service/src/gen-config.cr

require "crinja"

require "passwd"

require "./service/service.cr"
require "./config.cr"

def sanitize_path(path)
	path.gsub /\/\/+/, "/"
end

class Service
	alias CrinjaHash = Hash(String, Hash(String, Int32) | String | Crinja::Callable::Instance | Int32 | Nil)
	def to_genconfig
		CrinjaHash.new.tap do |entry|
			entry["name"] = name
			entry["id"] = full_id
			entry["environment"] = environment.name
			entry["root"] = root
			entry["domain"] = domain
			entry["ports"] = ports

			if !non_runnable
				user = Passwd.new("/etc/passwd", "/etc/group")
					.try &.get_user(user_name).not_nil!

				entry["uid"] = user.uid
				entry["gid"] = user.gid
				entry["user"] = user.login
			end

			entry["consumers"] = Crinja.function do
				token = arguments.varargs[0].to_s

				get_consumers(token).map &.id
			end

			entry["provider"] = Crinja.function do
				token = arguments.varargs[0].to_s

				providers.find(&.[0].==(token)).try &.[1]
			end
		end
	end
end

module GenConfig
	# FIXME: The fuck has this become.
	alias Variables =
		String |
		Array(String) | Array(Variables) |
		Hash(String, String) |
		Service::CrinjaHash |
		Array(Service::CrinjaHash) |
		Hash(String, Array(Service::CrinjaHash)) |
		Hash(String, Service::CrinjaHash) |
		Crinja::Callable::Instance

	def self.parse_options(unparsed : Array(String))
		options = ARGV.map(&.split '=')

		hash = Hash(String, Variables).new

		options.each do |entry|
			key, value = entry

			old_value = hash[key]?

			case old_value
			when nil
				hash[key] = value
			when String
				hash[key] = [old_value, value]
			when Array(String)
				old_value << value
			end
		end

		hash
	end
end

class GenConfig::Exception < Exception
end

class GenConfig::Context
	getter root : String

	def initialize(@root)
	end

	def generate(template, target : String, options : Hash(String, Variables))
		context = Service::Context.new
		context.load

		target_file = File.open target, "w"

		sources = [
			"#{SYSTEM_CONFIGURATION_DIRECTORY}/templates",
			"#{SHARED_DATA_DIRECTORY}/templates"
		]

		sources = sources
			.map(&.+("/#{template}.j2"))
			.map { |x| sanitize_path x }

		source = sources.find do |source|
			if File.exists? source
				puts "Generating '#{target}' from '#{source}'"

				next true
			end
		end

		unless source
			raise Exception.new "Could not find template to generate file ('#{target}')."
		end

		if service_id = ENV["SERVICE_ID"]?
			if service = context.get_service_by_id service_id
				environment = service.environment

				options["service"] = service.to_genconfig

				options["providers"] = service.providers.compact_map do |token, provider|
					provider = context.get_service_by_id provider

					next unless provider

					{token, provider.to_genconfig}
				end.to_h

				options["consumers"] = service.provides
					.map(&.token)
					.map{ |token|
						{token, service.get_consumers(token).map &.to_genconfig}
					}
					.to_h
			end
		end

		options["get_service"] = Crinja.function do
			context.get_service_by_id(arguments.varargs[0].to_s).try &.to_genconfig
		end

		options["raise"] = Crinja.function do
			message = arguments.varargs.join "\n"

			raise Service::Exception.new "template error: #{message}"
		end

		# FIXME: Move this to a separate binary?
		options["random_password"] = Crinja.function do
			id = (arguments.varargs[0]? || options["id"]).to_s
			password_id = arguments.varargs[1]? || "main"

			_service = context.get_service_by_id(id).not_nil!

			# FIXME: hardcoded path
			password_file = "#{_service.root}/password_#{password_id}"

			if File.exists? password_file
				File.read password_file
			else
				password = `dd if=/dev/urandom bs=64 count=1 | base64 -`
				password = password.gsub('\n', "")

				File.write password_file, password

				password
			end
		end

		template = File.read source

		target_file << Crinja.render(template, options)
		target_file.close
	end
end

template = ARGV[0]?
target = ARGV[1]?

if target.nil?
	puts "usage: configure <template-name> <target> [option1=value1 [option2=value2 […]]]"
	exit 1
end

ARGV.shift
ARGV.shift

options = GenConfig.parse_options ARGV

begin
	GenConfig::Context.new("/").generate(template, target, options)
rescue e : GenConfig::Exception
	STDERR.puts "Fatal error: #{e.message}"
	exit 1
rescue e : Crinja::TypeError
	STDERR.puts "Error reading template: #{e.message}"
	exit 1
rescue e
	STDERR.puts "unhandled exception: #{e.message}"
	e.backtrace.map do |line|
		STDERR << "  - " << line << '\n'
	end
end