class Package::Instructions
	enum Status
		Success
		Failed
		Pass
	end

	class BuildDefault
		getter name : String
		getter callback : Proc(Context, Recipe, Status)
		def initialize(@name, &block : Proc(Context, Recipe, Status))
			@callback = block
		end
	end

	class Set < Array(String)
		def initialize(@defaults_if_empty = Array(BuildDefault).new)
			super()
		end
		# FIXME: def execute

		def run(context : Context, recipe : Recipe) : Instructions::Status
			if size > 0
				# FIXME: Maybe do that for [1] and the others, no?
				child = context.run recipe.building_directory, "sh", ["-c", self[0]]

				if child.exit_status == 0
					return Instructions::Status::Success
				else
					return Instructions::Status::Failed
				end
			end

			@defaults_if_empty.each do |default|
				Dir.cd recipe.building_directory

				rvalue = default.callback.call context, recipe

				if rvalue == Status::Pass
					next
				end

				return rvalue
			end

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

		def <<(other : BuildDefault)
			@defaults_if_empty << other
		end
	end

	getter configure = Set.new
	getter build = Set.new
	getter install = Set.new

	def initialize
		@build << BuildDefault.new "autotools" do |context, recipe|
			Dir.cd recipe.dirname

			unless File.exists? "configure"
				next Instructions::Status::Pass
			end

			child = context.run "./configure",  ["--prefix=/package"]

			if child.exit_status == 0
				Instructions::Status::Success
			else
				Instructions::Status::Failed
			end
		end

		@build << BuildDefault.new "make" do |context, recipe|
			Dir.cd recipe.dirname

			unless File.exists? "Makefile"
				next Instructions::Status::Pass
			end

			child = context.run "make"

			if child.exit_status == 0
				Instructions::Status::Success
			else
				Instructions::Status::Failed
			end
		end
	end

	def to_a
		[configure, build, install]
	end
end