command completion support

exe/formatron

@@ -6,11 +6,15 @@ require 'formatron/generators/bootstrap/cli'
 require 'formatron/generators/instance/cli'
 require 'formatron/configuration/deploy_cli'
 require 'formatron/configuration/destroy_cli'
+require 'formatron/completion/completion_script_cli'
+require 'formatron/completion/complete_cli'
 
 Formatron::CLI.include Formatron::Generators::Credentials::CLI
 Formatron::CLI.include Formatron::Generators::Bootstrap::CLI
 Formatron::CLI.include Formatron::Generators::Instance::CLI
 Formatron::CLI.include Formatron::Configuration::DeployCLI
 Formatron::CLI.include Formatron::Configuration::DestroyCLI
+Formatron::CLI.include Formatron::Completion::CompletionScriptCLI
+Formatron::CLI.include Formatron::Completion::CompleteCLI
 cli = Formatron::CLI.new
 cli.run

lib/formatron/completion.rb

@@ -0,0 +1,48 @@
+module Formatron
+  # command completion utilities
+  module Completion
+    def self.normalize_commands(commands)
+      commands.map { |command| command.split.join ' ' }
+    end
+
+    def self.filter_commands(entered, commands)
+      commands.select! do |command|
+        command.start_with? entered
+      end
+    end
+
+    def self.shift_commands(entered, current_word, commands)
+      length = entered.split.length
+      commands.map! do |command|
+        components = command.split
+        if length > 0
+          components.shift(length - 1)
+          components.shift if current_word.eql? ''
+        end
+        components[0]
+      end
+    end
+
+    def self.complete(entered, current_word, commands)
+      commands = normalize_commands commands
+      filter_commands entered, commands
+      shift_commands entered, current_word, commands
+      commands.uniq.join ' '
+    end
+
+    # rubocop:disable Metrics/LineLength
+    def self.completion_script(prefix)
+      <<-EOH.gsub(/^ {8}/, '')
+        _formatron_complete()  {
+          COMPREPLY=()
+          local word="${COMP_WORDS[COMP_CWORD]}"
+          local completions=$(#{prefix} ${COMP_WORDS[0]} complete "${COMP_LINE}" "$word")
+          COMPREPLY=( $(compgen -W "$completions" -- "$word") )
+        }
+
+        complete -F _formatron_complete formatron
+      EOH
+    end
+    # rubocop:enable Metrics/LineLength
+  end
+end

lib/formatron/completion/complete_cli.rb

@@ -0,0 +1,30 @@
+require_relative '../completion'
+
+module Formatron
+  module Completion
+    # CLI command for completion
+    module CompleteCLI
+      def complete_action(c)
+        c.action do |args|
+          entered = args[0].split
+          entered.shift
+          entered.shift if entered[0].eql? 'help'
+          entered = entered.join ' '
+          current_word = args[1] || ''
+          print Completion.complete entered, current_word, defined_commands.keys
+        end
+      end
+
+      def complete_formatron_command
+        command :complete do |c|
+          c.syntax = 'formatron complete CURRENT_LINE CURRENT_WORD'
+          c.summary = 'check the supplied line and word and suggest ' \
+                      'a list of command completions'
+          c.description = 'check the supplied line and word and suggest ' \
+                          'a list of command completions'
+          complete_action c
+        end
+      end
+    end
+  end
+end

lib/formatron/completion/completion_script_cli.rb

@@ -0,0 +1,25 @@
+require_relative '../completion'
+
+module Formatron
+  module Completion
+    # CLI command for completion enabling script
+    module CompletionScriptCLI
+      def completion_script_action(c)
+        c.action do |args|
+          print Completion.completion_script args[0]
+        end
+      end
+
+      def completion_script_formatron_command
+        command :'completion-script' do |c|
+          c.syntax = 'formatron completion-script PREFIX'
+          c.summary = 'Print a bash completion script to ' \
+                      'enable command completion'
+          c.description = 'Print a bash completion script to ' \
+                          'enable command completion'
+          completion_script_action c
+        end
+      end
+    end
+  end
+end