# Copyright (c) 2007, 2009 Samuel Williams. Released under the GNU GPLv3.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

require 'rexec/daemon/pidfile'
require 'rexec/task'

module RExec
	module Daemon
		# Daemon startup timeout
		TIMEOUT = 5

		# This module contains functionality related to starting and stopping the daemon, and code for processing command line input.
		module Controller
			# This function is called from the daemon executable. It processes ARGV and checks whether the user is asking for
			# <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt> or <tt>status</tt>.
			def self.daemonize(daemon)
				#puts "Running in #{WorkingDirectory}, logs in #{LogDirectory}"
				case !ARGV.empty? && ARGV[0]
				when 'start'
					start(daemon)
					status(daemon)
				when 'stop'
					stop(daemon)
					status(daemon)
					PidFile.cleanup(daemon)
				when 'restart'
					stop(daemon)
					PidFile.cleanup(daemon)
					start(daemon)
					status(daemon)
				when 'status'
					status(daemon)
				else
					puts "Invalid command. Please specify start, restart, stop or status."
					exit
				end
			end

			# This function starts the supplied daemon
			def self.start(daemon)
				puts "Starting daemon..."

				case PidFile.status(daemon)
				when :running
					$stderr.puts "Daemon already running!"
					return
				when :stopped
					# We are good to go...
				else
					$stderr.puts "Daemon in unknown state! Will clear previous state and continue."
					status(daemon)
					PidFile.clear(daemon)
				end

				daemon.prefork
				daemon.mark_err_log

				fork do
					Process.setsid
					exit if fork

					PidFile.store(daemon, Process.pid)

					File.umask 0000
					Dir.chdir daemon.working_directory

					$stdin.reopen "/dev/null"
					$stdout.reopen daemon.log_fn, "a"
					$stdout.sync = true
					
					$stderr.reopen daemon.err_fn, "a"
					$stderr.sync = true

					begin
						error = nil
						
						main = Thread.new do
							begin
								daemon.run
							rescue
								error = $!
							end
						end

						trap("INT") do
							begin
								daemon.shutdown
								main.exit
							rescue
								error = $!
							end
						end

						trap("TERM") do
							exit!
						end

						main.join

						raise error if error
					rescue
						$stderr.puts "=== Daemon Exception Backtrace @ #{Time.now.to_s} ==="
						$stderr.puts "#{$!.class}: #{$!.message}"
						$!.backtrace.each { |at| $stderr.puts at }
						$stderr.puts "=== Daemon Crashed ==="
						$stderr.flush
					ensure
						$stderr.puts "=== Daemon Stopping @ #{Time.now.to_s} ==="
						$stderr.flush
					end
				end

				puts "Waiting for daemon to start..."
				sleep 0.1
				timer = TIMEOUT
				pid = PidFile.recall(daemon)

				while pid == nil and timer > 0
					# Wait a moment for the forking to finish...
					puts "Waiting for daemon to start (#{timer}/#{TIMEOUT})"
					sleep 1

					# If the daemon has crashed, it is never going to start...
					break if daemon.crashed?

					pid = PidFile.recall(daemon)

					timer -= 1
				end
			end

			# Prints out the status of the daemon
			def self.status(daemon)
				case PidFile.status(daemon)
				when :running
					puts "Daemon status: running pid=#{PidFile.recall(daemon)}"
				when :unknown
					if daemon.crashed?
						puts "Daemon status: crashed"

						$stdout.flush
						daemon.tail_err_log($stderr)
					else
						puts "Daemon status: unknown"
					end
				when :stopped
					puts "Daemon status: stopped"
				end
			end

			# Stops the daemon process.
			def self.stop(daemon)
				puts "Stopping daemon..."

				# Check if the pid file exists...
				if !File.file?(daemon.pid_fn)
					puts "Pid file not found. Is the daemon running?"
					return
				end

				pid = PidFile.recall(daemon)

				# Check if the daemon is already stopped...
				unless PidFile.running(daemon)
					puts "Pid #{pid} is not running. Has daemon crashed?"
					return
				end

				pid = PidFile.recall(daemon)
				Process.kill("INT", pid)
				sleep 0.1

				# Kill/Term loop - if the daemon didn't die easily, shoot
				# it a few more times.
				attempts = 5
				while PidFile.running(daemon) and attempts > 0
					sig = (attempts < 2) ? "KILL" : "TERM"

					puts "Sending #{sig} to pid #{pid}..."
					Process.kill(sig, pid)

					sleep 1
					attempts -= 1
				end

				# If after doing our best the daemon is still running (pretty odd)...
				if PidFile.running(daemon)
					puts "Daemon appears to be still running!"
					return
				end

				# Otherwise the daemon has been stopped.
				PidFile.clear(daemon)
			end
		end
	end
end