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/*"

parser = uninitialized OptionParser

args = [] of String

force = false

alias Command = Proc(Array(String), Nil)
alias CommandTuple = Tuple(String, String, Command)
class CommandsList
	def initialize
		@commands = Array(CommandTuple).new
	end

	def push(name : String, description : String, &proc : Command)
		@commands << Tuple.new(name, description, proc)
	end

	def find(&block : Proc(CommandTuple, Bool))
		@commands.find do |tuple|
			if block.call tuple
				next true
			end
		end
	end

	def to_s
		"commands:\n\n"+ @commands.map do |tuple|
			"    %-32s %s" % [tuple[0], tuple[1]]
		end.join "\n"
	end
end
commands = CommandsList.new

commands.push "add", "Adds a service to an environment." do |args|
	providers = Hash(String, String).new
	domain = nil

	environment, service = Service.parse_id args[0]

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

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

		if match.nil? || match.size < 2
			raise ::Service::Exception.new "usage: service add <service> <token=provider>"
			next
		end

		_, key, value = match

		if key == "domain"
			domain = value
		else
			providers[key] = value
		end
	end

	Service.new(service, environment).tap do |service|
		if domain
			service.domain = domain
		end

		service.consumes.each do |token|
			provider = providers[token.token]?

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

			next if provider.nil? && token.optional

			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

		if service.requires_domain && !service.domain
			raise Service::Exception.new "'#{service.name}' requires a domain= parameter to be provided!"
		end
	end.write RC_DIRECTORY
end

commands.push "del", "Removes a service from an environment." do |args|
	if args.size < 1
		STDERR.puts "usage: service del <id> [id [...]]"
		exit 1
	end

	rvalue = 0
	args.each do |id|
		service = Service.get_by_id(id)

		if service.nil?
			STDERR.puts "#{id}: no such service"
			rvalue = 1
			next
		end

		revdeps = service.reverse_dependencies

		if revdeps.size > 1 && ! force
			STDERR.puts "#{id}: has reverse dependencies, use -f to force"
			rvalue = 2
			next
		end

		revdeps.reverse.each do |service|
			next if ! service.running? PID_DIRECTORY

			puts "stopping #{service.to_s}"
			service.stop PID_DIRECTORY
		end

		revdeps.reverse.each do |service|
			service.remove RC_DIRECTORY
		end
	end

	exit rvalue
end

commands.push "start", "Starts a service." do
	services = args.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
end

commands.push "stop", "Stops a running service." do |args|
	services = args.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|
		next if ! service.running? PID_DIRECTORY

		service.reverse_dependencies.reverse.each do |service|
			next if ! service.running? PID_DIRECTORY

			puts "stopping #{service.to_s}"
			service.stop PID_DIRECTORY
		end
	end
end

commands.push "status", "Prints the status of services." do |args|
	child = Process.run "#{OWN_LIBEXEC_DIR}/status", args,
		output: Process::Redirect::Inherit,
		error: Process::Redirect::Inherit
	return_value = (child.exit_status / 256).to_i

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

	exit return_value
end

commands.push "show", "Shows a service's configuration and state." do |args|
	if args.size < 1
		STDERR << "usage: service show <id> [id [...]]\n"
		next
	end

	args.each do |arg|
		environment_name, service_name = Service.parse_id arg

		service = Service.all.find do |service|
			service.name == service_name &&
				service.environment.name == environment_name
		end

		if service
			puts service.summary
		else
			STDERR << "No such service is registered.\n"
			exit 2
		end
	end
end

commands.push "add-environment", "Creates a new (empty) environment." do |arg|
	if arg.size != 1
		STDERR.puts "usage: service add-environment <name>"
		exit 1
	end

	Environment.new(arg[0]).write ENVIRONMENTS_DIRECTORY
end

commands.push "list-environments", "Lists all currently defined environments.s", do |arg|
	Environment.all.map do |env|
		puts env.to_s
	end
end

commands.push "del-environment", "Removes an empty environment." do |arg|
	rvalue = 0

	arg.each do |arg|
		environment = Environment.all.find &.name.==(arg)

		if environment.nil?
			STDERR.puts "#{arg}: no such environment"
			rvalue = 2
			next
		end

		if Service.all.select(&.environment.name.==(environment.name)).size > 0
			STDERR.puts "#{arg}: is not empty"
			rvalue = 1
			next
		end

		environment.remove ENVIRONMENTS_DIRECTORY
	end

	exit rvalue
end

commands.push "help", "Prints this help message." do
	puts parser
	puts
	puts commands.to_s
end

parser = OptionParser.parse do |cli|
	cli.banner = "usage: service <command> [options]\n" +
		"options:\n"

	cli.on "-h", "--help", "Prints this help message." do
		puts cli
		puts
		puts commands.to_s
		exit 0
	end
	cli.on "-f", "--force", "Ignores warnings and executes dangerous operations." do
		force = true
	end

	cli.unknown_args do |x|
		args = x
	end
end

command = commands.find &.[0].==(args[0]?)
if command.nil?
	STDERR << parser << "\n"
	STDERR << "\n"
	STDERR << commands.to_s << "\n"
	exit 1
end

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

begin
	args.shift
	command.[2].call(args)
rescue e : Service::Exception
	STDERR << e.message << "\n"
	exit 2
end