#!/bin/bash

function osxiso() {

  local app # path for "Install OS X <version>.app"

  function usage() {
    cat <<EOF

Usage: ${0##*/} <Yosemite|Mavericks>

  Description:
    Create a bootable ISO of OS X, from the installation file.

EOF
    exit 1
  }

  function build() {
    local temp="${0%/*}/temp"
    local dist="${0%/*}/dist"
    local iso="$dist/$1.iso"
    local mpapp="/Volumes/install_app"
    local mpbuild="/Volumes/install_build"

    function detachmps() {
      echo "Attempting to detach mountpoints"

      # Unmount the installer image
      [[ ! -d  "$mpapp" ]] || hdiutil detach "/Volumes/install_app"

      # Unmount the sparse bundle
      [[ ! -d  "$mpbuild" ]] || hdiutil detach "/Volumes/install_build"
    }

    function cleanup() {
      # Unmount the installer image
      [[ ! -d  "$mpapp" ]] || hdiutil detach "/Volumes/install_app"

      # Unmount the sparse bundle
      [[ ! -d  "$mpbuild" ]] || hdiutil detach "/Volumes/install_build"

      # Remove temp directory
      rm -rf "$temp"
    }

    function abort() {
      printf "\nCommand returned with error, aborting ...\n\n"
      exit 2
    }

    trap cleanup EXIT
    trap abort ERR

    # Attempt cleanup of any previous attempts
    # detachmps
    cleanup

    # Prepare to do work
    mkdir -p "$temp"
    mkdir -p "$dist"

    # Mount the installer image
    hdiutil attach "$app/Contents/SharedSupport/InstallESD.dmg" -noverify -nobrowse -mountpoint "/Volumes/install_app"

    # Convert the boot image to a sparse bundle
    hdiutil convert "/Volumes/install_app/BaseSystem.dmg" -format UDSP -o "$temp/$1"

    # Increase the sparse bundle capacity to accommodate the packages
    hdiutil resize -size 8g "$temp/$1.sparseimage"

    # Mount the sparse bundle for package addition
    hdiutil attach "$temp/$1.sparseimage" -noverify -nobrowse -mountpoint "/Volumes/install_build"

    # Remove Package link and replace with actual files
    rm "/Volumes/install_build/System/Installation/Packages"
    cp -rp "/Volumes/install_app/Packages" "/Volumes/install_build/System/Installation/"

    # Copy "$1" installer dependencies
    cp -rp "/Volumes/install_app/BaseSystem.chunklist" "/Volumes/install_build/BaseSystem.chunklist"
    cp -rp "/Volumes/install_app/BaseSystem.dmg" "/Volumes/install_build/BaseSystem.dmg"

    # Detach mounts
    detachmps

    # Resize the partition in the sparse bundle to remove any free space
    hdiutil resize -size "$(hdiutil resize -limits $temp/$1.sparseimage | tail -n 1 | awk '{ print $1 }')b" "$temp/$1.sparseimage"

    # Convert the sparse bundle to ISO/CD master
    hdiutil convert "$temp/$1.sparseimage" -format UDTO -o "$temp/$1"

    # Rename the ISO and move it to the distribution "dist" dir
    mv "$temp/$1.cdr" "$iso"

    cleanup

    printf "\n========== FINISHED ==========\n\n"
    printf "ISO is located at '%s'\n\n" "$iso"
  }

  # Verify OS X Version
  [[ $# -ne 0 ]] || usage
  local versions=(
    Yosemite
    Mavericks
  )
  for version in "${versions[@]}"; do
    if [[ "$1" = "$version" ]]; then
      app="/Applications/Install OS X $1.app"

      if [[ ! -e "$app" ]]; then
        cat <<EOF

  Missing: $app

  * You can install it with the App Store

EOF
        exit 1
      fi

      # Do Work
      build "$1"
      exit $?
    fi
  done

  # Invalid version provided
  usage
}

## Export or run
if [[ ${BASH_SOURCE[0]} != $0 ]]; then
  export -f osxiso
else
  osxiso "$@"
fi