# Duration to wait before taken modification into account (in minutes).
duration = 5

if ARGV.size != 2
	puts "usage: #{PROGRAM_NAME} dnsmanagerd-bind9-dir powerdns-bind9-dir"
	exit 0
end

class BrainlessLog
	class_property last_text_size : Int32 = 0

	# In case the lastly `unimportant` written string is to be kept on-screen.
	def self.important(str : String)
		unimportant "" # Clear the line and last_text_size = 0
		STDOUT.puts str
	end

	# Log something that isn't important, meaning text that will be
	# rewritten in-place since we don't really want to read it.
	# WARNING: user may want to keep the lastly written string, `keep` it.
	def self.unimportant(str : String)
		STDOUT.write ("\r" + (" " * self.last_text_size)).to_slice # Clear the line.
		self.last_text_size = str.size
		STDOUT.write ("\r" + str).to_slice
	end

	# In case the last `unimportant` string is to be kept on-screen.
	def self.keep
		STDOUT.puts "" unless self.last_text_size == 0
	end

	# In case the last `unimportant` string should be removed.
	def self.flush
		unimportant "" if self.last_text_size > 0
	end
end

class Context
	class_property dnsmanagerd_dir : String = ""
	class_property powerdns_dir    : String = ""
end

def copy_domain_files(domain : String) : Nil
	src  = "#{Context.dnsmanagerd_dir}/#{domain}"
	dest = "#{Context.powerdns_dir}/#{domain}"
	BrainlessLog.important "copying #{src} -> #{dest}"
	i = File.info src
	File.copy src, dest
rescue e : File::AccessDeniedError
	BrainlessLog.important "You don't have enough rights: #{e}"
rescue e : File::Error
	BrainlessLog.important "File error: #{e}"
end

def run_process(cmd : String, params : Array(String), env : Hash(String, String)) : Nil
	unless Process.run(cmd, params, env,
			true # clear environment
			# input:   Process::Redirect::Inherit,
			# output:  Process::Redirect::Inherit,
			# error:   Process::Redirect::Inherit
			).success?
		puts "cannot run #{cmd} #{params.join(' ')}"
	end
end

def pdns_reload(domain : String) : Nil
	BrainlessLog.important "reloading a domain: pdns_control bind-reload-now #{domain}"
	run_process("pdns_control", [ "bind-reload-now", domain ], { "HOME" => "/" })
end

def update_domain(domain : String) : Nil
	BrainlessLog.important "domain to reload: #{domain}"
	copy_domain_files domain
	pdns_reload domain
end

def pdns_add(domain : String) : Nil
	BrainlessLog.important "adding a new domain: pdns_control bind-add-zone #{Context.powerdns_dir}/#{domain}"
	run_process("pdns_control",
			[ "bind-add-zone", domain, "#{Context.powerdns_dir}/#{domain}" ],
			{ "HOME" => "/" })
end

def add_domain(domain : String) : Nil
	BrainlessLog.important "domain to add: #{domain}"
	copy_domain_files domain
	pdns_add domain
end

def delete_file(path : String)
	File.delete path
rescue e : File::AccessDeniedError
	BrainlessLog.important "You don't have enough rights: #{e}"
end

def del_domain(domain : String) : Nil
	BrainlessLog.important "domain to delete: #{domain}"
	delete_file "#{Context.powerdns_dir}/#{domain}"
	# TODO: pdns_control ???
end

Context.dnsmanagerd_dir = ARGV[0]
Context.powerdns_dir    = ARGV[1]

dnsmanagerd_dir_content = Dir.children(Context.dnsmanagerd_dir).select { |d| ! d.ends_with? ".wip" }
powerdns_dir_content    = Dir.children(Context.powerdns_dir)

both = dnsmanagerd_dir_content & powerdns_dir_content
both.each do |d|
	i1 = File.info "#{Context.dnsmanagerd_dir}/#{d}"
	i2 = File.info "#{Context.powerdns_dir}/#{d}"

	if i1.modification_time > i2.modification_time
		# Wait for a few minutes before changing anything, to avoid useless reloads.
		if Time.local > i1.modification_time.shift minutes: duration
			BrainlessLog.important "#{d}: updating"
			update_domain d
		else
			BrainlessLog.unimportant "#{d}: has been modified less than #{duration} minute ago, do not update yet"
		end
	else
		BrainlessLog.unimportant "#{d}: hasn't been modified"
	end
end
BrainlessLog.flush

to_add = dnsmanagerd_dir_content - powerdns_dir_content
to_add.each { |d| add_domain d }

to_delete = powerdns_dir_content - dnsmanagerd_dir_content
to_delete.each { |d| del_domain d }