# Copyright, 2014, by Samuel G. D. Williams. <http://www.codeotaku.com>
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

require 'rainbow'

module Process
	class 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 `start`, `stop`, `restart`, `status`.
			def self.daemonize(daemon, argv = ARGV)
				case argv.shift
				when 'start'
					start(daemon)
					status(daemon)
				when 'stop'
					stop(daemon)
					status(daemon)
					ProcessFile.cleanup(daemon)
				when 'restart'
					stop(daemon)
					ProcessFile.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 Rainbow("Starting daemon...").color(:blue)

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

				daemon.prefork
				daemon.mark_log

				fork do
					Process.setsid
					exit if fork

					ProcessFile.store(daemon, Process.pid)

					File.umask 0000
					Dir.chdir daemon.working_directory

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

					begin
						daemon.startup
						
						trap("INT") do
							daemon.shutdown
						end
					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 Rainbow("Waiting for daemon to start...").color(:blue)
				sleep 0.1
				timer = TIMEOUT
				pid = ProcessFile.recall(daemon)

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

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

					pid = ProcessFile.recall(daemon)

					timer -= 1
				end
			end

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

						$stdout.flush
						$stderr.puts Rainbow("Dumping daemon crash log:").color(:red)
						daemon.tail_log($stderr)
					else
						puts Rainbow("Daemon status: unknown").color(:red)
					end
				when :stopped
					puts Rainbow("Daemon status: stopped").color(:blue)
				end
			end

			# Stops the daemon process.
			def self.stop(daemon)
				puts Rainbow("Stopping daemon...").color(:blue)

				# Check if the pid file exists...
				unless File.file?(daemon.process_file_path)
					puts Rainbow("Pid file not found. Is the daemon running?").color(:red)
					return
				end

				pid = ProcessFile.recall(daemon)

				# Check if the daemon is already stopped...
				unless ProcessFile.running(daemon)
					puts Rainbow("Pid #{pid} is not running. Has daemon crashed?").color(:red)

					daemon.tail_log($stderr)

					return
				end

				# Interrupt the process group:
				pgid = -Process.getpgid(pid)
				Process.kill("INT", pgid)
				sleep 0.1

				sleep 1 if ProcessFile.running(daemon)

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

					puts Rainbow("Sending #{sig} to process group #{pgid}...").color(:red)
					Process.kill(sig, pgid)

					attempts -= 1
					sleep 1
				end

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

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