#!/usr/bin/env bash

usage() {
  cat <<EOF
USAGE

  $0 [--help] [--debug] [--docker]

SUMMARY

  Compile the Tree-sitter WASM library. This will create two files in the
  \`lib/binding_web\` directory: \`tree-sitter.js\` and \`tree-sitter.wasm\`.

REQUIREMENTS

  You must have either the \`emcc\` command or the \`docker\` command
  on your PATH for this to work.

OPTIONS

  --help:   Display this message.
  --debug:  Compile the library more quickly, with fewer optimizations
            and more runtime assertions.
  --docker: Run emscripten using docker, even if \`emcc\` is installed.
            By default, \`emcc\` will be run directly when available.

EOF
}

set -e

WEB_DIR=lib/binding_web
SRC_DIR=lib/src
EMSCRIPTEN_VERSION=$(< cli/loader/emscripten-version)

verbose=0
force_docker=0
emscripten_flags=(-O3 --minify 0)

while (($# > 0)); do
  case "$1" in
    --debug)
      emscripten_flags=(-s ASSERTIONS=1 -s SAFE_HEAP=1 -O0 -g)
      ;;

    --help)
      usage
      exit 0
      ;;

    --docker)
      force_docker=1
      ;;

    -v|--verbose)
      verbose=1
      ;;

    *)
      usage
      printf "Unrecognized argument '%s'\n" "$1" >&2
      exit 1
      ;;
  esac
  shift
done

if [[ $verbose == 1 ]]; then
  emscripten_flags+=(-s VERBOSE=1 -v)
fi

emcc=
docker=
if [[ $force_docker == 0 ]] && command -v emcc > /dev/null; then
  emcc=emcc
elif command -v docker > /dev/null; then
  # detect which one to use
  docker=docker
elif command -v podman > /dev/null; then
  docker=podman
fi

if [[ -z $emcc ]] && [[ -n $docker ]]; then
  if [[ $docker == podman ]]; then
    export PODMAN_USERNS=keep-id
  fi
  emcc="$docker run                       \
    --rm                                  \
    -v $PWD:/src:Z                        \
    -u $UID                               \
    emscripten/emsdk:$EMSCRIPTEN_VERSION  \
    emcc"
fi

if [[ -z $emcc ]]; then
  if [[ $force_docker == 1 ]]; then
    # shellcheck disable=SC2016
    printf 'You must have `docker` or `podman` in your PATH to run this script with --docker\n' >&2
  else
    # shellcheck disable=SC2016
    printf 'You must have either `docker`, `podman`, or `emcc` in your PATH to run this script\n' >&2
  fi
  exit 1
fi

mkdir -p target/scratch

runtime_methods=stringToUTF16,AsciiToString

# Remove quotes, add leading underscores, remove newlines, remove trailing comma.
exported_functions=$(
    cat ${SRC_DIR}/wasm/stdlib-symbols.txt ${WEB_DIR}/exports.txt |
    sed -e 's/"//g;s/^/_/g' | tr -d '\n' | sed -e 's/,$//'
)

# Use emscripten to generate `tree-sitter.js` and `tree-sitter.wasm`
# in the `target/scratch` directory
$emcc                                            \
  -s WASM=1                                      \
  -s INITIAL_MEMORY=33554432                     \
  -s ALLOW_MEMORY_GROWTH=1                       \
  -s SUPPORT_BIG_ENDIAN=1                        \
  -s MAIN_MODULE=2                               \
  -s FILESYSTEM=0                                \
  -s NODEJS_CATCH_EXIT=0                         \
  -s NODEJS_CATCH_REJECTION=0                    \
  -s EXPORTED_FUNCTIONS="${exported_functions}"  \
  -s EXPORTED_RUNTIME_METHODS=$runtime_methods   \
  "${emscripten_flags[@]}"                       \
  -fno-exceptions                                \
  -std=c11                                       \
  -D 'fprintf(...)='                             \
  -D NDEBUG=                                     \
  -I ${SRC_DIR}                                  \
  -I lib/include                                 \
  --js-library ${WEB_DIR}/imports.js             \
  --pre-js ${WEB_DIR}/prefix.js                  \
  --post-js ${WEB_DIR}/binding.js                \
  --post-js ${WEB_DIR}/suffix.js                 \
  lib/src/lib.c                                  \
  ${WEB_DIR}/binding.c                           \
  -o target/scratch/tree-sitter.js

mv target/scratch/tree-sitter.js ${WEB_DIR}/tree-sitter.js
mv target/scratch/tree-sitter.wasm ${WEB_DIR}/tree-sitter.wasm