#!/usr/bin/env ruby

# vim: set nosta noet ts=4 sw=4:

require 'securerandom'

require 'net/ssh'

require 'net/sftp'

require 'inversion'

require 'symphony'

require 'symphony/task'

require 'symphony/tasks/ssh'

### A base class for connecting to a remote host, then uploading and

### executing an Inversion templated script.

###

### This isn't designed to be used directly.  To use this in your

### environment, you'll want to subclass it, add the behaviors

### that make sense for you, then super() back to the parent in the

### #work method.

###

### It expects the payload to contain the following keys:

###

###    host:       (required) The hostname to connect to

###    template:   (required) A path to the Inversion templated script

###    port:       (optional) The port to connect to (defaults to 22)

###    user:       (optional) The user to connect as (defaults to root)

###    key:        (optional) The path to an SSH private key

###    attributes: (optional) Additional data to attach to the template

###    nocleanup:  (optional) Leave the remote script after execution? (default to false)

###    tempdir:    (optional) The destination temp directory.  (defaults to /tmp)

###

###

### Additionally, this class responds to the 'symphony.ssh' configurability

### key.  Currently, you can override the default ssh user and private key.

###

### Textual output of the command is stored in the @output instance variable.

###

###

###    require 'symphony'

###    require 'symphony/tasks/sshscript'

###

###    class YourTask < Symphony::Task::SSHScript

###        timeout 30

###        subscribe_to 'ssh.script.*'

###

###        def work( payload, metadata )

###            status = super

###            puts "Remote script said: %s" % [ @output ]

###            return status.success?

###        end

###    end

###

class Symphony::Task::SSHScript < Symphony::Task

	# Template config

	#

	TEMPLATE_OPTS = {

		ignore_unknown_tags: false,

		on_render_error:     :propagate,

		strip_tag_lines:     true

	}

	# The defaults to use when connecting via SSH

	#

	DEFAULT_SSH_OPTIONS = {

		auth_methods:            [ 'publickey' ],

		compression:             true,

		config:                  false,

		keys_only:               true,

		verify_host_key:         :never,

		global_known_hosts_file: '/dev/null',

		user_known_hosts_file:   '/dev/null'

	}

	### Perform the ssh connection, render the template, send it, and

	### execute it.

	###

	def work( payload, metadata )

		template   = payload[ 'template' ]

		attributes = payload[ 'attributes' ] || {}

		port       = payload[ 'port' ]    || 22

		user       = payload[ 'user' ]    || Symphony::Task::SSH.user

		key        = payload[ 'key'  ]    || Symphony::Task::SSH.key

		nocleanup  = payload[ 'nocleanup' ]

		tempdir    = payload[ 'tempdir' ] || '/tmp'

		raise ArgumentError, "Missing required option 'template'" unless template

		raise ArgumentError, "Missing required option 'host'"     unless payload[ 'host' ]

		remote_filename = self.make_remote_filename( template, tempdir )

		source = self.generate_script( template, attributes )

		ssh_options = DEFAULT_SSH_OPTIONS.merge( port: port, keys: Array(key) )

		ssh_options.merge!(

			logger: Loggability[ Net::SSH ],

			verbose: :debug

		) if payload[ 'debug' ]

		Net::SSH.start( payload['host'], user, ssh_options ) do |conn|

			self.log.debug "Uploading script (%d bytes) to %s:%s." %

				[ source.bytesize, payload['host'], remote_filename ]

			self.upload_script( conn, source, remote_filename )

			self.log.debug "  done with the upload."

			self.run_script( conn, remote_filename, nocleanup )

			self.log.debug "Output was:\n#{@output}"

		end

		return true

	end

	#########

	protected

	#########

	### Generate a unique filename for the script on the remote host,

	### based on +template+ name.

	###

	def make_remote_filename( template, tempdir="/tmp" )

		basename = File.basename( template, File.extname(template) )

		tmpname  = "%s/%s-%s" % [

			tempdir,

			basename,

			SecureRandom.hex( 6 )

		]

		return tmpname

	end

	### Generate a script by loading the script +template+, populating it with

	### +attributes+, and returning the rendered output.

	###

	def generate_script( template, attributes )

		tmpl = Inversion::Template.load( template, TEMPLATE_OPTS )

		tmpl.attributes.merge!( attributes )

		tmpl.task = self

		return tmpl.render

	end

	### Upload the templated +source+ via the ssh +conn+ to an

	### executable file named +remote_filename+.

	###

	def upload_script( conn, source, remote_filename )

		conn.sftp.file.open( remote_filename, "w", 0755 ) do |fh|

			fh.print( source )

		end

	end

	### Run the +remote_filename+ via the ssh +conn+.  The script

	### will be deleted automatically unless +nocleanup+ is true.

	###

	def run_script( conn, remote_filename, nocleanup=false )

		@output = conn.exec!( remote_filename )

		conn.exec!( "rm #{remote_filename}" ) unless nocleanup

	end

end # Symphony::Task::SSHScript