Add task lists to issues and merge requests

Make the Markdown parser recognize "[x]" or "[ ]" at the beginning of a
list item and turn it into a checkbox input.  Users who can modify the
issue or MR can toggle the checkboxes directly or edit the Markdown to
manage the tasks.  Task status is also displayed in the MR and issue
lists.

app/assets/javascripts/issue.js.coffee

@@ -6,4 +6,28 @@ class Issue
     $(".issue-box .inline-update").on "change", "#issue_assignee_id", ->
       $(this).submit()
 
+    if $("a.btn-close").length
+      $("li.task-list-item input:checkbox").prop("disabled", false)
+
+    $(".task-list-item input:checkbox").on "click", ->
+      is_checked = $(this).prop("checked")
+      if $(this).is(":checked")
+        state_event = "task_check"
+      else
+        state_event = "task_uncheck"
+
+      mr_url = $("form.edit-issue").first().attr("action")
+      mr_num = mr_url.match(/\d+$/)
+      task_num = 0
+      $("li.task-list-item input:checkbox").each( (index, e) =>
+        if e == this
+          task_num = index + 1
+      )
+
+      $.ajax
+        type: "PATCH"
+        url: mr_url
+        data: "issue[state_event]=" + state_event +
+          "&issue[task_num]=" + task_num
+
 @Issue = Issue

app/assets/javascripts/merge_request.js.coffee

@@ -17,6 +17,8 @@ class MergeRequest
 
     disableButtonIfEmptyField '#commit_message', '.accept_merge_request'
 
+    if $("a.close-mr-link").length
+      $("li.task-list-item input:checkbox").prop("disabled", false)
 
   # Local jQuery finder
   $: (selector) ->
@@ -72,6 +74,27 @@ class MergeRequest
       this.$('.remove_source_branch_in_progress').hide()
       this.$('.remove_source_branch_widget.failed').show()
 
+    this.$(".task-list-item input:checkbox").on "click", ->
+      is_checked = $(this).prop("checked")
+      if $(this).is(":checked")
+        state_event = "task_check"
+      else
+        state_event = "task_uncheck"
+
+      mr_url = $("form.edit-merge_request").first().attr("action")
+      mr_num = mr_url.match(/\d+$/)
+      task_num = 0
+      $("li.task-list-item input:checkbox").each( (index, e) =>
+        if e == this
+          task_num = index + 1
+      )
+
+      $.ajax
+        type: "PATCH"
+        url: mr_url
+        data: "merge_request[state_event]=" + state_event +
+          "&merge_request[task_num]=" + task_num
+
   activateTab: (action) ->
     this.$('.merge-request-tabs li').removeClass 'active'
     this.$('.tab-content').hide()

app/assets/stylesheets/generic/common.scss

@@ -356,3 +356,6 @@ table {
   font-size: 42px;
 }
 
+.task-status {
+  margin-left: 10px;
+}

app/assets/stylesheets/generic/lists.scss

@@ -122,3 +122,7 @@ ul.bordered-list {
     }
   }
 }
+
+li.task-list-item {
+  list-style-type: none;
+}

app/controllers/projects/issues_controller.rb

@@ -152,7 +152,7 @@ class Projects::IssuesController < Projects::ApplicationController
   def issue_params
     params.require(:issue).permit(
       :title, :assignee_id, :position, :description,
-      :milestone_id, :state_event, label_ids: []
+      :milestone_id, :state_event, :task_num, label_ids: []
     )
   end
 end

app/controllers/projects/merge_requests_controller.rb

@@ -250,7 +250,7 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     params.require(:merge_request).permit(
       :title, :assignee_id, :source_project_id, :source_branch,
       :target_project_id, :target_branch, :milestone_id,
-      :state_event, :description, label_ids: []
+      :state_event, :description, :task_num, label_ids: []
     )
   end
 end

app/models/concerns/taskable.rb

@@ -0,0 +1,51 @@
+# Contains functionality for objects that can have task lists in their
+# descriptions.  Task list items can be added with Markdown like "* [x] Fix
+# bugs".
+#
+# Used by MergeRequest and Issue
+module Taskable
+  TASK_PATTERN_MD = /^(?<bullet> *[*-] *)\[(?<checked>[ xX])\]/.freeze
+  TASK_PATTERN_HTML = /^<li>\[(?<checked>[ xX])\]/.freeze
+
+  # Change the state of a task list item for this Taskable.  Edit the object's
+  # description by finding the nth task item and changing its checkbox
+  # placeholder to "[x]" if +checked+ is true, or "[ ]" if it's false.
+  # Note: task numbering starts with 1
+  def update_nth_task(n, checked)
+    index = 0
+    check_char = checked ? 'x' : ' '
+
+    # Do this instead of using #gsub! so that ActiveRecord detects that a field
+    # has changed.
+    self.description = self.description.gsub(TASK_PATTERN_MD) do |match|
+      index += 1
+      case index
+      when n then "#{$LAST_MATCH_INFO[:bullet]}[#{check_char}]"
+      else match
+      end
+    end
+
+    save
+  end
+
+  # Return true if this object's description has any task list items.
+  def tasks?
+    description && description.match(TASK_PATTERN_MD)
+  end
+
+  # Return a string that describes the current state of this Taskable's task
+  # list items, e.g. "20 tasks (12 done, 8 unfinished)"
+  def task_status
+    return nil unless description
+
+    num_tasks = 0
+    num_done = 0
+
+    description.scan(TASK_PATTERN_MD) do
+      num_tasks += 1
+      num_done += 1 unless $LAST_MATCH_INFO[:checked] == ' '
+    end
+
+    "#{num_tasks} tasks (#{num_done} done, #{num_tasks - num_done} unfinished)"
+  end
+end

app/models/issue.rb

@@ -23,6 +23,7 @@ require 'file_size_validator'
 class Issue < ActiveRecord::Base
   include Issuable
   include InternalId
+  include Taskable
 
   ActsAsTaggableOn.strict_case_match = true
 

app/models/merge_request.rb

@@ -25,6 +25,7 @@ require Rails.root.join("lib/static_model")
 
 class MergeRequest < ActiveRecord::Base
   include Issuable
+  include Taskable
   include InternalId
 
   belongs_to :target_project, foreign_key: :target_project_id, class_name: "Project"

app/services/issues/update_service.rb

@@ -8,9 +8,14 @@ module Issues
         Issues::ReopenService.new(project, current_user, {}).execute(issue)
       when 'close'
         Issues::CloseService.new(project, current_user, {}).execute(issue)
+      when 'task_check'
+        issue.update_nth_task(params[:task_num].to_i, true)
+      when 'task_uncheck'
+        issue.update_nth_task(params[:task_num].to_i, false)
       end
 
-      if params.present? && issue.update_attributes(params.except(:state_event))
+      if params.present? && issue.update_attributes(params.except(:state_event,
+                                                                  :task_num))
         issue.reset_events_cache
 
         if issue.previous_changes.include?('milestone_id')
@@ -28,5 +33,12 @@ module Issues
 
       issue
     end
+
+    private
+
+    def update_task(issue, params, checked)
+      issue.update_nth_task(params[:task_num].to_i, checked)
+      params.except!(:task_num)
+    end
   end
 end

app/services/merge_requests/update_service.rb

@@ -17,9 +17,15 @@ module MergeRequests
         MergeRequests::ReopenService.new(project, current_user, {}).execute(merge_request)
       when 'close'
         MergeRequests::CloseService.new(project, current_user, {}).execute(merge_request)
+      when 'task_check'
+        merge_request.update_nth_task(params[:task_num].to_i, true)
+      when 'task_uncheck'
+        merge_request.update_nth_task(params[:task_num].to_i, false)
       end
 
-      if params.present? && merge_request.update_attributes(params.except(:state_event))
+      if params.present? && merge_request.update_attributes(
+        params.except(:state_event, :task_num)
+      )
         merge_request.reset_events_cache
 
         if merge_request.previous_changes.include?('milestone_id')

app/views/projects/issues/_issue.html.haml

@@ -26,6 +26,10 @@
       %span
         %i.fa.fa-clock-o
         = issue.milestone.title
+    - if issue.tasks?
+      %span.task-status
+        = issue.task_status
+
     .pull-right
       %small updated #{time_ago_with_tooltip(issue.updated_at, 'bottom', 'issue_update_ago')}
 

app/views/projects/issues/show.html.haml

@@ -48,7 +48,7 @@
     .description
       .wiki
         = preserve do
-          = markdown @issue.description
+          = markdown(@issue.description, parse_tasks: true)
   .context
     %cite.cgray
       = render partial: 'issue_context', locals: { issue: @issue }

app/views/projects/merge_requests/_merge_request.html.haml

@@ -27,7 +27,9 @@
       %span
         %i.fa.fa-clock-o
         = merge_request.milestone.title
-
+    - if merge_request.tasks?
+      %span.task-status
+        = merge_request.task_status
 
     .pull-right
       %small updated #{time_ago_with_tooltip(merge_request.updated_at, 'bottom', 'merge_request_updated_ago')}

app/views/projects/merge_requests/show/_mr_box.html.haml

@@ -18,7 +18,7 @@
     .description
       .wiki
         = preserve do
-          = markdown @merge_request.description
+          = markdown(@merge_request.description, parse_tasks: true)
 
   .context
     %cite.cgray

lib/gitlab/markdown.rb

@@ -33,6 +33,11 @@ module Gitlab
 
     attr_reader :html_options
 
+    def gfm_with_tasks(text, project = @project, html_options = {})
+      text = gfm(text, project, html_options)
+      parse_tasks(text)
+    end
+
     # Public: Parse the provided text with GitLab-Flavored Markdown
     #
     # text         - the source text
@@ -265,5 +270,24 @@ module Gitlab
       )
       link_to("#{prefix_text}##{identifier}", url, options)
     end
+
+    # Turn list items that start with "[ ]" into HTML checkbox inputs.
+    def parse_tasks(text)
+      li_tag = '<li class="task-list-item">'
+      unchecked_box = '<input type="checkbox" value="on" disabled />'
+      checked_box = unchecked_box.sub(/\/>$/, 'checked="checked" />')
+
+      # Regexp captures don't seem to work when +text+ is an
+      # ActiveSupport::SafeBuffer, hence the `String.new`
+      String.new(text).gsub(Taskable::TASK_PATTERN_HTML) do
+        checked = $LAST_MATCH_INFO[:checked].downcase == 'x'
+
+        if checked
+          "#{li_tag}#{checked_box}"
+        else
+          "#{li_tag}#{unchecked_box}"
+        end
+      end
+    end
   end
 end

lib/redcarpet/render/gitlab_html.rb

@@ -47,6 +47,10 @@ class Redcarpet::Render::GitlabHTML < Redcarpet::Render::HTML
     unless @template.instance_variable_get("@project_wiki") || @project.nil?
       full_document = h.create_relative_links(full_document)
     end
-    h.gfm(full_document)
+    if @options[:parse_tasks]
+      h.gfm_with_tasks(full_document)
+    else
+      h.gfm(full_document)
+    end
   end
 end