require 'erb'
require 'fileutils'
PhusionPassenger.require_passenger_lib 'platform_info/apache'
PhusionPassenger.require_passenger_lib 'platform_info/ruby'

# A class for starting, stopping and restarting Apache, and for manipulating
# its configuration file. This is used by the integration tests.
#
# Before a test begins, the test instructs Apache2Controller to create an Apache
# configuration folder, which contains an Apache configuration file and other
# configuration resources that Apache needs. The Apache configuration file is
# created from a template (see Apache2Controller::STUB_DIR).
# The test can define configuration customizations. For example, it can tell
# Apache2Controller to add configuration options, virtual host definitions, etc.
#
# After the configuration folder has been created, Apache2Controller will start
# Apache. After Apache has been started, the test will be run. Apache2Controller
# will stop Apache after the test is done.
#
# Apache2Controller ensures that starting, stopping and restarting are not prone
# to race conditions. For example, it ensures that when #start returns, Apache
# really is listening on its server socket instead of still initializing.
#
# == Usage
#
# Suppose that you want to test a hypothetical "AlwaysPrintHelloWorld"
# Apache configuration option. Then you can write the following test:
#
#   apache = Apache2Controller.new
#
#   # Add a configuration option to the configuration file.
#   apache << "AlwaysPrintHelloWorld on"
#
#   # Write configuration file and start Apache with that configuration file.
#   apache.start
#
#   begin
#       response_body = http_get("http://localhost:#{apache.port}/some/url")
#       response_body.should == "hello world!"
#   ensure
#       apache.stop
#   end
class Apache2Controller
  include PhusionPassenger
  STUB_DIR = File.expand_path(File.dirname(__FILE__) + "/../stub/apache2")

  class VHost
    attr_accessor :domain
    attr_accessor :document_root
    attr_accessor :additional_configs

    def initialize(domain, document_root)
      @domain = domain
      @document_root = document_root
      @additional_configs = []
    end

    def <<(config)
      @additional_configs << config
    end
  end

  attr_accessor :port
  attr_accessor :vhosts
  attr_reader :server_root

  def initialize(options = nil)
    set(options) if options
    @port = 64506
    @vhosts = []
    @extra = []
    @server_root = File.expand_path('tmp.apache2')
    @passenger_root = File.expand_path(PhusionPassenger.install_spec)
    @mod_passenger = PhusionPassenger.apache2_module_path
  end

  def set(options)
    options.each_pair do |key, value|
      instance_variable_set("@#{key}", value)
    end
  end

  # Create an Apache configuration folder and start Apache on that
  # configuration folder. This method does not return until Apache
  # has done initializing.
  #
  # If Apache is already started, this this method will stop Apache first.
  def start
    if running?
      stop
    else
      File.unlink("#{@server_root}/httpd.pid") rescue nil
    end

    if File.exist?(@server_root)
      FileUtils.rm_r(@server_root)
    end
    FileUtils.mkdir_p(@server_root)
    write_config_file
    FileUtils.cp("#{STUB_DIR}/mime.types", @server_root)

    if !system(PlatformInfo.httpd, "-f", "#{@server_root}/httpd.conf", "-k", "start")
      raise "Could not start an Apache server."
    end

    begin
      # Wait until the PID file has been created.
      Timeout::timeout(20) do
        while !File.exist?("#{@server_root}/httpd.pid")
          sleep(0.1)
        end
      end
      # Wait until Apache is listening on the server port.
      Timeout::timeout(7) do
        done = false
        while !done
          begin
            socket = TCPSocket.new('localhost', @port)
            socket.close
            done = true
          rescue Errno::ECONNREFUSED
            sleep(0.1)
          end
        end
      end
    rescue Timeout::Error
      raise "Could not start an Apache server."
    end
    Dir["#{@server_root}/*"].each do |filename|
      if File.file?(filename)
        File.chmod(0666, filename)
      end
    end
  end

  def graceful_restart
    write_config_file
    if !system(PlatformInfo.httpd, "-f", "#{@server_root}/httpd.conf", "-k", "graceful")
      raise "Cannot restart Apache."
    end
  end

  # Stop Apache and delete its configuration folder. This method waits
  # until Apache is done with its shutdown procedure.
  #
  # This method does nothing if Apache is already stopped.
  def stop
    pid_file = "#{@server_root}/httpd.pid"
    if File.exist?(pid_file)
      begin
        pid = File.read(pid_file).strip.to_i
        Process.kill('SIGTERM', pid)
      rescue Errno::ESRCH
        # Looks like a stale pid file.
        FileUtils.rm_r(@server_root)
        return
      end
    end
    begin
      # Wait until the PID file is removed.
      Timeout::timeout(17) do
        while File.exist?(pid_file)
          sleep(0.1)
        end
      end
      # Wait until the server socket is closed.
      Timeout::timeout(7) do
        done = false
        while !done
          begin
            socket = TCPSocket.new('localhost', @port)
            socket.close
            sleep(0.1)
          rescue SystemCallError
            done = true
          end
        end
      end
    rescue Timeout::Error
      raise "Unable to stop Apache."
    end
    if File.exist?(@server_root)
      FileUtils.chmod_R(0777, @server_root)
      FileUtils.rm_r(@server_root)
    end
  end

  # Define a virtual host configuration block for the Apache configuration
  # file. If there was already a vhost definition with the same domain name,
  # then it will be overwritten.
  #
  # The given document root will be created if it doesn't exist.
  def set_vhost(domain, document_root)
    FileUtils.mkdir_p(document_root)
    vhost = VHost.new(domain, document_root)
    if block_given?
      yield vhost
    end
    vhosts.reject! {|host| host.domain == domain}
    vhosts << vhost
  end

  # Checks whether this Apache instance is running.
  def running?
    if File.exist?("#{@server_root}/httpd.pid")
      pid = File.read("#{@server_root}/httpd.pid").strip
      begin
        Process.kill(0, pid.to_i)
        return true
      rescue Errno::ESRCH
        return false
      rescue SystemCallError
        return true
      end
    else
      return false
    end
  end

  # Defines a configuration snippet to be added to the Apache configuration file.
  def <<(line)
    @extra << line
  end

private
  def get_binding
    return binding
  end

  def write_config_file
    template = ERB.new(File.read("#{STUB_DIR}/httpd.conf.erb"))
    File.open("#{@server_root}/httpd.conf", 'w') do |f|
      f.write(template.result(get_binding))
    end
  end

  def modules_dir
    @@modules_dir ||= `#{PlatformInfo.apxs2} -q LIBEXECDIR`.strip
  end

  def builtin_modules
    @@builtin_modules ||= `#{PlatformInfo.httpd} -l`.split("\n").grep(/\.c$/).map do |line|
      line.strip
    end
  end

  def has_builtin_module?(name)
    return builtin_modules.include?(name)
  end

  def has_module?(name)
    return File.exist?("#{modules_dir}/#{name}")
  end

  def we_are_root?
    return Process.uid == 0
  end
end
