#!/usr/bin/env bash
# build_zstd_linux.sh - 用官方源码编译 libzstd.a (x86_64 Linux)
# 产出：linux/lib/libzstd.a  （覆盖旧版本）
#
# 用法（在 WSL 或 Linux 下）：
#   cd linux && bash build_zstd_linux.sh

set -euo pipefail
cd "$(dirname "$0")"

ZSTD_VERSION="1.5.6"
ZSTD_TAR="zstd-${ZSTD_VERSION}.tar.gz"
ZSTD_URL="https://github.com/facebook/zstd/releases/download/v${ZSTD_VERSION}/${ZSTD_TAR}"
ZSTD_DIR="zstd-${ZSTD_VERSION}"
BUILD_DIR="zstd_build"
OUT_DIR="lib"

# --- 下载源码 ---
if [[ ! -d "$ZSTD_DIR" ]]; then
    echo "Downloading zstd $ZSTD_VERSION..."
    wget -q "$ZSTD_URL" -O "$ZSTD_TAR" || curl -sSL "$ZSTD_URL" -o "$ZSTD_TAR"
    tar xf "$ZSTD_TAR"
    rm "$ZSTD_TAR"
fi

# --- CMake 构建 ---
rm -rf "$BUILD_DIR"
cmake \
    -B "$BUILD_DIR" -S "$ZSTD_DIR/build/cmake" \
    -DCMAKE_BUILD_TYPE=Release \
    -DCMAKE_C_FLAGS="-O2 -g0" \
    -DZSTD_BUILD_STATIC=ON \
    -DZSTD_BUILD_SHARED=OFF \
    -DZSTD_BUILD_PROGRAMS=OFF \
    -DZSTD_BUILD_TESTS=OFF \
    -DZSTD_LEGACY_SUPPORT=0

cmake --build "$BUILD_DIR" --config Release -j"$(nproc)"

# --- 拷贝产物 ---
mkdir -p "$OUT_DIR"
cp "$BUILD_DIR/lib/libzstd.a" "$OUT_DIR/libzstd.a"
strip --strip-debug "$OUT_DIR/libzstd.a" 2>/dev/null || true
ls -lh "$OUT_DIR/libzstd.a"

rm -rf "$BUILD_DIR" "$ZSTD_DIR"

echo
echo "===== Done ====="
echo "libzstd.a 已写入 linux/lib/libzstd.a"