#!/usr/bin/env bash
# The package a site serves under /wai/pkg-vector/: the sink of wai.graphics.vector as
# one WebAssembly module, wai_vector.wasm, which a page instantiates with no imports
# and no glue script.
#
#   bash wai/wai-vector/wasm/build-pkg.sh [<out-dir>]
#
# Writes <out-dir>/wai_vector.wasm (default wai/wai-vector/wasm/dist/pkg-vector, which
# git ignores) and prints its size and SHA-256.
#
# The module is WebAssembly 1.0 and nothing later: no SIMD, no threads, no bulk
# memory, no sign-extension operators, no saturating conversions, no reference types,
# no multi-value. That is enforced twice.
#
#   1. By the target. The module is built for wasm32v1-none, whose precompiled core
#      and alloc are themselves WebAssembly 1.0. Those of wasm32-unknown-unknown are
#      not: they use bulk memory, sign extension and reference types, and the linker
#      carries what they use into any module linked against them, whatever
#      -C target-cpu or -C target-feature the build passes. That target has no std, so
#      the crate is no_std with its own allocator (src/heap.rs).
#   2. By reading the result. check-mvp.mjs decodes the module that was built: every
#      section, type, segment and instruction must be 1.0's; and, as a package, it
#      must have no imports, no exported function with a 64-bit parameter or result,
#      no floating point, and exactly the exported functions listed below. The build
#      fails otherwise, and leaves no module in <out-dir>.
#
# The crate is built without its default feature, so the module has the sink's
# exports and not the recomputation of the conformance vectors.
#
# The same source gives different module bytes on different hosts, so the SHA-256
# printed here names this build and not the source. What every host's build has in
# common is what it computes: the frames of wai/vector-conformance, checked in three
# browser engines by wai/wai-vector/browser/run.mjs.
#
# Needs bash, cargo with the wasm32v1-none target (rustup target add wasm32v1-none)
# and node >= 18.
set -euo pipefail

if [ $# -gt 1 ]; then
  echo "usage: bash build-pkg.sh [<out-dir>]" >&2
  exit 2
fi
CRATE="$(cd "$(dirname "$0")" && pwd -P)"
OUT="${1:-$CRATE/dist/pkg-vector}"
# The package's exported functions. A function added to the sink is added here.
FUNCTIONS=wv_add_set,wv_alloc,wv_close,wv_cost,wv_free,wv_open,wv_out_len,wv_out_ptr,wv_projection,wv_render,wv_sha256,wv_transcript

for t in cargo node; do
  command -v "$t" >/dev/null || { echo "pkg-vector: needs $t" >&2; exit 1; }
done
mkdir -p "$OUT"
OUT="$(cd "$OUT" && pwd -P)"
rm -f "$OUT/wai_vector.wasm"

cd "$CRATE"
# Asked of the toolchain this crate builds with, before anything is built.
LIBDIR="$(rustc --print target-libdir --target wasm32v1-none 2>/dev/null || true)"
if [ -z "$LIBDIR" ] || [ ! -d "$LIBDIR" ]; then
  echo "pkg-vector: this toolchain has no wasm32v1-none target (rustup target add wasm32v1-none)" >&2
  exit 1
fi
cargo build --locked --release --target wasm32v1-none --no-default-features
TARGET_DIR="$(cargo metadata --locked --format-version 1 --no-deps \
  | node -e 'let s = ""; process.stdin.on("data", (d) => { s += d; }).on("end", () => console.log(JSON.parse(s).target_directory));')"
BUILT="$TARGET_DIR/wasm32v1-none/release/wai_vector_wasm.wasm"
[ -f "$BUILT" ] || { echo "pkg-vector: the build left no $BUILT" >&2; exit 1; }

node "$CRATE/check-mvp.mjs" "$BUILT" --package --functions "$FUNCTIONS"

cp "$BUILT" "$OUT/wai_vector.wasm"
echo "pkg-vector: $OUT/wai_vector.wasm"