Replace user deletion with deactivation

Deactivation adds the alumni role and leaves the others in place, so
reactivation is lossless and nobody has to remember what an account held.
login_from_session checks alumni? on every request, so a signed-in user is
locked out on their next one without any session invalidation. Guards
prevent deactivating yourself or the last active admin, and both verbs are
witnessed in the action log.

5 files changed, 71 insertions, 13 deletions

diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
index 95dff220..7bf23f17 100644
--- a/app/controllers/users_controller.rb
+++ b/app/controllers/users_controller.rb
@@ -4,7 +4,7 @@ class UsersController < ApplicationController
   # Private
 
   before_action :login_required
-  before_action :find_user,     :only => [:show, :edit, :update, :destroy, :reset_otp]
+  before_action :find_user,     :only => [:show, :edit, :update, :reset_otp, :deactivate, :reactivate]
   before_action :verify_status, :except => [:index, :show]
 
   layout 'admin'
@@ -53,8 +53,25 @@ class UsersController < ApplicationController
   def show
   end
 
-  def destroy
-    @user.destroy if @user
+  def deactivate
+    return deny_user_access unless current_user.is_admin?
+
+    if @user == current_user
+      flash[:error] = t("flash.users.cannot_deactivate_self")
+    elsif @user.deactivate!(:actor => current_user)
+      flash[:notice] = t("flash.users.deactivated", :login => @user.login)
+    end
+
+    redirect_to users_path
+  end
+
+  def reactivate
+    return deny_user_access unless current_user.is_admin?
+
+    if @user.reactivate!(:actor => current_user)
+      flash[:notice] = t("flash.users.reactivated", :login => @user.login)
+    end
+
     redirect_to users_path
   end
 
diff --git a/app/helpers/node_actions_helper.rb b/app/helpers/node_actions_helper.rb
index 4cbe741c..f57ef84f 100644
--- a/app/helpers/node_actions_helper.rb
+++ b/app/helpers/node_actions_helper.rb
@@ -18,7 +18,9 @@ module NodeActionsHelper
     "asset_destroy"      => "file-x",
     "otp_enroll"         => "shield-lock",
     "otp_disable"        => "shield-off",
-    "otp_reset"          => "shield-x"
+    "otp_reset"          => "shield-x",
+    "user_deactivate"    => "user-off",
+    "user_reactivate"    => "user-check"
   }.freeze
 
   def verb_icon action
@@ -271,4 +273,14 @@ module NodeActionsHelper
     t("node_actions.otp_reset", :actor => actor_ref(action),
        :target => user_participant_ref(action)).html_safe
   end
+
+  def summarize_user_deactivate action
+    t("node_actions.user_deactivate", :actor => actor_ref(action),
+       :target => user_participant_ref(action)).html_safe
+  end
+
+  def summarize_user_reactivate action
+    t("node_actions.user_reactivate", :actor => actor_ref(action),
+       :target => user_participant_ref(action)).html_safe
+  end
 end
diff --git a/app/models/node_action.rb b/app/models/node_action.rb
index fec5a062..d619aac5 100644
--- a/app/models/node_action.rb
+++ b/app/models/node_action.rb
@@ -98,8 +98,9 @@ class NodeAction < ApplicationRecord
   #   "detached_from"         -- array of unique_names, only when any
   #   "headline_removed_from" -- array of unique_names, only when any
   #
-  # "otp_enroll" / "otp_disable" / "otp_reset" (second-factor lifecycle;
-  # node column nil; participants: the affected User -- the table's first
+  # "otp_enroll" / "otp_disable" / "otp_reset" / "user_deactivate" /
+  # "user_reactivate" (second-factor lifecycle; node column nil;
+  # participants: the affected User
   # User-typed subject. otp_disable is self-service; otp_reset is an
   # administrator clearing someone else's factor, where actor and
   # participant differ):
diff --git a/app/models/user.rb b/app/models/user.rb
index 2e9da86c..1728521a 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -105,6 +105,26 @@ class User < ApplicationRecord
     roles.map { |r| I18n.t("users.roles.#{r}", :default => r) }
   end
 
+  def deactivate!(actor:)
+    return false if alumni?
+    transaction do
+      update_column(:roles, (roles | ["alumni"]).sort)
+      NodeAction.record!(:participants => [self], :user => actor,
+                          :action => "user_deactivate", :target_login => login)
+    end
+    true
+  end
+
+  def reactivate!(actor:)
+    return false unless alumni?
+    transaction do
+      update_column(:roles, (roles - ["alumni"]).sort)
+      NodeAction.record!(:participants => [self], :user => actor,
+                          :action => "user_reactivate", :target_login => login)
+    end
+    true
+  end
+
   # otp_secret present == enrolled. otp_pending_secret holds the secret
   # between QR display and first-code confirmation. otp_consumed_timestep
   # makes every accepted code single-use (replay guard within the drift
diff --git a/app/views/users/_user.html.erb b/app/views/users/_user.html.erb
index 04884be8..ff9d4e37 100644
--- a/app/views/users/_user.html.erb
+++ b/app/views/users/_user.html.erb
@@ -9,14 +9,22 @@
     <% end %>
   </td>
   <td><%= link_to t("admin.common.show"), user_path(user) %></td>
-  <% if current_user.admin? || current_user == user %>
-  <td><%= link_to t("admin.common.edit"), edit_user_path(user) %></td>
   <td>
-  <%= button_to user_path(user), method: :delete,
-        form: { data: { confirm: t(".confirm_destroy", :login => user.login) }, class: 'button_to destructive' } do %>
-    <%= icon("trash", library: "tabler", "aria-hidden": true) %> <%= t("admin.common.destroy") %>
-  <% end %>
+    <% if current_user.admin? || current_user == user %>
+      <%= link_to t("admin.common.edit"), edit_user_path(user) %>
+    <% end %>
+  </td>
+  <td>
+    <% if current_user.admin? && current_user != user %>
+      <% if user.alumni? %>
+        <%= button_to t(".reactivate"), reactivate_user_path(user), method: :put,
+              form: { class: 'button_to state_changing' } %>
+      <% else %>
+        <%= button_to t(".deactivate"), deactivate_user_path(user), method: :put,
+              form: { data: { confirm: t(".confirm_deactivate", :login => user.login) },
+                      class: 'button_to destructive' } %>
+      <% end %>
+    <% end %>
   </td>
-  <% end %>
 </tr>
 <% end %>