Generate the .icns for the macOS app

Instead of adding it to the repo.

script/build-app

@@ -1,11 +1,12 @@
 #!/bin/bash
 # Build "native" desktop app using nativefier
 # https://github.com/jiahaog/nativefier
+set -e
 
 if [ "$(uname)" != "Darwin" ]; then
   echo "MacOS is the only platform currently supported" >&2
   exit 1
-fi 
+fi
 
 if [ ! -f beehive ]; then
   echo "Run 'make embed' first." >&2
@@ -18,16 +19,25 @@ if !which nativefier >/dev/null 2>&1; then
   exit 1
 fi
 
+BASE_PATH="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd )"
 OS_NAME=$(node -e "console.log(os.platform())")
 OS_ARCH=$(node -e "console.log(os.arch())")
 
+cleanup_osx() {
+  if [ -f "$icns_file" ]; then
+    rm -f $icns_file
+  fi
+}
+
 if [ "$OS_NAME" = "darwin" ]; then
+  trap cleanup_osx EXIT
   BIN_PATH=build/app/Beehive-$OS_NAME-$OS_ARCH/Beehive.app/Contents/MacOS/
-  nativefier -e 1.6.6 --icon assets/beehive.icns --name Beehive http://localhost:8181 build/app
+  icns_file=$($BASE_PATH/build-icns)
+  nativefier -e 1.6.6 --icon $icns_file --name Beehive http://localhost:8181 build/app
   cp beehive $BIN_PATH/beehived
   chmod +x $BIN_PATH/beehived
   mv $BIN_PATH/Beehive $BIN_PATH/Beehive.bin
-  
+
   cat > $BIN_PATH/Beehive << "EOF"
 #!/bin/bash
 set -e

script/build-icns

@@ -0,0 +1,30 @@
+#!/bin/bash
+set -e
+
+tmpd=$TMPDIR/beehive.iconset
+icns=$TMPDIR/beehive.icns
+logfile=$TMPDIR/build-icns.log
+
+cleanup() {
+  rm -rf $tmpd
+  rm -f $logfile
+}
+
+trap cleanup EXIT
+
+{
+  mkdir $tmpd
+  sips -z 16 16    assets/logo.png --out $tmpd/icon_16x16.png
+  sips -z 32 32    assets/logo.png --out $tmpd/[email protected]
+  sips -z 32 32    assets/logo.png --out $tmpd/icon_32x32.png
+  sips -z 64 64    assets/logo.png --out $tmpd/[email protected]
+  sips -z 128 128  assets/logo.png --out $tmpd/icon_128x128.png
+  sips -z 256 256  assets/logo.png --out $tmpd/[email protected]
+  sips -z 256 256  assets/logo.png --out $tmpd/icon_256x256.png
+  sips -z 512 512  assets/logo.png --out $tmpd/[email protected]
+  sips -z 512 512  assets/logo.png --out $tmpd/icon_512x512.png
+  cp assets/logo.png $tmpd/[email protected]
+  iconutil -c icns $tmpd
+} > $logfile 2>&1
+
+echo $icns