use bytemuck::{Pod, Zeroable};
use std::{borrow::Cow, time::Instant};
use wgpu::{util::DeviceExt, AstcBlock, AstcChannel};

const IMAGE_SIZE: u32 = 128;

#[derive(Clone, Copy, Pod, Zeroable)]
#[repr(C)]
struct Vertex {
    pos: [f32; 3],
    normal: [f32; 3],
}

struct Entity {
    vertex_count: u32,
    vertex_buf: wgpu::Buffer,
}

// Note: we use the Y=up coordinate space in this example.
struct Camera {
    time: Instant,
    pos: glam::Vec3,
    vel: glam::Vec3,
    gravity: glam::Vec3,
    friction: f32,
    screen_size: (u32, u32),
    offset: glam::Vec3,
    fov: f32,
    yaw: f32,
    pitch: f32,
    controls: u32,
    mv: f32,
    grounded: bool,
    walkspeed: f32,
}

const CONTROL_MOVEFORWARD:u32 = 0b00000001;
const CONTROL_MOVEBACK:u32 = 0b00000010;
const CONTROL_MOVERIGHT:u32 = 0b00000100;
const CONTROL_MOVELEFT:u32 = 0b00001000;
const CONTROL_MOVEUP:u32 = 0b00010000;
const CONTROL_MOVEDOWN:u32 = 0b00100000;
const CONTROL_JUMP:u32 = 0b01000000;
const CONTROL_ZOOM:u32 = 0b10000000;

const FORWARD_DIR:glam::Vec3 = glam::Vec3::new(0.0,0.0,-1.0);
const RIGHT_DIR:glam::Vec3 = glam::Vec3::new(1.0,0.0,0.0);
const UP_DIR:glam::Vec3 = glam::Vec3::new(0.0,1.0,0.0);

fn get_control_dir(controls: u32) -> glam::Vec3{
    //don't get fancy just do it
    let mut control_dir:glam::Vec3 = glam::Vec3::new(0.0,0.0,0.0);
    if controls & CONTROL_MOVEFORWARD == CONTROL_MOVEFORWARD {
        control_dir+=FORWARD_DIR;
    }
    if controls & CONTROL_MOVEBACK == CONTROL_MOVEBACK {
        control_dir+=-FORWARD_DIR;
    }
    if controls & CONTROL_MOVELEFT == CONTROL_MOVELEFT {
        control_dir+=-RIGHT_DIR;
    }
    if controls & CONTROL_MOVERIGHT == CONTROL_MOVERIGHT {
        control_dir+=RIGHT_DIR;
    }
    if controls & CONTROL_MOVEUP == CONTROL_MOVEUP {
        control_dir+=UP_DIR;
    }
    if controls & CONTROL_MOVEDOWN == CONTROL_MOVEDOWN {
        control_dir+=-UP_DIR;
    }
    return control_dir
}

    #[inline]
    fn perspective_rh(fov_y_slope: f32, aspect_ratio: f32, z_near: f32, z_far: f32) -> glam::Mat4 {
        //glam_assert!(z_near > 0.0 && z_far > 0.0);
        let r = z_far / (z_near - z_far);
        glam::Mat4::from_cols(
            glam::Vec4::new(1.0/(fov_y_slope * aspect_ratio), 0.0, 0.0, 0.0),
            glam::Vec4::new(0.0, 1.0/fov_y_slope, 0.0, 0.0),
            glam::Vec4::new(0.0, 0.0, r, -1.0),
            glam::Vec4::new(0.0, 0.0, r * z_near, 0.0),
        )
    }

impl Camera {
    fn to_uniform_data(&self) -> [f32; 16 * 3 + 4] {
        let aspect = self.screen_size.0 as f32 / self.screen_size.1 as f32;
        let fov = if self.controls&CONTROL_ZOOM==0 {
            self.fov
        }else{
            self.fov/5.0
        };
        let proj = perspective_rh(fov, aspect, 1.0, 200.0);
        let view = (glam::Mat4::from_translation(self.pos+self.offset) * glam::Mat4::from_euler(glam::EulerRot::YXZ, self.yaw, self.pitch, 0f32)).inverse();
        let proj_inv = proj.inverse();

        let mut raw = [0f32; 16 * 3 + 4];
        raw[..16].copy_from_slice(&AsRef::<[f32; 16]>::as_ref(&proj)[..]);
        raw[16..32].copy_from_slice(&AsRef::<[f32; 16]>::as_ref(&proj_inv)[..]);
        raw[32..48].copy_from_slice(&AsRef::<[f32; 16]>::as_ref(&view)[..]);
        raw[48..51].copy_from_slice(AsRef::<[f32; 3]>::as_ref(&self.pos));
        raw[51] = 1.0;
        raw
    }
}

pub struct Skybox {
    camera: Camera,
    sky_pipeline: wgpu::RenderPipeline,
    entity_pipeline: wgpu::RenderPipeline,
    ground_pipeline: wgpu::RenderPipeline,
    bind_group: wgpu::BindGroup,
    camera_buf: wgpu::Buffer,
    entities: Vec<Entity>,
    depth_view: wgpu::TextureView,
    staging_belt: wgpu::util::StagingBelt,
}

impl Skybox {
    const DEPTH_FORMAT: wgpu::TextureFormat = wgpu::TextureFormat::Depth24Plus;

    fn create_depth_texture(
        config: &wgpu::SurfaceConfiguration,
        device: &wgpu::Device,
    ) -> wgpu::TextureView {
        let depth_texture = device.create_texture(&wgpu::TextureDescriptor {
            size: wgpu::Extent3d {
                width: config.width,
                height: config.height,
                depth_or_array_layers: 1,
            },
            mip_level_count: 1,
            sample_count: 1,
            dimension: wgpu::TextureDimension::D2,
            format: Self::DEPTH_FORMAT,
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
            label: None,
            view_formats: &[],
        });

        depth_texture.create_view(&wgpu::TextureViewDescriptor::default())
    }
}

fn add_obj(device:&wgpu::Device,entities:& mut Vec<Entity>,source:&[u8]){
    let data = obj::ObjData::load_buf(&source[..]).unwrap();
    let mut vertices = Vec::new();
    for object in data.objects {
        for group in object.groups {
            vertices.clear();
            for poly in group.polys {
                for end_index in 2..poly.0.len() {
                    for &index in &[0, end_index - 1, end_index] {
                        let obj::IndexTuple(position_id, _texture_id, normal_id) =
                            poly.0[index];
                        vertices.push(Vertex {
                            pos: data.position[position_id],
                            normal: data.normal[normal_id.unwrap()],
                        })
                    }
                }
            }
            let vertex_buf = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
                label: Some("Vertex"),
                contents: bytemuck::cast_slice(&vertices),
                usage: wgpu::BufferUsages::VERTEX,
            });
            entities.push(Entity {
                vertex_count: vertices.len() as u32,
                vertex_buf,
            });
        }
    }
}

impl strafe_client::framework::Example for Skybox {
    fn optional_features() -> wgpu::Features {
        wgpu::Features::TEXTURE_COMPRESSION_ASTC
            | wgpu::Features::TEXTURE_COMPRESSION_ETC2
            | wgpu::Features::TEXTURE_COMPRESSION_BC
    }

    fn init(
        config: &wgpu::SurfaceConfiguration,
        _adapter: &wgpu::Adapter,
        device: &wgpu::Device,
        queue: &wgpu::Queue,
    ) -> Self {
        let mut entities = Vec::<Entity>::new();
        add_obj(device,& mut entities,include_bytes!("../models/teslacyberv3.0.obj"));
        add_obj(device,& mut entities,include_bytes!("../models/suzanne.obj"));

        let bind_group_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
            label: None,
            entries: &[
                wgpu::BindGroupLayoutEntry {
                    binding: 0,
                    visibility: wgpu::ShaderStages::VERTEX | wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Buffer {
                        ty: wgpu::BufferBindingType::Uniform,
                        has_dynamic_offset: false,
                        min_binding_size: None,
                    },
                    count: None,
                },
                wgpu::BindGroupLayoutEntry {
                    binding: 1,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Texture {
                        sample_type: wgpu::TextureSampleType::Float { filterable: true },
                        multisampled: false,
                        view_dimension: wgpu::TextureViewDimension::Cube,
                    },
                    count: None,
                },
                wgpu::BindGroupLayoutEntry {
                    binding: 2,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
                    count: None,
                },
            ],
        });

        // Create the render pipeline
        let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: None,
            source: wgpu::ShaderSource::Wgsl(Cow::Borrowed(include_str!("shader.wgsl"))),
        });

        let camera = Camera {
            time: Instant::now(),
            pos: glam::Vec3::new(5.0,0.0,5.0),
            vel: glam::Vec3::new(0.0,0.0,0.0),
            gravity: glam::Vec3::new(0.0,-100.0,0.0),
            friction: 90.0,
            screen_size: (config.width, config.height),
            offset: glam::Vec3::new(0.0,4.5,0.0),
            fov: 1.0, //fov_slope = tan(fov_y/2)
            pitch: 0.0,
            yaw: 0.0,
            mv: 2.7,
            controls:0,
            grounded: true,
            walkspeed: 18.0,
        };
        let camera_uniforms = camera.to_uniform_data();
        let camera_buf = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
            label: Some("Camera"),
            contents: bytemuck::cast_slice(&camera_uniforms),
            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
        });

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

        // Create the render pipelines
        let sky_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("Sky"),
            layout: Some(&pipeline_layout),
            vertex: wgpu::VertexState {
                module: &shader,
                entry_point: "vs_sky",
                buffers: &[],
            },
            fragment: Some(wgpu::FragmentState {
                module: &shader,
                entry_point: "fs_sky",
                targets: &[Some(config.view_formats[0].into())],
            }),
            primitive: wgpu::PrimitiveState {
                front_face: wgpu::FrontFace::Cw,
                ..Default::default()
            },
            depth_stencil: Some(wgpu::DepthStencilState {
                format: Self::DEPTH_FORMAT,
                depth_write_enabled: false,
                depth_compare: wgpu::CompareFunction::LessEqual,
                stencil: wgpu::StencilState::default(),
                bias: wgpu::DepthBiasState::default(),
            }),
            multisample: wgpu::MultisampleState::default(),
            multiview: None,
        });
        let entity_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("Entity"),
            layout: Some(&pipeline_layout),
            vertex: wgpu::VertexState {
                module: &shader,
                entry_point: "vs_entity",
                buffers: &[wgpu::VertexBufferLayout {
                    array_stride: std::mem::size_of::<Vertex>() as wgpu::BufferAddress,
                    step_mode: wgpu::VertexStepMode::Vertex,
                    attributes: &wgpu::vertex_attr_array![0 => Float32x3, 1 => Float32x3],
                }],
            },
            fragment: Some(wgpu::FragmentState {
                module: &shader,
                entry_point: "fs_entity",
                targets: &[Some(config.view_formats[0].into())],
            }),
            primitive: wgpu::PrimitiveState {
                front_face: wgpu::FrontFace::Cw,
                ..Default::default()
            },
            depth_stencil: Some(wgpu::DepthStencilState {
                format: Self::DEPTH_FORMAT,
                depth_write_enabled: true,
                depth_compare: wgpu::CompareFunction::LessEqual,
                stencil: wgpu::StencilState::default(),
                bias: wgpu::DepthBiasState::default(),
            }),
            multisample: wgpu::MultisampleState::default(),
            multiview: None,
        });
        let ground_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("Ground"),
            layout: Some(&pipeline_layout),
            vertex: wgpu::VertexState {
                module: &shader,
                entry_point: "vs_ground",
                buffers: &[],
            },
            fragment: Some(wgpu::FragmentState {
                module: &shader,
                entry_point: "fs_ground",
                targets: &[Some(config.view_formats[0].into())],
            }),
            primitive: wgpu::PrimitiveState {
                front_face: wgpu::FrontFace::Cw,
                ..Default::default()
            },
            depth_stencil: Some(wgpu::DepthStencilState {
                format: Self::DEPTH_FORMAT,
                depth_write_enabled: true,
                depth_compare: wgpu::CompareFunction::LessEqual,
                stencil: wgpu::StencilState::default(),
                bias: wgpu::DepthBiasState::default(),
            }),
            multisample: wgpu::MultisampleState::default(),
            multiview: None,
        });

        let sampler = device.create_sampler(&wgpu::SamplerDescriptor {
            label: None,
            address_mode_u: wgpu::AddressMode::ClampToEdge,
            address_mode_v: wgpu::AddressMode::ClampToEdge,
            address_mode_w: wgpu::AddressMode::ClampToEdge,
            mag_filter: wgpu::FilterMode::Linear,
            min_filter: wgpu::FilterMode::Linear,
            mipmap_filter: wgpu::FilterMode::Linear,
            ..Default::default()
        });

        let device_features = device.features();

        let skybox_format = if device_features.contains(wgpu::Features::TEXTURE_COMPRESSION_ASTC) {
            log::info!("Using ASTC");
            wgpu::TextureFormat::Astc {
                block: AstcBlock::B4x4,
                channel: AstcChannel::UnormSrgb,
            }
        } else if device_features.contains(wgpu::Features::TEXTURE_COMPRESSION_ETC2) {
            log::info!("Using ETC2");
            wgpu::TextureFormat::Etc2Rgb8UnormSrgb
        } else if device_features.contains(wgpu::Features::TEXTURE_COMPRESSION_BC) {
            log::info!("Using BC");
            wgpu::TextureFormat::Bc1RgbaUnormSrgb
        } else {
            log::info!("Using plain");
            wgpu::TextureFormat::Bgra8UnormSrgb
        };

        let size = wgpu::Extent3d {
            width: IMAGE_SIZE,
            height: IMAGE_SIZE,
            depth_or_array_layers: 6,
        };

        let layer_size = wgpu::Extent3d {
            depth_or_array_layers: 1,
            ..size
        };
        let max_mips = layer_size.max_mips(wgpu::TextureDimension::D2);

        log::debug!(
            "Copying {:?} skybox images of size {}, {}, 6 with {} mips to gpu",
            skybox_format,
            IMAGE_SIZE,
            IMAGE_SIZE,
            max_mips,
        );

        let bytes = match skybox_format {
            wgpu::TextureFormat::Astc {
                block: AstcBlock::B4x4,
                channel: AstcChannel::UnormSrgb,
            } => &include_bytes!("../images/astc.dds")[..],
            wgpu::TextureFormat::Etc2Rgb8UnormSrgb => &include_bytes!("../images/etc2.dds")[..],
            wgpu::TextureFormat::Bc1RgbaUnormSrgb => &include_bytes!("../images/bc1.dds")[..],
            wgpu::TextureFormat::Bgra8UnormSrgb => &include_bytes!("../images/bgra.dds")[..],
            _ => unreachable!(),
        };

        let image = ddsfile::Dds::read(&mut std::io::Cursor::new(&bytes)).unwrap();

        let texture = device.create_texture_with_data(
            queue,
            &wgpu::TextureDescriptor {
                size,
                mip_level_count: max_mips,
                sample_count: 1,
                dimension: wgpu::TextureDimension::D2,
                format: skybox_format,
                usage: wgpu::TextureUsages::TEXTURE_BINDING | wgpu::TextureUsages::COPY_DST,
                label: None,
                view_formats: &[],
            },
            &image.data,
        );

        let texture_view = texture.create_view(&wgpu::TextureViewDescriptor {
            label: None,
            dimension: Some(wgpu::TextureViewDimension::Cube),
            ..wgpu::TextureViewDescriptor::default()
        });
        let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: &bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: camera_buf.as_entire_binding(),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::TextureView(&texture_view),
                },
                wgpu::BindGroupEntry {
                    binding: 2,
                    resource: wgpu::BindingResource::Sampler(&sampler),
                },
            ],
            label: None,
        });

        let depth_view = Self::create_depth_texture(config, device);

        Skybox {
            camera,
            sky_pipeline,
            entity_pipeline,
            ground_pipeline,
            bind_group,
            camera_buf,
            entities,
            depth_view,
            staging_belt: wgpu::util::StagingBelt::new(0x100),
        }
    }

    #[allow(clippy::single_match)]
    fn update(&mut self, event: winit::event::WindowEvent) {
        match event {
            winit::event::WindowEvent::KeyboardInput {
                input:
                    winit::event::KeyboardInput {
                        state,
                        virtual_keycode: Some(keycode),
                        ..
                    },
                ..
            } => {
                match (state,keycode) {
                    (k,winit::event::VirtualKeyCode::W) => match k {
                        winit::event::ElementState::Pressed => self.camera.controls|=CONTROL_MOVEFORWARD,
                        winit::event::ElementState::Released => self.camera.controls&=!CONTROL_MOVEFORWARD,
                    }
                    (k,winit::event::VirtualKeyCode::A) => match k {
                        winit::event::ElementState::Pressed => self.camera.controls|=CONTROL_MOVELEFT,
                        winit::event::ElementState::Released => self.camera.controls&=!CONTROL_MOVELEFT,
                    }
                    (k,winit::event::VirtualKeyCode::S) => match k {
                        winit::event::ElementState::Pressed => self.camera.controls|=CONTROL_MOVEBACK,
                        winit::event::ElementState::Released => self.camera.controls&=!CONTROL_MOVEBACK,
                    }
                    (k,winit::event::VirtualKeyCode::D) => match k {
                        winit::event::ElementState::Pressed => self.camera.controls|=CONTROL_MOVERIGHT,
                        winit::event::ElementState::Released => self.camera.controls&=!CONTROL_MOVERIGHT,
                    }
                    (k,winit::event::VirtualKeyCode::E) => match k {
                        winit::event::ElementState::Pressed => self.camera.controls|=CONTROL_MOVEUP,
                        winit::event::ElementState::Released => self.camera.controls&=!CONTROL_MOVEUP,
                    }
                    (k,winit::event::VirtualKeyCode::Q) => match k {
                        winit::event::ElementState::Pressed => self.camera.controls|=CONTROL_MOVEDOWN,
                        winit::event::ElementState::Released => self.camera.controls&=!CONTROL_MOVEDOWN,
                    }
                    (k,winit::event::VirtualKeyCode::Space) => match k {
                        winit::event::ElementState::Pressed => self.camera.controls|=CONTROL_JUMP,
                        winit::event::ElementState::Released => self.camera.controls&=!CONTROL_JUMP,
                    }
                    (k,winit::event::VirtualKeyCode::Z) => match k {
                        winit::event::ElementState::Pressed => self.camera.controls|=CONTROL_ZOOM,
                        winit::event::ElementState::Released => self.camera.controls&=!CONTROL_ZOOM,
                    }
                    _ => (),
                }
            }
            _ => {}
        }
    }

    fn move_mouse(&mut self, delta: (f64,f64)) {
        self.camera.pitch=(self.camera.pitch as f64+delta.1/-512.) as f32;
        self.camera.yaw=(self.camera.yaw as f64+delta.0/-512.) as f32;
    }

    fn resize(
        &mut self,
        config: &wgpu::SurfaceConfiguration,
        device: &wgpu::Device,
        _queue: &wgpu::Queue,
    ) {
        self.depth_view = Self::create_depth_texture(config, device);
        self.camera.screen_size = (config.width, config.height);
    }

    fn render(
        &mut self,
        view: &wgpu::TextureView,
        device: &wgpu::Device,
        queue: &wgpu::Queue,
        _spawner: &strafe_client::framework::Spawner,
    ) {
        let time = Instant::now();

        //physique
        let dt=(time-self.camera.time).as_secs_f32();
        self.camera.time=time;
        let camera_mat=glam::Mat3::from_euler(glam::EulerRot::YXZ,self.camera.yaw,0f32,0f32);
        let control_dir=camera_mat*get_control_dir(self.camera.controls&(CONTROL_MOVELEFT|CONTROL_MOVERIGHT|CONTROL_MOVEFORWARD|CONTROL_MOVEBACK)).normalize_or_zero();
        let d=self.camera.vel.dot(control_dir);
        if d<self.camera.mv {
            self.camera.vel+=(self.camera.mv-d)*control_dir;
        }
        self.camera.vel+=self.camera.gravity*dt;
        self.camera.pos+=self.camera.vel*dt;
        if self.camera.pos.y<0.0{
            self.camera.pos.y=0.0;
            self.camera.vel.y=0.0;
            self.camera.grounded=true;
        }
        if self.camera.grounded&&(self.camera.controls&CONTROL_JUMP)!=0 {
            self.camera.grounded=false;
            self.camera.vel+=glam::Vec3::new(0.0,0.715588/2.0*100.0,0.0);
        }
        if self.camera.grounded {
            let applied_friction=self.camera.friction*dt;
            let targetv=control_dir*self.camera.walkspeed;
            let diffv=targetv-self.camera.vel;
            if applied_friction*applied_friction<diffv.length_squared() {
                self.camera.vel+=applied_friction*diffv.normalize();
            } else {
                self.camera.vel=targetv;
            }
        }

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

        // update rotation
        let camera_uniforms = self.camera.to_uniform_data();
        self.staging_belt
            .write_buffer(
                &mut encoder,
                &self.camera_buf,
                0,
                wgpu::BufferSize::new((camera_uniforms.len() * 4) as wgpu::BufferAddress).unwrap(),
                device,
            )
            .copy_from_slice(bytemuck::cast_slice(&camera_uniforms));

        self.staging_belt.finish();

        {
            let mut rpass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                label: None,
                color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                    view,
                    resolve_target: None,
                    ops: wgpu::Operations {
                        load: wgpu::LoadOp::Clear(wgpu::Color {
                            r: 0.1,
                            g: 0.2,
                            b: 0.3,
                            a: 1.0,
                        }),
                        store: true,
                    },
                })],
                depth_stencil_attachment: Some(wgpu::RenderPassDepthStencilAttachment {
                    view: &self.depth_view,
                    depth_ops: Some(wgpu::Operations {
                        load: wgpu::LoadOp::Clear(1.0),
                        store: false,
                    }),
                    stencil_ops: None,
                }),
            });

            rpass.set_bind_group(0, &self.bind_group, &[]);

            rpass.set_pipeline(&self.entity_pipeline);
            for entity in self.entities.iter() {
                rpass.set_vertex_buffer(0, entity.vertex_buf.slice(..));
                rpass.draw(0..entity.vertex_count, 0..1);
            }

            rpass.set_pipeline(&self.ground_pipeline);
            //rpass.set_index_buffer(&[0u16,1,2,1,2,3][..] as wgpu::BufferSlice, wgpu::IndexFormat::Uint16);
            //rpass.draw_indexed(0..4, 0, 0..1);
            rpass.draw(0..6, 0..1);

            rpass.set_pipeline(&self.sky_pipeline);
            rpass.draw(0..3, 0..1);
        }

        queue.submit(std::iter::once(encoder.finish()));

        self.staging_belt.recall();
    }
}

fn main() {
    strafe_client::framework::run::<Skybox>(
        format!("Strafe Client v{}",
            env!("CARGO_PKG_VERSION")
        ).as_str()
    );
}