/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

use crate::{
    device::RenderPassContext,
    resource,
    BufferAddress,
    PipelineLayoutId,
    RawString,
    ShaderModuleId,
    U32Array,
};

use bitflags::bitflags;

pub type ShaderLocation = u32;

#[repr(C)]
#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq)]
pub enum BlendFactor {
    Zero = 0,
    One = 1,
    SrcColor = 2,
    OneMinusSrcColor = 3,
    SrcAlpha = 4,
    OneMinusSrcAlpha = 5,
    DstColor = 6,
    OneMinusDstColor = 7,
    DstAlpha = 8,
    OneMinusDstAlpha = 9,
    SrcAlphaSaturated = 10,
    BlendColor = 11,
    OneMinusBlendColor = 12,
}

#[repr(C)]
#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq)]
pub enum BlendOperation {
    Add = 0,
    Subtract = 1,
    ReverseSubtract = 2,
    Min = 3,
    Max = 4,
}

impl Default for BlendOperation {
    fn default() -> Self {
        BlendOperation::Add
    }
}

bitflags! {
    #[repr(transparent)]
    pub struct ColorWrite: u32 {
        const RED = 1;
        const GREEN = 2;
        const BLUE = 4;
        const ALPHA = 8;
        const COLOR = 7;
        const ALL = 15;
    }
}

impl Default for ColorWrite {
    fn default() -> Self {
        ColorWrite::ALL
    }
}

#[repr(C)]
#[derive(Clone, Debug, PartialEq)]
pub struct BlendDescriptor {
    pub src_factor: BlendFactor,
    pub dst_factor: BlendFactor,
    pub operation: BlendOperation,
}

impl BlendDescriptor {
    pub const REPLACE: Self = BlendDescriptor {
        src_factor: BlendFactor::One,
        dst_factor: BlendFactor::Zero,
        operation: BlendOperation::Add,
    };

    pub fn uses_color(&self) -> bool {
        match (self.src_factor, self.dst_factor) {
            (BlendFactor::BlendColor, _)
            | (BlendFactor::OneMinusBlendColor, _)
            | (_, BlendFactor::BlendColor)
            | (_, BlendFactor::OneMinusBlendColor) => true,
            (_, _) => false,
        }
    }
}

impl Default for BlendDescriptor {
    fn default() -> Self {
        BlendDescriptor::REPLACE
    }
}

#[repr(C)]
#[derive(Clone, Debug)]
pub struct ColorStateDescriptor {
    pub format: resource::TextureFormat,
    pub alpha_blend: BlendDescriptor,
    pub color_blend: BlendDescriptor,
    pub write_mask: ColorWrite,
}

#[repr(C)]
#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq)]
pub enum StencilOperation {
    Keep = 0,
    Zero = 1,
    Replace = 2,
    Invert = 3,
    IncrementClamp = 4,
    DecrementClamp = 5,
    IncrementWrap = 6,
    DecrementWrap = 7,
}

impl Default for StencilOperation {
    fn default() -> Self {
        StencilOperation::Keep
    }
}

#[repr(C)]
#[derive(Clone, Debug, PartialEq)]
pub struct StencilStateFaceDescriptor {
    pub compare: resource::CompareFunction,
    pub fail_op: StencilOperation,
    pub depth_fail_op: StencilOperation,
    pub pass_op: StencilOperation,
}

impl StencilStateFaceDescriptor {
    pub const IGNORE: Self = StencilStateFaceDescriptor {
        compare: resource::CompareFunction::Always,
        fail_op: StencilOperation::Keep,
        depth_fail_op: StencilOperation::Keep,
        pass_op: StencilOperation::Keep,
    };
}

impl Default for StencilStateFaceDescriptor {
    fn default() -> Self {
        StencilStateFaceDescriptor::IGNORE
    }
}

#[repr(C)]
#[derive(Clone, Debug)]
pub struct DepthStencilStateDescriptor {
    pub format: resource::TextureFormat,
    pub depth_write_enabled: bool,
    pub depth_compare: resource::CompareFunction,
    pub stencil_front: StencilStateFaceDescriptor,
    pub stencil_back: StencilStateFaceDescriptor,
    pub stencil_read_mask: u32,
    pub stencil_write_mask: u32,
}

impl DepthStencilStateDescriptor {
    pub fn needs_stencil_reference(&self) -> bool {
        !self.stencil_front.compare.is_trivial() || !self.stencil_back.compare.is_trivial()
    }
}

#[repr(C)]
#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq)]
pub enum IndexFormat {
    Uint16 = 0,
    Uint32 = 1,
}

#[repr(C)]
#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq)]
pub enum VertexFormat {
    Uchar2 = 1,
    Uchar4 = 3,
    Char2 = 5,
    Char4 = 7,
    Uchar2Norm = 9,
    Uchar4Norm = 11,
    Char2Norm = 14,
    Char4Norm = 16,
    Ushort2 = 18,
    Ushort4 = 20,
    Short2 = 22,
    Short4 = 24,
    Ushort2Norm = 26,
    Ushort4Norm = 28,
    Short2Norm = 30,
    Short4Norm = 32,
    Half2 = 34,
    Half4 = 36,
    Float = 37,
    Float2 = 38,
    Float3 = 39,
    Float4 = 40,
    Uint = 41,
    Uint2 = 42,
    Uint3 = 43,
    Uint4 = 44,
    Int = 45,
    Int2 = 46,
    Int3 = 47,
    Int4 = 48,
}

#[repr(C)]
#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq)]
pub enum InputStepMode {
    Vertex = 0,
    Instance = 1,
}

#[repr(C)]
#[derive(Clone, Debug)]
pub struct VertexAttributeDescriptor {
    pub offset: BufferAddress,
    pub format: VertexFormat,
    pub shader_location: ShaderLocation,
}

#[repr(C)]
#[derive(Debug)]
pub struct VertexBufferDescriptor {
    pub stride: BufferAddress,
    pub step_mode: InputStepMode,
    pub attributes: *const VertexAttributeDescriptor,
    pub attributes_length: usize,
}

#[repr(C)]
#[derive(Debug)]
pub struct VertexInputDescriptor {
    pub index_format: IndexFormat,
    pub vertex_buffers: *const VertexBufferDescriptor,
    pub vertex_buffers_length: usize,
}

#[repr(C)]
#[derive(Debug)]
pub struct ShaderModuleDescriptor {
    pub code: U32Array,
}

#[repr(C)]
#[derive(Debug)]
pub struct ProgrammableStageDescriptor {
    pub module: ShaderModuleId,
    pub entry_point: RawString,
}

#[repr(C)]
#[derive(Debug)]
pub struct ComputePipelineDescriptor {
    pub layout: PipelineLayoutId,
    pub compute_stage: ProgrammableStageDescriptor,
}

#[derive(Debug)]
pub struct ComputePipeline<B: hal::Backend> {
    pub(crate) raw: B::ComputePipeline,
    pub(crate) layout_id: PipelineLayoutId,
}

#[repr(C)]
#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq)]
pub enum PrimitiveTopology {
    PointList = 0,
    LineList = 1,
    LineStrip = 2,
    TriangleList = 3,
    TriangleStrip = 4,
}

#[repr(C)]
#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq)]
pub enum FrontFace {
    Ccw = 0,
    Cw = 1,
}

impl Default for FrontFace {
    fn default() -> Self {
        FrontFace::Ccw
    }
}

#[repr(C)]
#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq)]
pub enum CullMode {
    None = 0,
    Front = 1,
    Back = 2,
}

impl Default for CullMode {
    fn default() -> Self {
        CullMode::None
    }
}

#[repr(C)]
#[derive(Clone, Debug, Default)]
pub struct RasterizationStateDescriptor {
    pub front_face: FrontFace,
    pub cull_mode: CullMode,
    pub depth_bias: i32,
    pub depth_bias_slope_scale: f32,
    pub depth_bias_clamp: f32,
}

#[repr(C)]
#[derive(Debug)]
pub struct RenderPipelineDescriptor {
    pub layout: PipelineLayoutId,
    pub vertex_stage: ProgrammableStageDescriptor,
    pub fragment_stage: *const ProgrammableStageDescriptor,
    pub primitive_topology: PrimitiveTopology,
    pub rasterization_state: *const RasterizationStateDescriptor,
    pub color_states: *const ColorStateDescriptor,
    pub color_states_length: usize,
    pub depth_stencil_state: *const DepthStencilStateDescriptor,
    pub vertex_input: VertexInputDescriptor,
    pub sample_count: u32,
    pub sample_mask: u32,
    pub alpha_to_coverage_enabled: bool,
}

bitflags! {
    #[repr(transparent)]
    pub struct PipelineFlags: u32 {
        const BLEND_COLOR = 1;
        const STENCIL_REFERENCE = 2;
    }
}

#[derive(Debug)]
pub struct RenderPipeline<B: hal::Backend> {
    pub(crate) raw: B::GraphicsPipeline,
    pub(crate) layout_id: PipelineLayoutId,
    pub(crate) pass_context: RenderPassContext,
    pub(crate) flags: PipelineFlags,
    pub(crate) index_format: IndexFormat,
    pub(crate) sample_count: u8,
    pub(crate) vertex_strides: Vec<(BufferAddress, InputStepMode)>,
}