elm-format-wrapper that allows to ignore blocks of code

elm-format-wrapper

#!/usr/bin/env bash

# elm-format-wrapper 1.0.0
#
# Usage:
#   elm-format-wrapper [--help] [--action=ACTION] PATH...
#
# Description:
#   Format paths like elm-format, but allow ignoring blocks of code:
#
#     --elm-format-ignore-begin
#     don't format code here...
#     --elm-format-ignore-end
#
# Available options:
#   --action=format (this is the default action)
#       reformat each file
#
#   --action=diff
#       show patch that would be applied if action would be "format"
#       instead of formating the files.
#
#   -h, --help
#       show this help :)
#
#   --output=PATH
#   --output PATH
#       write formatted file to PATH.
#       If multiple files are formatted, then the last one will end up in
#       the output path.  This option is mainly for compatibility with
#       elm-format.
#
#   --yes
#       ignored; this option is for compatibility with elm-format
#     
set -efu
help() {
  gsed -rn '
    0,/^$/{
      /#!/d
      s/^# ?//p
    }
  ' "$0"
}
action=format
output=
for arg; do
  shift
  case $arg in
    --action=*)
      action=''${arg#*=}
      case $action in
        diff) continue;;
        format) continue;;
      esac
      echo "error: bad action: $action" >&2
      exit 1
      ;;
    --output)
      output=$1
      shift
      continue
      ;;
    --output=*)
      output=''${arg#*=}
      continue
      ;;
    --yes)
      continue
      ;;
    -h|--help)
      help
      exit
      ;;
    -*)
      echo "error: bad argument: $arg" >&2
      help >&2
      exit 1
  esac
  set -- "$@" "$arg"
done
action_format() {(
  old=$1
  new=$2
  if test -n "$output"; then
    cp "$new" "$output"
  else
    cp "$new" "$old"
  fi
)}
action_diff() {(
  old=$1
  new=$2
  diff -u --color "$old" "$new"
  if test -n "$output"; then
    cp "$new" "$output"
  fi
)}
temp=$(mktemp -t elm-format-wrapper.XXXXXXXX)
clean() {
  rm "$temp"
}
trap clean EXIT
yes n |
elm-format "$@" |
gsed -rn '
  /^This will overwrite the following files to use Elm.s preferred style:$/,/^This cannot be undone!/{
    s/^\s*(\S+)$/\1/p
  }
' |
while IFS= read -r path; do
  cat "$path" |
  gsed -r '
    /^--elm-format-ignore-begin$/,/^--elm-format-ignore-end$/{
      s/^/--@/
    }
  ' |
  elm-format --stdin > "$temp"
  gsed -ir '
    /^--@--elm-format-ignore-begin$/,/^--@--elm-format-ignore-end$/{
      s/^--@//
    }
  ' "$temp"
  action_"$action" "$path" "$temp"
done