#!/usr/bin/env bash
# Builds one wasm-bindgen crate for the browser and drops the JS glue and the
# .wasm where a page serves them from.
#
# Usage: scripts/build-wasm.sh [crate out-dir out-name]
#
# With no arguments it builds crates/didbot-site-anim into site/public/wasm/
# as site-anim.js + site-anim_bg.wasm, which is what scripts/build-site.sh
# calls it for: Astro's public/ passthrough copies that directory into dist/
# untouched, so nothing else has to know this ran. The three arguments name
# another crate, output directory and output name, and are all given or none
# are; scripts/build-dashboard-wasm.sh, scripts/build-policy-wasm.sh and
# scripts/build-policy-anim-wasm.sh are the other callers.
#
# This is its own script because it is the one step needing a toolchain the
# rest of the site build does not: the wasm32-unknown-unknown target and a
# wasm-bindgen-cli whose version matches the wasm-bindgen crate dependency
# exactly (the two talk a private ABI to each other; a mismatch fails loudly,
# which is the whole reason the version is pinned rather than "whatever is
# installed").
#
# `cargo build --workspace` and `cargo test --workspace` never need this: the
# wasm32 target is only touched here, on purpose (see
# crates/didbot-site-anim/Cargo.toml's own comment on why the crate builds
# fine natively without it). This script is the opt-in.
set -euo pipefail

cd "$(dirname "$0")/.."

case "$#" in
  0)
    crate="didbot-site-anim"
    out_dir="site/public/wasm"
    out_name="site-anim"
    ;;
  3)
    crate="$1"
    out_dir="$2"
    out_name="$3"
    ;;
  *)
    echo "usage: $0 [crate out-dir out-name]" >&2
    exit 2
    ;;
esac

locked_version="$(
  awk '
    /^name = "wasm-bindgen"$/ { want = 1; next }
    want && /^version = / { gsub(/"/, "", $3); print $3; exit }
  ' Cargo.lock
)"

if [ -z "$locked_version" ]; then
  echo "build-wasm: could not find wasm-bindgen's locked version in Cargo.lock" >&2
  exit 1
fi

if ! rustup target list --installed 2>/dev/null | grep -qx wasm32-unknown-unknown; then
  echo "build-wasm: the wasm32-unknown-unknown target is not installed." >&2
  echo "  Install it with: rustup target add wasm32-unknown-unknown" >&2
  exit 1
fi

if ! command -v wasm-bindgen >/dev/null 2>&1; then
  echo "build-wasm: wasm-bindgen-cli is not installed." >&2
  echo "  Install the version matching Cargo.lock ($locked_version) with:" >&2
  echo "    cargo install wasm-bindgen-cli --version $locked_version --locked" >&2
  exit 1
fi

installed_version="$(wasm-bindgen --version | awk '{print $2}')"
if [ "$installed_version" != "$locked_version" ]; then
  echo "build-wasm: wasm-bindgen-cli $installed_version does not match Cargo.lock's wasm-bindgen $locked_version." >&2
  echo "  wasm-bindgen and wasm-bindgen-cli speak a private ABI and must match exactly. Reinstall with:" >&2
  echo "    cargo install wasm-bindgen-cli --version $locked_version --locked" >&2
  exit 1
fi

# Which profile each crate is worth building under, rather than an argument, so
# that the two call sites that build `didbot-site-anim` cannot drift apart.
#
# `didbot-policy-check` is megabytes of policy engine a visitor waits on, and
# the root Cargo.toml's `wasm-release` takes a third off it. `didbot-site-anim`
# is a per-frame numeric loop, which that profile leaves the same size to within
# a few dozen bytes while running its cellular automaton at roughly half the
# rate, so it builds under `release`.
case "$crate" in
  didbot-policy-check) profile="wasm-release" ;;
  *) profile="release" ;;
esac

echo "=== cargo build: $crate for wasm32-unknown-unknown ===" >&2
cargo build -p "$crate" --target wasm32-unknown-unknown --profile "$profile"

wasm_in="${CARGO_TARGET_DIR:-target}/wasm32-unknown-unknown/$profile/${crate//-/_}.wasm"
if [ ! -f "$wasm_in" ]; then
  echo "build-wasm: expected build output at $wasm_in, found nothing" >&2
  exit 1
fi

echo "=== wasm-bindgen: generating the JS glue in $out_dir ===" >&2
# Only this module's files: policy-site/public/wasm/ holds two modules.
rm -f "$out_dir/$out_name.js" "$out_dir/$out_name.d.ts" \
  "$out_dir/${out_name}_bg.wasm" "$out_dir/${out_name}_bg.wasm.d.ts"
mkdir -p "$out_dir"
wasm-bindgen --target web --out-dir "$out_dir" --out-name "$out_name" "$wasm_in"

size_bytes="$(wc -c <"$out_dir/${out_name}_bg.wasm")"
echo "build-wasm: done — $out_dir/${out_name}_bg.wasm is ${size_bytes} bytes" >&2