service/src/service.cr

require "option_parser"
require "yaml"
require "colorize"

require "./config.cr"

# TODO:
#   - Be more declarative about the definition of commands.

require "./service/*"

args = [] of String

parser = OptionParser.parse! do |parser|
	parser.banner = "usage: service <command> [options]\n" +
		"\n" +
		"commands:\n" +
		"    start                     Starts a stopped or dead service.\n" +
		"    stop                      Stops a running service.\n" +
		"    status                    Shows the current state of a service.\n" +
		"    show                      Describe a service in detail.\n" +
		"    add                       Add a service to an environment.\n" +
		"    del                       Remove a service from an environment.\n" +
		"    list                      Lists registered services.\n" +
		"    list-environments         Lists registered environments.\n" +
		"\n" +
		"options:\n"

	parser.on "-h", "--help", "Prints this help message." do
		puts parser
		exit 0
	end
	parser.unknown_args do |x|
		args = x
	end
end

command = args[0]?
if command.nil?
	STDERR << parser << "\n"
	exit 1
end

ServiceDefinition.load SERVICES_DIRECTORY
Environment.load ENVIRONMENTS_DIRECTORY
Service.load RC_DIRECTORY

begin
	if args[0] == "help"
		puts parser
	elsif args[0] == "add"
		environment : String? = nil
		providers = Hash(String, String).new

		args.each_with_index do |arg, i|
			next if i == 0

			match = arg.match /(.*)=(.*)/

			if match.nil?
				# FIXME: Check environment is not defined already.
				environment = arg
				next
			end

			providers[match[1]] = match[2]
		end

		Service.new(args[1], environment).tap do |service|
			service.consumes.each do |token|
				provider = providers[token.token]?

				if provider.nil?
					provider = service.get_default_provider token.token
				end

				if provider.nil?
					STDERR.puts "This service consumes a “#{token.token}” token, but you have not specified what other service is supposed to provide it."
					STDERR.puts "Use the `service add #{args[1]} #{token.token}=<provider>` syntax to specify it."
					exit 1
				end

				service.providers[token.token] = provider
			end
			pp! service.providers
		end.write RC_DIRECTORY
	elsif args[0] == "del"
		Service.new(args[1], args[2]?).remove RC_DIRECTORY
	elsif args[0] == "start"
		services = args[1..args.size].map do |arg|
			service = Service.get_by_id(arg)

			unless service
				raise Service::Exception.new "Service '#{arg}' does not exist."
			end

			service
		end

		services.each do |service|
			service.dependency_tree.flatten.reverse.each do |service|
				next if service.running? PID_DIRECTORY

				puts "starting #{service.to_s}"
				service.start PID_DIRECTORY, LOG_DIRECTORY
			end
		end
	elsif args[0] == "stop"
		services = args[1..args.size].map do |arg|
			service = Service.get_by_id(arg)

			unless service
				raise Service::Exception.new "Service '#{arg}' does not exist."
			end

			service
		end

		services.each do |service|
			# FIXME: Build revdep tree and stop services started as dependencies?
			next if ! service.running? PID_DIRECTORY
			# FIXME: Should we remove duplicate services from the
			#        tree once flattened?
			service.reverse_dependency_tree.flatten.reverse.each do |service|
				next if ! service.running? PID_DIRECTORY

				puts "stopping #{service.to_s}"
				service.stop PID_DIRECTORY
			end
		end
	elsif args[0] == "status"
		child = Process.run "#{OWN_LIBEXEC_DIR}/status", [args[1]],
			output: Process::Redirect::Inherit,
			error: Process::Redirect::Inherit
		return_value = child.exit_status / 256

		# Errors not registered here should probably be verbose in `status`.
		if return_value == 1
			STDERR << "No such service.\n"
		end

		exit return_value
	elsif args[0] == "show"
		service = Service.all.find do |service|
			unless service.name == args[1]
				next false
			end

			env = args[2]? || "root"
			if service.environment.name != env
				next false
			end

			true
		end
		if service
			puts service.summary
		else
			STDERR << "No such service is registered.\n"
			exit 2
		end
	elsif args[0] == "list"
		Service.all.map do |service|
			puts service.to_s
		end
	elsif args[0] == "list-environments"
		Environment.all.map do |env|
			puts env.to_s
		end
	else
		STDERR << parser << "\n"
		exit 1
	end
rescue e : Service::Exception
	STDERR << e.message << "\n"
	exit 2
end