#!/bin/bash
# Build libflame as a WebAssembly static library using Emscripten.
#
# Usage: ./build-wasm.sh              (single-threaded)
#        PTHREAD=1 ./build-wasm.sh    (compile with -pthread so the library
#            can link into shared-memory/threaded wasm modules; installs as
#            libflame-mt.a alongside the single-threaded libflame.a)
# Requires: emsdk (expected at ~/emsdk, or already on PATH)
set -euo pipefail

PTHREAD=${PTHREAD:-0}
EXTRA_CFLAGS=""
if [ "$PTHREAD" = "1" ]; then
  EXTRA_CFLAGS=" -pthread"
fi

cd "$(dirname "$0")"
ROOT=$(pwd)
PREFIX=$ROOT/install

if ! command -v emcc >/dev/null 2>&1; then
  source ~/emsdk/emsdk_env.sh
fi

# 1. Clone
if [ ! -d libflame ]; then
  git clone --depth 1 https://github.com/flame/libflame
fi
cd libflame

# 2. Patch: libflame declares the Fortran-style BLAS as returning void, but the
#    f2c'd built-in BLAS defines those routines returning int. Harmless on
#    native targets, but a fatal signature mismatch under wasm-ld (calls
#    through mismatched signatures fail wasm validation).
sed -i 's/^void     F77_/int      F77_/' src/base/flamec/blis/include/blis_prototypes_blas.h

# 3. Configure. Notes:
#    - No --host triple: the bundled config.sub predates wasm; emcc via CC is enough.
#    - Fortran autodetection must be off (Emscripten has no Fortran compiler).
#    - builtin-blas uses the f2c C translations, so the library is self-contained.
#    - lapack2flame + legacy-lapack adds a full LAPACK API (f2c C sources, no Fortran).
emconfigure ./configure \
  --prefix="$PREFIX" \
  --disable-autodetect-f77-ldflags \
  --disable-autodetect-f77-name-mangling \
  --enable-builtin-blas \
  --enable-lapack2flame \
  --enable-legacy-lapack \
  --disable-dynamic-build \
  --enable-static-build \
  --enable-vector-intrinsics=none \
  CC=emcc AR=emar RANLIB=emranlib

# 4. configure doesn't know optimization flags for the "emcc" vendor; add -O2.
sed -i "s/^COPTFLAGS    := *\$/COPTFLAGS    := -O2$EXTRA_CFLAGS/" config/*/config.mk

# 5. Build.
make -j"$(nproc)"

# 6. Re-archive from the full object tree. The Makefile's incremental
#    archiving (ar_obj_list) only covers objects compiled in the current make
#    run, which can leave the archive stale or incomplete across rebuilds.
LIBDIR=$(dirname "$(find lib -name libflame.a)")
rm -f "$LIBDIR/libflame.a"
find obj -name '*.o' | sort | xargs -n 500 emar crs "$LIBDIR/libflame.a"

# 7. Install (single flattened FLAME.h + libflame.a).
if [ "$PTHREAD" = "1" ]; then
  mkdir -p "$PREFIX/lib"
  cp "$LIBDIR/libflame.a" "$PREFIX/lib/libflame-mt.a"
  echo "Done. Library: $PREFIX/lib/libflame-mt.a"
else
  make install
  echo "Done. Library: $PREFIX/lib/libflame.a  Header: $PREFIX/include/FLAME.h"
fi