#!/usr/bin/env bash

# This script compares the compiler output (in wat format)
# between the currently built version and the previous version
#
# With -f from -t to other branches can be selected (anything that git
# rev-parse understands)

old="$(git rev-parse HEAD)"
new=""

WASM2WAT="wasm2wat --no-check"

while getopts "f:t:" o; do
    case "${o}" in
        f)
            old="$(git rev-parse ${OPTARG})"
            ;;
        t)
            new="$(git rev-parse ${OPTARG})"
            ;;
    esac
done
shift $((OPTIND-1))

function build_ref_to {
  rm -f $2-moc
  if [ -z "$1" ]
  then
    echo "Building $2 moc from working copy.."
    chronic nix-build \
      --argstr path "$(realpath "$(dirname $0)/..")" \
      -E '{path}: ((import path) {}).moc' \
      -o $2-moc/
  else
    echo "Building $2 moc (rev $1).."
    chronic nix-build \
      --argstr ref "$(git for-each-ref --count 1 --contains "$1" --format '%(refname)')" \
      --argstr rev "$1" \
      --argstr path "$(realpath "$(dirname $0)/..")" \
      -E '
      {rev, ref, path}:
      let checkout = (builtins.fetchGit {url = path; ref = ref; rev = rev;}).outPath; in
      builtins.trace checkout (
      ((import checkout) {}).moc)' \
      -o $2-moc/
  fi
  test -x $2-moc/bin/moc || exit 1
}
build_ref_to "$old" old
build_ref_to "$new" new

mkdir -p compare-out/

if [[ $# -eq 0 ]] ; then
    args="*/*.mo"
else
    args="$@"
fi

for file in $args
do
  if [ ! -e $file ]
  then
    echo "Motoko file $file does not exist."
    exit 1
  fi

  base=$(basename $file .mo)

  mangled=$file.mangled
  sed 's,^.*//OR-CALL,//CALL,g' $file > $mangled

  rm -rf compare-out/$base.old
  mkdir compare-out/$base.old
  old-moc/bin/moc $mangled --omit-metadata motoko:compiler -ref-system-api -g -o compare-out/$base.old/$base.wasm 2> compare-out/$base.old/$base.stderr
  test ! -e compare-out/$base.old/$base.wasm ||
  $WASM2WAT compare-out/$base.old/$base.wasm >& compare-out/$base.old/$base.wat
  #wasm-objdump -s -h -d compare-out/$base.old/$base.wasm > compare-out/$base.old/$base.dump

  rm -rf compare-out/$base.new
  mkdir compare-out/$base.new
  new-moc/bin/moc $mangled --omit-metadata motoko:compiler -ref-system-api -g -o compare-out/$base.new/$base.wasm 2> compare-out/$base.new/$base.stderr
  test ! -e compare-out/$base.new/$base.wasm ||
  $WASM2WAT compare-out/$base.new/$base.wasm >& compare-out/$base.new/$base.wat
  #wasm-objdump -s -h -d compare-out/$base.new/$base.wasm > compare-out/$base.new/$base.dump

  diff -r -N -u10 compare-out/$base.old compare-out/$base.new

  rm -f $mangled
  rm -rf compare-out/$base.old
  rm -rf compare-out/$base.new
done
rmdir compare-out/