colconv 0.1.0

use super::super::*;
use crate::{ColorMatrix, row::scalar};

/// Pack one V410 word: `(v << 20) | (y << 10) | u` with each channel masked
/// to 10-bit range.
fn pack_v410(u: u32, y: u32, v: u32) -> u32 {
  let u = u & 0x3FF;
  let y = y & 0x3FF;
  let v = v & 0x3FF;
  (v << 20) | (y << 10) | u
}

/// Builds a deterministic pseudo-random V410 packed buffer of `width` words.
fn pseudo_random_v410(width: usize, seed: usize) -> std::vec::Vec<u32> {
  (0..width)
    .map(|i| {
      let u = (i.wrapping_mul(seed).wrapping_add(seed * 3)) & 0x3FF;
      let y = (i.wrapping_mul(seed * 5).wrapping_add(seed * 7)) & 0x3FF;
      let v = (i.wrapping_mul(seed * 11).wrapping_add(seed * 13)) & 0x3FF;
      pack_v410(u as u32, y as u32, v as u32)
    })
    .collect()
}

fn check_rgb<const ALPHA: bool>(width: usize, matrix: ColorMatrix, full_range: bool) {
  let p = pseudo_random_v410(width, 0xAA55);
  let bpp = if ALPHA { 4 } else { 3 };
  let mut s = std::vec![0u8; width * bpp];
  let mut k = std::vec![0u8; width * bpp];
  scalar::v410_to_rgb_or_rgba_row::<ALPHA, false>(&p, &mut s, width, matrix, full_range);
  unsafe {
    v410_to_rgb_or_rgba_row::<ALPHA, false>(&p, &mut k, width, matrix, full_range);
  }
  assert_eq!(
    s,
    k,
    "NEON v410→{} diverges (width={width}, matrix={matrix:?}, full_range={full_range})",
    if ALPHA { "RGBA" } else { "RGB" }
  );
}

fn check_rgb_u16<const ALPHA: bool>(width: usize, matrix: ColorMatrix, full_range: bool) {
  let p = pseudo_random_v410(width, 0xAA55);
  let bpp = if ALPHA { 4 } else { 3 };
  let mut s = std::vec![0u16; width * bpp];
  let mut k = std::vec![0u16; width * bpp];
  scalar::v410_to_rgb_u16_or_rgba_u16_row::<ALPHA, false>(&p, &mut s, width, matrix, full_range);
  unsafe {
    v410_to_rgb_u16_or_rgba_u16_row::<ALPHA, false>(&p, &mut k, width, matrix, full_range);
  }
  assert_eq!(
    s,
    k,
    "NEON v410→{} u16 diverges (width={width}, matrix={matrix:?}, full_range={full_range})",
    if ALPHA { "RGBA" } else { "RGB" }
  );
}

fn check_luma(width: usize) {
  let p = pseudo_random_v410(width, 0xC001);
  let mut s = std::vec![0u8; width];
  let mut k = std::vec![0u8; width];
  scalar::v410_to_luma_row::<false>(&p, &mut s, width);
  unsafe {
    v410_to_luma_row::<false>(&p, &mut k, width);
  }
  assert_eq!(s, k, "NEON v410→luma diverges (width={width})");
}

fn check_luma_u16(width: usize) {
  let p = pseudo_random_v410(width, 0xC001);
  let mut s = std::vec![0u16; width];
  let mut k = std::vec![0u16; width];
  scalar::v410_to_luma_u16_row::<false>(&p, &mut s, width);
  unsafe {
    v410_to_luma_u16_row::<false>(&p, &mut k, width);
  }
  assert_eq!(s, k, "NEON v410→luma u16 diverges (width={width})");
}

#[test]
#[cfg_attr(miri, ignore = "NEON SIMD intrinsics unsupported by Miri")]
fn neon_v410_rgb_matches_scalar_all_matrices() {
  for m in [
    ColorMatrix::Bt601,
    ColorMatrix::Bt709,
    ColorMatrix::Bt2020Ncl,
    ColorMatrix::Smpte240m,
    ColorMatrix::Fcc,
    ColorMatrix::YCgCo,
  ] {
    for full in [true, false] {
      check_rgb::<false>(8, m, full);
      check_rgb::<true>(8, m, full);
      check_rgb_u16::<false>(8, m, full);
      check_rgb_u16::<true>(8, m, full);
    }
  }
}

#[test]
#[cfg_attr(miri, ignore = "NEON SIMD intrinsics unsupported by Miri")]
fn neon_v410_matches_scalar_widths() {
  for w in [1usize, 2, 3, 4, 5, 7, 8, 9, 15, 16, 17, 1920, 1921, 1923] {
    check_rgb::<false>(w, ColorMatrix::Bt709, false);
    check_rgb::<true>(w, ColorMatrix::Bt709, true);
    check_rgb_u16::<false>(w, ColorMatrix::Bt2020Ncl, true);
    check_rgb_u16::<true>(w, ColorMatrix::Bt601, false);
  }
}

#[test]
#[cfg_attr(miri, ignore = "NEON SIMD intrinsics unsupported by Miri")]
fn neon_v410_luma_matches_scalar_widths() {
  for w in [1usize, 2, 3, 4, 5, 7, 8, 9, 15, 16, 17, 1920, 1921, 1923] {
    check_luma(w);
    check_luma_u16(w);
  }
}

/// Build a V410 packed buffer for `width` pixels where:
/// - Y[n] = n + 1 (10-bit value; luma_u16 output = n+1 directly)
/// - U[n] = 2n + 1 (10-bit value; one U per pixel — V410 is 4:4:4)
/// - V[n] = 512 (neutral 10-bit midpoint, bias-subtracted = 0)
///
/// V410 layout (per u32 word):
///   bits[29:20] = V (10-bit)
///   bits[19:10] = Y (10-bit)
///   bits[9:0]   = U (10-bit)
///   bits[31:30] = padding (zero)
fn build_v410_packed_y_n_plus_1_u_2n_plus_1_v_neutral(width: usize) -> std::vec::Vec<u32> {
  (0..width)
    .map(|n| {
      let y = (n as u32) + 1;
      let u = 2 * (n as u32) + 1;
      let v = 512u32;
      (v << 20) | (y << 10) | u
    })
    .collect()
}

/// Multi-channel lane-order regression — encodes pixel index in BOTH Y AND U
/// so we catch per-channel asymmetric mask bugs that a Y-only test would miss.
/// Pattern from Ship 12d AYUV64 backport.
///
/// Asserts:
/// - `luma_u16_row` output = [1..=W] (Y values direct, no shift)
/// - SIMD RGB output == scalar RGB output (any lane-order bug diverges)
#[test]
#[cfg_attr(
  miri,
  ignore = "SIMD-dispatched row kernels use intrinsics unsupported by Miri"
)]
fn neon_v410_lane_order_per_pixel_y_and_u() {
  const W: usize = 8;
  let packed = build_v410_packed_y_n_plus_1_u_2n_plus_1_v_neutral(W);

  // Part 1: Luma natural-order (u16, no shift loss)
  let mut luma = std::vec![0u16; W];
  unsafe {
    v410_to_luma_u16_row::<false>(&packed, &mut luma, W);
  }
  let expected_luma: std::vec::Vec<u16> = (1..=W as u16).collect();
  assert_eq!(luma, expected_luma, "neon v410 luma reorder bug");

  // Part 2: SIMD vs scalar parity (catches U/Y channel swap bugs)
  let mut simd_rgb = std::vec![0u8; W * 3];
  let mut scalar_rgb = std::vec![0u8; W * 3];
  unsafe {
    v410_to_rgb_or_rgba_row::<false, false>(
      &packed,
      &mut simd_rgb,
      W,
      crate::ColorMatrix::Bt709,
      false,
    );
  }
  scalar::v410_to_rgb_or_rgba_row::<false, false>(
    &packed,
    &mut scalar_rgb,
    W,
    crate::ColorMatrix::Bt709,
    false,
  );
  assert_eq!(
    simd_rgb, scalar_rgb,
    "neon v410 SIMD vs scalar diverges — lane-order bug"
  );
}

/// SIMD-level BE-vs-LE parity test: probes the `bswap_u32x4_if_be<BE>`
/// gate at the SIMD layer (per-backend tests use `BE=false`; dispatcher
/// BE-vs-LE comparisons use `use_simd=false`, so this gate is otherwise
/// untested).
///
/// On an LE host:
/// - SIMD `<BE=false>` on LE input  → gate doesn't fire → exercises no-swap path.
/// - SIMD `<BE=true>`  on BE input  → gate fires        → exercises swap path.
///
/// On a BE host (s390x QEMU when Phase 3 lands), the same test exercises the
/// opposite quadrant.
///
/// Widths chosen to cover the SIMD main loop (>=8 multiples) + scalar tail
/// (e.g. 17 = 16-lane main + 1 tail; 33 = 32-lane main + 1 tail).
#[test]
#[cfg_attr(miri, ignore = "NEON SIMD intrinsics unsupported by Miri")]
fn neon_v410_be_le_simd_parity() {
  // Construct LE/BE buffers from raw bytes via `to_le_bytes` / `to_be_bytes`
  // so semantics are host-independent. The earlier `swap_bytes` pattern only
  // validated this on LE hosts (on BE hosts both buffers degenerate to
  // equal-but-wrong values and the test passed vacuously).
  for w in [7usize, 8, 17, 33] {
    let intended = pseudo_random_v410(w, 0xBEEF);
    let le_bytes: std::vec::Vec<u8> = intended.iter().flat_map(|v| v.to_le_bytes()).collect();
    let be_bytes: std::vec::Vec<u8> = intended.iter().flat_map(|v| v.to_be_bytes()).collect();
    let le: std::vec::Vec<u32> = le_bytes
      .chunks_exact(4)
      .map(|b| u32::from_ne_bytes([b[0], b[1], b[2], b[3]]))
      .collect();
    let be: std::vec::Vec<u32> = be_bytes
      .chunks_exact(4)
      .map(|b| u32::from_ne_bytes([b[0], b[1], b[2], b[3]]))
      .collect();

    // u8 RGB / RGBA
    for (alpha, bpp) in [(false, 3usize), (true, 4)] {
      let mut out_le = std::vec![0u8; w * bpp];
      let mut out_be = std::vec![0u8; w * bpp];
      unsafe {
        if alpha {
          v410_to_rgb_or_rgba_row::<true, false>(&le, &mut out_le, w, ColorMatrix::Bt709, false);
          v410_to_rgb_or_rgba_row::<true, true>(&be, &mut out_be, w, ColorMatrix::Bt709, false);
        } else {
          v410_to_rgb_or_rgba_row::<false, false>(&le, &mut out_le, w, ColorMatrix::Bt709, false);
          v410_to_rgb_or_rgba_row::<false, true>(&be, &mut out_be, w, ColorMatrix::Bt709, false);
        }
      }
      assert_eq!(
        out_le, out_be,
        "neon v410 BE-vs-LE SIMD parity failed (alpha={alpha}, w={w}) — endian gate broken"
      );
    }

    // u16 RGB / RGBA
    for (alpha, bpp) in [(false, 3usize), (true, 4)] {
      let mut out_le = std::vec![0u16; w * bpp];
      let mut out_be = std::vec![0u16; w * bpp];
      unsafe {
        if alpha {
          v410_to_rgb_u16_or_rgba_u16_row::<true, false>(
            &le,
            &mut out_le,
            w,
            ColorMatrix::Bt709,
            true,
          );
          v410_to_rgb_u16_or_rgba_u16_row::<true, true>(
            &be,
            &mut out_be,
            w,
            ColorMatrix::Bt709,
            true,
          );
        } else {
          v410_to_rgb_u16_or_rgba_u16_row::<false, false>(
            &le,
            &mut out_le,
            w,
            ColorMatrix::Bt709,
            true,
          );
          v410_to_rgb_u16_or_rgba_u16_row::<false, true>(
            &be,
            &mut out_be,
            w,
            ColorMatrix::Bt709,
            true,
          );
        }
      }
      assert_eq!(
        out_le, out_be,
        "neon v410 BE-vs-LE SIMD parity failed (u16, alpha={alpha}, w={w}) — endian gate broken"
      );
    }

    // luma u8
    {
      let mut out_le = std::vec![0u8; w];
      let mut out_be = std::vec![0u8; w];
      unsafe {
        v410_to_luma_row::<false>(&le, &mut out_le, w);
        v410_to_luma_row::<true>(&be, &mut out_be, w);
      }
      assert_eq!(
        out_le, out_be,
        "neon v410 BE-vs-LE SIMD parity failed (luma u8, w={w}) — endian gate broken"
      );
    }

    // luma u16
    {
      let mut out_le = std::vec![0u16; w];
      let mut out_be = std::vec![0u16; w];
      unsafe {
        v410_to_luma_u16_row::<false>(&le, &mut out_le, w);
        v410_to_luma_u16_row::<true>(&be, &mut out_be, w);
      }
      assert_eq!(
        out_le, out_be,
        "neon v410 BE-vs-LE SIMD parity failed (luma u16, w={w}) — endian gate broken"
      );
    }
  }
}