Dependency trees.

- Were tested for `start` and seem to work fine with them.
  - `stop` still ignores them compteley at the moment. We’ll need to
    remember what has been started as a dependency and what has not to
    make `stop` work with reverse-dependency-trees.

src/main.cr

@@ -167,7 +167,7 @@ class Service
 			Environment.get environment_name
 		end
 
-		consumes.map do |consume|
+		@consumes.each do |consume|
 			@providers[consume.token] = consume.from
 		end
 	end
@@ -313,21 +313,45 @@ class Service
 		File.delete "#{path}/#{name}.#{@environment.name}.yaml"
 	end
 
-	# TODO:
-	#   - Improve error handling when a string is not a proper reference to a
-	#     service instance.
 	def self.get_by_id(id)
 		matches = id.match /[^\/]*/
-		unless matches
+		unless matches # Should not happen, above regex would always match.
 			raise Exception.new "FIXME"
 		end
 		environment_name = matches[0]
-		service_name = id.sub 0..matches[0].size, ""
+		service_name = if environment_name == id
+			environment_name = "root"
+			id
+		else
+			id.sub 0..matches[0].size, ""
+		end
 
 		@@all.find do |service|
 			service.name == service_name
 		end
 	end
+
+	alias DependencyTree = Array(DependencyTree) | Service
+
+	# Returns a dependency tree.
+	# You’ll probably want to flatten and reverse it afterwards.
+	def dependency_tree
+		tree = [self] of DependencyTree
+
+		@consumes.each do |token|
+			service = Service.get_by_id token.from
+
+			unless service
+				# FIXME: Does it make the dep tree invalid?
+				# FIXME: Only optional deps should be fine.
+				next
+			end
+
+			tree << service.dependency_tree
+		end
+
+		tree
+	end
 end
 
 args = [] of String
@@ -374,8 +398,18 @@ begin
 	elsif args[0] == "del"
 		Service.new(args[1], args[2]?).remove "rc"
 	elsif args[0] == "start"
-		Service.new(args[1], args[2]?).start "pid", "log"
+		#service = Service.new(args[1], args[2]?)
+		service = Service.get_by_id(args[1]).not_nil!
+		service.dependency_tree.flatten.reverse.each do |service|
+			if service.status("pid") == Service::Status::Running
+				next
+			end
+
+			puts "starting #{service.to_s}"
+			service.start "pid", "log"
+		end
 	elsif args[0] == "stop"
+		# FIXME: Build revdep tree and stop services started as dependencies?
 		Service.new(args[1], args[2]?).stop "pid"
 	elsif args[0] == "status"
 		puts Service.new(args[1], args[2]?).status "pid"