#[path = "../framework.rs"]
mod framework;

#[derive(Clone, Copy)]
struct Vertex {
    _pos: [f32; 4],
    _tex_coord: [f32; 2],
}

fn vertex(pos: [i8; 3], tc: [i8; 2]) -> Vertex {
    Vertex {
        _pos: [pos[0] as f32, pos[1] as f32, pos[2] as f32, 1.0],
        _tex_coord: [tc[0] as f32, tc[1] as f32],
    }
}

fn create_vertices() -> (Vec<Vertex>, Vec<u16>) {
    let vertex_data = [
        // top (0, 0, 1)
        vertex([-1, -1, 1], [0, 0]),
        vertex([1, -1, 1], [1, 0]),
        vertex([1, 1, 1], [1, 1]),
        vertex([-1, 1, 1], [0, 1]),
        // bottom (0, 0, -1)
        vertex([-1, 1, -1], [1, 0]),
        vertex([1, 1, -1], [0, 0]),
        vertex([1, -1, -1], [0, 1]),
        vertex([-1, -1, -1], [1, 1]),
        // right (1, 0, 0)
        vertex([1, -1, -1], [0, 0]),
        vertex([1, 1, -1], [1, 0]),
        vertex([1, 1, 1], [1, 1]),
        vertex([1, -1, 1], [0, 1]),
        // left (-1, 0, 0)
        vertex([-1, -1, 1], [1, 0]),
        vertex([-1, 1, 1], [0, 0]),
        vertex([-1, 1, -1], [0, 1]),
        vertex([-1, -1, -1], [1, 1]),
        // front (0, 1, 0)
        vertex([1, 1, -1], [1, 0]),
        vertex([-1, 1, -1], [0, 0]),
        vertex([-1, 1, 1], [0, 1]),
        vertex([1, 1, 1], [1, 1]),
        // back (0, -1, 0)
        vertex([1, -1, 1], [0, 0]),
        vertex([-1, -1, 1], [1, 0]),
        vertex([-1, -1, -1], [1, 1]),
        vertex([1, -1, -1], [0, 1]),
    ];

    let index_data: &[u16] = &[
        0, 1, 2, 2, 3, 0, // top
        4, 5, 6, 6, 7, 4, // bottom
        8, 9, 10, 10, 11, 8, // right
        12, 13, 14, 14, 15, 12, // left
        16, 17, 18, 18, 19, 16, // front
        20, 21, 22, 22, 23, 20, // back
    ];

    (vertex_data.to_vec(), index_data.to_vec())
}

fn create_texels(size: usize) -> Vec<u8> {
    use std::iter;

    (0 .. size * size)
        .flat_map(|id| {
            // get high five for recognizing this ;)
            let cx = 3.0 * (id % size) as f32 / (size - 1) as f32 - 2.0;
            let cy = 2.0 * (id / size) as f32 / (size - 1) as f32 - 1.0;
            let (mut x, mut y, mut count) = (cx, cy, 0);
            while count < 0xFF && x * x + y * y < 4.0 {
                let old_x = x;
                x = x * x - y * y + cx;
                y = 2.0 * old_x * y + cy;
                count += 1;
            }
            iter::once(0xFF - (count * 5) as u8)
                .chain(iter::once(0xFF - (count * 15) as u8))
                .chain(iter::once(0xFF - (count * 50) as u8))
                .chain(iter::once(1))
        })
        .collect()
}

struct Example {
    vertex_buf: wgpu::Buffer,
    index_buf: wgpu::Buffer,
    index_count: usize,
    bind_group: wgpu::BindGroup,
    uniform_buf: wgpu::Buffer,
    pipeline: wgpu::RenderPipeline,
}

impl Example {
    fn generate_matrix(aspect_ratio: f32) -> cgmath::Matrix4<f32> {
        let mx_projection = cgmath::perspective(cgmath::Deg(45f32), aspect_ratio, 1.0, 10.0);
        let mx_view = cgmath::Matrix4::look_at(
            cgmath::Point3::new(1.5f32, -5.0, 3.0),
            cgmath::Point3::new(0f32, 0.0, 0.0),
            cgmath::Vector3::unit_z(),
        );
        let mx_correction = framework::OPENGL_TO_WGPU_MATRIX;
        mx_correction * mx_projection * mx_view
    }
}

impl framework::Example for Example {
    fn init(sc_desc: &wgpu::SwapChainDescriptor, device: &wgpu::Device) -> (Self, Option<wgpu::CommandBuffer>) {
        use std::mem;

        let mut init_encoder =
            device.create_command_encoder(&wgpu::CommandEncoderDescriptor { todo: 0 });

        // Create the vertex and index buffers
        let vertex_size = mem::size_of::<Vertex>();
        let (vertex_data, index_data) = create_vertices();
        let vertex_buf = device
            .create_buffer_mapped(vertex_data.len(), wgpu::BufferUsage::VERTEX)
            .fill_from_slice(&vertex_data);

        let index_buf = device
            .create_buffer_mapped(index_data.len(), wgpu::BufferUsage::INDEX)
            .fill_from_slice(&index_data);

        // Create pipeline layout
        let bind_group_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
            bindings: &[
                wgpu::BindGroupLayoutBinding {
                    binding: 0,
                    visibility: wgpu::ShaderStage::VERTEX,
                    ty: wgpu::BindingType::UniformBuffer {
                        dynamic: false,
                    },
                },
                wgpu::BindGroupLayoutBinding {
                    binding: 1,
                    visibility: wgpu::ShaderStage::FRAGMENT,
                    ty: wgpu::BindingType::SampledTexture {
                        multisampled: false,
                        dimension: wgpu::TextureViewDimension::D2,
                    },
                },
                wgpu::BindGroupLayoutBinding {
                    binding: 2,
                    visibility: wgpu::ShaderStage::FRAGMENT,
                    ty: wgpu::BindingType::Sampler,
                },
            ],
        });
        let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            bind_group_layouts: &[&bind_group_layout],
        });

        // Create the texture
        let size = 256u32;
        let texels = create_texels(size as usize);
        let texture_extent = wgpu::Extent3d {
            width: size,
            height: size,
            depth: 1,
        };
        let texture = device.create_texture(&wgpu::TextureDescriptor {
            size: texture_extent,
            array_layer_count: 1,
            mip_level_count: 1,
            sample_count: 1,
            dimension: wgpu::TextureDimension::D2,
            format: wgpu::TextureFormat::Rgba8UnormSrgb,
            usage: wgpu::TextureUsage::SAMPLED | wgpu::TextureUsage::COPY_DST,
        });
        let texture_view = texture.create_default_view();
        let temp_buf = device
            .create_buffer_mapped(texels.len(), wgpu::BufferUsage::COPY_SRC)
            .fill_from_slice(&texels);
        init_encoder.copy_buffer_to_texture(
            wgpu::BufferCopyView {
                buffer: &temp_buf,
                offset: 0,
                row_pitch: 4 * size,
                image_height: size,
            },
            wgpu::TextureCopyView {
                texture: &texture,
                mip_level: 0,
                array_layer: 0,
                origin: wgpu::Origin3d {
                    x: 0.0,
                    y: 0.0,
                    z: 0.0,
                },
            },
            texture_extent,
        );

        // Create other resources
        let sampler = device.create_sampler(&wgpu::SamplerDescriptor {
            address_mode_u: wgpu::AddressMode::ClampToEdge,
            address_mode_v: wgpu::AddressMode::ClampToEdge,
            address_mode_w: wgpu::AddressMode::ClampToEdge,
            mag_filter: wgpu::FilterMode::Nearest,
            min_filter: wgpu::FilterMode::Linear,
            mipmap_filter: wgpu::FilterMode::Nearest,
            lod_min_clamp: -100.0,
            lod_max_clamp: 100.0,
            compare_function: wgpu::CompareFunction::Always,
        });
        let mx_total = Self::generate_matrix(sc_desc.width as f32 / sc_desc.height as f32);
        let mx_ref: &[f32; 16] = mx_total.as_ref();
        let uniform_buf = device
            .create_buffer_mapped(
                16,
                wgpu::BufferUsage::UNIFORM | wgpu::BufferUsage::COPY_DST,
            )
            .fill_from_slice(mx_ref);

        // Create bind group
        let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: &bind_group_layout,
            bindings: &[
                wgpu::Binding {
                    binding: 0,
                    resource: wgpu::BindingResource::Buffer {
                        buffer: &uniform_buf,
                        range: 0 .. 64,
                    },
                },
                wgpu::Binding {
                    binding: 1,
                    resource: wgpu::BindingResource::TextureView(&texture_view),
                },
                wgpu::Binding {
                    binding: 2,
                    resource: wgpu::BindingResource::Sampler(&sampler),
                },
            ],
        });

        // Create the render pipeline
        let vs_bytes =
            framework::load_glsl(include_str!("shader.vert"), framework::ShaderStage::Vertex);
        let fs_bytes = framework::load_glsl(
            include_str!("shader.frag"),
            framework::ShaderStage::Fragment,
        );
        let vs_module = device.create_shader_module(&vs_bytes);
        let fs_module = device.create_shader_module(&fs_bytes);

        let pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            layout: &pipeline_layout,
            vertex_stage: wgpu::ProgrammableStageDescriptor {
                module: &vs_module,
                entry_point: "main",
            },
            fragment_stage: Some(wgpu::ProgrammableStageDescriptor {
                module: &fs_module,
                entry_point: "main",
            }),
            rasterization_state: Some(wgpu::RasterizationStateDescriptor {
                front_face: wgpu::FrontFace::Ccw,
                cull_mode: wgpu::CullMode::Back,
                depth_bias: 0,
                depth_bias_slope_scale: 0.0,
                depth_bias_clamp: 0.0,
            }),
            primitive_topology: wgpu::PrimitiveTopology::TriangleList,
            color_states: &[wgpu::ColorStateDescriptor {
                format: sc_desc.format,
                color_blend: wgpu::BlendDescriptor::REPLACE,
                alpha_blend: wgpu::BlendDescriptor::REPLACE,
                write_mask: wgpu::ColorWrite::ALL,
            }],
            depth_stencil_state: None,
            index_format: wgpu::IndexFormat::Uint16,
            vertex_buffers: &[wgpu::VertexBufferDescriptor {
                stride: vertex_size as wgpu::BufferAddress,
                step_mode: wgpu::InputStepMode::Vertex,
                attributes: &[
                    wgpu::VertexAttributeDescriptor {
                        format: wgpu::VertexFormat::Float4,
                        offset: 0,
                        shader_location: 0,
                    },
                    wgpu::VertexAttributeDescriptor {
                        format: wgpu::VertexFormat::Float2,
                        offset: 4 * 4,
                        shader_location: 1,
                    },
                ],
            }],
            sample_count: 1,
            sample_mask: !0,
            alpha_to_coverage_enabled: false,
        });

        // Done
        let this = Example {
            vertex_buf,
            index_buf,
            index_count: index_data.len(),
            bind_group,
            uniform_buf,
            pipeline,
        };
        (this, Some(init_encoder.finish()))
    }

    fn update(&mut self, _event: winit::event::WindowEvent) {
        //empty
    }

    fn resize(&mut self, sc_desc: &wgpu::SwapChainDescriptor, device: &wgpu::Device) -> Option<wgpu::CommandBuffer> {
        let mx_total = Self::generate_matrix(sc_desc.width as f32 / sc_desc.height as f32);
        let mx_ref: &[f32; 16] = mx_total.as_ref();

        let temp_buf = device
            .create_buffer_mapped(16, wgpu::BufferUsage::COPY_SRC)
            .fill_from_slice(mx_ref);

        let mut encoder =
            device.create_command_encoder(&wgpu::CommandEncoderDescriptor { todo: 0 });
        encoder.copy_buffer_to_buffer(&temp_buf, 0, &self.uniform_buf, 0, 64);
        Some(encoder.finish())
    }

    fn render(&mut self, frame: &wgpu::SwapChainOutput, device: &wgpu::Device) -> wgpu::CommandBuffer {
        let mut encoder =
            device.create_command_encoder(&wgpu::CommandEncoderDescriptor { todo: 0 });
        {
            let mut rpass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                color_attachments: &[wgpu::RenderPassColorAttachmentDescriptor {
                    attachment: &frame.view,
                    resolve_target: None,
                    load_op: wgpu::LoadOp::Clear,
                    store_op: wgpu::StoreOp::Store,
                    clear_color: wgpu::Color {
                        r: 0.1,
                        g: 0.2,
                        b: 0.3,
                        a: 1.0,
                    },
                }],
                depth_stencil_attachment: None,
            });
            rpass.set_pipeline(&self.pipeline);
            rpass.set_bind_group(0, &self.bind_group, &[]);
            rpass.set_index_buffer(&self.index_buf, 0);
            rpass.set_vertex_buffers(0, &[(&self.vertex_buf, 0)]);
            rpass.draw_indexed(0 .. self.index_count as u32, 0, 0 .. 1);
        }

        encoder.finish()
    }
}

fn main() {
    framework::run::<Example>("cube");
}