class Collector::Dovecot
	class Sieve
		def initialize store, prometheus
			@store = store
			@stored_into_mailbox         = prometheus.counter :stored_into_mailbox_total, docstring: 'A counter of mails stored in mailbox by sieve', labels: %i[process]
			@forwards                    = prometheus.counter :forwared_mails_total, docstring: 'A counter of mails forwareded to other address', labels: %i[process]
			@discarded_duplicate_forward = prometheus.counter :discarded_duplicate_forward_total, docstring: 'A counter of discarded duplicates, which will not be forwarded.', labels: %i[process]
			%w[lmtp deliver].each do |p|
				@stored_into_mailbox.increment by: 0, labels: {process: p}
				@forwards.increment by: 0, labels: {process: p}
				@discarded_duplicate_forward.increment by: 0, labels: {process: p}
			end
		end

		def collect entry, process, msg
			case msg
			when / stored mail into mailbox /
				# dovecot.service dovecot lmtp sieve: lmtp(dillo@nfotex.com)<935639><hhtGGv2ZVmLXRg4AQx2OcA>: sieve: msgid=<1649842684455734173.18148473471766045120@vlmpaymp001.at.inside>: stored mail into mailbox
				@stored_into_mailbox.increment labels: {process: process}
			when / forwarded to /
				@forwards.increment labels: {process: process}
			when / discarded duplicate forward to /
				@discarded_duplicate_forward.increment labels: {process: process}
			else
				STDERR.puts "# #{entry._systemd_unit} #{entry.syslog_identifier} sieve| #{entry.message}"
			end
		end
	end

	class Delivery
		def initialize store, prometheus, sieve, saved_mailbox, process
			@store, @sieve, @process = store, sieve, process
			@connect               = prometheus.counter "#{process}_connect_total", docstring: "A counter of connection via #{process}"
			@disconnect            = prometheus.counter "#{process}_disconnect_total", docstring: "A counter of disconnect at #{process}"
			@saved_mail_to_mailbox = saved_mailbox
		end

		def collect entry, msg
			case msg
			when /\AConnect from / then @connect.increment
			when /\ADisconnect from / then @disconnect.increment
			when /saved mail to / then @saved_mail_to_mailbox.increment labels: {process: @process}
			when /\Asieve: (.*)/ then @sieve.collect entry, @process, $1
			else STDERR.puts "# #{entry._systemd_unit} #{entry.syslog_identifier} delivery| #{entry.message}"
			end
		end
	end

	class Imap
		def initialize store, prometheus
			@connection_closed = prometheus.counter :connection_closed_total, docstring: 'A counter of closed connection on dovecot'
			@inactivity        = prometheus.counter :disconnected_inactivity_total, docstring: 'A counter for disconnect for inactivity.'
			@connection_stats  = prometheus.counter :connection_stats_total, docstring: 'A counter for observed statistics after disconnected.', labels: %i[disconnect_reason]
			@logged_out        = prometheus.counter :logged_out_total, docstring: 'A counter of logouts on dovecot'
			@maildir_scanning_took_long         = prometheus.summary :maildir_scanning_took_long_total, docstring: 'A summary of long taken maildir scanning by reason (why).', labels: %i[why]
			@maildir_scanning_took_long_rename  = prometheus.counter :maildir_scanning_took_long_renames_total, docstring: 'A counter of rename()-calls while long taken mail dir scanning'
			@maildir_scanning_took_long_readdir = prometheus.counter :maildir_scanning_took_long_readdirs_total, docstring: 'A counter of readdir()-calls while long taken mail dir scanning'
			disconnect_reasons = ['logged out', 'connection closed', 'inactivity']
			disconnect_reasons.each {|r| @connection_stats.increment by: 0, labels: {disconnect_reason: r} }
			@connection_stats =
				Hash[ *%i[in out deleted expunged trashed hdr_count hdr_bytes body_count body_bytes].flat_map {|t|
					[t, prometheus.counter( :"connection_stats_#{t}_total", docstring: "Counter for #{t} statistics observed after disconnected")]
				}]
		end

		def collect entry, msg
			case msg
			when /\ALogged out (.*)/
				# imap(srv_rt0@nfotex.com)<936759><IXxbn4bc4roqAQGQAGoGAWAUP//++Cw+>: Logged out in=38 out=804 deleted=0 expunged=0 trashed=0 hdr_count=0 hdr_bytes=0 body_count=0 body_bytes=0
				@logged_out.increment
				$1.split( ' ').each {|x| t, v = x.split('='); @connection_stats[t.to_sym]&.increment by: v.to_f }
			when /\AConnection closed \([^)]+\) (.*)/
				# imap(johannes@nfotex.com)<936668><R4OTgIbcCKRQbb9l>: Connection closed (EXAMINE finished 0.041 secs ago) in=5253 out=390971 deleted=0 expunged=0 trashed=0 hdr_count=14 hdr_bytes=6569 body_count=14 body_bytes=336589
				@connection_closed.increment
				$1.split( ' ').each {|x| t, v = x.split('='); @connection_stats[t.to_sym]&.increment by: v.to_f }
			when /\AConnection closed: .* failed: \([^)]+\) (.*)/
				# imap(wiz@nfotex.com)<1447340><0OOGu+XeasMqAoOIC8CCAHA59y+2iMag>: Connection closed: read(size=6100) failed: Connection reset by peer (UID FETCH finished 0.159 secs ago) in=2982 out=17044659 deleted=0 expunged=0 trashed=0 hdr_count=1 hdr_bytes=3724 body_count=169 body_bytes=16970415
				@connection_closed.increment
				$1.split( ' ').each {|x| t, v = x.split('='); @connection_stats[t.to_sym]&.increment by: v.to_f }
			when /\ADisconnected for inactivity (.*)/
				@inactivity.increment
				$1.split( ' ').each {|x| t, v = x.split('='); @connection_stats[t.to_sym]&.increment by: v.to_f }
			when /\AWarning: Maildir: Scanning .+? took (?<took>\d+) seconds \((?<readdir>\d+) readdir\(\)s, (?<rename>\d+) rename\(\)s to cur\/, why=0x(?<why>[0-9a-fA-F]+)\)/
				# Warning: Maildir: Scanning /var/mail/nfotex.com/wiz/mails/.Updates/cur took 49 seconds (86044 readdir()s, 0 rename()s to cur/, why=0x80)
				m = $~
				@maildir_scanning_took_long.observe m[:took].to_i, labels: m[:why].to_i(16)
				@maildir_scanning_took_long_rename.increment by: m[:rename].to_i
				@maildir_scanning_took_long_readdir.increment by: m[:readdir].to_i
			else
				STDERR.puts "# #{entry._systemd_unit} #{entry.syslog_identifier} imap| #{entry.message}"
			end
		end
	end

	class ImapLogin
		def initialize store, prometheus
			@store = store
			@logged_in    = prometheus.counter :logged_in_total, docstring: 'A counter of successfull logins to dovecot'
			@aborted      = prometheus.counter :login_aborted_total, docstring: 'A counter of aborted logins'
			@disconnected = prometheus.counter :login_disconnected_total, docstring: 'A counter of disconnections before successfully logged in', labels: %i[reason]
		end

		def collect entry, msg
			case msg
			when /\ALogin: user=/
				@logged_in.increment
			when /\ADisconnected:? \((.*?)\): user=</
				case $1
				when /\Ano auth attempts/
					@disconnected.increment labels: {reason: 'no auth attempts'}
				when /\Aauth failed/
					@disconnected.increment labels: {reason: 'auth failed'}
				when /\AToo many invalid commands /
					@disconnected.increment labels: {reason: 'too many invalid commands'}
				when /\AInactivity /
					@disconnected.increment labels: {reason: 'inactivity'}
				when /\ADisconnected /
					@disconnected.increment labels: {reason: 'disconnected'}
				else
					@disconnected.increment labels: {reason: '<any>'}
					STDERR.puts "# #{entry._systemd_unit} #{entry.syslog_identifier} Disconnected before login| #{entry.message}"
				end
			when /\AAborted login/
				@aborted.increment
			else
				STDERR.puts "# #{entry._systemd_unit} #{entry.syslog_identifier} imap-login| #{entry.message}"
			end
		end
	end

	def initialize store, prometheus
		@store = store
		@sieve                 = Sieve.new store, Collector::PrefixProxy.new( prometheus, :sieve)
		@lmtp                  = Delivery.new store, prometheus, @sieve, @saved_mail_to_mailbox, :lmtp
		@deliver               = Delivery.new store, prometheus, @sieve, @saved_mail_to_mailbox, :deliver
		@imap_login            = ImapLogin.new store, prometheus
		@imap                  = Imap.new store, prometheus
		@saved_mail_to_mailbox = prometheus.counter :saved_mail_to_mailbox_total, docstring: "A counter of saved mails to mailbox directly", labels: %i[process]
		@auth_errors           = prometheus.counter :auth_errors_total, docstring: "A counter of dovecot auth errors by type.", labels: %i[error]
	end

	def collect entry
		# STDERR.puts "dovecot| #{entry.message}"
		case entry.message
		when /\Aimap-login: (.*)/ then @imap_login.collect entry, $1
		when /\Aimap\([^)]+\)(?:<[^ ]+>)?: (.*)/ then @imap.collect entry, $1
		when /\Almtp\([^ ]+\)<[^ ]+>: (.*)/ then @lmtp.collect entry, $1
		when /\Almtp\([^ ]+\): (.*)/ then @lmtp.collect entry, $1
		when /\Adeliver(?:[^:]+): (.*)/ then @deliver.collect entry, $1
		when /\Aauth: Error: (.*)/
			case $1
			when /\ALDAP: Connection lost to LDAP server, /
				@auth_errors.increment labels: {error: "ldap connection lost"}
			else
				STDERR.puts "# #{entry._systemd_unit} #{entry.syslog_identifier}| #{entry.message}"
				@auth_errors.increment labels: {error: "<any>"}
			end
		else STDERR.puts "# #{entry._systemd_unit} #{entry.syslog_identifier}| #{entry.message}"
		end
	end
end