use std::hash::Hash;

#[cfg(feature = "serde-support")]
use serde::{Deserialize, Serialize};

/// Metal-specific shader package. Can be used to create a RafxShaderModuleDef, which in turn is
/// used to initialize a shader module GPU object
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde-support", derive(Serialize, Deserialize))]
pub enum RafxShaderPackageMetal {
    /// Raw uncompiled sorce code. Will be compiled at runtime.
    Src(String),
    /// Pre-built binary "metallib" file loaded into memory
    #[cfg_attr(feature = "serde-support", serde(with = "serde_bytes"))]
    LibBytes(Vec<u8>),
}

/// Vulkan-specific shader package. Can be used to create a RafxShaderModuleDef, which in turn is
/// used to initialize a shader module GPU object
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde-support", derive(Serialize, Deserialize))]
pub enum RafxShaderPackageVulkan {
    /// Raw SPV bytes, no alignment or endianness requirements.
    #[cfg_attr(feature = "serde-support", serde(with = "serde_bytes"))]
    SpvBytes(Vec<u8>),
}

#[derive(Debug, Clone, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde-support", derive(Serialize, Deserialize))]
#[doc(hidden)]
pub enum RafxShaderPackageEmpty {
    Empty,
}

/// Owns data necessary to create a shader module in (optionally) multiple APIs.
///
/// This struct can be serialized/deserialized and is intended to allow asset pipeline to store
/// a shader module to be created at runtime. The package can optionally include data for multiple
/// APIs allowing a single file to be used with whatever API is found at runtime.
#[derive(Debug, Clone, PartialEq, Eq, Hash, Default)]
#[cfg_attr(feature = "serde-support", derive(Serialize, Deserialize))]
pub struct RafxShaderPackage {
    pub metal: Option<RafxShaderPackageMetal>,
    pub vk: Option<RafxShaderPackageVulkan>,
}

impl RafxShaderPackage {
    /// Create a shader module def for use with a metal RafxDevice. Returns none if the package does
    /// not contain data necessary for metal
    #[cfg(feature = "rafx-metal")]
    pub fn metal_module_def(&self) -> Option<RafxShaderModuleDefMetal> {
        if let Some(metal) = self.metal.as_ref() {
            Some(match metal {
                RafxShaderPackageMetal::Src(src) => RafxShaderModuleDefMetal::MetalSrc(src),
                RafxShaderPackageMetal::LibBytes(lib) => {
                    RafxShaderModuleDefMetal::MetalLibBytes(lib)
                }
            })
        } else {
            None
        }
    }

    /// Create a shader module def for use with a vulkan RafxDevice. Returns none if the package
    /// does not contain data necessary for vulkan
    #[cfg(feature = "rafx-vulkan")]
    pub fn vulkan_module_def(&self) -> Option<RafxShaderModuleDefVulkan> {
        if let Some(vk) = self.vk.as_ref() {
            Some(match vk {
                RafxShaderPackageVulkan::SpvBytes(bytes) => {
                    RafxShaderModuleDefVulkan::VkSpvBytes(bytes)
                }
            })
        } else {
            None
        }
    }

    /// Create a shader module def for use with a vulkan RafxDevice. Returns none if the package
    /// does not contain data necessary for vulkan
    #[cfg(any(
        feature = "rafx-empty",
        not(any(feature = "rafx-metal", feature = "rafx-vulkan"))
    ))]
    #[doc(hidden)]
    pub fn empty_module_def(&self) -> Option<RafxShaderModuleDefEmpty> {
        Some(RafxShaderModuleDefEmpty::Empty(Default::default()))
    }

    pub fn module_def(&self) -> RafxShaderModuleDef {
        RafxShaderModuleDef {
            #[cfg(feature = "rafx-metal")]
            metal: self.metal_module_def(),
            #[cfg(feature = "rafx-vulkan")]
            vk: self.vulkan_module_def(),
            #[cfg(any(
                feature = "rafx-empty",
                not(any(feature = "rafx-metal", feature = "rafx-vulkan"))
            ))]
            #[doc(hidden)]
            empty: self.empty_module_def(),
        }
    }
}

/// Used to create a RafxShaderModule
///
/// This enum may be populated manually or created from a RafxShaderPackage.
#[derive(Copy, Clone, Hash)]
#[cfg(feature = "rafx-metal")]
pub enum RafxShaderModuleDefMetal<'a> {
    /// Metal source code
    MetalSrc(&'a str),
    /// Pre-compiled library loaded as bytes
    MetalLibBytes(&'a [u8]),
}

/// Used to create a RafxShaderModule
///
/// This enum may be populated manually or created from a RafxShaderPackage.
#[derive(Copy, Clone, Hash)]
#[cfg(feature = "rafx-vulkan")]
pub enum RafxShaderModuleDefVulkan<'a> {
    /// Raw SPV bytes, no alignment or endianness requirements.
    VkSpvBytes(&'a [u8]),
    /// Prepared SPV that's aligned and correct endian. No validation.
    VkSpvPrepared(&'a [u32]),
}

#[cfg(any(
    feature = "rafx-empty",
    not(any(feature = "rafx-metal", feature = "rafx-vulkan"))
))]
#[derive(Copy, Clone, Hash)]
#[doc(hidden)]
pub enum RafxShaderModuleDefEmpty<'a> {
    Empty(std::marker::PhantomData<&'a u32>),
}

/// Used to create a RafxShaderModule
///
/// This enum may be populated manually or created from a RafxShaderPackage.
#[derive(Copy, Clone, Hash)]
pub struct RafxShaderModuleDef<'a> {
    #[cfg(feature = "rafx-metal")]
    pub metal: Option<RafxShaderModuleDefMetal<'a>>,
    #[cfg(feature = "rafx-vulkan")]
    pub vk: Option<RafxShaderModuleDefVulkan<'a>>,
    #[cfg(any(
        feature = "rafx-empty",
        not(any(feature = "rafx-metal", feature = "rafx-vulkan"))
    ))]
    #[doc(hidden)]
    pub empty: Option<RafxShaderModuleDefEmpty<'a>>,
}