##   RSence
 #   Copyright 2008 Riassence Inc.
 #   http://riassence.com/
 #
 #   You should have received a copy of the GNU General Public License along
 #   with this software package. If not, contact licensing@riassence.com
 ##


# Use rubygems to load rack
require 'rubygems'

# Transporter is the top-level handler for calls coming from the javascript COMM.Transporter.
require 'transporter/transporter'

# Broker routes requests to the correct handler
require 'http/broker'


module RSence
  
  # @private  The process id of the launch process (usually the PID of the 'rsence' command)
  @@launch_pid = Process.pid
  
  # @private  Returns the pid of the process when starting up.
  #   PID is different for the forked child process or processes
  def self.launch_pid
    return @@launch_pid
  end

  # @private  The Controller module handles the daemonizing
  #   operations of the process referred to as +daemon+
  module Daemon
  
    # Writes the process id to disk, the pid_fn method of the daemon contains
    # the name of the pid file.
    def self.write_pid( daemon, pid )
      File.open( daemon.pid_fn, 'w' ) do |pidfile|
        pidfile.write( pid )
      end
    end
  
    # Reads the process id from disk, the pid_fn method of the daemon contains
    # the name of the pid file. Returns nil on errors.
    def self.read_pid( daemon )
      File.read( daemon.pid_fn ).to_i rescue nil
    end
  
    def self.responds?( daemon )
      wait_signal_response( daemon, 'USR2' )
    end
  
    # Reads the pid file and calls the process.
    # Returns true if the process responds, false otherwise (no process)
    def self.status( daemon )
      pid = read_pid( daemon )
      return nil if not pid
      return responds?( daemon )
    end
  
    # Redirects standard input and errors to the log files
    def self.start_logging( daemon )
      outpath = "#{daemon.log_fn}.stdout"
      errpath = "#{daemon.log_fn}.stderr"
      STDOUT.reopen( outpath, (File.exist?( outpath ) ? 'a' : 'w') )
      STDOUT.sync = true
      STDERR.reopen( errpath, (File.exist?( errpath ) ? 'a' : 'w') )
      STDERR.sync = true
    end
  
    # Writes a signal response file containing the pid.
    def self.write_signal_response( daemon, signal )
      pid = Process.pid.to_s
      pid_fn = daemon.pid_fn
      RSence::SIGComm.write_signal_response( pid, pid_fn, signal )
    end
  
    # Removes a signal response file.
    def self.delete_signal_response( daemon, signal )
      pid_fn = daemon.pid_fn
      RSence::SIGComm.delete_signal_response( pid_fn )
    end
  
    # Waits for a signal response.
    def self.wait_signal_response( daemon, signal, timeout = 10,
                                   debug_pre = false, debug_suf = false, sleep_secs = 0.2 )
      pid = read_pid( daemon )
      pid_fn = daemon.pid_fn
      return RSence::SIGComm.wait_signal_response( pid, pid_fn, signal, timeout, debug_pre, debug_suf, sleep_secs )
    end
  
    # Signal trapping for windows.
    # The only supported POSIX signal trappable seems to be INT (CTRL-C).
    def self.trap_windows_signals( daemon )
      ['INT'].each do | signal |
        Signal.trap( signal ) do
          puts "RSence killed with signal #{signal.inspect}" if RSence.args[:verbose]
          daemon.usr1
          daemon.stop
          puts "Shutdown complete."
          exit
        end
      end
    end
  
    # Traps common POSIX signals
    def self.trap_signals( daemon )
    
      # Triggered with 'kill -USR1 `cat rsence.pid`'
      Signal.trap( 'USR1' ) do 
        daemon.usr1
        write_signal_response( daemon, 'USR1' )
      end
      Signal.trap('USR2') do 
        daemon.usr2
        write_signal_response( daemon, 'USR2' )
      end
      ['INT', 'TERM', 'KILL'].each do | signal |
        Signal.trap( signal ) do
          puts "RSence killed with signal #{signal.inspect}" if RSence.args[:verbose]
          daemon.usr1
          daemon.stop
          delete_stale_pids( daemon )
          write_signal_response( daemon, signal )
          puts "Shutdown complete."
          exit
        end
      end
      Signal.trap('HUP') do
        daemon.stop
        daemon.start
      end
    end
  
    # Removes all pid files that were left around if a process died unexpectedly.
    def self.delete_stale_pids( daemon )
      ( pid_fn_path, pid_fn_name ) = File.split( daemon.pid_fn )
      Dir.entries( pid_fn_path ).each do | item_fn |
        item_path = File.join( pid_fn_path, item_fn )
        if item_fn.start_with?( pid_fn_name ) and File.file?( item_path )
          puts "Stale pid file (#{item_fn}), removing.." if RSence.args[:verbose]
          File.delete( item_path )
        end
      end
    end
  
    # Creates pid file and traps signal.
    def self.init_pid( daemon )
      if RSence.pid_support?
        is_running = status( daemon )
        if is_running
          puts "RSence is already running."
          puts "Stop the existing process first: see 'rsence help stop'"
          if RSence.launch_pid != Process.pid
            Process.kill( 'INT', RSence.launch_pid )
          end
          exit
        elsif not is_running
          delete_stale_pids( daemon )
        end
        trap_signals( daemon )
        pid = Process.pid
        write_pid( daemon, pid ) 
        return pid
      else
        trap_windows_signals( daemon )
        return false
      end
    end
  
    # Inits the pid, signals and then starts the server in the foreground
    def self.run( daemon )
      init_pid( daemon )
      daemon.run
      exit
    end
  
    # Inits the pid, signals and then starts the daemon in
    # the background and waits until the daemon sends the TERM signal.
    def self.start( daemon )
      fork do
        exit if fork
        init_pid( daemon )
        daemon.start
      end
      Signal.trap('INT') do
        puts "RSence startup failed. Please inspect the log and/or run in debug mode."
        exit
      end
      Signal.trap('TERM') do
        puts "RSence is online at http://#{daemon.addr}:#{daemon.port}/"
        exit
      end
      sleep 1 while true
    end
  
    # Sends the USR1 signal to the process, which in turn
    # calls the save method of the daemon.
    def self.save( daemon )
      status_ = status( daemon )
      if status_
        if wait_signal_response( daemon, 'USR1', 10, 'saving.', 'saved', 0.3 )
          puts "Session data saved."
        else
          puts "Warning: saving timed out! Session data not saved."
        end
      elsif status_ == false
        puts "Warning, no such process (#{pid}) running: unable to save."
      elsif status_ == nil
        puts "No pid file: unable to save."
      else
        throw "Unexpected process status: #{status_.inspect}"
      end
    end
  
    # Sends the TERM signal to the process, which in turn
    # calls the stop method of the daemon
    def self.stop( daemon )#,is_restart=false)
      status_ = status( daemon )
      if status_
        if wait_signal_response( daemon, 'TERM', 10, 'killing.', 'killed', 0.3 )
          puts "RSence is terminated now."
        else
          puts "Warning: termination timed out!"
          puts "RSence might still be running, please ensure manually."
        end
      elsif status_ == false
        puts "Warning, no such process (#{read_pid(daemon)}) running."
      elsif status_ == nil
        puts "Warning, no pid file (process not running)."
      else
        throw "Unexpected process status: #{status_.inspect}"
      end
    end
  
    # Main entry point called from the daemon process passing +self+ as +daemon+.
    def self.daemonize( daemon )
    
      # Uses the command-line tool command to decide what to do.
      case RSence.cmd
      when :run
        run( daemon )
      when :start
        start( daemon )
      when :stop
        stop( daemon )
      when :restart
        stop( daemon )
        start( daemon )
      when :save
        save( daemon )
      end
    end
  
  end

  # @private  Simple process control, constructed here and called from Daemon::Controller
  class HTTPDaemon
  
    # RSence top-level run handler. Almost identical to start.
    def run
    
      puts "Starting as a foreground process." if RSence.args[:verbose]
      puts "Press CTRL-C to terminate."
    
      @transporter = Transporter.new
    
      conf = RSence.config[:http_server]
    
      unless RSence.args[:log_fg]
        Daemon.start_logging( self )
      end
    
      # This is the main http handler instance:
      @broker = Broker.start(
        @transporter,
        conf
      )
    
    end
  
    # Returns the pid file path.
    def pid_fn
      RSence.config[:daemon][:pid_fn]
    end
  
    # Returns the log path.
    def log_fn
      RSence.config[:daemon][:log_fn]
    end
  
    # Returns the configured bind address
    def addr
      RSence.config[:http_server][:bind_address]
    end
  
    # Returns the configured port.
    def port
      RSence.config[:http_server][:port]
    end
  
    # Called by Controller#start, contains RSence-specific operations
    def start
    
      @transporter = Transporter.new
    
      conf = RSence.config[:http_server]
    
      unless RSence.args[:log_fg]
        Daemon.start_logging( self )
        STDIN.reopen( "/dev/null" )
      end
    
      Process.setsid
    
      # This is the main http handler instance:
      @broker = Broker.start(
        @transporter,
        conf
      )
      yield @broker
    
    end
  
    # Called by Controller#stop, contains RSence-specific operations
    def stop
      @transporter.shutdown
    end
  
    # Called on USR1 signals (save data)
    def usr1
      save
    end
  
    # Save state
    def save
      puts "#{Time.now.strftime('%Y-%m-%d %H:%M:%S')} -- Saving state..."
      transporter_state = @transporter.online?
      @transporter.online = false
      @transporter.plugins.delegate(:flush)
      @transporter.sessions.store_sessions
      @transporter.online = transporter_state
      puts "#{Time.now.strftime('%Y-%m-%d %H:%M:%S')} -- State saved."
    end
  
    # Called on USR2 signals ("Alive?")
    def usr2
      puts "#{Time.now.strftime('%Y-%m-%d %H:%M:%S')} -- RSence version #{RSence.version} is running."
    end
  
    # Main entry point, daemonizes itself using Controller.
    def daemonize!
      Daemon.daemonize( self )
    end
  
  end
end