# -*- ruby -*-
#encoding: utf-8

require 'tty/spinner'
require 'msgpack'

require 'arborist/cli' unless defined?( Arborist::CLI )
require 'arborist/client'
require 'arborist/event_api'

# Command to watch events in an Arborist manager.
module Arborist::CLI::Watch
	extend Arborist::CLI::Subcommand

	HEARTBEAT_CHARACTERS = %w[💓 💗]

	desc 'Watch events in an Arborist manager'

	command :watch do |cmd|
		cmd.action do |globals, options, args|
			client = Arborist::Client.new
			sock = client.event_api

			subid = subscribe_to_node_events( client )
			prompt.say "Subscription %p" % [ subid ]

			# Watch for system events as well
			prompt.say "Subscribing to manager heartbeat events."
			sock.subscribe( 'sys.heartbeat' )

			spinner = TTY::Spinner.new( "[           :spinner           ] waiting for events...\r",
				frames: HEARTBEAT_CHARACTERS, hide_cursor: true )

			begin
				last_runid = nil
				prompt.say "Watching for events on manager at %s" % [ client.event_api_url ]
				loop do
					msg = sock.receive
					subid, event = Arborist::EventAPI.decode( msg )

					case subid
					when 'sys.heartbeat'
						this_runid = event['run_id']

						if last_runid && last_runid != this_runid
							self.log.warn "Manager restart: re-subscribing."
							sock.unsubscribe( subid )
							subid = subscribe_to_node_events( client )
							prompt.say "New subscription %p" % [ subid ]
						else
							self.log.debug "Manager is alive (runid: %s)" % [ this_runid ]
						end

						spinner.spin
						last_runid = this_runid
					when 'sys.node_added'
						prompt.say "[%s] «Node added» %s\n" % [
							hl.dark.white( Time.now.strftime('%Y-%m-%d %H:%M:%S %Z') ),
							hl.bold.cyan( event['node'] )
						]
					when 'sys.node_removed'
						prompt.say "[%s] »Node removed« %s\n" % [
							hl.dark.white( Time.now.strftime('%Y-%m-%d %H:%M:%S %Z') ),
							hl.dark.cyan( event['node'] )
						]
					else
						prompt.say "[%s] %s\n" % [
							hl.dark.white( Time.now.strftime('%Y-%m-%d %H:%M:%S %Z') ),
							hl.dark.white( dump_event( event ) )
						]
					end
				end
			ensure
				self.log.info "Unsubscribing from subscription %p" % [ subid ]
				client.unsubscribe( subid )
			end
		end
	end


	###############
	module_function
	###############

	### Establish a subscription to all node events via the specified +client+.
	def subscribe_to_node_events( client )
		subid = client.subscribe( identifier: '_' )
		sock = client.event_api

		sock.subscribe( subid )
		return subid
	end


	### Return a String representation of the specified +event+.
	def dump_event( event )
		event_type = event['type']
		id = event['identifier']

		case event_type
		when 'node.update'
			type, status, errors = event['data'].values_at( *%w'type status errors' )
			return "%s updated: %s is %s%s" % [
				hl.cyan( id ),
				type,
				hl.decorate( status, status.to_sym ),
				errors ? " (#{errors})" : ''
			]
		when 'node.delta'
			pairs = diff_pairs( event['data'] )
			return "%s delta, changes: %s" % [ hl.cyan( id ), pairs ]
		else
			return "%s event: %p" % [ hl.dark.white( event_type ), event ]
		end
	end


	### Return a string showing the differences in a delta event's change +data+.
	def diff_pairs( data )
		diff = data.collect do |key, pairs|
			if pairs.is_a?( Hash )
				diff_pairs( pairs )
			else
				val1, val2 = *pairs
				"%s: %s -> %s" % [
					hl.dark.white( key ),
					hl.yellow( val1 ),
					hl.bold.yellow( val2 )
				]
			end
		end

		return hl.dark.white( diff.join(', ') )
	end


end # module Arborist::CLI::Watch