add user account deletion (right to be forgotten)

app/routes/users.py

@@ -4,7 +4,12 @@ from flask import (
 from functools import wraps
 from ..db import db
 from ..lib.babycode import babycode_to_html, BABYCODE_VERSION
-from ..models import Users, Sessions, Subscriptions, Avatars, PasswordResetLinks, InviteKeys, BookmarkCollections, BookmarkedThreads, Mentions, PostHistory
+from ..models import (
+    Users, Sessions, Subscriptions,
+    Avatars, PasswordResetLinks, InviteKeys,
+    BookmarkCollections, BookmarkedThreads,
+    Mentions, PostHistory,
+    )
 from ..constants import InfoboxKind, PermissionLevel
 from ..auth import digest, verify
 from wand.image import Image
@@ -197,6 +202,53 @@ def get_prefers_theme():
 
     return session['theme']
 
+
+def anonymize_user(user_id):
+    deleted_user = Users.find({'username': 'deleteduser'})
+
+    from ..models import Threads, Posts
+    from ..lib.babycode import sanitize
+    threads = Threads.findall({'user_id': user_id})
+    posts = Posts.findall({'user_id': user_id})
+
+    revs_q = """SELECT DISTINCT m.revision_id FROM mentions m
+            WHERE m.mentioned_user_id = ?"""
+
+    mentioned_revs = db.query(revs_q, int(user_id))
+    with db.transaction():
+        for thread in threads:
+            thread.update({'user_id': int(deleted_user.id)})
+        for post in posts:
+            post.update({'user_id': int(deleted_user.id)})
+
+        revs = {}
+        for rev in mentioned_revs:
+            ph = PostHistory.find({'id': int(rev['revision_id'])})
+            ms = Mentions.findall({
+                    'mentioned_user_id': int(user_id),
+                    'revision_id': int(rev['revision_id'])
+                })
+            data = {
+                'text': sanitize(ph.original_markup),
+                'mentions': ms,
+            }
+            data['mentions'] = sorted(data['mentions'], key=lambda x: int(x.end_index), reverse=True)
+            revs[rev['revision_id']] = data
+
+        for rev_id, data in revs.items():
+            text = data['text']
+            for mention in data['mentions']:
+                text = text[:mention.start_index] + '@deleteduser' + text[mention.end_index:]
+                mention.delete()
+
+            res = babycode_to_html(text)
+            ph = PostHistory.find({'id': int(rev_id)})
+            ph.update({
+                'original_markup': text.unescape(),
+                'content': res.result,
+            })
+
+
 @bp.get("/log_in")
 @redirect_if_logged_in(".page", username = lambda: get_active_user().username)
 def log_in():
@@ -756,3 +808,34 @@ def bookmark_collections(username):
 
     collections = target_user.get_bookmark_collections()
     return render_template('users/bookmark_collections.html', collections=collections)
+
+
+@bp.get('/<username>/delete-account')
+@login_required
+@redirect_to_own
+def delete_page(username):
+    target_user = get_active_user()
+
+    return render_template('users/delete_page.html')
+
+
+@bp.post('/<username>/delete-account')
+@login_required
+@redirect_to_own
+def delete_page_confirm(username):
+    target_user = get_active_user()
+
+    password = request.form.get('password', default='')
+
+    if not verify(target_user.password_hash, password):
+        flash('Incorrect password.', InfoboxKind.ERROR)
+        return redirect(url_for('.delete_page', username=username))
+
+    anonymize_user(target_user.id)
+    sessions = Sessions.findall({'user_id': int(target_user.id)})
+    for session_obj in sessions:
+        session_obj.delete()
+
+    session.clear()
+    target_user.delete()
+    return redirect(url_for('topics.all_topics'))

app/templates/users/delete_page.html

@@ -0,0 +1,15 @@
+{% extends 'base.html' %}
+{% block title %}delete confirmation{% endblock %}
+{% block content %}
+<div class="darkbg login-container">
+  <h1>Confirm account deletion</h1>
+  <p>Are you sure you want to delete your account on {{ config.SITE_NAME }}? <strong>This action is irreversible.</strong> Your posts and threads will remain accessible to preserve history but will be de-personalized, showing up as authored by a system user. Posts that @mention you will also mention the system user instead.</p>
+  <p>If you wish for any and all content relating to you to be removed, you will have to ask {{ config.SITE_NAME }}'s administrators separately.</p>
+  <p>If you are sure, please confirm your current password below.</p>
+  <form method="post">
+    <label for="password">Confirm password</label>
+    <input type="password" id="password" name="password" required autocomplete="current-password">
+    <input class="critical" type="submit" value="Delete account">
+  </form>
+</div>
+{% endblock %}

app/templates/users/settings.html

@@ -43,5 +43,8 @@
     <input type="password" id="new_password2" name="new_password2" pattern="(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[\W_])(?!.*\s).{10,}" title="10+ chars with: 1 uppercase, 1 lowercase, 1 number, 1 special char, and no spaces" required autocomplete="new-password"><br>
     <input class="warn" type="submit" value="Change password">
   </form>
+  <div>
+    <a class="linkbutton critical" href="{{ url_for('users.delete_page', username=active_user.username) }}">Delete account</a>
+  </div>
 </div>
 {% endblock %}