Show tips when implementing an exercise

app/controllers/exercises_controller.rb

@@ -262,6 +262,30 @@ class ExercisesController < ApplicationController
                else
                  current_user.id
                end
+
+    # Order of elements is important and will be kept
+    available_tips = ExerciseTip.where(exercise: @exercise)
+                                .order(rank: :asc, parent_exercise_tip_id: :asc)
+
+    # Transform result set in a hash and prepare (temporary) children array.
+    # The children array will contain the sorted list of nested tips,
+    # shown for learners in the output sidebar with cards.
+    # Hash - Key: exercise_tip.id, value: exercise_tip Object loaded from database
+    nested_tips = available_tips.each_with_object({}) do |exercise_tip, hash|
+      exercise_tip.children = []
+      hash[exercise_tip.id] = exercise_tip
+    end
+
+    available_tips.each do |tip|
+      # A tip without a parent cannot be a children
+      next if tip.parent_exercise_tip_id.blank?
+
+      # Link tips if they are related
+      nested_tips[tip.parent_exercise_tip_id].children << tip
+    end
+
+    # Return an array with top-level tips
+    @tips = nested_tips.values.select { |tip| tip.parent_exercise_tip_id.nil? }
   end
 
   def set_course_token

app/javascript/packs/highlight.js

@@ -12,4 +12,4 @@ import hljs from 'highlight.js'
 window.hljs = hljs;
 
 // CSS
-import 'highlight.js/styles/default.css'
+import 'highlight.js/styles/tomorrow.css'

app/views/exercises/_editor_output.html.slim

@@ -55,6 +55,8 @@ div.h-100 id='output_sidebar_uncollapsed' class='d-none col-sm-12 enforce-bottom
             ul.body
         #output.mt-2
           pre = t('exercises.implement.no_output_yet')
+        - unless @embed_options[:disable_hints] or @tips.blank?
+          = render(partial: 'tips_content')
         - if CodeOcean::Config.new(:code_ocean).read[:flowr][:enabled] && !@embed_options[:disable_hints] && !@embed_options[:hide_test_results]
           #flowrHint.card.text-white.bg-info data-url=CodeOcean::Config.new(:code_ocean).read[:flowr][:url] role='tab'
             .card-header = t('exercises.implement.flowr.heading')

app/views/exercises/_tips_content.html.slim

@@ -0,0 +1,13 @@
+- content_for :head do
+  // Force a full page reload, see https://github.com/turbolinks/turbolinks/issues/326.
+     Otherwise, code might not be highlighted correctly (race condition)
+  meta name='turbolinks-visit-control' content='reload'
+  = javascript_pack_tag('highlight', 'data-turbolinks-track': true)
+  = stylesheet_pack_tag('highlight', media: 'all', 'data-turbolinks-track': true)
+
+#tips.card.text-white.bg-info.mt-2 role="tab" style="display: block;"
+  .card-header.py-2
+    i.fa.fa-lightbulb
+    = t('exercises.implement.tips.heading')
+  .card-body.text-dark.bg-white.p-2
+    = render(partial: 'tips/collapsed_card', collection: @tips, as: :exercise_tip)

app/views/tips/_collapsed_card.html.slim

@@ -0,0 +1,24 @@
+- tip = exercise_tip.tip
+.card.mb-2
+  .card-header.p-2 id="tip-heading-#{exercise_tip.id}" role="tab"
+    .card-title.mb-0
+      a.collapsed aria-controls="tip-collapse-#{exercise_tip.id}" aria-expanded="false" data-parent="#tips" data-toggle="collapse" href="#tip-collapse-#{exercise_tip.id}"
+        .clearfix role="button"
+          i.fa aria-hidden="true"
+          span
+            = t('activerecord.models.tip.one')
+            =< exercise_tip.rank
+            = ": #{tip.title}" if tip.title?
+  .card.card-collapse.collapse id="tip-collapse-#{exercise_tip.id}" aria-labelledby="tip-heading-#{exercise_tip.id}" role="tabpanel"
+    .card-body.p-3
+      h5
+        = t('exercises.implement.tips.description')
+      = tip.description
+      - if tip.example?
+        h5.mt-2
+          = t('exercises.implement.tips.example')
+        pre
+          code.mh-100 class="language-#{tip.file_type.editor_mode.gsub("ace/mode/", "")}"
+            = tip.example
+      .mb-4
+      = render(partial: 'tips/collapsed_card', collection: exercise_tip.children, as: :exercise_tip)

config/locales/de.yml

@@ -125,6 +125,11 @@ de:
         title: Titel
         description: Beschreibung
         example: Beispiel
+      exercise_tip:
+        tip: Tipp
+        exercise: Aufgabe
+        rank: Rang
+        parent_exercise_tip: Übergeordneter Tipp
       file_template:
         name: "Name"
         file_type: "Dateityp"
@@ -207,6 +212,9 @@ de:
       study_group:
         one: Lerngruppe
         other: Lerngruppen
+      tip:
+        one: Tipp
+        other: Tipps
       tag:
         one: Tag
         other: Tags
@@ -407,6 +415,10 @@ de:
         text: "Uns ist aufgefallen, dass du schon lange an dieser Aufgabe arbeitest. Möchtest du vielleicht später weiter machen um erstmal auf neue Gedanken zu kommen?"
       error_hints:
         heading: "Hinweise"
+      tips:
+        heading: Tipps
+        description: Erklärung
+        example: Beispiel
       flowr:
         heading: "Weitere Hinweise | Unterstützt von StackOverflow"
         go_to_question: "Lösung ansehen"

config/locales/en.yml

@@ -122,9 +122,14 @@ en:
         usage: Used
         difficulty: Share on the Exercise
       tip:
-        title: title
+        title: Title
-        description: description
+        description: Description
-        example: example
+        example: Example
+      exercise_tip:
+        tip: Tip
+        exercise: Exercise
+        rank: Rank
+        parent_exercise_tip: Parent Tip
       file_template:
         name: "Name"
         file_type: "File Type"
@@ -207,6 +212,9 @@ en:
       study_group:
         one: Study Group
         other: Study Groups
+      tip:
+        one: Tip
+        other: Tips
       tag:
         one: Tag
         other: Tags
@@ -407,6 +415,10 @@ en:
         text: "We recognized that you are already working quite a while on this exercise. We would like to encourage you to take a break and come back later."
       error_hints:
         heading: "Hints"
+      tips:
+        heading: Tips
+        description: Description
+        example: Example
       flowr:
         heading: "Gain more insights here | Powered by StackOverflow"
         go_to_question: "Go to answer"