FEATURE: per-topic unsubscribe option in emails

[akshayutture-augment]

Test 2

---

Replicated from ai-code-review-evaluation/discourse-greptile#2

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[akshayutture-augment]

@greptileai

[greptile-apps]

Greptile Overview

Confidence Score: 1/5

• This PR has a critical bug that will cause runtime crashes when users try to unsubscribe
• The unsubscribe controller action contains a critical nil reference bug on line 105-113 of app/controllers/topics_controller.rb. When TopicUser.find_by returns nil (which happens when a user hasn't previously interacted with a topic), calling .notification_level will raise a NoMethodError. This will break the unsubscribe functionality completely for new topic interactions.
• app/controllers/topics_controller.rb requires immediate attention to fix the nil reference bug in the unsubscribe action

Important Files Changed

File Analysis

Filename	Score	Overview
app/controllers/topics_controller.rb	1/5	Added unsubscribe action with nil reference bug on TopicUser lookup
app/assets/javascripts/discourse/controllers/topic-unsubscribe.js.es6	3/5	New controller with typo in function name (stopNotificiations)
app/models/topic.rb	5/5	Added unsubscribe_url method
app/mailers/user_notifications.rb	5/5	Added unsubscribe_url to email context and minor refactoring

Sequence Diagram

sequenceDiagram
    participant User
    participant Email
    participant Browser
    participant TopicsController
    participant TopicUser
    participant TopicView
    participant MessageBus

    User->>Email: Receives notification email
    Email->>Email: Contains unsubscribe_url link
    User->>Browser: Clicks unsubscribe link
    Browser->>TopicsController: GET /t/:slug/:id/unsubscribe
    TopicsController->>TopicsController: ensure_logged_in filter
    TopicsController->>TopicView: Create TopicView
    TopicView-->>TopicsController: Return topic data
    TopicsController->>TopicUser: find_by(user_id, topic_id)
    TopicUser-->>TopicsController: Return TopicUser (or nil)
    TopicsController->>TopicUser: Update notification_level
    TopicUser->>TopicUser: save!
    TopicUser->>MessageBus: Publish notification_level_change
    TopicsController->>Browser: Render topic show page
    Browser-->>User: Display unsubscribe confirmation

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[greptile-apps]

_{18 files reviewed, 2 comments}

_{Edit Code Review Agent Settings | Greptile}

[greptile-apps]

logic: find_by returns nil if no TopicUser record exists, causing NoMethodError on line 107

Suggested change

	tu = TopicUser.find_by(user_id: current_user.id, topic_id: params[:topic_id])
	if tu.notification_level > TopicUser.notification_levels[:regular]
	tu.notification_level = TopicUser.notification_levels[:regular]
	else
	tu.notification_level = TopicUser.notification_levels[:muted]
	end
	tu.save!
	tu = TopicUser.find_by(user_id: current_user.id, topic_id: params[:topic_id])
	if tu
	if tu.notification_level > TopicUser.notification_levels[:regular]
	tu.notification_level = TopicUser.notification_levels[:regular]
	else
	tu.notification_level = TopicUser.notification_levels[:muted]
	end
	tu.save!
	else
	TopicUser.create!(
	user_id: current_user.id,
	topic_id: params[:topic_id],
	notification_level: TopicUser.notification_levels[:muted]
	)
	end

Prompt To Fix With AI

This is a comment left during a code review.
Path: app/controllers/topics_controller.rb
Line: 105:113

Comment:
**logic:** `find_by` returns `nil` if no `TopicUser` record exists, causing `NoMethodError` on line 107

```suggestion
    tu = TopicUser.find_by(user_id: current_user.id, topic_id: params[:topic_id])

    if tu
      if tu.notification_level > TopicUser.notification_levels[:regular]
        tu.notification_level = TopicUser.notification_levels[:regular]
      else
        tu.notification_level = TopicUser.notification_levels[:muted]
      end

      tu.save!
    else
      TopicUser.create!(
        user_id: current_user.id,
        topic_id: params[:topic_id],
        notification_level: TopicUser.notification_levels[:muted]
      )
    end
```

How can I resolve this? If you propose a fix, please make it concise.

[greptile-apps]

syntax: typo in function name: 'Notificiations' should be 'Notifications'

Suggested change

	stopNotificiationsText: function() {
	stopNotificationsText: function() {

Prompt To Fix With AI

This is a comment left during a code review.
Path: app/assets/javascripts/discourse/controllers/topic-unsubscribe.js.es6
Line: 5:5

Comment:
**syntax:** typo in function name: 'Notificiations' should be 'Notifications'

```suggestion
  stopNotificationsText: function() {
```

How can I resolve this? If you propose a fix, please make it concise.