Merge branch 'issue_2296' into 'master'

Generate system note after Task item has been updated on Issue or Merge Request.

Reference: #2296 

Everytime the User check or uncheck a Task Item from the Issue or
Merge Request description, a new update is going to be
added to the activity logs of the Issue or Merge Request.

Note that when using the edit form, you can only update the Task item
status or add/delete/modify existing ones. Doing both actions is not
fully supported.

See merge request !1848

6 files changed, 74 insertions, 20 deletions

diff --git a/app/models/concerns/issuable.rb b/app/models/concerns/issuable.rb
index 98ad5e76da7..68138688aab 100644
--- a/app/models/concerns/issuable.rb
+++ b/app/models/concerns/issuable.rb
@@ -161,4 +161,9 @@ module Issuable
   def notes_with_associations
     notes.includes(:author, :project)
   end
+
+  def updated_tasks
+    Taskable.get_updated_tasks(old_content: previous_changes['description'].first,
+                               new_content: description)
+  end
 end
diff --git a/app/models/concerns/taskable.rb b/app/models/concerns/taskable.rb
index 660e58b876d..df2a9e3e84b 100644
--- a/app/models/concerns/taskable.rb
+++ b/app/models/concerns/taskable.rb
@@ -7,14 +7,39 @@ require 'task_list/filter'
 #
 # Used by MergeRequest and Issue
 module Taskable
+  COMPLETED    = 'completed'.freeze
+  INCOMPLETE   = 'incomplete'.freeze
+  ITEM_PATTERN = /
+    ^
+    (?:\s*[-+*]|(?:\d+\.))? # optional list prefix
+    \s*                     # optional whitespace prefix
+    (\[\s\]|\[[xX]\])       # checkbox
+    (\s.+)                  # followed by whitespace and some text.
+  /x
+
+  def self.get_tasks(content)
+    content.to_s.scan(ITEM_PATTERN).map do |checkbox, label|
+      # ITEM_PATTERN strips out the hyphen, but Item requires it. Rabble rabble.
+      TaskList::Item.new("- #{checkbox}", label.strip)
+    end
+  end
+
+  def self.get_updated_tasks(old_content:, new_content:)
+    old_tasks, new_tasks = get_tasks(old_content), get_tasks(new_content)
+
+    new_tasks.select.with_index do |new_task, i|
+      old_task = old_tasks[i]
+      next unless old_task
+
+      new_task.source == old_task.source && new_task.complete? != old_task.complete?
+    end
+  end
+
   # Called by `TaskList::Summary`
   def task_list_items
     return [] if description.blank?
 
-    @task_list_items ||= description.scan(TaskList::Filter::ItemPattern).collect do |item|
-      # ItemPattern strips out the hyphen, but Item requires it. Rabble rabble.
-      TaskList::Item.new("- #{item}")
-    end
+    @task_list_items ||= Taskable.get_tasks(description)
   end
 
   def tasks
diff --git a/app/services/issuable_base_service.rb b/app/services/issuable_base_service.rb
index 11d2b08bba7..2556f06e2d3 100644
--- a/app/services/issuable_base_service.rb
+++ b/app/services/issuable_base_service.rb
@@ -27,6 +27,12 @@ class IssuableBaseService < BaseService
       old_branch, new_branch)
   end
 
+  def create_task_status_note(issuable)
+    issuable.updated_tasks.each do |task|
+      SystemNoteService.change_task_status(issuable, issuable.project, current_user, task)
+    end
+  end
+
   def filter_params(issuable_ability_name = :issue)
     params[:assignee_id]  = "" if params[:assignee_id] == IssuableFinder::NONE
     params[:milestone_id] = "" if params[:milestone_id] == IssuableFinder::NONE
@@ -47,14 +53,7 @@ class IssuableBaseService < BaseService
 
     if params.present? && issuable.update_attributes(params.merge(updated_by: current_user))
       issuable.reset_events_cache
-
-      if issuable.labels != old_labels
-        create_labels_note(
-          issuable,
-          issuable.labels - old_labels,
-          old_labels - issuable.labels)
-      end
-
+      handle_common_system_notes(issuable, old_labels: old_labels)
       handle_changes(issuable)
       issuable.create_new_cross_references!(current_user)
       execute_hooks(issuable, 'update')
@@ -71,4 +70,19 @@ class IssuableBaseService < BaseService
       close_service.new(project, current_user, {}).execute(issuable)
     end
   end
+
+  def handle_common_system_notes(issuable, options = {})
+    if issuable.previous_changes.include?('title')
+      create_title_change_note(issuable, issuable.previous_changes['title'].first)
+    end
+
+    if issuable.previous_changes.include?('description') && issuable.tasks?
+      create_task_status_note(issuable)
+    end
+
+    old_labels = options[:old_labels]
+    if old_labels && (issuable.labels != old_labels)
+      create_labels_note(issuable, issuable.labels - old_labels, old_labels - issuable.labels)
+    end
+  end
 end
diff --git a/app/services/issues/update_service.rb b/app/services/issues/update_service.rb
index 7c112f731a7..a55a04dd5e0 100644
--- a/app/services/issues/update_service.rb
+++ b/app/services/issues/update_service.rb
@@ -13,10 +13,6 @@ module Issues
         create_assignee_note(issue)
         notification_service.reassigned_issue(issue, current_user)
       end
-
-      if issue.previous_changes.include?('title')
-        create_title_change_note(issue, issue.previous_changes['title'].first)
-      end
     end
 
     def reopen_service
diff --git a/app/services/merge_requests/update_service.rb b/app/services/merge_requests/update_service.rb
index a5db3776eb6..5ff2cc03dda 100644
--- a/app/services/merge_requests/update_service.rb
+++ b/app/services/merge_requests/update_service.rb
@@ -30,10 +30,6 @@ module MergeRequests
         notification_service.reassigned_merge_request(merge_request, current_user)
       end
 
-      if merge_request.previous_changes.include?('title')
-        create_title_change_note(merge_request, merge_request.previous_changes['title'].first)
-      end
-
       if merge_request.previous_changes.include?('target_branch') ||
           merge_request.previous_changes.include?('source_branch')
         merge_request.mark_as_unchecked
diff --git a/app/services/system_note_service.rb b/app/services/system_note_service.rb
index 708c2f00486..7e2bc834176 100644
--- a/app/services/system_note_service.rb
+++ b/app/services/system_note_service.rb
@@ -341,4 +341,22 @@ class SystemNoteService
 
     "* #{commit_ids} - #{commits_text} from branch `#{branch}`\n"
   end
+
+  # Called when the status of a Task has changed
+  #
+  # noteable  - Noteable object.
+  # project   - Project owning noteable
+  # author    - User performing the change
+  # new_task  - TaskList::Item object.
+  #
+  # Example Note text:
+  #
+  #   "Soandso marked the task Whatever as completed."
+  #
+  # Returns the created Note object
+  def self.change_task_status(noteable, project, author, new_task)
+    status_label = new_task.complete? ? Taskable::COMPLETED : Taskable::INCOMPLETE
+    body = "Marked the task **#{new_task.source}** as #{status_label}"
+    create_note(noteable: noteable, project: project, author: author, note: body)
+  end
 end