enum Package::BuildStatus
	Success
	Failed
	Pass
end

class Package::Backend::Building
	getter phase : String
	getter name : String
	getter callback : Proc(Context, Recipe, BuildStatus)
	def initialize(@phase, @name, &block : Proc(Context, Recipe, BuildStatus))
		@callback = block
	end
	def build(context : Context, recipe : Recipe)
		@callback.call context, recipe
	end
end

class Package::Instructions
	class Set < Array(String)
		getter phase : String
		def initialize(@phase)
			super()
		end
		# FIXME: def execute

		def run(context : Context, recipe : Recipe) : BuildStatus
			if size > 0
				each do |command|
					child = Do.run recipe.building_directory, "sh", ["-x", "-c", command]

					if child.exit_status != 0
						return BuildStatus::Failed
					end
				end

				return BuildStatus::Success
			end

			context.building_backends.select(&.phase.==(@phase)).each do |backend|
				Dir.cd recipe.building_directory

				rvalue = backend.build context, recipe

				if rvalue == BuildStatus::Pass
					next
				end

				return rvalue
			end

			BuildStatus::Pass
		rescue e
			# Possible TODO: print the origin of the exception (backend, user-provided code, other/unknown).
			STDERR << "Exception caught: " << e.message << "\n"
			BuildStatus::Failed
		end
	end

	# FIXME: Switch to an enum at some point?
	getter configure  = Set.new "configure"
	getter build      = Set.new "build"
	getter install    = Set.new "install"

	def to_a
		[configure, build, install]
	end
end