// Copyright (c) 2016 The vulkano developers
// Licensed under the Apache License, Version 2.0
// <LICENSE-APACHE or
// https://www.apache.org/licenses/LICENSE-2.0> or the MIT
// license <LICENSE-MIT or https://opensource.org/licenses/MIT>,
// at your option. All files in the project carrying such
// notice may not be copied, modified, or distributed except
// according to those terms.

//! Configures how the color output of the fragment shader is written to the attachment.
//!
//! # Blending in details
//!
//! There are three kinds of color attachments for the purpose of blending:
//!
//! - Attachments with a floating-point or fixed point format.
//! - Attachments with a (non-normalized) integer format.
//! - Attachments with a normalized integer format.
//!
//! For floating-point and fixed-point formats, the blending operation is applied. For integer
//! formats, the logic operation is applied. For normalized integer formats, the logic operation
//! will take precedence if it is activated, otherwise the blending operation is applied.

use crate::{
    macros::{vulkan_bitflags, vulkan_enum},
    pipeline::StateMode,
};

/// Describes how the color output of the fragment shader is written to the attachment. See the
/// documentation of the `blend` module for more info.
#[derive(Clone, Debug)]
pub struct ColorBlendState {
    /// Sets the logical operation to perform between the incoming fragment color and the existing
    /// fragment in the framebuffer attachment.
    ///
    /// If set to `Some`, the [`logic_op`](crate::device::Features::logic_op) feature must be
    /// enabled on the device. If set to `Some(Dynamic)`, then the
    /// [`extended_dynamic_state2_logic_op`](crate::device::Features::extended_dynamic_state2_logic_op)
    /// feature must also be enabled on the device.
    pub logic_op: Option<StateMode<LogicOp>>,

    /// Sets the blend and output state for each color attachment. The number of elements must match
    /// the number of color attachments in the framebuffer.
    ///
    /// If there are multiple elements, and the `blend` and `color_write_mask` members of each
    /// element differ, then the [`independent_blend`](crate::device::Features::independent_blend)
    /// feature must be enabled on the device.
    pub attachments: Vec<ColorBlendAttachmentState>,

    /// The constant color to use for some of the `BlendFactor` variants.
    pub blend_constants: StateMode<[f32; 4]>,
}

impl ColorBlendState {
    /// Creates a `ColorBlendState` with logical operations disabled, blend constants set to zero,
    /// and `num` attachment entries that have blending disabled, and color write and all color
    /// components enabled.
    #[inline]
    pub fn new(num: u32) -> Self {
        Self {
            logic_op: None,
            attachments: (0..num)
                .map(|_| ColorBlendAttachmentState {
                    blend: None,
                    color_write_mask: ColorComponents::all(),
                    color_write_enable: StateMode::Fixed(true),
                })
                .collect(),
            blend_constants: StateMode::Fixed([0.0, 0.0, 0.0, 0.0]),
        }
    }

    /// Enables logical operations with the given logical operation.
    #[inline]
    pub fn logic_op(mut self, logic_op: LogicOp) -> Self {
        self.logic_op = Some(StateMode::Fixed(logic_op));
        self
    }

    /// Enables logical operations with a dynamic logical operation.
    #[inline]
    pub fn logic_op_dynamic(mut self) -> Self {
        self.logic_op = Some(StateMode::Dynamic);
        self
    }

    /// Enables blending for all attachments, with the given parameters.
    #[inline]
    pub fn blend(mut self, blend: AttachmentBlend) -> Self {
        self.attachments
            .iter_mut()
            .for_each(|attachment_state| attachment_state.blend = Some(blend));
        self
    }

    /// Enables blending for all attachments, with alpha blending.
    #[inline]
    pub fn blend_alpha(mut self) -> Self {
        self.attachments
            .iter_mut()
            .for_each(|attachment_state| attachment_state.blend = Some(AttachmentBlend::alpha()));
        self
    }

    /// Enables blending for all attachments, with additive blending.
    #[inline]
    pub fn blend_additive(mut self) -> Self {
        self.attachments.iter_mut().for_each(|attachment_state| {
            attachment_state.blend = Some(AttachmentBlend::additive())
        });
        self
    }

    /// Sets the color write mask for all attachments.
    #[inline]
    pub fn color_write_mask(mut self, color_write_mask: ColorComponents) -> Self {
        self.attachments
            .iter_mut()
            .for_each(|attachment_state| attachment_state.color_write_mask = color_write_mask);
        self
    }

    /// Sets the blend constants.
    #[inline]
    pub fn blend_constants(mut self, constants: [f32; 4]) -> Self {
        self.blend_constants = StateMode::Fixed(constants);
        self
    }

    /// Sets the blend constants as dynamic.
    #[inline]
    pub fn blend_constants_dynamic(mut self) -> Self {
        self.blend_constants = StateMode::Dynamic;
        self
    }
}

impl Default for ColorBlendState {
    /// Returns [`ColorBlendState::new(1)`].
    #[inline]
    fn default() -> Self {
        Self::new(1)
    }
}

vulkan_enum! {
    /// Which logical operation to apply to the output values.
    ///
    /// The operation is applied individually for each channel (red, green, blue and alpha).
    ///
    /// Only relevant for integer or unsigned attachments.
    ///
    /// Also note that some implementations don't support logic operations.
    #[non_exhaustive]
    LogicOp = LogicOp(i32);

    /// Returns `0`.
    Clear = CLEAR,

    /// Returns `source & destination`.
    And = AND,

    /// Returns `source & !destination`.
    AndReverse = AND_REVERSE,

    /// Returns `source`.
    Copy = COPY,

    /// Returns `!source & destination`.
    AndInverted = AND_INVERTED,

    /// Returns `destination`.
    Noop = NO_OP,

    /// Returns `source ^ destination`.
    Xor = XOR,

    /// Returns `source | destination`.
    Or = OR,

    /// Returns `!(source | destination)`.
    Nor = NOR,

    /// Returns `!(source ^ destination)`.
    Equivalent = EQUIVALENT,

    /// Returns `!destination`.
    Invert = INVERT,

    /// Returns `source | !destination.
    OrReverse = OR_REVERSE,

    /// Returns `!source`.
    CopyInverted = COPY_INVERTED,

    /// Returns `!source | destination`.
    OrInverted = OR_INVERTED,

    /// Returns `!(source & destination)`.
    Nand = NAND,

    /// Returns `!0` (all bits set to 1).
    Set = SET,

}

impl Default for LogicOp {
    #[inline]
    fn default() -> LogicOp {
        LogicOp::Noop
    }
}

/// Describes how a framebuffer color attachment is handled in the pipeline during the color
/// blend stage.
#[derive(Clone, Debug)]
pub struct ColorBlendAttachmentState {
    /// The blend parameters for the attachment.
    ///
    /// If set to `None`, blending is disabled, and all incoming pixels will be used directly.
    pub blend: Option<AttachmentBlend>,

    /// Sets which components of the final pixel value are written to the attachment.
    pub color_write_mask: ColorComponents,

    /// Sets whether anything at all is written to the attachment. If enabled, the pixel data
    /// that is written is determined by the `color_write_mask`. If disabled, the mask is ignored
    /// and nothing is written.
    ///
    /// If set to anything other than `Fixed(true)`, the
    /// [`color_write_enable`](crate::device::Features::color_write_enable) feature must be enabled
    /// on the device.
    pub color_write_enable: StateMode<bool>,
}

/// Describes how the blending system should behave for an attachment.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct AttachmentBlend {
    /// The operation to apply between the color components of the source and destination pixels,
    /// to produce the final pixel value.
    pub color_op: BlendOp,

    /// The operation to apply to the source color component before applying `color_op`.
    pub color_source: BlendFactor,

    /// The operation to apply to the destination color component before applying `color_op`.
    pub color_destination: BlendFactor,

    /// The operation to apply between the alpha component of the source and destination pixels,
    /// to produce the final pixel value.
    pub alpha_op: BlendOp,

    /// The operation to apply to the source alpha component before applying `alpha_op`.
    pub alpha_source: BlendFactor,

    /// The operation to apply to the destination alpha component before applying `alpha_op`.
    pub alpha_destination: BlendFactor,
}

impl AttachmentBlend {
    /// Builds an `AttachmentBlend` where the output of the fragment shader is ignored and the
    /// destination is untouched.
    #[inline]
    pub fn ignore_source() -> Self {
        Self {
            color_op: BlendOp::Add,
            color_source: BlendFactor::Zero,
            color_destination: BlendFactor::DstColor,
            alpha_op: BlendOp::Add,
            alpha_source: BlendFactor::Zero,
            alpha_destination: BlendFactor::DstColor,
        }
    }

    /// Builds an `AttachmentBlend` where the output will be merged with the existing value
    /// based on the alpha of the source.
    #[inline]
    pub fn alpha() -> Self {
        Self {
            color_op: BlendOp::Add,
            color_source: BlendFactor::SrcAlpha,
            color_destination: BlendFactor::OneMinusSrcAlpha,
            alpha_op: BlendOp::Add,
            alpha_source: BlendFactor::SrcAlpha,
            alpha_destination: BlendFactor::OneMinusSrcAlpha,
        }
    }

    /// Builds an `AttachmentBlend` where the colors are added, and alpha is set to the maximum of
    /// the two.
    #[inline]
    pub fn additive() -> Self {
        Self {
            color_op: BlendOp::Add,
            color_source: BlendFactor::One,
            color_destination: BlendFactor::One,
            alpha_op: BlendOp::Max,
            alpha_source: BlendFactor::One,
            alpha_destination: BlendFactor::One,
        }
    }
}

impl From<AttachmentBlend> for ash::vk::PipelineColorBlendAttachmentState {
    #[inline]
    fn from(val: AttachmentBlend) -> Self {
        ash::vk::PipelineColorBlendAttachmentState {
            blend_enable: ash::vk::TRUE,
            src_color_blend_factor: val.color_source.into(),
            dst_color_blend_factor: val.color_destination.into(),
            color_blend_op: val.color_op.into(),
            src_alpha_blend_factor: val.alpha_source.into(),
            dst_alpha_blend_factor: val.alpha_destination.into(),
            alpha_blend_op: val.alpha_op.into(),
            color_write_mask: ash::vk::ColorComponentFlags::empty(), // Overwritten by GraphicsPipelineBuilder
        }
    }
}

vulkan_enum! {
    /// The operation that takes `source` (output from the fragment shader), `destination` (value
    /// currently in the framebuffer attachment) and `blend_constant` input values,
    /// and produces new inputs to be fed to `BlendOp`.
    ///
    /// Some operations take `source1` as an input, representing the second source value. The
    /// [`dual_src_blend`](crate::device::Features::dual_src_blend) feature must be enabled on the
    /// device when these are used.
    #[non_exhaustive]
    BlendFactor = BlendFactor(i32);

    /// Always `0`.
    Zero = ZERO,

    /// Always `1`.
    One = ONE,

    /// `source` component-wise.
    SrcColor = SRC_COLOR,

    /// `1 - source` component-wise.
    OneMinusSrcColor = ONE_MINUS_SRC_COLOR,

    /// `destination` component-wise.
    DstColor = DST_COLOR,

    /// `1 - destination` component-wise.
    OneMinusDstColor = ONE_MINUS_DST_COLOR,

    /// `source.a` for all components.
    SrcAlpha = SRC_ALPHA,

    /// `1 - source.a` for all components.
    OneMinusSrcAlpha = ONE_MINUS_SRC_ALPHA,

    /// `destination.a` for all components.
    DstAlpha = DST_ALPHA,

    /// `1 - destination.a` for all components.
    OneMinusDstAlpha = ONE_MINUS_DST_ALPHA,

    /// `blend_constants` component-wise.
    ConstantColor = CONSTANT_COLOR,

    /// `1 - blend_constants` component-wise.
    OneMinusConstantColor = ONE_MINUS_CONSTANT_COLOR,

    /// `blend_constants.a` for all components.
    ConstantAlpha = CONSTANT_ALPHA,

    /// `1 - blend_constants.a` for all components.
    OneMinusConstantAlpha = ONE_MINUS_CONSTANT_ALPHA,

    /// For the alpha component, always `1`. For the color components,
    /// `min(source.a, 1 - destination.a)` for all components.
    SrcAlphaSaturate = SRC_ALPHA_SATURATE,

    /// `source1` component-wise.
    Src1Color = SRC1_COLOR,

    /// `1 - source1` component-wise.
    OneMinusSrc1Color = ONE_MINUS_SRC1_COLOR,

    /// `source1.a` for all components.
    Src1Alpha = SRC1_ALPHA,

    /// `1 - source1.a` for all components.
    OneMinusSrc1Alpha = ONE_MINUS_SRC1_ALPHA,
}

vulkan_enum! {
    /// The arithmetic operation that is applied between the `source` and `destination` component
    /// values, after the appropriate `BlendFactor` is applied to both.
    #[non_exhaustive]
    BlendOp = BlendOp(i32);

    /// `source + destination`.
    Add = ADD,

    /// `source - destination`.
    Subtract = SUBTRACT,

    /// `destination - source`.
    ReverseSubtract = REVERSE_SUBTRACT,

    /// `min(source, destination)`.
    Min = MIN,

    /// `max(source, destination)`.
    Max = MAX,

    /*
    // TODO: document
    Zero = ZERO_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Src = SRC_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Dst = DST_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    SrcOver = SRC_OVER_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    DstOver = DST_OVER_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    SrcIn = SRC_IN_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    DstIn = DST_IN_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    SrcOut = SRC_OUT_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    DstOut = DST_OUT_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    SrcAtop = SRC_ATOP_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    DstAtop = DST_ATOP_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Xor = XOR_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Multiply = MULTIPLY_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Screen = SCREEN_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Overlay = OVERLAY_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Darken = DARKEN_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Lighten = LIGHTEN_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Colordodge = COLORDODGE_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Colorburn = COLORBURN_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Hardlight = HARDLIGHT_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Softlight = SOFTLIGHT_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Difference = DIFFERENCE_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Exclusion = EXCLUSION_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Invert = INVERT_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    InvertRgb = INVERT_RGB_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Lineardodge = LINEARDODGE_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Linearburn = LINEARBURN_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Vividlight = VIVIDLIGHT_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Linearlight = LINEARLIGHT_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Pinlight = PINLIGHT_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Hardmix = HARDMIX_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    HslHue = HSL_HUE_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    HslSaturation = HSL_SATURATION_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    HslColor = HSL_COLOR_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    HslLuminosity = HSL_LUMINOSITY_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Plus = PLUS_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    PlusClamped = PLUS_CLAMPED_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    PlusClampedAlpha = PLUS_CLAMPED_ALPHA_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    PlusDarker = PLUS_DARKER_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Minus = MINUS_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    MinusClamped = MINUS_CLAMPED_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Contrast = CONTRAST_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    InvertOvg = INVERT_OVG_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Red = RED_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Green = GREEN_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },

    // TODO: document
    Blue = BLUE_EXT {
        device_extensions: [ext_blend_operation_advanced],
    },
     */
}

vulkan_bitflags! {
    /// A mask specifying color components that can be written to a framebuffer attachment.
    ColorComponents = ColorComponentFlags(u32);

    /// The red component.
    r = R,

    /// The green component.
    g = G,

    /// The blue component.
    b = B,

    /// The alpha component.
    a = A,
}