use image::GenericImageView;
use std::path::Path;


pub struct Texture {
    pub texture: wgpu::Texture,
    pub view: wgpu::TextureView,
    pub sampler: wgpu::Sampler,
}

impl Texture {
    pub const DEPTH_FORMAT: wgpu::TextureFormat = wgpu::TextureFormat::Depth32Float;

    pub fn load<P: AsRef<Path>>(
        device: &wgpu::Device,
        path: P,
        is_normal_map: bool,
    ) -> Result<(Self, wgpu::CommandBuffer), failure::Error> {
        // Needed to appease the borrow checker
        let path_copy = path.as_ref().to_path_buf();
        let label = path_copy.to_str();
        
        let img = image::open(path)?;
        Self::from_image(device, &img, label, is_normal_map)
    }

    pub fn create_depth_texture(device: &wgpu::Device, sc_desc: &wgpu::SwapChainDescriptor, label: &str) -> Self {
        let size = wgpu::Extent3d {
            width: sc_desc.width,
            height: sc_desc.height,
            depth: 1,
        };
        let desc = wgpu::TextureDescriptor {
            label: Some(label),
            size,
            array_layer_count: 1,
            mip_level_count: 1,
            sample_count: 1,
            dimension: wgpu::TextureDimension::D2,
            format: Self::DEPTH_FORMAT,
            usage: wgpu::TextureUsage::OUTPUT_ATTACHMENT
                | wgpu::TextureUsage::SAMPLED 
                | wgpu::TextureUsage::COPY_SRC,
        };
        let texture = device.create_texture(&desc);

        let view = texture.create_default_view();
        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::Linear,
            min_filter: wgpu::FilterMode::Linear,
            mipmap_filter: wgpu::FilterMode::Nearest,
            lod_min_clamp: -100.0,
            lod_max_clamp: 100.0,
            compare: wgpu::CompareFunction::LessEqual,
        });

        Self { texture, view, sampler }
    }

    #[allow(dead_code)]
    pub fn from_bytes(
        device: &wgpu::Device, 
        bytes: &[u8], 
        label: &str, 
        is_normal_map: bool,
    ) -> Result<(Self, wgpu::CommandBuffer), failure::Error> {
        let img = image::load_from_memory(bytes)?;
        Self::from_image(device, &img, Some(label), is_normal_map)
    }

    pub fn from_image(
        device: &wgpu::Device,
        img: &image::DynamicImage,
        label: Option<&str>,
        is_normal_map: bool,
    ) -> Result<(Self, wgpu::CommandBuffer), failure::Error> {
        let rgba = img.to_rgba();
        let dimensions = img.dimensions();

        let size = wgpu::Extent3d {
            width: dimensions.0,
            height: dimensions.1,
            depth: 1,
        };
        let texture = device.create_texture(&wgpu::TextureDescriptor {
            label,
            size,
            array_layer_count: 1,
            mip_level_count: 1,
            sample_count: 1,
            dimension: wgpu::TextureDimension::D2,
            format: if is_normal_map {
                wgpu::TextureFormat::Rgba8Unorm
            } else {
                wgpu::TextureFormat::Rgba8UnormSrgb
            },
            usage: wgpu::TextureUsage::SAMPLED | wgpu::TextureUsage::COPY_DST,
        });

        let buffer = device.create_buffer_with_data(
            &rgba, 
            wgpu::BufferUsage::COPY_SRC,
        );

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

        encoder.copy_buffer_to_texture(
            wgpu::BufferCopyView {
                buffer: &buffer,
                offset: 0,
                bytes_per_row: 4 * dimensions.0,
                rows_per_image: dimensions.1,
            }, 
            wgpu::TextureCopyView {
                texture: &texture,
                mip_level: 0,
                array_layer: 0,
                origin: wgpu::Origin3d::ZERO,
            }, 
            size,
        );

        let cmd_buffer = encoder.finish();

        let view = texture.create_default_view();
        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::Linear,
            min_filter: wgpu::FilterMode::Nearest,
            mipmap_filter: wgpu::FilterMode::Nearest,
            lod_min_clamp: -100.0,
            lod_max_clamp: 100.0,
            compare: wgpu::CompareFunction::Always,
        });
        
        Ok((Self { texture, view, sampler }, cmd_buffer))
    }
}