#!/usr/bin/env ruby
require 'rubygems'
require 'sys/uname'
require 'pathname'
require 'optparse'
require 'rexml/document'
require 'fileutils'

class XPCOMCoreRubyGemInstaller
  attr_accessor :no_dry_run, :install_global, :install_local, :fix_path
  
  KnownAppIds = {'Firefox' => '{ec8030f7-c20a-464f-9b0e-13a3a9e97384}'}
  KnownVendors = %w[Mozilla]
  ScriptName = Pathname(__FILE__).basename
  SysName = Sys::Uname.sysname.downcase.to_sym
  InstallPathBuilders = {:linux => {}, :darwin => {}}
  GeckoCommands = %w[firefox-bin firefox xulrunner-bin]
  ProfilePath = Pathname("~/.profile").expand_path
  
  # Linux install path builders
  InstallPathBuilders[:linux][:global] = [
    lambda {|vendor,app,extension| Pathname("/usr/lib") + vendor + "extensions" + app + extension },
    lambda {|vendor,app,extension| Pathname("/usr/lib64") + vendor + "extensions" + app + extension },
    lambda {|vendor,app,extension| Pathname("/usr/share") + vendor + "extensions" + app + extension }
  ]
  InstallPathBuilders[:linux][:local] = [
    lambda {|vendor,app,extension| Pathname("~/.#{vendor}") + "extensions" + app + extension }
  ]
  
  # Mac OS X install path builders
  InstallPathBuilders[:darwin][:global] = [
    lambda {|vendor,app,extension| Pathname("/Library/Application Support") + vendor + "Extensions" + app + extension }
  ]
  InstallPathBuilders[:darwin][:local] = [
    lambda {|vendor,app,extension| Pathname("~/Library/Application Support") + vendor + "Extensions" + app + extension }
  ]

  GeckoLocations = {:linux => [], :darwin => []}
  GeckoLocations[:darwin] << Pathname("/Applications/Firefox.app/Contents/MacOS/firefox-bin")
  GeckoLocations[:darwin] << Pathname("/Library/Frameworks/XUL.framework/xulrunner-bin")
  
  def initialize(args, options = {})
    @args = args
    @options = options
    @option_parser = OptionParser.new do |opts|
      opts.banner = "Usage: #{ScriptName} [options]"
      opts.on("--install-global", "Install the XPCOMCore gem bootstrap code globally.", method(:install_global=))
      opts.on("--install-local", "Install the XPCOMCore gem bootstrap code for the current user only.", method(:install_local=))
      opts.on("--fix-path", "Checks the path for an executable Gecko installation and fixes it if necessary.", method(:fix_path=))
      opts.on("--do-it", "By default, we do a dry run and show the user what would happen. This forces the actual install.", method(:no_dry_run=))
    end
  end

  def dry_run?
    !no_dry_run
  end
  
  def go!
    @option_parser.parse(@args)
    install_opts = {:install_global => install_global, :install_local => install_local}
    if !install_opts.values.any?
      puts @option_parser
      exit(1)
    end
    read_install_manifest
    install_opts.each do |opt_name,value|
      send(:"do_#{opt_name}") if value
      log("All done!.")
    end
  rescue OptionParser::InvalidOption => e
    invalid_option(e)
  end

private

  def invalid_option(exception)
    puts exception.message
    puts @option_parser
    exit(1)
  end
  
  def do_install_global
    do_install(:global) && rewrite_path
  end
  
  def do_install_local
    do_install(:local) && rewrite_path
  end
  
  def do_install(scope)
    each_vendor_and_app_name_and_app_id do |vendor, app_name, app_id|
      if install_extension(scope, vendor, app_id)
        next(true)
      else
        log("No app install location for application '#{app_name}' by vendor '#{vendor}' exists. Skipping.")
        next(false)
      end
    end.any?
  end
  
  def each_vendor_and_app_name_and_app_id
    KnownVendors.each do |vendor_name|
      KnownAppIds.each do |app_name, app_id|
        yield(vendor_name, app_name, app_id)
      end
    end
  end
  
  def install_extension(scope, vendor, app_id)
    raise "Couldn't read extension id from install manifest" if extension_id.empty?
    InstallPathBuilders[SysName][scope].select do |path_builder|
      log("Performing a #{scope} install...")
      install_path = path_builder[vendor, app_id, extension_id].expand_path
      if !install_path.parent.exist?
        log("Directory '#{install_path.parent}' doesn't exist - skipping installation to this location.")
        next(false)
      else
        copy_extension_to(install_path)
        next(true)
      end
    end.any?
  end
  
  def read_install_manifest
    manifest_contents = (@options[:extension_path] + "install.rdf").read
    @install_manifest = REXML::Document.new(manifest_contents)
  end
  
  def extension_path
    @options[:extension_path]
  end
  
  def extension_id
    @extension_id ||= @install_manifest.root.elements["Description/em:id"].text
  end
  
  def copy_extension_to(install_path)
    if install_path.parent.writable?
      log("Copying '#{extension_path}' to '#{install_path}'")
      copy_dir(extension_path, install_path)
    else
      log("Path '#{install_path}' isn't writable. Maybe you need to run this as root and try again if installing globally?")
    end
  end
  
  def log(str)
    puts("#{dry_run? ? "[DRY RUN]" : "[INSTALLER]"} #{str}")
  end
  
  def copy_dir(src_path, install_path)
    return false if dry_run?
    FileUtils.cp_r(src_path.expand_path.to_s + "/.", install_path.to_s)
  end
  
  def rewrite_path
    return false unless fix_path
    gecko_available = check_path
    rewrite_profile unless gecko_available
  end
  
  def check_path
    GeckoCommands.collect do |cmd|
      `#{cmd} -v 2>/dev/null`
      $? == 0
    end.any?
  end
  
  def rewrite_profile
    log("I couldn't find any of '#{GeckoCommands.join(", ")}'. Doing my best attempt to rectify this.")
    send(:"rewrite_profile_for_#{SysName}")
  end
  
  def rewrite_profile_for_linux
    log("Sorry. You're on your own here. Check your distribution's documentation for details - for example, Firefox may be installed under a different name.")
  end
  
  def rewrite_profile_for_darwin
    loc = GeckoLocations[:darwin].detect {|p| p.exist?}
    unless loc
      log("I can't find Firefox installed on your system. Sorry.")
      exit(1)
    end
    log("Awesome. I found a Gecko installation at '#{loc}'. Rewriting your .profile to include this in the $PATH.")
    rewrite_path_with_location(loc.parent)
  end
  
  def rewrite_path_with_location(path_entry)
    profile_entry = %Q[PATH="#{path_entry}:$PATH"]
    log("Adding .profile entry: #{profile_entry}")
    if dry_run?
      log("Not adding an entry due to running in dry run mode.")
    else
      ProfilePath.open("a") do |io|
        io << "\n"
        io.puts("# This and the following lines automatically added by xpcomcore-rubygem on #{Time.now}.")
        io.puts(profile_entry)
      end
      log(".profile entry added. You may need to source your .profile again or log in and out for it to take effect.")
    end
  end
  
end

installer = XPCOMCoreRubyGemInstaller.new(ARGV, :extension_path => (Pathname(__FILE__).parent.parent + "extension").expand_path)
installer.go!