extract-dmg-layout.sh

#!/usr/bin/env bash
set -euo pipefail
IFS=$'\n\t'

usage() {
  cat <<'EOF'
extract-dmg-layout.sh — extract Finder layout settings from an existing DMG.

This mounts the DMG, opens the disk in Finder, and queries:
  - window position/size
  - icon size / text size
  - background picture path (if set)
  - icon positions for *.app and the Applications link (if present)

Usage:
  scripts/extract-dmg-layout.sh --dmg /path/Old.dmg [--export-dir dist/dmg-layout]

Options:
  --dmg PATH         Path to .dmg file (required)
  --export-dir DIR   Where to copy the extracted background image (default: dist/dmg-layout)
  -h, --help         Show help

Output:
  Prints a ready-to-paste create-dmg snippet using the extracted values.
EOF
}

DMG_PATH=""
EXPORT_DIR="dist/dmg-layout"

while [[ $# -gt 0 ]]; do
  case "$1" in
    --dmg) DMG_PATH="${2:-}"; shift 2 ;;
    --export-dir) EXPORT_DIR="${2:-}"; shift 2 ;;
    -h|--help) usage; exit 0 ;;
    *)
      echo "Unknown arg: $1" >&2
      usage >&2
      exit 2 ;;
  esac
done

if [[ -z "$DMG_PATH" ]]; then
  echo "Missing required --dmg" >&2
  usage >&2
  exit 2
fi
if [[ ! -f "$DMG_PATH" || "${DMG_PATH##*.}" != "dmg" ]]; then
  echo "--dmg must point to a .dmg file: $DMG_PATH" >&2
  exit 2
fi

for tool in hdiutil osascript; do
  if ! command -v "$tool" >/dev/null 2>&1; then
    echo "Missing required tool: $tool" >&2
    exit 127
  fi
done

TMP_ROOT="$(mktemp -d)"
cleanup() {
  set +e
  if [[ -n "${MOUNTPOINT:-}" ]]; then
    hdiutil detach "$MOUNTPOINT" >/dev/null 2>&1 || hdiutil detach -force "$MOUNTPOINT" >/dev/null 2>&1
  fi
  rm -rf "$TMP_ROOT"
}
trap cleanup EXIT

ATTACH_OUT="$(hdiutil attach -nobrowse -readonly -noverify "$DMG_PATH")"
MOUNTPOINT="$(printf '%s\n' "$ATTACH_OUT" | awk '/\/Volumes\// {print $NF; exit}')"
if [[ -z "$MOUNTPOINT" || ! -d "$MOUNTPOINT" ]]; then
  echo "Failed to find mountpoint for DMG." >&2
  echo "hdiutil output:" >&2
  printf '%s\n' "$ATTACH_OUT" >&2
  exit 1
fi

VOLNAME="$(basename "$MOUNTPOINT")"

APP_PATH="$(find "$MOUNTPOINT" -maxdepth 1 -name '*.app' -print -quit || true)"
APP_NAME=""
if [[ -n "$APP_PATH" ]]; then
  APP_NAME="$(basename "$APP_PATH")"
fi
if [[ -z "$APP_NAME" ]]; then
  echo "No .app found at DMG root: $MOUNTPOINT" >&2
  echo "Contents:" >&2
  ls -la "$MOUNTPOINT" >&2
  exit 1
fi

RESULT="$(
  osascript <<EOF
on _toText(v)
  try
    return v as text
  on error
    return ""
  end try
end _toText

on run
  set volName to "${VOLNAME}"
  set appName to "${APP_NAME}"

  tell application "Finder"
    activate
    tell disk volName
      open
      delay 0.5

      set w to container window
      set b to bounds of w
      set leftX to item 1 of b
      set topY to item 2 of b
      set rightX to item 3 of b
      set bottomY to item 4 of b
      set winW to (rightX - leftX)
      set winH to (bottomY - topY)

      set vo to icon view options of w
      set iconSize to icon size of vo
      set textSize to text size of vo

      set bgPosix to ""
      try
        set bgAlias to background picture of vo
        set bgPosix to POSIX path of (bgAlias as alias)
      end try

      set appX to ""
      set appY to ""
      try
        set p to position of item appName of w
        set appX to item 1 of p
        set appY to item 2 of p
      end try

      set appsX to ""
      set appsY to ""
      try
        set p2 to position of item "Applications" of w
        set appsX to item 1 of p2
        set appsY to item 2 of p2
      end try

      close w

      set outText to ""
      set outText to outText & "win_x=" & my _toText(leftX) & linefeed
      set outText to outText & "win_y=" & my _toText(topY) & linefeed
      set outText to outText & "win_w=" & my _toText(winW) & linefeed
      set outText to outText & "win_h=" & my _toText(winH) & linefeed
      set outText to outText & "icon_size=" & my _toText(iconSize) & linefeed
      set outText to outText & "text_size=" & my _toText(textSize) & linefeed
      set outText to outText & "bg_path=" & my _toText(bgPosix) & linefeed
      set outText to outText & "app_x=" & my _toText(appX) & linefeed
      set outText to outText & "app_y=" & my _toText(appY) & linefeed
      set outText to outText & "apps_x=" & my _toText(appsX) & linefeed
      set outText to outText & "apps_y=" & my _toText(appsY) & linefeed

      return outText
    end tell
  end tell
end run
EOF
)"

WIN_X=""; WIN_Y=""; WIN_W=""; WIN_H=""; ICON_SIZE=""; TEXT_SIZE=""; BG_PATH=""; APP_X=""; APP_Y=""; APPS_X=""; APPS_Y=""
while IFS='=' read -r k v; do
  [[ -z "${k:-}" ]] && continue
  case "$k" in
    win_x) WIN_X="$v" ;;
    win_y) WIN_Y="$v" ;;
    win_w) WIN_W="$v" ;;
    win_h) WIN_H="$v" ;;
    icon_size) ICON_SIZE="$v" ;;
    text_size) TEXT_SIZE="$v" ;;
    bg_path) BG_PATH="$v" ;;
    app_x) APP_X="$v" ;;
    app_y) APP_Y="$v" ;;
    apps_x) APPS_X="$v" ;;
    apps_y) APPS_Y="$v" ;;
  esac
done <<<"$RESULT"

sanitize_num() {
  # keep digits, optional leading '-', and optional '.'; strip commas/spaces/locale artifacts
  local in="${1:-}"
  in="${in//,/}"
  in="${in// /}"
  printf '%s' "$in" | tr -cd '0-9.-' | sed 's/^\.\+//'
}

WIN_X="$(sanitize_num "$WIN_X")"
WIN_Y="$(sanitize_num "$WIN_Y")"
WIN_W="$(sanitize_num "$WIN_W")"
WIN_H="$(sanitize_num "$WIN_H")"
ICON_SIZE="$(sanitize_num "$ICON_SIZE")"
TEXT_SIZE="$(sanitize_num "$TEXT_SIZE")"
APP_X="$(sanitize_num "$APP_X")"
APP_Y="$(sanitize_num "$APP_Y")"
APPS_X="$(sanitize_num "$APPS_X")"
APPS_Y="$(sanitize_num "$APPS_Y")"

mkdir -p "$EXPORT_DIR"

BACKGROUND_ARG=()
if [[ -n "$BG_PATH" && -f "$BG_PATH" ]]; then
  BG_BASENAME="$(basename "$BG_PATH")"
  BG_OUT="$EXPORT_DIR/$BG_BASENAME"
  cp -f "$BG_PATH" "$BG_OUT"
  BACKGROUND_ARG=(--background "$BG_OUT")
fi

if [[ ${#BACKGROUND_ARG[@]} -eq 0 ]]; then
  # Common case: background image lives in the DMG at /.background/*
  BG_FALLBACK="$(find "$MOUNTPOINT" -maxdepth 2 -path '*/.background/*' -type f \( -iname '*.png' -o -iname '*.jpg' -o -iname '*.jpeg' -o -iname '*.gif' \) -print -quit 2>/dev/null || true)"
  if [[ -n "$BG_FALLBACK" && -f "$BG_FALLBACK" ]]; then
    BG_BASENAME="$(basename "$BG_FALLBACK")"
    BG_OUT="$EXPORT_DIR/$BG_BASENAME"
    cp -f "$BG_FALLBACK" "$BG_OUT"
    BACKGROUND_ARG=(--background "$BG_OUT")
    BG_PATH="$BG_FALLBACK"
  fi
fi

echo "Mounted volume: $VOLNAME"
echo "Detected app: $APP_NAME"
[[ -n "$BG_PATH" ]] && echo "Background: $BG_PATH" || echo "Background: (none detected)"
echo
echo "create-dmg flags:"
echo "  --volname \"$VOLNAME\""
echo "  --window-pos $WIN_X $WIN_Y"
echo "  --window-size $WIN_W $WIN_H"
echo "  --icon-size $ICON_SIZE"
echo "  --text-size $TEXT_SIZE"
if [[ ${#BACKGROUND_ARG[@]} -gt 0 ]]; then
  echo "  --background \"${BACKGROUND_ARG[1]}\""
fi
if [[ -n "$APP_X" && -n "$APP_Y" ]]; then
  echo "  --icon \"$APP_NAME\" $APP_X $APP_Y"
fi
if [[ -n "$APPS_X" && -n "$APPS_Y" ]]; then
  echo "  --app-drop-link $APPS_X $APPS_Y"
fi

echo
echo "Example:"
echo "create-dmg \\"
echo "  --volname \"$VOLNAME\" \\"
echo "  --window-pos $WIN_X $WIN_Y \\"
echo "  --window-size $WIN_W $WIN_H \\"
echo "  --icon-size $ICON_SIZE \\"
echo "  --text-size $TEXT_SIZE \\"
if [[ ${#BACKGROUND_ARG[@]} -gt 0 ]]; then
  echo "  --background \"${BACKGROUND_ARG[1]}\" \\"
fi
if [[ -n "$APP_X" && -n "$APP_Y" ]]; then
  echo "  --icon \"$APP_NAME\" $APP_X $APP_Y \\"
fi
if [[ -n "$APPS_X" && -n "$APPS_Y" ]]; then
  echo "  --app-drop-link $APPS_X $APPS_Y \\"
fi
echo "  out.dmg /path/to/source_folder"