// CNN v3 — Encoder level 0
// Conv(20->4, 3x3, zero-pad) + FiLM + ReLU
//
// Input:  feat_tex0 (rgba32uint, 8xf16), feat_tex1 (rgba32uint, 12ch u8norm)  full-res
// Output: enc0_out  (rgba16float, 4ch)                                   full-res
//
// Weight layout (f16, OIHW + bias):
//   [0 .. 20*4*9)  conv: w[out][in][ky][kx]
//   [720 .. +4)    bias: b[out]

#include "cnn_v3/common"

const ENC0_IN:  u32 = 20u;
const ENC0_OUT: u32 = 4u;

struct Params {
    weight_offset: u32,
    _pad: vec3u,
    gamma: vec4f,
    beta:  vec4f,
}

@group(0) @binding(0) var feat_tex0: texture_2d<u32>;
@group(0) @binding(1) var feat_tex1: texture_2d<u32>;
@group(0) @binding(2) var<storage, read> weights: array<u32>;
@group(0) @binding(3) var<uniform> params: Params;
@group(0) @binding(4) var enc0_out: texture_storage_2d<rgba16float, write>;

// Unpack all 20 feature channels at coord. Returns zeros for OOB (zero-padding).
fn load_feat(coord: vec2i, dims: vec2i) -> array<f32, 20> {
    if (coord.x < 0 || coord.y < 0 || coord.x >= dims.x || coord.y >= dims.y) {
        return array<f32, 20>(0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.);
    }
    let t0 = textureLoad(feat_tex0, coord, 0);
    let t1 = textureLoad(feat_tex1, coord, 0);
    let a = unpack2x16float(t0.x);
    let b = unpack2x16float(t0.y);
    let c = unpack2x16float(t0.z);
    let d = unpack2x16float(t0.w);
    let e = unpack4x8unorm(t1.x);
    let f = unpack4x8unorm(t1.y);
    let g = unpack4x8unorm(t1.z);
    return array<f32, 20>(
        a.x, a.y, b.x, b.y, c.x, c.y, d.x, d.y,
        e.x, e.y, e.z, e.w,
        f.x, f.y, f.z, f.w,
        g.x, g.y, g.z, g.w
    );
}

@compute @workgroup_size(8, 8)
fn enc0_main(@builtin(global_invocation_id) id: vec3u) {
    let coord = vec2i(id.xy);
    let dims  = vec2i(textureDimensions(feat_tex0));
    if (coord.x >= dims.x || coord.y >= dims.y) { return; }

    let wo = params.weight_offset;
    var out: array<f32, ENC0_OUT>;

    for (var o: u32 = 0u; o < ENC0_OUT; o++) {
        var sum = get_w(wo, ENC0_OUT * ENC0_IN * 9u + o);  // bias
        for (var ky: i32 = -1; ky <= 1; ky++) {
            for (var kx: i32 = -1; kx <= 1; kx++) {
                let feat = load_feat(coord + vec2i(kx, ky), dims);
                let ki   = u32(ky + 1) * 3u + u32(kx + 1);
                for (var i: u32 = 0u; i < ENC0_IN; i++) {
                    sum += get_w(wo, o * ENC0_IN * 9u + i * 9u + ki) * feat[i];
                }
            }
        }
        out[o] = max(0.0, params.gamma[o] * sum + params.beta[o]);
    }

    textureStore(enc0_out, coord, vec4f(out[0], out[1], out[2], out[3]));
}