#!/bin/bash
# Compile a preprocessed UCE unit into a PIC WebAssembly side module.
set -euo pipefail
cd "$(dirname "$0")"
cd ..

SRC_DIR="$1"
DEST_DIR="$2"
SRC_FN="$3"
PP_FN="$4"
WASM_FN="$5"
UNIT_CACHE_DIR="${6:-$DEST_DIR}"

SDK=${WASI_SDK:-/opt/wasi-sdk}
ABI_VERSION=${UCE_UNIT_ABI_VERSION:-$(awk '/^#define UCE_WASM_CORE_ABI_VERSION / {print $3; exit}' src/wasm/abi.h)}
ROOT=$(pwd)
OBJ_FN="$DEST_DIR/$PP_FN.wasm.o"
ABI_TMP="$DEST_DIR/$PP_FN.uce-abi.txt"
MODULE_TMP="$DEST_DIR/$PP_FN.uce-module.txt"
WASM_TMP="$DEST_DIR/$WASM_FN.tmp.$$"
MAP_TMP="$DEST_DIR/$WASM_FN.source-map.tmp.$$"
PCH_ENABLED=${UCE_WASM_UNIT_PCH:-1}
PCH_DIR=${UCE_WASM_PCH_DIR:-$UNIT_CACHE_DIR/.pch}
COMMON_FLAGS=(
	--target=wasm32-wasip1
	-fPIC -fvisibility=hidden -fvisibility-inlines-hidden
	-O1 -g -std=c++20
	# The server captures this script's output and treats any non-empty result as
	# a compile failure (then drops the .wasm), so a successful build must be
	# silent; warnings are intentionally suppressed.
	-w
	# must match the core build ABI: units with RTTI/EH enabled import
	# typeinfo/unwind symbols the -fno-rtti/-fno-exceptions core cannot provide
	-fno-exceptions -fno-rtti
	-D__UCE_WASM_UNIT__
	-DPLATFORM_NAME=\"wasm32-wasip1\"
)

if [ ! -x "$SDK/bin/clang++" ] || [ ! -x "$SDK/bin/wasm-ld" ] || [ ! -x "$SDK/bin/llvm-objcopy" ] || [ ! -x "$SDK/bin/llvm-dwarfdump" ]; then
	echo "wasi-sdk tools not found; set WASI_SDK" >&2
	exit 1
fi

TOOLCHAIN_ID=$(${SDK}/bin/clang++ --version | head -n 1)
HEADER_HASH=$(find src/lib -maxdepth 1 -name '*.h' -type f -print0 | sort -z | xargs -0 sha1sum | sha1sum | cut -c1-16)
FLAGS_HASH=$(printf '%s\0' "${COMMON_FLAGS[@]}" -Isrc/lib | sha1sum | cut -c1-16)
PCH_KEY=$(printf '%s\n%s\n%s\n%s\n' "$ABI_VERSION" "$TOOLCHAIN_ID" "$HEADER_HASH" "$FLAGS_HASH" | sha1sum | cut -c1-16)
PCH_FN="$PCH_DIR/uce_lib-wasm-unit-$PCH_KEY.pch"
PCH_TMP="$PCH_FN.tmp.$$"

mkdir -p "$DEST_DIR" >/dev/null 2>&1
trap 'rm -f "$OBJ_FN" "$ABI_TMP" "$MODULE_TMP" "$WASM_TMP" "$MAP_TMP" "$PCH_TMP"' EXIT

build_pch_if_needed() {
	if [ "$PCH_ENABLED" = "0" ]; then
		return 0
	fi
	mkdir -p "$PCH_DIR"
	exec 9>"$PCH_FN.lock"
	flock 9
	if [ -s "$PCH_FN" ] && [ -z "$(find src/lib -maxdepth 1 -name '*.h' -type f -newer "$PCH_FN" -print -quit)" ]; then
		flock -u 9
		exec 9>&-
		return 0
	fi
	"$SDK/bin/clang++" "${COMMON_FLAGS[@]}" \
		-Isrc/lib \
		-x c++-header src/lib/uce_lib.h -o "$PCH_TMP"
	mv "$PCH_TMP" "$PCH_FN"
	flock -u 9
	exec 9>&-
}

cat > "$ABI_TMP" <<EOF
format=uce-wasm-unit-abi-v1
unit_abi_version=$ABI_VERSION
toolchain=$TOOLCHAIN_ID
source=$SRC_FN
EOF
printf '%s' "$(basename "$WASM_TMP")" > "$MODULE_TMP"

build_pch_if_needed
PCH_FLAGS=()
if [ "$PCH_ENABLED" != "0" ]; then
	PCH_FLAGS=(-include-pch "$PCH_FN")
fi

"$SDK/bin/clang++" "${COMMON_FLAGS[@]}" \
	-I"$SRC_DIR" -I"$ROOT/src/lib" \
	"${PCH_FLAGS[@]}" \
	-c "$DEST_DIR/$PP_FN" -o "$OBJ_FN"

"$SDK/bin/wasm-ld" -shared --experimental-pic \
	--gc-sections \
	--unresolved-symbols=import-dynamic \
	--Bsymbolic \
	"$OBJ_FN" -o "$WASM_TMP" \
	--export-if-defined=__uce_set_current_request \
	--export-if-defined=__uce_render \
	--export-if-defined=__uce_component \
	--export-if-defined=__uce_websocket \
	--export-if-defined=__uce_cli \
	--export-if-defined=__uce_serve_http \
	--export-if-defined=__uce_once \
	--export-if-defined=__uce_init

python3 scripts/build_unit_source_map.py \
	--dwarfdump "$SDK/bin/llvm-dwarfdump" \
	--wasm "$WASM_TMP" \
	--module "$(basename "$WASM_TMP")" \
	--output "$MAP_TMP"

"$SDK/bin/llvm-objcopy" --strip-debug \
	--add-section=uce.abi="$ABI_TMP" \
	--add-section=uce.module="$MODULE_TMP" \
	"$WASM_TMP"

python3 scripts/check_unit_wasm.py "$WASM_TMP" --abi-version "$ABI_VERSION" --llvm-nm "$SDK/bin/llvm-nm"
mv "$MAP_TMP" "$DEST_DIR/$WASM_FN.source-map"
mv "$WASM_TMP" "$DEST_DIR/$WASM_FN"

rm -f "$OBJ_FN" "$ABI_TMP" "$MODULE_TMP"