//
// Copyright 2021-Present (c) Raja Lehtihet & Wael El Oraiby
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors
// may be used to endorse or promote products derived from this software without
// specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
use rs_ctypes::*;
use rs_math3d::*;

use core::sync::atomic::*;
use core::ops::{Deref, DerefMut};

pub trait IntrusiveCounter {
    fn increment(&mut self);
    fn decrement(&mut self) -> isize;
}

#[repr(C)]
pub struct IntrusivePtr<T : IntrusiveCounter + ?Sized> {
    object  : *mut T,
}

impl<T: IntrusiveCounter> IntrusivePtr<T> {
    pub fn new(mut t: T) -> Self {
        t.increment();
        let b = Box::new(t);
        let r = Box::into_raw(b);
        let s = Self { object: r };
        s
    }
}

impl<T: IntrusiveCounter + ?Sized> IntrusivePtr<T> {
    pub fn as_ref(&self) -> *const T { self.object }
    pub(crate) unsafe fn into_raw_mut(self) -> *mut T { let obj = self.object; std::mem::forget(self); obj }
    pub(crate) unsafe fn from_raw_no_increment(raw: *mut T) -> Self { Self { object: raw } }
    pub(crate) unsafe fn from_raw_increment(raw: *mut T) -> Self { (*raw).increment(); Self { object: raw } }
}

impl<T: IntrusiveCounter + ?Sized> Drop for IntrusivePtr<T> {
    fn drop(&mut self) {
        unsafe {
            let rc = (*self.object).decrement();
            if rc == 1 {
                Box::from_raw(self.object);
            }
        }
    }
}

impl<T: IntrusiveCounter + ?Sized> Clone for IntrusivePtr<T> {
    fn clone(&self) -> Self {
        unsafe { (*self.object).increment() };
        Self { object : self.object }
    }
}

impl<T: IntrusiveCounter + ?Sized> Deref for IntrusivePtr<T> {
    type Target = T;

    fn deref(&self) -> &Self::Target {
        unsafe { &(*self.object) }
    }
}

impl<T: IntrusiveCounter + ?Sized> DerefMut for IntrusivePtr<T> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        unsafe { &mut (*self.object) }
    }
}

impl<T: IntrusiveCounter + ?Sized> core::borrow::Borrow<T> for IntrusivePtr<T> {
    fn borrow(&self) -> &T {
        &**self
    }
}

pub enum ResourceType {
    DeviceBuffer,
    Texture,
    RenderTarget,
    Shader,
    Pipeline,
    FrameBuffer,
}

#[repr(C)]
pub struct Resource<Desc> {
    res_type: ResourceType,
    res_id  : usize,
    desc    : Desc,
    depends_on  : Option<IntrusivePtr<dyn Driver>>,   /// resources depend on drivers or other resources
    rc      : AtomicIsize,
}

impl<Desc> Resource<Desc> {
    pub(crate)  fn new(res_type: ResourceType, res_id: usize, desc: Desc, depends_on : Option<IntrusivePtr<dyn Driver>>) -> Self {
        Self { res_type: res_type, res_id : res_id, desc: desc, depends_on: depends_on, rc: AtomicIsize::new(0) }
    }
    pub(crate)  fn res_id(&self) -> usize { self.res_id }
    pub         fn desc(&self) -> &Desc { &self.desc }
}

impl<Desc> IntrusiveCounter for Resource<Desc> {
    fn increment(&mut self) { self.rc.fetch_add(1, Ordering::SeqCst); }
    fn decrement(&mut self) -> isize {
        self.rc.fetch_sub(1, Ordering::SeqCst)
    }
}

impl<Desc> Drop for Resource<Desc> {
    fn drop(&mut self) {
        match &mut self.depends_on {
            Some(driver)    => driver.delete_resource(&self.res_type, self.res_id),
            _ => panic!("No driver!")
        }
    }
}

////////////////////////////////////////////////////////////////////////////////
/// Attributes
////////////////////////////////////////////////////////////////////////////////

pub trait AttributeDataTypeGetter {
    fn get_attribute_type() -> VertexFormat;
}

// i8 type
impl AttributeDataTypeGetter for i8 {
    fn get_attribute_type() -> VertexFormat { VertexFormat::SByte }
}

impl AttributeDataTypeGetter for Vector2<i8> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::SByte2 }
}

impl AttributeDataTypeGetter for Vector3<i8> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::SByte3 }
}

impl AttributeDataTypeGetter for Vector4<i8> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::SByte4 }
}

// u8 type
impl AttributeDataTypeGetter for u8 {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Byte }
}

impl AttributeDataTypeGetter for Vector2<u8> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Byte2 }
}

impl AttributeDataTypeGetter for Vector3<u8> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Byte3 }
}

impl AttributeDataTypeGetter for Vector4<u8> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Byte4 }
}

// s16 type
impl AttributeDataTypeGetter for i16 {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Short }
}

impl AttributeDataTypeGetter for Vector2<i16> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Short2 }
}

impl AttributeDataTypeGetter for Vector3<i16> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Short3 }
}

impl AttributeDataTypeGetter for Vector4<i16> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Short4 }
}

// f32 type
impl AttributeDataTypeGetter for f32 {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Float }
}

impl AttributeDataTypeGetter for Vector2<f32> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Float2 }
}

impl AttributeDataTypeGetter for Vector3<f32> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Float3 }
}

impl AttributeDataTypeGetter for Vector4<f32> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Float4 }
}

// i32 type
impl AttributeDataTypeGetter for i32 {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Int }
}

impl AttributeDataTypeGetter for Vector2<i32> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Int2 }
}

impl AttributeDataTypeGetter for Vector3<i32> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Int3 }
}

impl AttributeDataTypeGetter for Vector4<i32> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Int4 }
}

// u32 type
impl AttributeDataTypeGetter for u32 {
    fn get_attribute_type() -> VertexFormat { VertexFormat::UInt }
}

impl AttributeDataTypeGetter for Vector2<u32> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::UInt2 }
}

impl AttributeDataTypeGetter for Vector3<u32> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::UInt3 }
}

impl AttributeDataTypeGetter for Vector4<u32> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::UInt4 }
}


// matrix type
impl AttributeDataTypeGetter for Matrix2<f32> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Float2x2 }
}

impl AttributeDataTypeGetter for Matrix3<f32> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Float3x3 }
}

impl AttributeDataTypeGetter for Matrix4<f32> {
    fn get_attribute_type() -> VertexFormat { VertexFormat::Float4x4 }
}

////////////////////////////////////////////////////////////////////////////////
/// Uniforms
////////////////////////////////////////////////////////////////////////////////

pub trait UniformDataTypeGetter {
    fn get_uniform_type() -> UniformDataType;
}

impl UniformDataTypeGetter for u32 {
    fn get_uniform_type() -> UniformDataType { UniformDataType::UInt }
}

impl UniformDataTypeGetter for Vector2<u32> {
    fn get_uniform_type() -> UniformDataType { UniformDataType::UInt2 }
}

impl UniformDataTypeGetter for Vector3<u32> {
    fn get_uniform_type() -> UniformDataType { UniformDataType::UInt3 }
}

impl UniformDataTypeGetter for Vector4<u32> {
    fn get_uniform_type() -> UniformDataType { UniformDataType::UInt4 }
}

impl UniformDataTypeGetter for i32 {
    fn get_uniform_type() -> UniformDataType { UniformDataType::Int }
}

impl UniformDataTypeGetter for Vector2<i32> {
    fn get_uniform_type() -> UniformDataType { UniformDataType::Int2 }
}

impl UniformDataTypeGetter for Vector3<i32> {
    fn get_uniform_type() -> UniformDataType { UniformDataType::Int3 }
}

impl UniformDataTypeGetter for Vector4<i32> {
    fn get_uniform_type() -> UniformDataType { UniformDataType::Int4 }
}

impl UniformDataTypeGetter for f32 {
    fn get_uniform_type() -> UniformDataType { UniformDataType::Float }
}

impl UniformDataTypeGetter for Vector2<f32> {
    fn get_uniform_type() -> UniformDataType { UniformDataType::Float2 }
}

impl UniformDataTypeGetter for Vector3<f32> {
    fn get_uniform_type() -> UniformDataType { UniformDataType::Float3 }
}

impl UniformDataTypeGetter for Vector4<f32> {
    fn get_uniform_type() -> UniformDataType { UniformDataType::Float4 }
}

impl UniformDataTypeGetter for Matrix2<f32> {
    fn get_uniform_type() -> UniformDataType { UniformDataType::Float2x2 }
}

impl UniformDataTypeGetter for Matrix3<f32> {
    fn get_uniform_type() -> UniformDataType { UniformDataType::Float3x3 }
}

impl UniformDataTypeGetter for Matrix4<f32> {
    fn get_uniform_type() -> UniformDataType { UniformDataType::Float4x4 }
}

////////////////////////////////////////////////////////////////////////////////
/// Macros
////////////////////////////////////////////////////////////////////////////////
#[macro_export]
macro_rules! offset_of {
    ($Struct:path, $field:ident) => ({
        // Using a separate function to minimize unhygienic hazards
        // (e.g. unsafety of #[repr(packed)] field borrows).
        // Uncomment `const` when `const fn`s can juggle pointers.
        /*const*/ fn offset() -> usize {
            let u = std::mem::MaybeUninit::<$Struct>::uninit();
            // Use pattern-matching to avoid accidentally going through Deref.
            let &$Struct { $field: ref f, .. } = unsafe { &*u.as_ptr() };
            let o = (f as *const _ as usize).wrapping_sub(&u as *const _ as usize);
            // Triple check that we are within `u` still.
            assert!((0..=std::mem::size_of_val(&u)).contains(&o));
            o
        }
        offset()
    })
}

#[macro_export]
macro_rules! render_data {
    () => {};
    (vertex $name:ident { $($field_name:ident: $field_type:ty,)* }) => {
        #[repr(C)]
        #[derive(Debug, Copy, Clone)]
        struct $name {
            $($field_name: $field_type,)*
        }

        impl $crate::VertexTrait for $name {
            // This is purely an example—not a good one.
            fn get_attribute_descriptors() -> Vec<$crate::VertexAttributeDesc> {
                vec![$($crate::VertexAttributeDesc::new(stringify!($field_name).to_string(), <$field_type>::get_attribute_type(), $crate::offset_of!($name, $field_name))),*]
            }

            fn get_attribute_names() -> Vec<String> {
                vec![$(stringify!($field_name).to_string()),*]
            }

            fn stride() -> usize {
                core::mem::size_of::<Self>()
            }
        }
    };

    (vertex $name:ident { $($field_name:ident: $field_type:ty,)* } $($e:tt)*) => {
        $crate::render_data! { vertex $name {
            $($field_name: $field_type,)*
        } }
        $crate::render_data! { $($e)* }
    };

    (pub vertex $name:ident { $($field_name:ident: $field_type:ty,)* }) => {
        #[repr(C)]
        #[derive(Debug, Copy, Clone)]
        pub struct $name {
            $($field_name: $field_type,)*
        }

        impl $crate::renderer::VertexTrait for $name {
            // This is purely an example—not a good one.
            fn get_attribute_descriptors() -> Vec<$crate::VertexAttributeDesc> {
                vec![$($crate::VertexAttributeDesc::new(stringify!($field_name).to_string(), <$field_type>::get_attribute_type(), $crate::offset_of!($name, $field_name))),*]
            }

            fn get_attribute_names() -> Vec<String> {
                vec![$(stringify!($field_name).to_string()),*]
            }

            fn stride() -> usize {
                core::mem::size_of::<Self>()
            }
        }
    };

    (pub vertex $name:ident { $($field_name:ident: $field_type:ty,)* } $($e:tt)*) => {
        $crate::render_data! { pub vertex $name {
            $($field_name: $field_type,)*
        } }
        $crate::render_data! { $($e)* }
    };

    (uniforms $name:ident {
        $($field_name:ident: $field_type:ty,)*
    }) => {
        #[repr(C)]
        #[derive(Debug, Copy, Clone)]
        struct $name {
            $($field_name: $field_type,)*
        }

        impl $crate::UniformBlockTrait for $name {
            // This is purely an example—not a good one.
            fn get_uniform_descriptors() -> Vec<UniformDataDesc> {
                vec![$(UniformDataDesc::new(stringify!($field_name).to_string(), <$field_type>::get_uniform_type(), 1, $crate::offset_of!($name, $field_name))),*]
            }

            fn get_uniform_names() -> Vec<String> {
                vec![$(stringify!($field_name).to_string()),*]
            }
        }
    };

    (uniforms $name:ident {
        $($field_name:ident: $field_type:ty,)*
    } $($e:tt)*) => {
        $crate::render_data! { uniforms $name {
            $($field_name: $field_type,)*
        } }
        $crate::render_data! { $($e)* }
    };
}

////////////////////////////////////////////////////////////////////////////////
/// VertexAttributeDesc
////////////////////////////////////////////////////////////////////////////////

#[derive(Clone)]
pub enum VertexFormat {
    Byte,
    Byte2,
    Byte3,
    Byte4,

    SByte,
    SByte2,
    SByte3,
    SByte4,

    Short,
    Short2,
    Short3,
    Short4,

    Int,
    Int2,
    Int3,
    Int4,

    UInt,
    UInt2,
    UInt3,
    UInt4,

    Float,
    Float2,
    Float3,
    Float4,

    Float2x2,
    Float3x3,
    Float4x4,
}


#[derive(Clone)]
pub struct VertexAttributeDesc {
    name        : String,
    format      : VertexFormat,
    offset      : usize,
}

impl VertexAttributeDesc {
    pub fn new(name: String, format: VertexFormat, offset: usize) -> Self {
        Self {
            name        : name,
            format      : format,
            offset      : offset,
        }
    }

    pub fn name(&self)      -> &String  { &self.name        }
    pub fn format(&self)    -> VertexFormat   { self.format.clone() }
    pub fn offset(&self)    -> usize    { self.offset       }
}

pub trait VertexTrait {
    fn get_attribute_descriptors() -> Vec<VertexAttributeDesc>;
    fn get_attribute_names() -> Vec<String>;
    fn stride() -> usize;
}



////////////////////////////////////////////////////////////////////////////////
/// UniformBlock
////////////////////////////////////////////////////////////////////////////////

#[derive(Clone)]
pub enum UniformDataType {
    UInt,
    UInt2,
    UInt3,
    UInt4,
    Int,
    Int2,
    Int3,
    Int4,
    Float,
    Float2,
    Float3,
    Float4,
    Float2x2,
    Float3x3,
    Float4x4,
}

#[derive(Clone)]
pub struct UniformDesc {
    name        : String,
    format      : UniformDataType,
    count       : usize,
}

impl UniformDesc {
    pub fn new(name: String, format: UniformDataType, count: usize) -> Self { Self { name: name, format: format, count: count } }
    pub fn name(&self)      -> &str     { self.name.as_str() }
    pub fn format(&self)    -> UniformDataType { self.format.clone() }
    pub fn count(&self)     -> usize    { self.count }
}

#[derive(Clone)]
pub struct UniformDataDesc {
    pub desc        : UniformDesc,
    pub offset      : usize,
}

impl UniformDataDesc {
    pub fn new(name: String, format: UniformDataType, count: usize, offset: usize) -> Self { Self { desc: UniformDesc::new(name, format, count), offset: offset } }
    pub fn offset(&self)    -> usize    { self.offset }
    pub fn desc(&self)      -> &UniformDesc   { &self.desc }
}

pub trait UniformBlockTrait {
    fn get_uniform_descriptors() -> Vec<UniformDataDesc>;
    fn get_uniform_names() -> Vec<String>;
}

////////////////////////////////////////////////////////////////////////////////
/// Buffers
////////////////////////////////////////////////////////////////////////////////

pub trait Payload {
    fn ptr(&self) -> *const u8;
    fn size(&self) -> usize;
}

impl<T> Payload for Vec<T> {
    fn ptr(&self) -> *const u8 { self.as_ptr() as *const u8 }
    fn size(&self) -> usize { ::core::mem::size_of::<T>() * self.len() }
}

impl<T> Payload for &[T] {
    fn ptr(&self) -> *const u8 { self.as_ptr() as *const u8 }
    fn size(&self) -> usize { ::core::mem::size_of::<T>() * self.len() }
}

pub enum Usage {
    Static(Box<dyn Payload>),
    Dynamic(usize),
    Streamed(usize),
}

impl Usage {
    // pub fn new_static<T>(data: &Vec<T>) -> Usage {
    //     let p = data.as_ptr();
    //     let nd = p as *const u8;
    //     Self::Static(nd, data.len() * std::mem::size_of::<T>())
    // }

    pub fn new_dynamic<T>(len: usize) -> Usage {
        Self::Dynamic(len * std::mem::size_of::<T>())
    }

    pub fn new_streamed<T>(len: usize) -> Usage {
        Self::Dynamic(len * std::mem::size_of::<T>())
    }

    pub fn size(&self) -> usize {
        match self {
            Usage::Static(b)        => b.size(),
            Usage::Dynamic(s)       => *s,
            Usage::Streamed(s)      => *s,
        }
    }
}


pub struct DeviceBufferMapping {
    pub ptr     : *mut u8,
    pub offset  : usize,
    pub size    : usize,
    pub buff    : DeviceBufferPtr,
}



pub enum DeviceBufferDesc {
    Vertex(Usage),
    Index(Usage),
    Pixel(Usage),
}

impl DeviceBufferDesc {
    pub fn size(&self) -> usize {
        match self {
            Self::Vertex(u) |
            Self::Index(u)  |
            Self::Pixel(u)  => u.size(),
        }
    }
}

pub type DeviceBuffer       = Resource<DeviceBufferDesc>;
pub type DeviceBufferPtr    = IntrusivePtr<DeviceBuffer>;

////////////////////////////////////////////////////////////////////////////////
/// ImageDesc
////////////////////////////////////////////////////////////////////////////////

#[derive(Clone, Copy)]
pub enum WrapMode {
    Repeat,
    ClampToEdge,
    ClampToBorder,
    MirroredRepeat,
}

#[derive(Clone)]
pub struct PixelChannel {
    pub size    : usize,
    pub wrap    : WrapMode,
}

impl PixelChannel {
    pub fn default(size: usize) -> Self {
        Self {
            size    : size,
            wrap    : WrapMode::Repeat,
        }
    }

    pub fn resize(mut self, size: usize) -> Self {
        self.size   = size;
        self
    }

    pub fn with_wrap(mut self, wrap: WrapMode) -> Self {
        self.wrap   = wrap;
        self
    }
}

#[derive(Clone)]
pub enum SamplerType {
    Sampler2D    (PixelChannel, PixelChannel),
}

#[derive(Clone, Debug)]
pub enum Filter {
    Nearest,
    Linear,
    NearestMipmapNearest,
    NearestMipmapLinear,
    LinearMipmapNearest,
    LinearMipmapLinear,
}

#[derive(Clone, Debug)]
pub enum PixelFormat {
    RGB8U,
    RGBA8U,
    R8U,
    RGB32U,
    RGBA32U,
    R32U,

    RGB32F,
    RGBA32F,
    R32F,

    D16,
    D32,
    D24S8,
    D32S8,

    RGB8(MinMagFilter),
    RGBA8(MinMagFilter),
    R8(MinMagFilter),
}

#[derive(Clone, Debug)]
pub struct MinMagFilter {
    pub min_filter  : Filter,
    pub mag_filter  : Filter,
}

impl MinMagFilter {
    pub fn default() -> Self {
        Self {
            min_filter  : Filter::Nearest,
            mag_filter  : Filter::Nearest,
        }
    }

    pub fn with_min_filter(mut self, filter: Filter) -> Self {
        self.min_filter = filter;
        self
    }

    pub fn with_mag_filter(mut self, filter: Filter) -> Self {
        self.mag_filter = filter;
        self
    }
}

#[derive(Debug)]
pub enum OrigSurfaceType {
    UInt,
    Float,
}

pub enum OrigSurfaceClass {
    Color,
    Depth,
}

impl PixelFormat {
    pub fn to_orig_surface_type(&self) -> OrigSurfaceType {
        match self {
            PixelFormat::RGB8U => OrigSurfaceType::UInt,
            PixelFormat::RGBA8U => OrigSurfaceType::UInt,
            PixelFormat::R8U => OrigSurfaceType::UInt,
            PixelFormat::RGB32U => OrigSurfaceType::UInt,
            PixelFormat::RGBA32U => OrigSurfaceType::UInt,
            PixelFormat::R32U => OrigSurfaceType::UInt,

            PixelFormat::RGB32F => OrigSurfaceType::Float,
            PixelFormat::RGBA32F => OrigSurfaceType::Float,
            PixelFormat::R32F => OrigSurfaceType::Float,
            PixelFormat::D16 => OrigSurfaceType::Float,
            PixelFormat::D32 => OrigSurfaceType::Float,
            PixelFormat::D24S8 => OrigSurfaceType::Float,
            PixelFormat::D32S8 => OrigSurfaceType::Float,
            PixelFormat::RGB8(_) => OrigSurfaceType::Float,
            PixelFormat::RGBA8(_) => OrigSurfaceType::Float,
            PixelFormat::R8(_) => OrigSurfaceType::Float,
        }
    }
}

#[derive(Clone)]
pub struct SamplerDesc {
    pub image_type  : SamplerType,
    pub mip_maps    : usize,
    pub pixel_format: PixelFormat,
}

impl SamplerDesc {
    pub fn default(width: usize, height: usize) -> Self {
        Self {
            image_type  : SamplerType::Sampler2D(PixelChannel::default(width), PixelChannel::default(height)),
            mip_maps    : 0,
            pixel_format: PixelFormat::RGBA8U,
        }
    }

    pub fn with_wrap_mode(mut self, wrap: WrapMode) -> Self {
        let image_type =
            match self.image_type {
                SamplerType::Sampler2D(mut w, mut h) => {
                    w.wrap  = wrap;
                    h.wrap  = wrap;
                    SamplerType::Sampler2D(w, h)
                }
            };
        self.image_type = image_type;
        self
    }

    pub fn with_pixel_format(mut self, pf: PixelFormat) -> Self {
        self.pixel_format   = pf;
        self
    }

    pub fn with_mip_maps(mut self, levels: usize) -> Self {
        self.mip_maps   = levels;
        self
    }

    pub fn width(&self) -> usize {
        match self.image_type {
            SamplerType::Sampler2D(PixelChannel { size, wrap: _ }, _) => size,
            _ => panic!("no width!")
        }
    }

    pub fn height(&self) -> usize {
        match self.image_type {
            SamplerType::Sampler2D(_, PixelChannel { size, wrap: _ }) => size,
            _ => panic!("no height!")
        }
    }

}
pub struct TextureDesc {
    pub sampler_desc    : SamplerDesc,
    pub payload         : Option<Box<dyn Payload>>
}

pub struct RenderTargetDesc {
    pub sampler_desc    : SamplerDesc,
    pub sample_count    : usize
}

pub type Texture    = Resource<TextureDesc>;
pub type TexturePtr = IntrusivePtr<Texture>;

pub type RenderTarget       = Resource<RenderTargetDesc>;
pub type RenderTargetPtr    = IntrusivePtr<RenderTarget>;

////////////////////////////////////////////////////////////////////////////////
/// ShaderDesc
////////////////////////////////////////////////////////////////////////////////
#[derive(Clone)]
pub struct ShaderDesc {
    pub vertex_shader       : String,
    pub pixel_shader        : String,

    pub vertex_attributes   : Vec<Vec<String>>,
    pub vertex_uniforms     : Vec<String>,
    pub vertex_surfaces     : Vec<String>,

    pub pixel_uniforms      : Vec<String>,
    pub pixel_surfaces      : Vec<String>,
}

pub type Shader     = Resource<ShaderDesc>;
pub type ShaderPtr  = IntrusivePtr<Shader>;

////////////////////////////////////////////////////////////////////////////////
/// Binding
////////////////////////////////////////////////////////////////////////////////
#[derive(Clone, Eq, PartialEq)]
pub enum IndexType {
    None,
    UInt16,
    UInt32,
}

pub trait IndexTypeTrait {
    fn to_index_type() -> IndexType;
}

impl IndexTypeTrait for u16 {
    fn to_index_type() -> IndexType { IndexType::UInt16 }
}

impl IndexTypeTrait for u32 {
    fn to_index_type() -> IndexType { IndexType::UInt32 }
}

#[derive(Clone)]
pub struct Bindings {
    pub vertex_buffers  : Vec<DeviceBufferPtr>,
    pub index_buffer    : Option<DeviceBufferPtr>,

    pub vertex_images   : Vec<TexturePtr>,
    pub pixel_images    : Vec<TexturePtr>,
}

////////////////////////////////////////////////////////////////////////////////
/// PipelineDesc
////////////////////////////////////////////////////////////////////////////////
#[derive(Clone)]
pub enum PrimitiveType {
    Points,
    Lines,
    LineStrip,
    Triangles,
    TriangleStrip,
}

#[derive(Clone)]
pub enum CullMode {
    Winding,
    None,
}

#[derive(Clone)]
pub enum FaceWinding {
    CCW,
    CW,
}

#[derive(Clone)]
pub struct VertexBufferLayout {
    pub buffer_id           : usize,
    pub vertex_attributes   : Vec<VertexAttributeDesc>,
    pub stride              : usize,
    pub divisor             : usize,
}

#[derive(Clone)]
pub enum BlendFactor {
    Zero,
    One,

    SrcColor,
    OneMinusSrcColor,
    SrcAlpha,
    OneMinusSrcAlpha,

    DstColor,
    OneMinusDstColor,
    DstAlpha,
    OneMinusDstAlpha,

    SrcAlphaSaturate,
    ConstantColor,
    OneMinusConstantColor,
    ConstantAlpha,
    OneMinusConstantAlpha,
}


#[derive(Clone)]
pub struct Blend {
    pub src_factor_rgb      : BlendFactor,
    pub src_factor_alpha    : BlendFactor,

    pub dst_factor_rgb      : BlendFactor,
    pub dst_factor_alpha    : BlendFactor,
}

impl Blend {
    pub fn default() -> Self {
        Self {
            src_factor_rgb          : BlendFactor::One,
            src_factor_alpha        : BlendFactor::One,

            dst_factor_rgb          : BlendFactor::OneMinusSrcAlpha,
            dst_factor_alpha        : BlendFactor::OneMinusSrcAlpha,
        }
    }
}

#[derive(Clone)]
pub enum BlendOp {
    None,
    Add(Blend),
    Subtract(Blend),
    ReverseSubtract(Blend),
}


#[derive(Clone)]
pub struct PipelineDesc {
    pub primitive_type      : PrimitiveType,
    pub shader              : ShaderPtr,

    // layout
    pub buffer_layouts      : Vec<VertexBufferLayout>,

    //
    pub uniform_descs       : Vec<UniformDataDesc>,
    pub index_type          : IndexType,

    pub face_winding        : FaceWinding,
    pub cull_mode           : CullMode,

    pub depth_write         : bool,
    pub depth_test          : bool,

    pub blend               : BlendOp,
}

pub type Pipeline   = Resource<PipelineDesc>;
pub type PipelinePtr= IntrusivePtr<Pipeline>;

////////////////////////////////////////////////////////////////////////////////
/// Pass
////////////////////////////////////////////////////////////////////////////////
#[derive(Clone)]
pub enum ColorPassAction {
    Clear(Color4b),
    Previous,
}

#[derive(Clone)]
pub enum DepthPassAction {
    Clear(f32),
    Previous,
}

#[derive(Clone)]
pub enum SurfaceAttachment {
    Texture(TexturePtr),
    RenderTarget(RenderTargetPtr)
}

impl SurfaceAttachment {
    pub fn pixel_format(&self) -> PixelFormat {
        match self {
            SurfaceAttachment::Texture(tex) => tex.desc.sampler_desc.pixel_format.clone(),
            SurfaceAttachment::RenderTarget(rt) => rt.desc.sampler_desc.pixel_format.clone(),
        }
    }
}

#[derive(Clone)]
pub struct FrameBufferDesc {
    pub color_attachements          : [Option<SurfaceAttachment>; 4],
    pub depth_stencil_attachement   : SurfaceAttachment,
}

pub type FrameBuffer    = Resource<FrameBufferDesc>;
pub type FrameBufferPtr = IntrusivePtr<FrameBuffer>;

pub struct Pass {
    pub width           : usize,
    pub height          : usize,
    pub frame_buffer    : Option<FrameBufferPtr>,
    pub color_actions   : [ColorPassAction; 4],
    pub depth_action    : DepthPassAction,
}

////////////////////////////////////////////////////////////////////////////////
/// Readback surface
////////////////////////////////////////////////////////////////////////////////
pub enum ReadbackPayload {
    RGB32U(Vec<Vector3<u32>>),
    RGBA32U(Vec<Vector4<u32>>),
    R32U(Vec<u32>),

    RGB32F(Vec<Vec3f>),
    RGBA32F(Vec<Vec4f>),
    R32F(Vec<f32>),

    Depth(Vec<f32>),
}

pub enum ReadbackError {
    NoReadbackFromRenderTarget,
    RectOutOfBound,
}

pub enum ReadbackResult {
    Ok(ReadbackPayload),
    Error(ReadbackError)
}

////////////////////////////////////////////////////////////////////////////////
/// Capabilities
////////////////////////////////////////////////////////////////////////////////
pub struct DriverCaps {
    pub max_2d_surface_dimension    : Dimensioni,
}

////////////////////////////////////////////////////////////////////////////////
/// Driver
////////////////////////////////////////////////////////////////////////////////
pub trait Driver : IntrusiveCounter {
    fn get_caps(&self) -> &DriverCaps;
    fn create_device_buffer(&mut self, desc: DeviceBufferDesc) -> Option<DeviceBufferPtr>;
    fn create_texture(&mut self, desc: TextureDesc) -> Option<TexturePtr>;
    fn create_render_target(&mut self, desc: RenderTargetDesc) -> Option<RenderTargetPtr>;
    fn create_shader(&mut self, desc: ShaderDesc) -> Option<ShaderPtr>;
    fn create_pipeline(&mut self, desc: PipelineDesc) -> Option<PipelinePtr>;
    fn create_frame_buffer(&mut self, desc: FrameBufferDesc) -> Option<FrameBufferPtr>;

    fn delete_resource(&mut self, resource_type: &ResourceType, res_id: usize);

    fn update_device_buffer(&mut self, dev_buf: &mut DeviceBufferPtr, offset: usize, pl: &dyn Payload);
    fn update_texture(&mut self, dev_buf: &mut TexturePtr, pl: Box<dyn Payload>);

    fn begin_pass(&mut self, pass: &Pass);
    fn end_pass(&mut self);

    fn set_viewport(&mut self, x: u32, y: u32, w: u32, h: u32);
    fn set_scissor(&mut self, x: u32, y: u32, w: u32, h: u32);

    fn draw(&mut self, pipe: &Pipeline, bindings: &Bindings, uniforms: *const c_void, prim_count: u32, instance_count: u32);

    fn read_back(&mut self, surface: &TexturePtr, x: u32, y: u32, w: u32, h: u32) -> Option<ReadbackPayload>;
}

pub type DriverPtr = IntrusivePtr<dyn Driver>;


#[cfg(test)]
mod tests {
    use super::*;

    struct InTest {
        s: String,
        r: core::sync::atomic::AtomicIsize,
    }

    impl IntrusiveCounter for InTest {
        fn increment(&mut self) { self.r.fetch_add(1, Ordering::SeqCst); }
        fn decrement(&mut self) -> isize {
            self.r.fetch_sub(1, Ordering::SeqCst)
        }
    }

    impl Drop for InTest {
        fn drop(&mut self) {}
    }

    #[test]
    fn test_intrusive() {
        let it = InTest { s: String::from("Hello World"), r : core::sync::atomic::AtomicIsize::new(0) };
        let p = IntrusivePtr::new(it);
        format!("r: {}", p.s);
    }
}