class Build::Files::Monitor

def add(handle)
	handle.directories.each do |directory|
		@directories[directory] << handle
		
		# We just added the first handle:
		if @directories[directory].size == 1
			# If the handle already existed, this might trigger unnecessarily.
			@updated = true
		end
	end
	
	handle
end

def delay_deletions
	@deletions = []
	
	yield
	
	@deletions.each do |handle|
		purge(handle)
	end
	
	@deletions = nil
end

def delete(handle)
	if @deletions
		@deletions << handle
	else
		purge(handle)
	end
end

def initialize
	@directories = Hash.new { |hash, key| hash[key] = Set.new }
	
	@updated = false
	
	@deletions = nil
end

def purge(handle)
	handle.directories.each do |directory|
		@directories[directory].delete(handle)
		
		# Remove the entire record if there are no handles:
		if @directories[directory].size == 0
			@directories.delete(directory)
			
			@updated = true
		end
	end
end

def roots
	@directories.keys
end

def run(options = {}, &block)
	default_driver = case RUBY_PLATFORM
		when /linux/i; :inotify
		when /darwin/i; :fsevent
		else; :polling
	end
	
	if driver = options.fetch(:driver, default_driver)
		method_name = "run_with_#{driver}"
		Files.send(method_name, self, options, &block)
	end
end

def track_changes(files, &block)
	handle = Handle.new(self, files, &block)
	
	add(handle)
end

def update(directories, *args)
	delay_deletions do
		directories.each do |directory|
			# directory = File.realpath(directory)
			
			@directories[directory].each do |handle|
				handle.changed!(*args)
			end
		end
	end
end