#
# Author:: Adam Jacob (<adam@chef.io>)
# Copyright:: Copyright (c) Chef Software Inc.
# License:: Apache License, Version 2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

require_relative "../knife"

class Chef
  class Knife
    class Ssh < Knife

      deps do
        require_relative "../mixin/shell_out"
        require "net/ssh" unless defined?(Net::SSH)
        require "net/ssh/multi"
        require "readline"
        require_relative "../exceptions"
        require_relative "../search/query"
        require_relative "../util/path_helper"

        include Chef::Mixin::ShellOut
      end

      attr_writer :password

      banner "knife ssh QUERY COMMAND (options)"

      option :concurrency,
        short: "-C NUM",
        long: "--concurrency NUM",
        description: "The number of concurrent connections.",
        default: nil,
        proc: lambda { |o| o.to_i }

      option :ssh_attribute,
        short: "-a ATTR",
        long: "--attribute ATTR",
        description: "The attribute to use for opening the connection - default depends on the context."

      option :manual,
        short: "-m",
        long: "--manual-list",
        boolean: true,
        description: "QUERY is a space separated list of servers.",
        default: false

      option :prefix_attribute,
        long: "--prefix-attribute ATTR",
        description: "The attribute to use for prefixing the output - default depends on the context."

      option :ssh_user,
        short: "-x USERNAME",
        long: "--ssh-user USERNAME",
        description: "The ssh username."

      option :ssh_password,
        short: "-P [PASSWORD]",
        long: "--ssh-password [PASSWORD]",
        description: "The ssh password - will prompt if flag is specified but no password is given.",
        # default to a value that can not be a password (boolean)
        # so we can effectively test if this parameter was specified
        # without a value
        default: false

      option :ssh_port,
        short: "-p PORT",
        long: "--ssh-port PORT",
        description: "The ssh port.",
        proc: Proc.new { |key| key.strip }

      option :ssh_timeout,
        short: "-t SECONDS",
        long: "--ssh-timeout SECONDS",
        description: "The ssh connection timeout.",
        proc: Proc.new { |key| key.strip.to_i },
        default: 120

      option :ssh_gateway,
        short: "-G GATEWAY",
        long: "--ssh-gateway GATEWAY",
        description: "The ssh gateway.",
        proc: Proc.new { |key| key.strip }

      option :ssh_gateway_identity,
        long: "--ssh-gateway-identity SSH_GATEWAY_IDENTITY",
        description: "The SSH identity file used for gateway authentication."

      option :forward_agent,
        short: "-A",
        long: "--forward-agent",
        description: "Enable SSH agent forwarding.",
        boolean: true

      option :ssh_identity_file,
        short: "-i IDENTITY_FILE",
        long: "--ssh-identity-file IDENTITY_FILE",
        description: "The SSH identity file used for authentication."

      option :host_key_verify,
        long: "--[no-]host-key-verify",
        description: "Verify host key, enabled by default.",
        boolean: true,
        default: true

      option :on_error,
        short: "-e",
        long: "--exit-on-error",
        description: "Immediately exit if an error is encountered.",
        boolean: true,
        default: false

      option :duplicated_fqdns,
        long: "--duplicated-fqdns",
        description: "Behavior if FQDNs are duplicated, ignored by default.",
        proc: Proc.new { |key| key.strip.to_sym },
        default: :ignore

      option :tmux_split,
        long: "--tmux-split",
        description: "Split tmux window.",
        boolean: true,
        default: false

      def session
        ssh_error_handler = Proc.new do |server|
          if config[:on_error]
            # Net::SSH::Multi magic to force exception to be re-raised.
            throw :go, :raise
          else
            ui.warn "Failed to connect to #{server.host} -- #{$!.class.name}: #{$!.message}"
            $!.backtrace.each { |l| Chef::Log.debug(l) }
          end
        end

        @session ||= Net::SSH::Multi.start(concurrent_connections: config[:concurrency], on_error: ssh_error_handler)
      end

      def configure_gateway
        if config[:ssh_gateway]
          gw_host, gw_user = config[:ssh_gateway].split("@").reverse
          gw_host, gw_port = gw_host.split(":")
          gw_opts = session_options(gw_host, gw_port, gw_user, gateway: true)
          user = gw_opts.delete(:user)

          begin
            # Try to connect with a key.
            session.via(gw_host, user, gw_opts)
          rescue Net::SSH::AuthenticationFailed
            prompt = "Enter the password for #{user}@#{gw_host}: "
            gw_opts[:password] = prompt_for_password(prompt)
            # Try again with a password.
            session.via(gw_host, user, gw_opts)
          end
        end
      end

      def configure_session
        list = config[:manual] ? @name_args[0].split(" ") : search_nodes
        if list.length == 0
          if @search_count == 0
            ui.fatal("No nodes returned from search")
          else
            ui.fatal("#{@search_count} #{@search_count > 1 ? "nodes" : "node"} found, " +
                     "but does not have the required attribute to establish the connection. " +
                     "Try setting another attribute to open the connection using --attribute.")
          end
          exit 10
        end
        if %i{warn fatal}.include?(config[:duplicated_fqdns])
          fqdns = list.map { |v| v[0] }
          if fqdns.count != fqdns.uniq.count
            duplicated_fqdns = fqdns.uniq
            ui.send(config[:duplicated_fqdns],
              "SSH #{duplicated_fqdns.count > 1 ? "nodes are" : "node is"} " +
              "duplicated: #{duplicated_fqdns.join(",")}")
            exit 10 if config[:duplicated_fqdns] == :fatal
          end
        end
        session_from_list(list)
      end

      def get_prefix_attribute(item)
        # Order of precedence for prefix
        # 1) config value (cli or knife config)
        # 2) nil
        msg = "Using node attribute '%s' as the prefix: %s"
        if item["prefix"]
          Chef::Log.debug(sprintf(msg, config[:prefix_attribute], item["prefix"]))
          item["prefix"]
        else
          nil
        end
      end

      def get_ssh_attribute(item)
        # Order of precedence for ssh target
        # 1) config value (cli or knife config)
        # 2) cloud attribute
        # 3) fqdn
        msg = "Using node attribute '%s' as the ssh target: %s"
        if item["target"]
          Chef::Log.debug(sprintf(msg, config[:ssh_attribute], item["target"]))
          item["target"]
        elsif !item.dig("cloud", "public_hostname").to_s.empty?
          Chef::Log.debug(sprintf(msg, "cloud.public_hostname", item["cloud"]["public_hostname"]))
          item["cloud"]["public_hostname"]
        else
          Chef::Log.debug(sprintf(msg, "fqdn", item["fqdn"]))
          item["fqdn"]
        end
      end

      def search_nodes
        list = []
        query = Chef::Search::Query.new
        required_attributes = { fqdn: ["fqdn"], cloud: ["cloud"] }

        separator = ui.presenter.attribute_field_separator

        if config[:prefix_attribute]
          required_attributes[:prefix] = config[:prefix_attribute].split(separator)
        end

        if config[:ssh_attribute]
          required_attributes[:target] = config[:ssh_attribute].split(separator)
        end

        @search_count = 0
        query.search(:node, @name_args[0], filter_result: required_attributes, fuzz: true) do |item|
          @search_count += 1
          # we should skip the loop to next iteration if the item
          # returned by the search is nil
          next if item.nil?

          # next if we couldn't find the specified attribute in the
          # returned node object
          host = get_ssh_attribute(item)
          next if host.nil?

          prefix = get_prefix_attribute(item)
          ssh_port = item.dig("cloud", "public_ssh_port")
          srv = [host, ssh_port, prefix]
          list.push(srv)
        end

        list
      end

      # Net::SSH session options hash for global options. These should be
      # options that will apply to the gateway connection in addition to the
      # main one.
      #
      # @since 12.5.0
      # @param host [String] Hostname for this session.
      # @param port [String] SSH port for this session.
      # @param user [String] Optional username for this session.
      # @param gateway [Boolean] Flag: host or gateway key
      # @return [Hash<Symbol, Object>]
      def session_options(host, port, user = nil, gateway: false)
        ssh_config = Net::SSH.configuration_for(host, true)
        {}.tap do |opts|
          opts[:user] = user || config[:ssh_user] || ssh_config[:user]
          if !gateway && config[:ssh_identity_file]
            opts[:keys] = File.expand_path(config[:ssh_identity_file])
            opts[:keys_only] = true
          elsif gateway && config[:ssh_gateway_identity]
            opts[:keys] = File.expand_path(config[:ssh_gateway_identity])
            opts[:keys_only] = true
          elsif config[:ssh_password]
            opts[:password] = config[:ssh_password]
          end
          # Don't set the keys to nil if we don't have them.
          forward_agent = config[:forward_agent] || ssh_config[:forward_agent]
          opts[:forward_agent] = forward_agent unless forward_agent.nil?
          port ||= ssh_config[:port]
          opts[:port] = port unless port.nil?
          opts[:logger] = Chef::Log.with_child(subsystem: "net/ssh") if Chef::Log.level == :trace
          unless config[:host_key_verify]
            opts[:verify_host_key] = false
            opts[:user_known_hosts_file] = "/dev/null"
          end
          if ssh_config[:keepalive]
            opts[:keepalive] = true
            opts[:keepalive_interval] = ssh_config[:keepalive_interval]
          end
          # maintain support for legacy key types / ciphers / key exchange algorithms.
          # most importantly this adds back support for DSS host keys
          # See https://github.com/net-ssh/net-ssh/pull/709
          opts[:append_all_supported_algorithms] = true
        end
      end

      def session_from_list(list)
        list.each do |item|
          host, ssh_port, prefix = item
          prefix = host unless prefix
          Chef::Log.debug("Adding #{host}")
          session_opts = session_options(host, ssh_port, gateway: false)
          # Handle port overrides for the main connection.
          session_opts[:port] = config[:ssh_port] if config[:ssh_port]
          # Handle connection timeout
          session_opts[:timeout] = config[:ssh_timeout] if config[:ssh_timeout]
          # Handle session prefix
          session_opts[:properties] = { prefix: prefix }
          # Create the hostspec.
          hostspec = session_opts[:user] ? "#{session_opts.delete(:user)}@#{host}" : host
          # Connect a new session on the multi.
          session.use(hostspec, session_opts)

          @longest = prefix.length if prefix.length > @longest
        end

        session
      end

      def fixup_sudo(command)
        command.sub(/^sudo/, "sudo -p 'knife sudo password: '")
      end

      def print_data(host, data)
        @buffers ||= {}
        if leftover = @buffers[host]
          @buffers[host] = nil
          print_data(host, leftover + data)
        else
          if newline_index = data.index("\n")
            line = data.slice!(0...newline_index)
            data.slice!(0)
            print_line(host, line)
            print_data(host, data)
          else
            @buffers[host] = data
          end
        end
      end

      def print_line(host, data)
        padding = @longest - host.length
        str = ui.color(host, :cyan) + (" " * (padding + 1)) + data
        ui.msg(str)
      end

      def ssh_command(command, subsession = nil)
        exit_status = 0
        subsession ||= session
        command = fixup_sudo(command)
        command.force_encoding("binary") if command.respond_to?(:force_encoding)
        begin
          open_session(subsession, command)
        rescue => e
          open_session(subsession, command, true)
        end
      end

      def open_session(subsession, command, pty = false)
        stderr = ""
        exit_status = 0
        subsession.open_channel do |chan|
          if config[:on_error] && exit_status != 0
            chan.close
          else
            chan.request_pty if pty
            chan.exec command do |ch, success|
              raise ArgumentError, "Cannot execute #{command}" unless success

              ch.on_data do |ichannel, data|
                print_data(ichannel.connection[:prefix], data)
                if /^knife sudo password: /.match?(data)
                  print_data(ichannel.connection[:prefix], "\n")
                  ichannel.send_data("#{get_password}\n")
                end
              end

              ch.on_extended_data do |_, _type, data|
                stderr += data
              end

              ch.on_request "exit-status" do |ichannel, data|
                exit_status = [exit_status, data.read_long].max
              end
            end
          end
        end
        session.loop
        exit_status
      end

      def get_password
        @password ||= prompt_for_password
      end

      def prompt_for_password(prompt = "Enter your password: ")
        ui.ask(prompt, echo: false)
      end

      # Present the prompt and read a single line from the console. It also
      # detects ^D and returns "exit" in that case. Adds the input to the
      # history, unless the input is empty. Loops repeatedly until a non-empty
      # line is input.
      def read_line
        loop do
          command = reader.readline("#{ui.color("knife-ssh>", :bold)} ", true)

          if command.nil?
            command = "exit"
            puts(command)
          else
            command.strip!
          end

          unless command.empty?
            return command
          end
        end
      end

      def reader
        Readline
      end

      def interactive
        puts "Connected to #{ui.list(session.servers_for.collect { |s| ui.color(s.host, :cyan) }, :inline, " and ")}"
        puts
        puts "To run a command on a list of servers, do:"
        puts "  on SERVER1 SERVER2 SERVER3; COMMAND"
        puts "  Example: on latte foamy; echo foobar"
        puts
        puts "To exit interactive mode, use 'quit!'"
        puts
        loop do
          command = read_line
          case command
          when "quit!"
            puts "Bye!"
            break
          when /^on (.+?); (.+)$/
            raw_list = $1.split(" ")
            server_list = []
            session.servers.each do |session_server|
              server_list << session_server if raw_list.include?(session_server.host)
            end
            command = $2
            ssh_command(command, session.on(*server_list))
          else
            ssh_command(command)
          end
        end
      end

      def screen
        tf = Tempfile.new("knife-ssh-screen")
        Chef::Util::PathHelper.home(".screenrc") do |screenrc_path|
          if File.exist? screenrc_path
            tf.puts("source #{screenrc_path}")
          end
        end
        tf.puts("caption always '%-Lw%{= BW}%50>%n%f* %t%{-}%+Lw%<'")
        tf.puts("hardstatus alwayslastline 'knife ssh #{@name_args[0]}'")
        window = 0
        session.servers_for.each do |server|
          tf.print("screen -t \"#{server.host}\" #{window} ssh ")
          tf.print("-i #{config[:ssh_identity_file]} ") if config[:ssh_identity_file]
          server.user ? tf.puts("#{server.user}@#{server.host}") : tf.puts(server.host)
          window += 1
        end
        tf.close
        exec("screen -c #{tf.path}")
      end

      def tmux
        ssh_dest = lambda do |server|
          identity = "-i #{config[:ssh_identity_file]} " if config[:ssh_identity_file]
          prefix = server.user ? "#{server.user}@" : ""
          "'ssh #{identity}#{prefix}#{server.host}'"
        end

        new_window_cmds = lambda do
          if session.servers_for.size > 1
            [""] + session.servers_for[1..].map do |server|
              if config[:tmux_split]
                "split-window #{ssh_dest.call(server)}; tmux select-layout tiled"
              else
                "new-window -a -n '#{server.host}' #{ssh_dest.call(server)}"
              end
            end
          else
            []
          end.join(" \\; ")
        end

        tmux_name = "'knife ssh #{@name_args[0].tr(":.", "=-")}'"
        begin
          server = session.servers_for.first
          cmd = ["tmux new-session -d -s #{tmux_name}",
                 "-n '#{server.host}'", ssh_dest.call(server),
                 new_window_cmds.call].join(" ")
          shell_out!(cmd)
          exec("tmux attach-session -t #{tmux_name}")
        rescue Chef::Exceptions::Exec
        end
      end

      def macterm
        begin
          require "appscript" unless defined?(Appscript)
        rescue LoadError
          STDERR.puts "You need the rb-appscript gem to use knife ssh macterm. `(sudo) gem install rb-appscript` to install"
          raise
        end

        Appscript.app("/Applications/Utilities/Terminal.app").windows.first.activate
        Appscript.app("System Events").application_processes["Terminal.app"].keystroke("n", using: :command_down)
        term = Appscript.app("Terminal")
        window = term.windows.first.get

        (session.servers_for.size - 1).times do |i|
          window.activate
          Appscript.app("System Events").application_processes["Terminal.app"].keystroke("t", using: :command_down)
        end

        session.servers_for.each_with_index do |server, tab_number|
          cmd = "unset PROMPT_COMMAND; echo -e \"\\033]0;#{server.host}\\007\"; ssh #{server.user ? "#{server.user}@#{server.host}" : server.host}"
          Appscript.app("Terminal").do_script(cmd, in: window.tabs[tab_number + 1].get)
        end
      end

      def cssh
        cssh_cmd = nil
        %w{csshX cssh}.each do |cmd|

          # Unix and Mac only
          cssh_cmd = shell_out!("which #{cmd}").stdout.strip
          break
        rescue Mixlib::ShellOut::ShellCommandFailed

        end
        raise Chef::Exceptions::Exec, "no command found for cssh" unless cssh_cmd

        # pass in the consolidated identity file option to cssh(X)
        if config[:ssh_identity_file]
          cssh_cmd << " --ssh_args '-i #{File.expand_path(config[:ssh_identity_file])}'"
        end

        session.servers_for.each do |server|
          cssh_cmd << " #{server.user ? "#{server.user}@#{server.host}" : server.host}"
        end
        Chef::Log.debug("Starting cssh session with command: #{cssh_cmd}")
        exec(cssh_cmd)
      end

      def get_stripped_unfrozen_value(value)
        return nil unless value

        value.strip
      end

      def configure_user
        config[:ssh_user] = get_stripped_unfrozen_value(config[:ssh_user] ||
                             Chef::Config[:knife][:ssh_user])
      end

      def configure_password
        if config.key?(:ssh_password) && config[:ssh_password].nil?
          # if we have an actual nil that means someone called "--ssh-password" with no value, so we prompt for a password
          config[:ssh_password] = get_password
        else
          # the false default of ssh_password results in a nil here
          config[:ssh_password] = get_stripped_unfrozen_value(config[:ssh_password])
        end
      end

      def configure_ssh_identity_file
        config[:ssh_identity_file] = get_stripped_unfrozen_value(config[:ssh_identity_file])
      end

      def configure_ssh_gateway_identity
        config[:ssh_gateway_identity] = get_stripped_unfrozen_value(config[:ssh_gateway_identity])
      end

      def run
        @longest = 0

        if @name_args.length < 1
          show_usage
          ui.fatal("You must specify the SEARCH QUERY.")
          exit(1)
        end

        configure_user
        configure_password
        @password = config[:ssh_password] if config[:ssh_password]

        # If a password was not given, check for SSH identity file.
        unless @password
          configure_ssh_identity_file
          configure_ssh_gateway_identity
        end

        configure_gateway
        configure_session

        exit_status =
          case @name_args[1]
          when "interactive"
            interactive
          when "screen"
            screen
          when "tmux"
            tmux
          when "macterm"
            macterm
          when "cssh"
            cssh
          else
            ssh_command(@name_args[1..].join(" "))
          end

        session.close
        if exit_status && exit_status != 0
          exit exit_status
        else
          exit_status
        end
      end

      private :search_nodes

    end
  end
end