None;
        Self {
            device,
            queue,
            window,
            surface_desc,
            surface,
            hidpi_factor,
            pipeline: render_pipeline,
            bind_group,
            imgui,
        }
    }

    fn setup_imgui(&mut self) {
        let mut context = imgui::Context::create();
        let mut platform = imgui_winit_support::WinitPlatform::new(&mut context);
        platform.attach_window(
            context.io_mut(),
            &self.window,
            imgui_winit_support::HiDpiMode::Default,
        );
        context.set_ini_filename(None);

        let font_size = (13.0 * self.hidpi_factor) as f32;
        context.io_mut().font_global_scale = (1.0 / self.hidpi_factor) as f32;

        context.fonts().add_font(&[FontSource::DefaultFontData {
            config: Some(imgui::FontConfig {
                oversample_h: 1,
                pixel_snap_h: true,
                size_pixels: font_size,
                ..Default::default()
            }),
        }]);

        //
        // Set up dear imgui wgpu renderer
        //
        let clear_color = wgpu::Color::BLACK;

        let renderer_config = RendererConfig {
            texture_format: self.surface_desc.format,
            ..Default::default()
        };

        let renderer = Renderer::new(&mut context, &self.device, &self.queue, renderer_config);

        let last_frame = Instant::now();
        let last_cursor = None;

        self.imgui = Some(ImguiState {
            context,
            platform,
            renderer,
            clear_color,
            last_frame,
            last_cursor,
        })
    }

    fn new(event_loop: &ActiveEventLoop, client: &EmulatorClient) -> Self {
        let mut window = Self::setup_gpu(event_loop, client);
        window.setup_imgui();
        window
    }
}

pub struct App {
    window: Option<AppWindow>,
    client: EmulatorClient,
    controller: ControllerState,
}

impl App {
    pub fn new(client: EmulatorClient) -> Self {
        let controller = ControllerState::new();
        client.send_command(EmulatorCommand::SetKeys(controller.pressed()));
        Self {
            window: None,
            client,
            controller,
        }
    }
}

impl ApplicationHandler for App {
    fn resumed(&mut self, event_loop: &ActiveEventLoop) {
        self.window = Some(AppWindow::new(event_loop, &self.client));
    }

    fn window_event(
        &mut self,
        event_loop: &ActiveEventLoop,
        window_id: winit::window::WindowId,
        event: WindowEvent,
    ) {
        let window = self.window.as_mut().unwrap();
        let imgui = window.imgui.as_mut().unwrap();

        match &event {
            WindowEvent::Resized(size) => {
                window.surface_desc.width = size.width;
                window.surface_desc.height = size.height;
                window
                    .surface
                    .configure(&window.device, &window.surface_desc);
            }
            WindowEvent::CloseRequested => event_loop.exit(),
            WindowEvent::KeyboardInput { event, .. } => {
                if self.controller.key_event(event) {
                    self.client
                        .send_command(EmulatorCommand::SetKeys(self.controller.pressed()));
                }
            }
            WindowEvent::RedrawRequested => {
                let now = Instant::now();
                imgui
                    .context
                    .io_mut()
                    .update_delta_time(now - imgui.last_frame);
                imgui.last_frame = now;

                let frame = match window.surface.get_current_texture() {
                    Ok(frame) => frame,
                    Err(e) => {
                        eprintln!("dropped frame: {e:?}");
                        return;
                    }
                };
                imgui
                    .platform
                    .prepare_frame(imgui.context.io_mut(), &window.window)
                    .expect("Failed to prepare frame");
                let ui = imgui.context.frame();
                let mut menu_height = 0.0;
                ui.main_menu_bar(|| {
                    menu_height = ui.window_size()[1];
                    ui.menu("ROM", || {
                        if ui.menu_item("Open ROM") {
                            let rom = native_dialog::FileDialog::new()
                                .add_filter("Virtual Boy ROMs", &["vb", "vbrom"])
                                .show_open_single_file()
                                .unwrap();
                            if let Some(path) = rom {
                                self.client.send_command(EmulatorCommand::LoadGame(path));
                            }
                        }
                        if ui.menu_item("Quit") {
                            event_loop.exit();
                        }
                    });
                    ui.menu("Emulation", || {
                        if self.client.is_running() {
                            if ui.menu_item("Pause") {
                                self.client.send_command(EmulatorCommand::Pause);
                            }
                        } else if ui.menu_item("Resume") {
                            self.client.send_command(EmulatorCommand::Resume);
                        }
                        if ui.menu_item("Reset") {
                            self.client.send_command(EmulatorCommand::Reset);
                        }
                    });
                    ui.menu("Video", || {
                        let current_dims = PhysicalSize::new(
                            window.surface_desc.width,
                            window.surface_desc.height,
                        )
                        .to_logical(window.hidpi_factor);
                        for scale in 1..=4 {
                            let label = format!("x{scale}");
                            let dims = LogicalSize::new(384 * scale, 224 * scale + 20);
                            let selected = dims == current_dims;
                            if ui.menu_item_config(label).selected(selected).build() {
                                if let Some(size) = window.window.request_inner_size(dims) {
                                    window.surface_desc.width = size.width;
                                    window.surface_desc.height = size.height;
                                    window
                                        .surface
                                        .configure(&window.device, &window.surface_desc);
                                }
                            }
                        }
                    });
                });

                let mut encoder: wgpu::CommandEncoder = window
                    .device
                    .create_command_encoder(&wgpu::CommandEncoderDescriptor { label: None });

                if imgui.last_cursor != ui.mouse_cursor() {
                    imgui.last_cursor = ui.mouse_cursor();
                    imgui.platform.prepare_render(ui, &window.window);
                }

                let view = frame
                    .texture
                    .create_view(&wgpu::TextureViewDescriptor::default());
                let mut rpass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                    label: None,
                    color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                        view: &view,
                        resolve_target: None,
                        ops: wgpu::Operations {
                            load: wgpu::LoadOp::Clear(imgui.clear_color),
                            store: wgpu::StoreOp::Store,
                        },
                    })],
                    depth_stencil_attachment: None,
                    timestamp_writes: None,
                    occlusion_query_set: None,
                });

                // Draw the game
                rpass.set_pipeline(&window.pipeline);
                let window_width = window.surface_desc.width as f32;
                let window_height = window.surface_desc.height as f32;
                let menu_height = menu_height * window.hidpi_factor as f32;
                let ((x, y), (width, height)) =
                    compute_game_bounds(window_width, window_height, menu_height);
                rpass.set_viewport(x, y, width, height, 0.0, 1.0);
                rpass.set_bind_group(0, &window.bind_group, &[]);
                rpass.draw(0..6, 0..1);

                // Draw the menu on top of the game
                rpass.set_viewport(0.0, 0.0, window_width, window_height, 0.0, 1.0);
                imgui
                    .renderer
                    .render(
                        imgui.context.render(),
                        &window.queue,
                        &window.device,
                        &mut rpass,
                    )
                    .expect("Rendering failed");

                drop(rpass);

                window.queue.submit(Some(encoder.finish()));

                frame.present();
            }
            _ => (),
        }

        imgui.platform.handle_event::<()>(
            imgui.context.io_mut(),
            &window.window,
            &Event::WindowEvent { window_id, event },
        );
    }

    fn user_event(&mut self, _event_loop: &ActiveEventLoop, event: ()) {
        let window = self.window.as_mut().unwrap();
        let imgui = window.imgui.as_mut().unwrap();
        imgui.platform.handle_event::<()>(
            imgui.context.io_mut(),
            &window.window,
            &Event::UserEvent(event),
        );
    }

    fn device_event(
        &mut self,
        _event_loop: &ActiveEventLoop,
        device_id: winit::event::DeviceId,
        event: winit::event::DeviceEvent,
    ) {
        let window = self.window.as_mut().unwrap();
        let imgui = window.imgui.as_mut().unwrap();
        imgui.platform.handle_event::<()>(
            imgui.context.io_mut(),
            &window.window,
            &Event::DeviceEvent { device_id, event },
        );
    }

    fn about_to_wait(&mut self, _event_loop: &ActiveEventLoop) {
        let window = self.window.as_mut().unwrap();
        let imgui = window.imgui.as_mut().unwrap();
        window.window.request_redraw();
        imgui.platform.handle_event::<()>(
            imgui.context.io_mut(),
            &window.window,
            &Event::AboutToWait,
        );
    }
}

fn compute_game_bounds(
    window_width: f32,
    window_height: f32,
    menu_height: f32,
) -> ((f32, f32), (f32, f32)) {
    let available_width = window_width;
    let available_height = window_height - menu_height;

    let width = available_width.min(available_height * 384.0 / 224.0);
    let height = available_height.min(available_width * 224.0 / 384.0);
    let x = (available_width - width) / 2.0;
    let y = menu_height + (available_height - height) / 2.0;
    ((x, y), (width, height))
}

#[derive(Clone, Copy, bytemuck::Pod, bytemuck::Zeroable)]
#[repr(C)]
struct Colors {
    left: [f32; 4],
    right: [f32; 4],
}