use std::ops::Range;

use lyon::math::Vector;
use lyon::tessellation::VertexBuffers;
use vector_tile::parse_tile;
use wgpu::util::DeviceExt;
use winit::dpi::PhysicalSize;
use winit::event::{ElementState, Event, KeyboardInput, VirtualKeyCode, WindowEvent};
use winit::event_loop::ControlFlow;
use winit::window::Window;

use crate::fps_meter::FPSMeter;
use crate::multisampling::create_multisampled_framebuffer;
use crate::piplines::*;
use crate::shader::*;
use crate::shader_ffi::*;
use crate::tesselation::{RustLogo, Tesselated};
use crate::texture::Texture;

pub struct SceneParams {
    pub target_zoom: f32,
    pub zoom: f32,
    pub target_scroll: Vector,
    pub scroll: Vector,
    pub show_points: bool,
    pub stroke_width: f32,
    pub target_stroke_width: f32,
}

const PRIM_BUFFER_LEN: usize = 256;

pub const DEFAULT_SCENE: SceneParams = SceneParams {
    target_zoom: 5.0,
    zoom: 5.0,
    target_scroll: Vector::new(70.0, 70.0),
    scroll: Vector::new(70.0, 70.0),
    show_points: false,
    stroke_width: 1.0,
    target_stroke_width: 1.0,
};

pub struct State {
    device: wgpu::Device,
    queue: wgpu::Queue,

    fps_meter: FPSMeter,

    surface: wgpu::Surface,
    surface_config: wgpu::SurfaceConfiguration,

    pub size: winit::dpi::PhysicalSize<u32>,

    render_pipeline: wgpu::RenderPipeline,
    bind_group: wgpu::BindGroup,

    sample_count: u32,
    multisampled_render_target: Option<wgpu::TextureView>,
    depth_texture: Texture,

    prims_uniform_buffer: wgpu::Buffer,
    globals_uniform_buffer: wgpu::Buffer,
    vertex_uniform_buffer: wgpu::Buffer,
    indices_uniform_buffer: wgpu::Buffer,

    num_instances: u32,
    stroke_prim_id: u32,
    fill_prim_id: u32,
    cpu_primitives: Vec<Primitive>,
    fill_range: Range<u32>,
    stroke_range: Range<u32>,

    scene: SceneParams,
}

impl State {
    pub async fn new(window: &Window) -> Self {
        let sample_count = 4;
        let stroke_prim_id = 0;
        let fill_prim_id = 1;

        let size = window.inner_size();

        let mut geometry: VertexBuffers<GpuVertex, u16> = VertexBuffers::new();

        let (stroke_range, fill_range) = if true {
            let tile = parse_tile("test-data/12-2176-1425.pbf").expect("failed loading tile");
            (
                0..tile.tesselate_stroke(&mut geometry, stroke_prim_id),
                0..0,
            )
        } else {
            let logo = RustLogo();
            let max_index = logo.tesselate_stroke(&mut geometry, stroke_prim_id);
            (
                0..max_index,
                max_index..max_index + logo.tesselate_fill(&mut geometry, fill_prim_id),
            )
        };

        let mut cpu_primitives = Vec::with_capacity(PRIM_BUFFER_LEN);
        for _ in 0..PRIM_BUFFER_LEN {
            cpu_primitives.push(Primitive {
                color: [1.0, 0.0, 0.0, 1.0],
                z_index: 0,
                width: 0.0,
                translate: [0.0, 0.0],
                angle: 0.0,
                ..Primitive::DEFAULT
            });
        }

        // Stroke primitive
        cpu_primitives[stroke_prim_id as usize] = Primitive {
            color: [0.0, 0.0, 0.0, 1.0],
            z_index: 3,
            width: 1.0,
            ..Primitive::DEFAULT
        };
        // Main fill primitive
        cpu_primitives[fill_prim_id as usize] = Primitive {
            color: [1.0, 1.0, 1.0, 1.0],
            z_index: 1,
            ..Primitive::DEFAULT
        };

        // create an instance
        let instance = wgpu::Instance::new(wgpu::Backends::all());

        // create an surface
        let surface = unsafe { instance.create_surface(window) };

        // create an adapter
        let adapter = instance
            .request_adapter(&wgpu::RequestAdapterOptions {
                power_preference: wgpu::PowerPreference::LowPower,
                compatible_surface: Some(&surface),
                force_fallback_adapter: false,
            })
            .await
            .unwrap();

        // create a device and a queue
        let (device, queue) = adapter
            .request_device(
                &wgpu::DeviceDescriptor {
                    label: None,
                    features: wgpu::Features::default(),
                    limits: wgpu::Limits::default(),
                },
                None,
            )
            .await
            .unwrap();

        let vertex_uniform_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
            label: None,
            contents: bytemuck::cast_slice(&geometry.vertices),
            usage: wgpu::BufferUsages::VERTEX,
        });

        let indices_uniform_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
            label: None,
            contents: bytemuck::cast_slice(&geometry.indices),
            usage: wgpu::BufferUsages::INDEX,
        });

        let prim_buffer_byte_size = (PRIM_BUFFER_LEN * std::mem::size_of::<Primitive>()) as u64;
        let globals_buffer_byte_size = std::mem::size_of::<Globals>() as u64;

        let prims_uniform_buffer = device.create_buffer(&wgpu::BufferDescriptor {
            label: Some("Prims ubo"),
            size: prim_buffer_byte_size,
            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
            mapped_at_creation: false,
        });

        let globals_uniform_buffer = device.create_buffer(&wgpu::BufferDescriptor {
            label: Some("Globals ubo"),
            size: globals_buffer_byte_size,
            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
            mapped_at_creation: false,
        });

        let bind_group_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
            label: Some("Bind group layout"),
            entries: &[
                wgpu::BindGroupLayoutEntry {
                    binding: 0,
                    visibility: wgpu::ShaderStages::VERTEX,
                    ty: wgpu::BindingType::Buffer {
                        ty: wgpu::BufferBindingType::Uniform,
                        has_dynamic_offset: false,
                        min_binding_size: wgpu::BufferSize::new(globals_buffer_byte_size),
                    },
                    count: None,
                },
                wgpu::BindGroupLayoutEntry {
                    binding: 1,
                    visibility: wgpu::ShaderStages::VERTEX,
                    ty: wgpu::BindingType::Buffer {
                        ty: wgpu::BufferBindingType::Uniform,
                        has_dynamic_offset: false,
                        min_binding_size: wgpu::BufferSize::new(prim_buffer_byte_size),
                    },
                    count: None,
                },
            ],
        });
        let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            label: Some("Bind group"),
            layout: &bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::Buffer(
                        globals_uniform_buffer.as_entire_buffer_binding(),
                    ),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Buffer(
                        prims_uniform_buffer.as_entire_buffer_binding(),
                    ),
                },
            ],
        });

        let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            bind_group_layouts: &[&bind_group_layout],
            push_constant_ranges: &[],
            label: None,
        });

        let vertex_module = device.create_shader_module(&create_vertex_module_descriptor());
        let fragment_module = device.create_shader_module(&create_fragment_module_descriptor());
        let mut render_pipeline_descriptor = create_map_render_pipeline_description(
            &pipeline_layout,
            create_map_vertex_state(&vertex_module),
            create_map_fragment_state(&fragment_module),
            sample_count,
        );
        let render_pipeline = device.create_render_pipeline(&render_pipeline_descriptor);

        // TODO: this isn't what we want: we'd need the equivalent of VK_POLYGON_MODE_LINE,
        // but it doesn't seem to be exposed by wgpu?
        render_pipeline_descriptor.primitive.topology = wgpu::PrimitiveTopology::LineList;

        let surface_config = wgpu::SurfaceConfiguration {
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
            format: wgpu::TextureFormat::Bgra8UnormSrgb,
            width: size.width,
            height: size.height,
            present_mode: wgpu::PresentMode::Mailbox,
        };

        surface.configure(&device, &surface_config);

        let depth_texture = Texture::create_depth_texture(&device, &surface_config, "depth_texture", sample_count);

        let multisampled_render_target = if sample_count > 1 {
            Some(create_multisampled_framebuffer(
                &device,
                &surface_config,
                sample_count,
            ))
        } else {
            None
        };

        Self {
            surface,
            device,
            queue,
            size,
            surface_config,
            render_pipeline,
            bind_group,
            multisampled_render_target,
            depth_texture,
            sample_count,
            fill_range,
            num_instances: 1,
            stroke_prim_id: 0,
            fill_prim_id: 1,
            scene: DEFAULT_SCENE,
            vertex_uniform_buffer,
            globals_uniform_buffer,
            prims_uniform_buffer,
            indices_uniform_buffer,
            fps_meter: FPSMeter::new(),
            stroke_range,
            cpu_primitives
        }
    }

    pub fn resize(&mut self, new_size: winit::dpi::PhysicalSize<u32>) {
        if new_size.width > 0 && new_size.height > 0 {
            self.size = new_size;
            self.surface_config.width = new_size.width;
            self.surface_config.height = new_size.height;
            self.surface.configure(&self.device, &self.surface_config);

            // Re-configure depth buffer
            self.depth_texture = Texture::create_depth_texture(&self.device, &self.surface_config, "depth_texture", self.sample_count);

            // Re-configure multi-sampling buffer
            self.multisampled_render_target = if self.sample_count > 1 {
                Some(create_multisampled_framebuffer(
                    &self.device,
                    &self.surface_config,
                    self.sample_count,
                ))
            } else {
                None
            };
        }
    }

    pub fn input(&mut self, event: &WindowEvent) -> bool {
        let scene = &mut self.scene;
        let found = match event {
            WindowEvent::KeyboardInput {
                input:
                    KeyboardInput {
                        state: ElementState::Pressed,
                        virtual_keycode: Some(key),
                        ..
                    },
                ..
            } => match key {
                VirtualKeyCode::PageDown => {
                    scene.target_zoom *= 0.8;
                    true
                }
                VirtualKeyCode::PageUp => {
                    scene.target_zoom *= 1.25;
                    true
                }
                VirtualKeyCode::Left => {
                    scene.target_scroll.x -= 50.0 / scene.target_zoom;
                    true
                }
                VirtualKeyCode::Right => {
                    scene.target_scroll.x += 50.0 / scene.target_zoom;
                    true
                }
                VirtualKeyCode::Up => {
                    scene.target_scroll.y -= 50.0 / scene.target_zoom;
                    true
                }
                VirtualKeyCode::Down => {
                    scene.target_scroll.y += 50.0 / scene.target_zoom;
                    true
                }
                VirtualKeyCode::P => {
                    scene.show_points = !scene.show_points;
                    true
                }
                VirtualKeyCode::A => {
                    scene.target_stroke_width /= 0.8;
                    true
                }
                VirtualKeyCode::Z => {
                    scene.target_stroke_width *= 0.8;
                    true
                }
                _key => false
            },
            _evt => false
        };

        found
    }

    pub fn render(&mut self) -> Result<(), wgpu::SurfaceError> {
        let frame = self.surface.get_current_texture()?;
        let scene = &mut self.scene;

        let frame_view = frame
            .texture
            .create_view(&wgpu::TextureViewDescriptor::default());

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

        self.queue.write_buffer(
            &self.globals_uniform_buffer,
            0,
            bytemuck::cast_slice(&[Globals {
                resolution: [
                    self.size.width as f32,
                    self.size.height as f32,
                ],
                zoom: scene.zoom,
                scroll_offset: scene.scroll.to_array(),
                _pad: 0.0,
            }]),
        );

        self.queue.write_buffer(
            &self.prims_uniform_buffer,
            0,
            bytemuck::cast_slice(&self.cpu_primitives),
        );

        {
            // A resolve target is only supported if the attachment actually uses anti-aliasing
            // So if sample_count == 1 then we must render directly to the surface's buffer
            let color_attachment = if let Some(msaa_target) = &self.multisampled_render_target {
                wgpu::RenderPassColorAttachment {
                    view: msaa_target,
                    ops: wgpu::Operations {
                        load: wgpu::LoadOp::Clear(wgpu::Color::WHITE),
                        store: true,
                    },
                    resolve_target: Some(&frame_view),
                }
            } else {
                wgpu::RenderPassColorAttachment {
                    view: &frame_view,
                    ops: wgpu::Operations {
                        load: wgpu::LoadOp::Clear(wgpu::Color::WHITE),
                        store: true,
                    },
                    resolve_target: None,
                }
            };

            let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                label: None,
                color_attachments: &[color_attachment],
                depth_stencil_attachment: Some(wgpu::RenderPassDepthStencilAttachment {
                    view: &self.depth_texture.view,
                    depth_ops: Some(wgpu::Operations {
                        load: wgpu::LoadOp::Clear(0.0),
                        store: true,
                    }),
                    stencil_ops: Some(wgpu::Operations {
                        load: wgpu::LoadOp::Clear(0),
                        store: true,
                    }),
                }),
            });

            pass.set_pipeline(&self.render_pipeline);
            pass.set_bind_group(0, &self.bind_group, &[]);
            pass.set_index_buffer(
                self.indices_uniform_buffer.slice(..),
                wgpu::IndexFormat::Uint16,
            );
            pass.set_vertex_buffer(0, self.vertex_uniform_buffer.slice(..));

            pass.draw_indexed(self.fill_range.clone(), 0, 0..(self.num_instances as u32));
            pass.draw_indexed(self.stroke_range.clone(), 0, 0..1);
        }

        self.queue.submit(Some(encoder.finish()));
        frame.present();

        Ok(())
    }

    pub fn update(&mut self) {
        let scene = &mut self.scene;
        let time_secs = self.fps_meter.time_secs;


        scene.zoom += (scene.target_zoom - scene.zoom) / 3.0;
        scene.scroll = scene.scroll + (scene.target_scroll - scene.scroll) / 3.0;
        scene.stroke_width =
            scene.stroke_width + (scene.target_stroke_width - scene.stroke_width) / 5.0;

        self.cpu_primitives[self.stroke_prim_id as usize].width = scene.stroke_width;
        self.cpu_primitives[self.stroke_prim_id as usize].color = [
            (time_secs * 0.8 - 1.6).sin() * 0.1 + 0.1,
            (time_secs * 0.5 - 1.6).sin() * 0.1 + 0.1,
            (time_secs - 1.6).sin() * 0.1 + 0.1,
            1.0,
        ];

        for idx in 2..(self.num_instances + 1) {
            self.cpu_primitives[idx as usize].translate = [
                (time_secs * 0.05 * idx as f32).sin() * (100.0 + idx as f32 * 10.0),
                (time_secs * 0.1 * idx as f32).sin() * (100.0 + idx as f32 * 10.0),
            ];
        }

        self.fps_meter.update_and_print()
    }
}