/*
 * // Copyright 2024 (c) the Radzivon Bartoshyk. All rights reserved.
 * //
 * // Use of this source code is governed by a BSD-style
 * // license that can be found in the LICENSE file.
 */

#[cfg(all(
    any(target_arch = "x86_64", target_arch = "x86"),
    target_feature = "avx2"
))]
use crate::avx::avx_channels_to_linear;
use crate::gamma_curves::TransferFunction;
use crate::image::ImageConfiguration;
#[cfg(all(
    any(target_arch = "aarch64", target_arch = "arm"),
    target_feature = "neon"
))]
use crate::neon::neon_channels_to_linear;
#[cfg(all(
    any(target_arch = "x86_64", target_arch = "x86"),
    target_feature = "sse4.1"
))]
use crate::sse::*;
use crate::Rgb;

#[inline(always)]
fn channels_to_linear<const CHANNELS_CONFIGURATION: u8, const USE_ALPHA: bool>(
    src: &[u8],
    src_stride: u32,
    dst: &mut [f32],
    dst_stride: u32,
    width: u32,
    height: u32,
    transfer_function: TransferFunction,
) {
    let image_configuration: ImageConfiguration = CHANNELS_CONFIGURATION.into();
    if USE_ALPHA {
        if !image_configuration.has_alpha() {
            panic!("Alpha may be set only on images with alpha");
        }
    }

    let mut src_offset = 0usize;
    let mut dst_offset = 0usize;

    let transfer = transfer_function.get_linearize_function();

    let channels = image_configuration.get_channels_count();

    let mut _wide_row_handle: Option<
        unsafe fn(usize, *const u8, usize, u32, *mut f32, usize, TransferFunction) -> usize,
    > = None;

    #[cfg(all(
        any(target_arch = "x86_64", target_arch = "x86"),
        target_feature = "sse4.1"
    ))]
    if is_x86_feature_detected!("sse4.1") {
        _wide_row_handle = match transfer_function {
            TransferFunction::Srgb => Some(
                sse_channels_to_linear::<
                    CHANNELS_CONFIGURATION,
                    USE_ALPHA,
                    { TransferFunction::Srgb as u8 },
                >,
            ),
            TransferFunction::Rec709 => Some(
                sse_channels_to_linear::<
                    CHANNELS_CONFIGURATION,
                    USE_ALPHA,
                    { TransferFunction::Rec709 as u8 },
                >,
            ),
            TransferFunction::Gamma2p2 => Some(
                sse_channels_to_linear::<
                    CHANNELS_CONFIGURATION,
                    USE_ALPHA,
                    { TransferFunction::Gamma2p2 as u8 },
                >,
            ),
            TransferFunction::Gamma2p8 => Some(
                sse_channels_to_linear::<
                    CHANNELS_CONFIGURATION,
                    USE_ALPHA,
                    { TransferFunction::Gamma2p8 as u8 },
                >,
            ),
        };
    }

    #[cfg(all(
        any(target_arch = "x86_64", target_arch = "x86"),
        target_feature = "avx2"
    ))]
    if is_x86_feature_detected!("avx2") {
        _wide_row_handle = match transfer_function {
            TransferFunction::Srgb => Some(
                avx_channels_to_linear::<
                    CHANNELS_CONFIGURATION,
                    USE_ALPHA,
                    { TransferFunction::Srgb as u8 },
                >,
            ),
            TransferFunction::Rec709 => Some(
                avx_channels_to_linear::<
                    CHANNELS_CONFIGURATION,
                    USE_ALPHA,
                    { TransferFunction::Rec709 as u8 },
                >,
            ),
            TransferFunction::Gamma2p2 => Some(
                avx_channels_to_linear::<
                    CHANNELS_CONFIGURATION,
                    USE_ALPHA,
                    { TransferFunction::Gamma2p2 as u8 },
                >,
            ),
            TransferFunction::Gamma2p8 => Some(
                avx_channels_to_linear::<
                    CHANNELS_CONFIGURATION,
                    USE_ALPHA,
                    { TransferFunction::Gamma2p8 as u8 },
                >,
            ),
        };
    }

    #[cfg(all(
        any(target_arch = "aarch64", target_arch = "arm"),
        target_feature = "neon"
    ))]
    {
        _wide_row_handle = match transfer_function {
            TransferFunction::Srgb => Some(
                neon_channels_to_linear::<
                    CHANNELS_CONFIGURATION,
                    USE_ALPHA,
                    { TransferFunction::Srgb as u8 },
                >,
            ),
            TransferFunction::Rec709 => Some(
                neon_channels_to_linear::<
                    CHANNELS_CONFIGURATION,
                    USE_ALPHA,
                    { TransferFunction::Rec709 as u8 },
                >,
            ),
            TransferFunction::Gamma2p2 => Some(
                neon_channels_to_linear::<
                    CHANNELS_CONFIGURATION,
                    USE_ALPHA,
                    { TransferFunction::Gamma2p2 as u8 },
                >,
            ),
            TransferFunction::Gamma2p8 => Some(
                neon_channels_to_linear::<
                    CHANNELS_CONFIGURATION,
                    USE_ALPHA,
                    { TransferFunction::Gamma2p8 as u8 },
                >,
            ),
        };
    }

    for _ in 0..height as usize {
        let mut _cx = 0usize;

        if let Some(dispatcher) = _wide_row_handle {
            unsafe {
                _cx = dispatcher(
                    _cx,
                    src.as_ptr(),
                    src_offset,
                    width,
                    dst.as_mut_ptr(),
                    dst_offset,
                    transfer_function,
                )
            }
        }

        let src_ptr = unsafe { src.as_ptr().add(src_offset) };
        let dst_ptr = unsafe { (dst.as_mut_ptr() as *mut u8).add(dst_offset) as *mut f32 };

        for x in _cx..width as usize {
            let px = x * channels;
            let dst = unsafe { dst_ptr.add(px) };
            let src = unsafe { src_ptr.add(px) };
            let r = unsafe {
                src.add(image_configuration.get_r_channel_offset())
                    .read_unaligned()
            };
            let g = unsafe {
                src.add(image_configuration.get_g_channel_offset())
                    .read_unaligned()
            };
            let b = unsafe {
                src.add(image_configuration.get_b_channel_offset())
                    .read_unaligned()
            };

            let rgb = Rgb::<u8>::new(r, g, b);
            let rgb_f32 = rgb.to_rgb_f32();

            unsafe {
                dst.write_unaligned(transfer(rgb_f32.r));
                dst.add(1).write_unaligned(transfer(rgb_f32.g));
                dst.add(2).write_unaligned(transfer(rgb_f32.b));
            }

            if USE_ALPHA && image_configuration.has_alpha() {
                let a = unsafe {
                    src.add(image_configuration.get_a_channel_offset())
                        .read_unaligned()
                };
                let a_lin = a as f32 * (1f32 / 255f32);
                unsafe {
                    dst.add(3).write_unaligned(a_lin);
                }
            }
        }

        src_offset += src_stride as usize;
        dst_offset += dst_stride as usize;
    }
}

/// This function converts RGB to Linear. This is much more effective than naive direct transformation
///
/// # Arguments
/// * `src` - A slice contains RGB data
/// * `src_stride` - Bytes per row for src data.
/// * `width` - Image width
/// * `height` - Image height
/// * `dst` - A mutable slice to receive linear data
/// * `dst_stride` - Bytes per row for dst data
/// * `transfer_function` - Transfer function from gamma to linear space. If you don't have specific pick `Srgb`
pub fn rgb_to_linear(
    src: &[u8],
    src_stride: u32,
    dst: &mut [f32],
    dst_stride: u32,
    width: u32,
    height: u32,
    transfer_function: TransferFunction,
) {
    channels_to_linear::<{ ImageConfiguration::Rgb as u8 }, false>(
        src,
        src_stride,
        dst,
        dst_stride,
        width,
        height,
        transfer_function,
    );
}

/// This function converts RGBA to Linear, Alpha channel is normalized. This is much more effective than naive direct transformation
///
/// # Arguments
/// * `src` - A slice contains RGBA data
/// * `src_stride` - Bytes per row for src data.
/// * `width` - Image width
/// * `height` - Image height
/// * `dst` - A mutable slice to receive Linear data
/// * `dst_stride` - Bytes per row for dst data
/// * `transfer_function` - Transfer function from gamma to linear space. If you don't have specific pick `Srgb`
pub fn rgba_to_linear(
    src: &[u8],
    src_stride: u32,
    dst: &mut [f32],
    dst_stride: u32,
    width: u32,
    height: u32,
    transfer_function: TransferFunction,
) {
    channels_to_linear::<{ ImageConfiguration::Rgba as u8 }, true>(
        src,
        src_stride,
        dst,
        dst_stride,
        width,
        height,
        transfer_function,
    );
}

/// This function converts BGRA to Linear, Alpha channel is normalized. This is much more effective than naive direct transformation
///
/// # Arguments
/// * `src` - A slice contains BGRA data
/// * `src_stride` - Bytes per row for src data.
/// * `width` - Image width
/// * `height` - Image height
/// * `dst` - A mutable slice to receive linear data
/// * `dst_stride` - Bytes per row for dst data
/// * `transfer_function` - Transfer function from gamma to linear space. If you don't have specific pick `Srgb`
pub fn bgra_to_linear(
    src: &[u8],
    src_stride: u32,
    dst: &mut [f32],
    dst_stride: u32,
    width: u32,
    height: u32,
    transfer_function: TransferFunction,
) {
    channels_to_linear::<{ ImageConfiguration::Bgra as u8 }, true>(
        src,
        src_stride,
        dst,
        dst_stride,
        width,
        height,
        transfer_function,
    );
}

/// This function converts BGR to Linear. This is much more effective than naive direct transformation
///
/// # Arguments
/// * `src` - A slice contains BGR data
/// * `src_stride` - Bytes per row for src data.
/// * `width` - Image width
/// * `height` - Image height
/// * `dst` - A mutable slice to receive Linear data
/// * `dst_stride` - Bytes per row for dst data
/// * `transfer_function` - Transfer function from gamma to linear space. If you don't have specific pick `Srgb`
pub fn bgr_to_linear(
    src: &[u8],
    src_stride: u32,
    dst: &mut [f32],
    dst_stride: u32,
    width: u32,
    height: u32,
    transfer_function: TransferFunction,
) {
    channels_to_linear::<{ ImageConfiguration::Bgr as u8 }, false>(
        src,
        src_stride,
        dst,
        dst_stride,
        width,
        height,
        transfer_function,
    );
}