#!/bin/sh
set -e
cd "$(dirname "$0")/.."
ZENA=${ZENA:-$(command -v zena-cli || true)}
if [ ! -x "$ZENA" ]; then
  echo "build: no Zena compiler. Put zena-cli on PATH or set ZENA to its path (see CONTRIBUTING.md)." >&2
  exit 1
fi
BIN=./node_modules/.bin
# Only the features zena already emits, so wasm-opt can't introduce ones engines don't ship yet
# (--all-features yields custom-descriptor `exact` types that Node 24 rejects). SIMD is for engine/rt.wat's v128
# scan loops (fixed-width SIMD ships in every engine that ships WasmGC).
FEATURES="--enable-simd --enable-gc --enable-reference-types --enable-bulk-memory --enable-sign-ext --enable-mutable-globals --enable-nontrapping-float-to-int"
# Both artifacts export only i32 functions plus memory, so no caller outside this
# module graph can reach an internal function or type: --closed-world is valid, and
# unlocks --gufa-optimizing's whole-program type/value inference.
# --one-caller-inline-max-function-size caps -Oz's single-caller inlining, which
# otherwise builds one function too big for V8 to keep in Liftoff: TurboFan then
# optimizes it, which is most of the RSS a short-lived call pays (7.9MiB at the
# default cap, 1.8MiB at 150; raw grows by about 150B, gzip drops by about 40B).
# --low-memory-unused lets optimize-added-constants fold `p + C` into a load or store's offset, which is
# exact unless p + C wraps past 4GiB into the low 1KiB; the engine's addresses are all small positive
# sums, and layout.mjs keeps the static data above 1KiB so nothing lives in that range anyway.
CLOSED="--low-memory-unused --closed-world --gufa-optimizing --one-caller-inline-max-function-size=150"
mkdir -p build

# Static tables (engine/*.wat, written by scripts/gen) are active data segments in modules that import the
# engine's memory; zena cannot declare a data segment itself, so wasm-merge links them in after compiling.
# engine/rt.wat, merged into every build, supplies the instructions zena has no intrinsic for; its exports
# are only there to satisfy the zena module's "rt" imports, so they are removed after the merge.
# merge <zena.wasm> <out.wasm> <data.wat>...
merge() {
  src=$1
  out=$2
  shift 2
  args=""
  for w in "$@"; do
    b=build/$(basename "$w" .wat).data.wasm
    "$BIN/wasm-as" "$w" -o "$b"
    args="$args $b $(basename "$w" .wat)"
  done
  # shellcheck disable=SC2086
  "$BIN/wasm-as" engine/rt.wat --enable-bulk-memory --enable-simd -o build/rt.wasm
  "$BIN/wasm-merge" "$src" engine build/rt.wasm rt $args $FEATURES -o "$out"
  "$BIN/wasm-opt" "$out" $FEATURES --remove-exports --pass-arg=remove-exports@move -o "$out"
}

# engine/hooks.zena is swapped in before each compile: strip.zena imports it, never
# engine/downlevel.zena directly, so the erase build's import graph never reaches
# engine/downlevel.zena and wasm-opt has no dead downlevel code to chase.
cp engine/hooks-erase.zena engine/hooks.zena
"$ZENA" -O s build engine/main-erase.zena -o build/erase.zena.wasm --target js
# -O2 rather than -Oz: about 1% more gzip for 8-20% more throughput (docs/architecture.md). The one-caller
# inline cap in $CLOSED, not the -O level, is what keeps post-tier-up RSS flat.
merge build/erase.zena.wasm build/erase.merged.wasm engine/keywords.wat engine/chartable.wat
"$BIN/wasm-opt" build/erase.merged.wasm $FEATURES $CLOSED -O2 --converge --precompute-propagate --simplify-locals-nostructure -O2 --converge -o build/erase.wasm

cp engine/hooks-downlevel.zena engine/hooks.zena
"$ZENA" -O s build engine/main-downlevel.zena -o build/downlevel.zena.wasm --target js
merge build/downlevel.zena.wasm build/downlevel.merged.wasm engine/keywords.wat engine/chartable.wat engine/downlevel-text.wat
"$BIN/wasm-opt" build/downlevel.merged.wasm $FEATURES $CLOSED -O2 --converge --precompute-propagate --simplify-locals-nostructure -O2 --converge -o build/downlevel.wasm
"$ZENA" -O s build engine/debug.zena -o build/downlevel-debug.zena.wasm --target js
merge build/downlevel-debug.zena.wasm build/downlevel-debug.wasm engine/keywords.wat engine/chartable.wat engine/downlevel-text.wat
rm -f engine/hooks.zena

wc -c build/erase.zena.wasm | awk '{print "erase.zena.wasm " $1 " bytes (before wasm-opt)"}'
wc -c build/erase.wasm | awk '{print "erase.wasm " $1 " bytes"}'
gzip -9c build/erase.wasm | wc -c | awk '{print "erase.wasm.gz " $1 " bytes"}'
wc -c build/downlevel.wasm | awk '{print "downlevel.wasm " $1 " bytes"}'
gzip -9c build/downlevel.wasm | wc -c | awk '{print "downlevel.wasm.gz " $1 " bytes"}'