#!/bin/bash

set -e

# Standalone script to install Xcode w/ CLI tools on a fresh OS X 10.8, via applescript.

# This might be more lovely (and maintainable) as ruby, if only we could have some handy
# gems that all need a compiler for native extensions. We don't, so do it old school.

# Some things:
#
# * This is handy: http://tldp.org/LDP/abs/html/
# * So is: https://developer.apple.com/library/mac/documentation/<snip>
#   <snip>AppleScript/Conceptual/AppleScriptLangGuide/
# * We need sudo.
# * The creds should be passed as two lines on stdin; this is the most secure way I know.
# * Do not run this script as root.
# * Do not source this script into another (including your current shell.)

function show_help {
cat <<HELP
Usage: echo -e 'user\npass' | $0 please

Scripted installation of Xcode with CLI tools from the App Store.

Unless 'please' is passed, show this help and do nothing.

Otherwise this will look for your apple credentials on two lines in stdin (id on the
first line, then password), which will be verified with Apple.  If nothing is supplied
on stdin, you will be prompted for credentials.

Using support for assistive devices and applescript, the App Store will be opened and
Xcode will be installed.  Xcode will then be opened and license agreement will be
accepted for you: to review that agreement now, visit the url below.  Finally, the
command-line utilities will be installed.

The Xcode license agreement: http://www.apple.com/legal/sla/docs/xcode.pdf

To enable support for assisitive devices, you may be prompted for your administrator
(sudo) password.
HELP
}

# Show the given message and exit with status 1.
function die {
  echo -e "Error: $*"
  exit 1
}

# Show the given message, followed by help, and exit with status 1.
function die_help {
  echo -e "Error: $*"
  echo
  show_help
  exit 1
}

[[ "$USER" == root ]] && die_help "Run this as a normal user, I'll sudo when I need to."

# A (very) poor man's headless browser.
#
# We follow redirects and deal with cookies.
#
# The first parameter should be a file for curl to use as a read-write cookie jar.
# Any remaining arguments (at least one more is required) are passed straight to curl.
#
# Since we use perl (HTML::Tree) elsewhere, we might be tempted to use LWP here and drop
# bash completely. However, getting the needed functionality simply (redirects, cookies)
# is apparently beyond the ken of several perlmonk threads.  So curl it is.
function http {
  [[ $# < 2 ]] && die "http helper doesn't understand '$@'"

  local cookies="$1"
  shift 1

  # --silent disables the progress bar
  # --location follows redirects
  # --cookie provides request cookies from the file
  # --cookie-jar writes response cookies back afterwards
  curl                        \
    --silent                  \
    --location                \
    --cookie      "$cookies"  \
    --cookie-jar  "$cookies"  \
    "$@"
}

# Parse the given html content with a bit of perl.
#
# The html should be the first positional parameter.  The perl should be passed on stdin
# (i.e. as an inline heredoc).  It may assume an HTML::Tree named $doc which has parsed
# the content is in scope.
#
# Be sure to use single-quoted heredocs.
function html {
  [[ $# == 1 ]] || die "html helper doesn't understand '$@'"

  # If I try to not buffer stdin before calling perl, something craps the bed and stdin
  # is lost.  So grab it up front and use -e instead.  Pray you don't need newlines.
  local script=$(cat)

  echo "$1" | perl -Mv5.12 -MHTML::Tree \
    -e 'my $doc = HTML::Tree->new();'   \
    -e '$doc->parse_file(\*STDIN);'     \
    -e "$script"
}

# Verify the credentials with Apple.
#
# Do this by simulating a login session to https://appleid.apple.com/.
#
# To acomplish this we use one of the few html parsing APIs available to a fresh 10.8
# install: the HTML::Tree module in perl.
function verify_credentials {
  [[ $# == 2 ]] || die "verify_credentials doesn't understand '$@'"

  # Parse arguments
  local apple_id="$1"
  local apple_password="$2"

  # Create the cookie file.
  local cookie_jar=$(mktemp /tmp/install-xcode.XXXXXX)

  # Try to clean it up on exit.  Note we only get one exit handler per process.
  trap "rm '$cookie_jar'" exit

  # Go to the apple id management app front page.
  local response=$(http "$cookie_jar" 'https://appleid.apple.com/')

  # Find the "Manage your Apple ID" link.
  local url=$(html "$response" <<'PERL'
    # Consider links..
    for ( $doc->look_down('_tag' => 'a') ) {
      # ..whose anchor text matches "Manage your Apple ID"
      say $_->attr('href') if $_->as_text() =~ m/Manage your Apple ID/;
    }
PERL
  )

  # Click it
  response=$(http "$cookie_jar" "$url")

  # Find the signIn field.  Grab its action url as well as all of its fields
  local url_and_query=$(html "$response" <<'PERL'
    use URI::Escape;

    for my $form ( $doc->look_down('_tag' => 'form') ) {
      # Skip anyone with the wrong id
      next unless $form->attr('id') =~ m/signIn/;

      # Grab the url
      say $form->attr('action');

      my @parameters = ();

      # Examine the form's fields to build up a query string to POST
      for my $input ( $form->look_down('_tag' => 'input') ) {
        my $name = uri_escape($input->attr('name'));

        # Skip these two, since we'll do them explictly after
        next if $name =~ m/theAccountName/ || $name =~ m/theAccountPW/;

        if ( defined($input->attr('value')) ) {
          my $value = uri_escape($input->attr('value'));

          push(@parameters, $name . "=" . $value);
        } else {
          push(@parameters, $name);
        }
      }

      # Print the parameters together as one query string
      say join("&", @parameters);

      # Ok, we're done.  Break the loop.
      last;
    }
PERL
  )

  # Parse the url out of the two-line result, (clumsily) resolve relative urls
  url=$(echo "$url_and_query" | head -n 1 | sed 's|^/|https://appleid.apple.com/|')

  # Parse query string out of the two-line result
  local query="$(echo "$url_and_query" | tail -n 1)$creds"

  # "Submit" the form
  response=$(http "$cookie_jar"       \
    -d "$query"                       \
    -d "theAccountName=$apple_id"     \
    -d "theAccountPW=$apple_password" \
    "$url"
  )

  html "$response" <<'PERL'
    for ( $doc->look_down('_tag' => 'a') ) {
      # We failed if we see a forgot password link.
      exit 1 if $_->as_text() =~ m/Forgot your password/;
    }
PERL
}

# Toggle support for assistive devices, a prerequisite for using applescript.
#
# This requires sudo.
#
# This is the same as the checkbox in the bottom left corner of the Universal Access
# system preferences panel.
function toggle_assistive_devices {
  [[ $# == 1 ]] || die "toggle_assistive_devices doesn't understand '$@'"

  local magic_file="/private/var/db/.AccessibilityAPIEnabled"

  if [[ "$1" == "on" ]]
  then
    echo -n a | sudo tee "$magic_file" > /dev/null 2>&1
    sudo chmod 444 "$magic_file"
  elif [[ "$1" == "off" ]]
  then
    sudo rm -f "$magic_file"
  else
    die "toggle_assistive_devices doesn't understand '$@'"
  fi
}

# Toggle requiring an administrator password for installing Apple software.
#
# This is the password prompt that Xcode presents when trying to install the command line
# tools.
#
# Requires sudo.
#
# Don't toggle this on without first toggling it off first.
function toggle_install_apple_software_check {
  [[ $# == 1 ]] || die "toggle_install_apple_software_check doesn't understand '$@'"

  local reverse=""

  if [[ "$1" == "on" ]]
  then
    reverse="-R"
  elif [[ "$1" == "off" ]]
  then
    : # no-op
  else
    die "toggle_install_apple_software_check doesn't understand '$@'"
  fi

  sudo patch $reverse -l -d / -p1 <<'PATCH' 2>&1 >/dev/null
--- a/etc/authorization 2013-09-11 23:04:16.000000000 -0700
+++ b/etc/authorization 2013-09-11 23:38:59.000000000 -0700
@@ -5190,7 +5190,7 @@
                <key>system.install.apple-software</key>
                <dict>
                        <key>class</key>
-                       <string>rule</string>
+                       <string>allow</string>
                        <key>comment</key>
                        <string>Checked when user is installing Apple-provided software.</string>
                        <key>default-button</key>
PATCH
}

# Open the App Store and download Xcode.
function download_xcode {
  [[ $# == 2 ]] || die "download_xcode doesn't understand '$@'"

  # Parse arguments
  local apple_id="$1"
  local apple_password="$2"

  # Do we already have Xcode?  We're done!
  [[ -d /Applications/Xcode.app ]] && return 0

  # Open the Xcode page within the App Store
  open 'macappstore://itunes.apple.com/us/app/xcode/id497799835'

  # Give it a moment
  sleep 2
        
  echo -e "$apple_id\n$apple_password" | osascript 3<&0 <<'APPLESCRIPT'
    on run argv
      # Parse arguments
      set stdin to do shell script "cat 0<&3"
      set appleId       to paragraph 1 of stdin
      set applePassword to paragraph 2 of stdin

      tell application "System Events"
        tell window "App Store" of process "App Store"
          set loaded to false
          repeat until loaded = true
            try
              # There's really no less brittle way I can find to navigate the UI.
              # Along with the Accessibility Inspector, "UI elements" is your friend:
              # i.e. "tell scroll area 1 to UI elements"
              # http://n8henrie.com/2013/03/a-strategy-for-ui-scripting-in-applescript/
              set installButtonContainer to group 1 of group 1 of UI element 1 of scroll area 1
              set installButton to button 1 of installButtonContainer

              set loaded to true
            on error
              delay 1
            end try
          end repeat

          if description of installButton = "Installed, Xcode" then
            tell application "App Store" to quit
            return  # It claims to be installed.
          end if

          if not description of installButton = "Install, Xcode, Free" then
            # What page are we looking at?  Is Xcode no longer free?  Bail.
            error "Can't find install button."
          end if

          # Petrov: Sir! The reason for having two keys is so that no one man may...
          click installButton

          # Give it a moment.
          delay 2

          # Regrab the reference, since they may have replaced it
          set installButton to button 1 of installButtonContainer

          # Do we need to confirm?
          if description of installButton = "Confirm, Install, Xcode, Free" then
            # Ramius: May what, Doctor?
            click installButton

            # Give it a moment.
            delay 2

            # Regrab the reference, since they may have replaced it
            set installButton to button 1 of installButtonContainer
          end if

          # Do we need to authenticate?
          # If so, we will be looking at a modal pop-down dialog for credentials.
          set needToAuthenticate to false
          try
            # We should now be looking at a modal pop-down dialog for credentials.
            set appleIdBox       to text field 2 of sheet 1
            set applePasswordBox to text field 1 of sheet 1
            set signInButton     to button 1     of sheet 1

            set needToAuthenticate to true
          on error
            # We may not be prompted for creds at all
          end try

          if needToAuthenticate = true then
            # Petrov: Arm the missiles, Captain.
            set value of appleIdBox       to appleId
            set value of applePasswordBox to applePassword

            # Give it a moment.
            delay 1

            # Ramius: Mmm, thank you for your concern Doctor.
            click signInButton

            # Give it a moment.
            delay 10

            # Regrab the reference
            set installButton to button 1 of installButtonContainer
          end if

          # At this point it should be downloading
          if not description of installButton = "Installing, Xcode" then
            error "Could not start install."
          end if

          # Busy wait..
          repeat while description of installButton = "Installing, Xcode"
            delay 5
            set installButton to button 1 of installButtonContainer
          end repeat

          if description of installButton = "Install, Xcode, Free" then
            error "Install paused or cancelled"
          else if not description of installButton = "Installed, Xcode" then
            error "Unknown error during installation"
          end if
        end tell
      end tell

      tell application "App Store" to quit
    end run
APPLESCRIPT
}

# Open Xcode, accept the license if needed and install the command line tools
function install_command_line_tools {
  [[ $# == 0 ]] || die "install_command_line_tools doesn't understand '$@'"

  # Do we already have (say) make and gcc? We're done!
  [ -r /usr/bin/make ] && [ -r /usr/bin/gcc ] && return 0

  # Open Xcode
  open /Applications/Xcode.app

  # Give it a moment
  sleep 10

  osascript <<'APPLESCRIPT'
    on run argv
      tell application "System Events"
        # Open Preferences
        keystroke "," using command down

        # Give it a moment
        delay 1

        # The window name changes based on selected tab, use the number.
        tell window 1 of process "Xcode"
          click button "Downloads" of tool bar 1
        end tell

        # Note the window reference has changed

        tell window "Downloads" of process "Xcode"
          set cliToolsRow to row 1 of table 1 of scroll area 1 of splitter group 1

          # There may be no button if installion is complete or in progress
          try
            click button "Install" of cliToolsRow
          on error
            # Nothing to do?  Try falling through
          end try
        end tell

#        # We may have to authenticate
#        set needToAuthenticate to false
#        try
#          set authenticationPopup to window 1 of process "SecurityAgent"
#          set needToAuthenticate to true
#        on error
#          # Then again maybe we don't
#        end try
#
#        if needToAuthenticate = true then
#          tell authenticationPopup
#            set adminPasswordBox to text field 2 of scroll area 1 of group 1
#            set installButton to button "Install Software" of group 2
#
#            set value of adminPasswordBox to adminPassword
#            click installButton
#          end tell
#        end if

        # Busy wait..
        tell window "Downloads" of process "Xcode"
          set installed to false
          repeat until installed = true
            delay 1
            try
              set cliToolsRow to row 1 of table 1 of scroll area 1 of splitter group 1
              set progressIndicator to static text 2 of cliToolsRow
              if value of progressIndicator = "Installed" then
                set installed to true
              else
                error "Unknown installation error"
              end if
            on error
              # No text field has appeared yet, it's probably the progress bar.
            end try
          end repeat
        end tell
      end tell

      tell application "Xcode" to quit
    end run
APPLESCRIPT
}

function main {
  # Assert the only argument is 'please' or show the help and bomb out.
  [[ $# != 1 || "$1" != 'please' ]] && show_help && exit 0

  local apple_id        # The user's apple id from stdin
  local apple_password  # The user's apple password, from stdin

  # Spawn a sudo refresh loop
  #while true
  #do
  #  sudo -v
  #  sleep 30
  #done &

  # Detect interactive shells and either read in the credentials or prompt
  if [ -t 0 ]
  then
    # Interactive
    read    -p 'Apple ID: '       apple_id
    read -s -p 'Apple Password: ' apple_password
    echo
  else
    # Non-interactive
    read apple_id && read apple_password ||
      die_help 'Please pass your apple credentials on standard in.'
  fi

  # Verify the credentials or die
  verify_credentials "$apple_id" "$apple_password" ||
    die 'Could not verify your credentials with Apple.  Sorry!'

  # Turn on support for assistive devices.
  toggle_assistive_devices on

  # Disable administrator auth check for installing command line tools
  toggle_install_apple_software_check off

  # Ensure Xcode is downloaded
  download_xcode "$apple_id" "$apple_password"

  # TODO: need to script accepting license.
  # Accept the license if needed and install command line tools
  install_command_line_tools

  # Put the administrator auth check back
  toggle_install_apple_software_check on

  # Turn assistive devices back off
  toggle_assistive_devices off

  # Kill the sudo refresh loop
  #kill %1
  #wait
}

main "$@"