Display slash commands outcome when previewing Markdown

Remove slash commands from Markdown preview and display their outcome next to
the text field.
Introduce new "explanation" block to our slash commands DSL.
Introduce optional "parse_params" block to slash commands DSL that allows to
process a parameter before it is passed to "explanation" or "command" blocks.
Pass path for previewing Markdown as "data" attribute instead of setting
a variable on "window".

1 files changed, 47 insertions, 5 deletions

diff --git a/lib/gitlab/slash_commands/dsl.rb b/lib/gitlab/slash_commands/dsl.rb
index 50b0937d267..614bafbe1b2 100644
--- a/lib/gitlab/slash_commands/dsl.rb
+++ b/lib/gitlab/slash_commands/dsl.rb
@@ -44,6 +44,22 @@ module Gitlab
           @params = 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
@@ -61,6 +77,24 @@ module Gitlab
           @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.
@@ -75,11 +109,13 @@ module Gitlab
 
           definition = CommandDefinition.new(
             name,
-            aliases:          aliases,
-            description:      @description,
-            params:           @params,
-            condition_block:  @condition_block,
-            action_block:     block
+            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
@@ -89,8 +125,14 @@ module Gitlab
           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