Rename "Slash commands" to "Quick actions"

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/27070

Deprecate "chat commands" in favor of "slash commands"

We looked for things like:

 - `slash commmand`
 - `slash_command`
 - `slash-command`
 - `SlashCommand`

3 files changed, 351 insertions, 0 deletions

diff --git a/lib/gitlab/quick_actions/command_definition.rb b/lib/gitlab/quick_actions/command_definition.rb
new file mode 100644
index 00000000000..3937d9c153a
--- /dev/null
+++ b/lib/gitlab/quick_actions/command_definition.rb
@@ -0,0 +1,89 @@
+module Gitlab
+  module QuickActions
+    class CommandDefinition
+      attr_accessor :name, :aliases, :description, :explanation, :params,
+        :condition_block, :parse_params_block, :action_block
+
+      def initialize(name, attributes = {})
+        @name = name
+
+        @aliases = attributes[:aliases] || []
+        @description = attributes[:description] || ''
+        @explanation = attributes[:explanation] || ''
+        @params = attributes[:params] || []
+        @condition_block = attributes[:condition_block]
+        @parse_params_block = attributes[:parse_params_block]
+        @action_block = attributes[:action_block]
+      end
+
+      def all_names
+        [name, *aliases]
+      end
+
+      def noop?
+        action_block.nil?
+      end
+
+      def available?(opts)
+        return true unless condition_block
+
+        context = OpenStruct.new(opts)
+        context.instance_exec(&condition_block)
+      end
+
+      def explain(context, opts, arg)
+        return unless available?(opts)
+
+        if explanation.respond_to?(:call)
+          execute_block(explanation, context, arg)
+        else
+          explanation
+        end
+      end
+
+      def execute(context, opts, arg)
+        return if noop? || !available?(opts)
+
+        execute_block(action_block, context, arg)
+      end
+
+      def to_h(opts)
+        context = OpenStruct.new(opts)
+
+        desc = description
+        if desc.respond_to?(:call)
+          desc = context.instance_exec(&desc) rescue ''
+        end
+
+        prms = params
+        if prms.respond_to?(:call)
+          prms = Array(context.instance_exec(&prms)) rescue params
+        end
+
+        {
+          name: name,
+          aliases: aliases,
+          description: desc,
+          params: prms
+        }
+      end
+
+      private
+
+      def execute_block(block, context, arg)
+        if arg.present?
+          parsed = parse_params(arg, context)
+          context.instance_exec(parsed, &block)
+        elsif block.arity == 0
+          context.instance_exec(&block)
+        end
+      end
+
+      def parse_params(arg, context)
+        return arg unless parse_params_block
+
+        context.instance_exec(arg, &parse_params_block)
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/quick_actions/dsl.rb b/lib/gitlab/quick_actions/dsl.rb
new file mode 100644
index 00000000000..a4a97236ffc
--- /dev/null
+++ b/lib/gitlab/quick_actions/dsl.rb
@@ -0,0 +1,140 @@
+module Gitlab
+  module QuickActions
+    module Dsl
+      extend ActiveSupport::Concern
+
+      included do
+        cattr_accessor :command_definitions, instance_accessor: false do
+          []
+        end
+
+        cattr_accessor :command_definitions_by_name, instance_accessor: false do
+          {}
+        end
+      end
+
+      class_methods do
+        # Allows to give a description to the next quick action.
+        # This description is shown in the autocomplete menu.
+        # It accepts a block that will be evaluated with the context given to
+        # `CommandDefintion#to_h`.
+        #
+        # Example:
+        #
+        #   desc do
+        #     "This is a dynamic description for #{noteable.to_ability_name}"
+        #   end
+        #   command :command_key do |arguments|
+        #     # Awesome code block
+        #   end
+        def desc(text = '', &block)
+          @description = block_given? ? block : text
+        end
+
+        # Allows to define params for the next quick action.
+        # These params are shown in the autocomplete menu.
+        #
+        # Example:
+        #
+        #   params "~label ~label2"
+        #   command :command_key do |arguments|
+        #     # Awesome code block
+        #   end
+        def params(*params, &block)
+          @params = block_given? ? block : params
+        end
+
+        # Allows to give an explanation of what the command will do when
+        # executed. This explanation is shown when rendering the Markdown
+        # preview.
+        #
+        # Example:
+        #
+        #   explanation do |arguments|
+        #     "Adds label(s) #{arguments.join(' ')}"
+        #   end
+        #   command :command_key do |arguments|
+        #     # Awesome code block
+        #   end
+        def explanation(text = '', &block)
+          @explanation = block_given? ? block : text
+        end
+
+        # Allows to define conditions that must be met in order for the command
+        # to be returned by `.command_names` & `.command_definitions`.
+        # It accepts a block that will be evaluated with the context given to
+        # `CommandDefintion#to_h`.
+        #
+        # Example:
+        #
+        #   condition do
+        #     project.public?
+        #   end
+        #   command :command_key do |arguments|
+        #     # Awesome code block
+        #   end
+        def condition(&block)
+          @condition_block = block
+        end
+
+        # Allows to perform initial parsing of parameters. The result is passed
+        # both to `command` and `explanation` blocks, instead of the raw
+        # parameters.
+        # It accepts a block that will be evaluated with the context given to
+        # `CommandDefintion#to_h`.
+        #
+        # Example:
+        #
+        #   parse_params do |raw|
+        #     raw.strip
+        #   end
+        #   command :command_key do |parsed|
+        #     # Awesome code block
+        #   end
+        def parse_params(&block)
+          @parse_params_block = block
+        end
+
+        # Registers a new command which is recognizeable from body of email or
+        # comment.
+        # It accepts aliases and takes a block.
+        #
+        # Example:
+        #
+        #   command :my_command, :alias_for_my_command do |arguments|
+        #     # Awesome code block
+        #   end
+        def command(*command_names, &block)
+          name, *aliases = command_names
+
+          definition = CommandDefinition.new(
+            name,
+            aliases: aliases,
+            description: @description,
+            explanation: @explanation,
+            params: @params,
+            condition_block: @condition_block,
+            parse_params_block: @parse_params_block,
+            action_block: block
+          )
+
+          self.command_definitions << definition
+
+          definition.all_names.each do |name|
+            self.command_definitions_by_name[name] = definition
+          end
+
+          @description = nil
+          @explanation = nil
+          @params = nil
+          @condition_block = nil
+          @parse_params_block = nil
+        end
+
+        def definition_by_name(name)
+          command_definitions_by_name[name.to_sym]
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/quick_actions/extractor.rb b/lib/gitlab/quick_actions/extractor.rb
new file mode 100644
index 00000000000..09576be7156
--- /dev/null
+++ b/lib/gitlab/quick_actions/extractor.rb
@@ -0,0 +1,122 @@
+module Gitlab
+  module QuickActions
+    # This class takes an array of commands that should be extracted from a
+    # given text.
+    #
+    # ```
+    # extractor = Gitlab::QuickActions::Extractor.new([:open, :assign, :labels])
+    # ```
+    class Extractor
+      attr_reader :command_definitions
+
+      def initialize(command_definitions)
+        @command_definitions = command_definitions
+      end
+
+      # Extracts commands from content and return an array of commands.
+      # The array looks like the following:
+      # [
+      #   ['command1'],
+      #   ['command3', 'arg1 arg2'],
+      # ]
+      # The command and the arguments are stripped.
+      # The original command text is removed from the given `content`.
+      #
+      # Usage:
+      # ```
+      # extractor = Gitlab::QuickActions::Extractor.new([:open, :assign, :labels])
+      # msg = %(hello\n/labels ~foo ~"bar baz"\nworld)
+      # commands = extractor.extract_commands(msg) #=> [['labels', '~foo ~"bar baz"']]
+      # msg #=> "hello\nworld"
+      # ```
+      def extract_commands(content, opts = {})
+        return [content, []] unless content
+
+        content = content.dup
+
+        commands = []
+
+        content.delete!("\r")
+        content.gsub!(commands_regex(opts)) do
+          if $~[:cmd]
+            commands << [$~[:cmd], $~[:arg]].reject(&:blank?)
+            ''
+          else
+            $~[0]
+          end
+        end
+
+        [content.strip, commands]
+      end
+
+      private
+
+      # Builds a regular expression to match known commands.
+      # First match group captures the command name and
+      # second match group captures its arguments.
+      #
+      # It looks something like:
+      #
+      #   /^\/(?<cmd>close|reopen|...)(?:( |$))(?<arg>[^\/\n]*)(?:\n|$)/
+      def commands_regex(opts)
+        names = command_names(opts).map(&:to_s)
+
+        @commands_regex ||= %r{
+            (?<code>
+              # Code blocks:
+              # ```
+              # Anything, including `/cmd arg` which are ignored by this filter
+              # ```
+
+              ^```
+              .+?
+              \n```$
+            )
+          |
+            (?<html>
+              # HTML block:
+              # <tag>
+              # Anything, including `/cmd arg` which are ignored by this filter
+              # </tag>
+
+              ^<[^>]+?>\n
+              .+?
+              \n<\/[^>]+?>$
+            )
+          |
+            (?<html>
+              # Quote block:
+              # >>>
+              # Anything, including `/cmd arg` which are ignored by this filter
+              # >>>
+
+              ^>>>
+              .+?
+              \n>>>$
+            )
+          |
+            (?:
+              # Command not in a blockquote, blockcode, or HTML tag:
+              # /close
+
+              ^\/
+              (?<cmd>#{Regexp.union(names)})
+              (?:
+                [ ]
+                (?<arg>[^\n]*)
+              )?
+              (?:\n|$)
+            )
+        }mx
+      end
+
+      def command_names(opts)
+        command_definitions.flat_map do |command|
+          next if command.noop?
+
+          command.all_names
+        end.compact
+      end
+    end
+  end
+end