require_relative 'protocol'
require_relative 'errors'

module Knot
end

class Knot::Zone
	attr_reader :protocol, :zone
	def initialize zone, protocol = nil
		@protocol = protocol || Protocol.new
		@zone, @transaction_opened = zone, 0
	end

	# If no transaction opened, yet, it opens a new transaction.
	# Counts calling begin.
	# Knot allowes only one global transaction, so if two clients tries to open a transaction,
	# the second will fail.  But the second client can change items in the same
	# transaction like the first client.
	# The first client, which calls commit or abort, wins and the transaction will be closed.
	# So, the transaction-handling is only safe, if one client connects to knot.
	def begin
		@transaction_opened += 1
		@protocol.call command: 'zone-begin', zone: @zone  if 1 == @transaction_opened
	end

	# Decreases opened transactions.
	# If opened transactions is zero, it stores items and closes transaction successfully.
	def commit
		@protocol.call command: 'zone-commit', zone: @zone  if 1 == @transaction_opened
		@transaction_opened -= 1  if 0 < @transaction_opened
	end

	# Closes transaction without saving immidiatly.
	# Counter of opened transaction will be reset to 0.
	def abort
		@protocol.call command: 'zone-abort', zone: @zone
		@transaction_opened = 0
	end

	# Opens transaction, calls yielded Proc and closes transaction after return.
	# If exception was raised, the transaction will be aborted.
	def transaction # :yield:
		self.begin
		yield self
	rescue Object
		self.abort
		raise
	ensure
		self.commit  unless $!
	end

	# zone operation

	def check()       @protocol.call command: 'zone-check', zone: @zone  end
	def reload()      @protocol.call command: 'zone-reload', zone: @zone  end
	def refresh()     @protocol.call command: 'zone-refresh', zone: @zone  end
	def notify()      @protocol.call command: 'zone-notify', zone: @zone  end
	def retransfer()  @protocol.call command: 'zone-retransfer', zone: @zone  end
	def sign()        @protocol.call command: 'zone-sign', zone: @zone  end
	def freeze()      @protocol.call command: 'zone-freeze', zone: @zone  end
	def thaw()        @protocol.call command: 'zone-thaw', zone: @zone  end
	def status( filter = nil)  @protocol.call command: 'zone-status', zone: @zone, filter: filter  end

	def stats( modul = nil, counter = nil)
		@protocol.call command: 'zone-stats', zone: @zone, module: modul, counter: counter
	end

	# zone manipulation

	def read() @protocol.call command: 'zone-read', zone: @zone end
	def diff() @protocol.call command: 'zone-diff', zone: @zone end
	
	# setting record
	# if data is nil, it will be unset.
	def set owner, ttl = nil, type, data
		@protocol.call command: data.nil? ? 'zone-unset' : 'zone-set',
			zone: @zone, owner: owner, ttl: ttl, type: type, data: data
	rescue Knot::Errors::EISRECORD, Knot::Errors::ENONODE, Knot::Errors::ENOENT
	end
	alias []= set

	def unset owner, type = nil, data = nil
		@protocol.call command: 'zone-unset',
			zone: @zone, owner: owner, type: type, data: data
	rescue Knot::Errors::ENONODE, Knot::Errors::ENOENT
	end
	alias delete unset
	alias del unset

	def get owner = nil, type = nil
		@protocol.call command: 'zone-get',
			zone: @zone, owner: owner, type: type
	rescue Knot::Errors::ENONODE, Knot::Errors::ENOENT
		nil
	end
	alias [] get
end

class Knot::Conf
	def initialize protocol = nil
		@protocol = protocol || Protocol.new
		@transaction_opened = 0
	end

	def begin
		@transaction_opened += 1
		@protocol.call command: 'conf-begin'   if 1 == @transaction_opened
	end

	def commit
		@protocol.call command: 'conf-commit'  if 1 == @transaction_opened
		@transaction_opened -= 1  if 0 < @transaction_opened
	end

	def abort
		@protocol.call command: 'conf-abort'
		@transaction_opened = 0
	end

	def transaction
		self.begin
		yield self
	rescue Object
		self.abort
		raise
	ensure
		self.commit
	end

	def parse_item k
		case k
		when Hash
			case k.keys.sort
			when %w[section], %w[id section], %w[item section], %w[id item section]
				k
			else
				raise ArgumentError, "Invalid Item-format"
			end

		when Array
			case k.length
			when 1 then {section: k[0]}
			when 2 then {section: k[0], item: k[1]}
			when 3 then {section: k[0], id: k[1], item: k[2]}
			else raise ArgumentError, "Invalid Item-format"
			end

		when /\A
					(?<section> [a-z0-9_-]+ )
					(?: \[ (?<id> [a-z0-9_.-]+) \] )?
					(?: \. (?<item>[a-z0-9_-]+) )?
				\z/xi

			$~.named_captures.delete_if {|_,v| v.nil? }

		else
			raise ArgumentError, "Invalid Item-format"
		end
	end

	def get item = nil
		@protocol.call (item ? parse_item( item) : {}).update( command: 'conf-get')
	end

	# Sets or adds a new value to item.
	# knot knows single-value items like `server.rundir` and multi-value items like `server.listen`.
	# If you set a single-value, it will replace the old value.  On a multi-value, it will add it.
	def set item, value
		@protocol.call parse_item( item).update( command: 'conf-set', data: value)
	end

	# Removes value from item.  If you provide a value, this value will be removed.
	def unset item, value = nil
		@protocol.call parse_item( item).update( command: 'conf-unset', data: value)
	end
	alias delete unset

	def list item = nil
		@protocol.call (item ? parse_item( item) : {}).update( command: 'conf-list')
	end

	def read item = nil
		@protocol.call (item ? parse_item( item) : {}).update( command: 'conf-read')
	end
end