#!/bin/sh
# build-gpu-burn.sh — build gpu_burn stress tool and output static-ish binary to DIST_DIR
#
# gpu_burn requires nvcc (CUDA toolkit). This script downloads a minimal CUDA toolkit
# runfile, extracts only nvcc + headers, builds gpu_burn, then cleans up the toolkit.
#
# Output: $DIST_DIR/gpu_burn  (ready to copy into ISO vendor/)
#
# Usage: sh build-gpu-burn.sh <dist-dir>

set -e

DIST_DIR="$1"
[ -n "$DIST_DIR" ] || { echo "usage: $0 <dist-dir>"; exit 1; }
mkdir -p "$DIST_DIR"

OUTPUT="$DIST_DIR/gpu_burn"
if [ -f "$OUTPUT" ] && [ -s "$OUTPUT" ]; then
    echo "=== gpu_burn cached: $OUTPUT ==="
    exit 0
fi

# CUDA toolkit version for building — only nvcc + headers needed, not the full runtime.
# Must be <= max CUDA version supported by the NVIDIA driver in VERSIONS.
# Driver 590.48.01 supports up to CUDA 13.1; use 12.6 (stable, widely tested).
CUDA_VERSION="12.8.1"
CUDA_BUILD="570.124.06"
CUDA_RUN="/var/tmp/cuda-${CUDA_VERSION}.run"
CUDA_DIR="/var/tmp/cuda-toolkit-${CUDA_VERSION}"

echo "=== building gpu_burn (CUDA ${CUDA_VERSION}) ==="

# Install build dependencies
apk add --quiet gcc g++ make git wget libxml2

# Download CUDA toolkit runfile if not cached
if [ ! -s "$CUDA_RUN" ]; then
    echo "=== downloading CUDA ${CUDA_VERSION} toolkit ==="
    wget -q --show-progress -O "$CUDA_RUN" \
        "https://developer.download.nvidia.com/compute/cuda/${CUDA_VERSION}/local_installers/cuda_${CUDA_VERSION}_${CUDA_BUILD}_linux.run"
fi

# Extract toolkit (nvcc + headers only — skip driver, samples, docs to save time/space)
if [ ! -d "$CUDA_DIR/bin/nvcc" ] && [ ! -f "$CUDA_DIR/bin/nvcc" ]; then
    echo "=== extracting CUDA toolkit ==="
    rm -rf "$CUDA_DIR"
    sh "$CUDA_RUN" \
        --silent \
        --toolkit \
        --toolkitpath="$CUDA_DIR" \
        --no-opengl-libs \
        --no-drm \
        --override 2>&1 | tail -5
fi

NVCC="$CUDA_DIR/bin/nvcc"
[ -f "$NVCC" ] || { echo "ERROR: nvcc not found after extraction: $NVCC"; exit 1; }
echo "nvcc: $("$NVCC" --version | head -1)"

# Clone gpu_burn source
GPU_BURN_DIR="/var/tmp/gpu-burn-src"
if [ ! -d "$GPU_BURN_DIR/.git" ]; then
    echo "=== cloning gpu-burn ==="
    git clone --depth=1 https://github.com/wilicc/gpu-burn.git "$GPU_BURN_DIR"
else
    echo "=== gpu-burn source already cloned ==="
fi

# Build
echo "=== building gpu_burn ==="
cd "$GPU_BURN_DIR"
make clean 2>/dev/null || true
CUDA_PATH="$CUDA_DIR" make 2>&1

[ -f "$GPU_BURN_DIR/gpu_burn" ] || { echo "ERROR: gpu_burn binary not produced"; exit 1; }

cp "$GPU_BURN_DIR/gpu_burn" "$OUTPUT"
cp "$GPU_BURN_DIR/compare.ptx" "$(dirname "$OUTPUT")/compare.ptx" 2>/dev/null || true

echo "=== gpu_burn build complete ==="
ls -lh "$OUTPUT"
echo "NOTE: compare.ptx must be present in same dir as gpu_burn at runtime"