#!/bin/sh
set -eu

usage() {
  echo "usage: select-module.sh selector|tag VALUE" >&2
  exit 2
}

[ "$#" -eq 2 ] || usage
mode=$1
value=$2
case "$mode" in
  selector|tag) ;;
  *) usage ;;
esac

script_dir=$(CDPATH= cd "$(dirname "$0")" && pwd)
mapping=${RELEASEKIT_MODULE_MAP:-$script_dir/release-modules.tsv}
[ -f "$mapping" ] || { echo "module map not found: $mapping" >&2; exit 2; }

tab=$(printf '\t')
matches=0
selected_selector=
selected_pattern=
selected_module=
selected_profile=

while IFS="$tab" read -r selector pattern module profile || [ -n "${selector:-}${pattern:-}${module:-}${profile:-}" ]; do
  case "${selector:-}" in
    ''|\#*) continue ;;
  esac
  fields=$(awk -F '\t' '{ print NF }' <<EOF
$selector$tab$pattern$tab$module$tab$profile
EOF
)
  [ "$fields" -eq 4 ] || { echo "module map row must have four tab-separated fields" >&2; exit 2; }
  [ -n "$pattern" ] && [ -n "$module" ] && [ -n "$profile" ] || {
    echo "module map row has an empty field for selector $selector" >&2
    exit 2
  }

  matched=false
  if [ "$mode" = selector ]; then
    [ "$selector" = "$value" ] && matched=true
  else
    # The value remains a shell pattern in this case statement; it is never eval'd.
    case "$value" in
      $pattern) matched=true ;;
    esac
  fi
  if [ "$matched" = true ]; then
    matches=$((matches + 1))
    selected_selector=$selector
    selected_pattern=$pattern
    selected_module=$module
    selected_profile=$profile
  fi
done < "$mapping"

if [ "$matches" -ne 1 ]; then
  if [ "$matches" -eq 0 ]; then
    echo "no module map row matches $mode $value" >&2
  else
    echo "module map has ambiguous rows for $mode $value" >&2
  fi
  exit 2
fi

printf '%s\t%s\t%s\t%s\n' \
  "$selected_selector" "$selected_pattern" "$selected_module" "$selected_profile"