Add more thorough user change eraser

lib/philomena/users.ex

@@ -18,6 +18,7 @@ defmodule Philomena.Users do
   alias Philomena.Galleries
   alias Philomena.Reports
   alias Philomena.Filters
+  alias Philomena.UserEraseWorker
   alias Philomena.UserRenameWorker
 
   ## Database getters
@@ -683,6 +684,20 @@ defmodule Philomena.Users do
     |> Repo.update()
   end
 
+  def erase_user(%User{} = user, %User{} = moderator) do
+    # Deactivate to prevent the user from racing these changes
+    {:ok, user} = deactivate_user(moderator, user)
+
+    # Rename to prevent usage for brand recognition SEO
+    random_hex = Base.encode16(:crypto.strong_rand_bytes(16), case: :lower)
+    {:ok, user} = update_user(user, %{name: "deactivated_#{random_hex}"})
+
+    # Enqueue a background job to perform the rest of the deletion
+    Exq.enqueue(Exq, "indexing", UserEraseWorker, [user.id, moderator.id])
+
+    {:ok, user}
+  end
+
   defp setup_roles(nil), do: nil
 
   defp setup_roles(user) do

lib/philomena/users/eraser.ex

@@ -0,0 +1,125 @@
+defmodule Philomena.Users.Eraser do
+  import Ecto.Query
+  alias Philomena.Repo
+
+  alias Philomena.Bans
+  alias Philomena.Comments.Comment
+  alias Philomena.Comments
+  alias Philomena.Galleries.Gallery
+  alias Philomena.Galleries
+  alias Philomena.Posts.Post
+  alias Philomena.Posts
+  alias Philomena.Topics.Topic
+  alias Philomena.Topics
+  alias Philomena.Images
+  alias Philomena.SourceChanges.SourceChange
+
+  alias Philomena.Users
+
+  @reason "Site abuse"
+  @wipe_ip %Postgrex.INET{address: {127, 0, 1, 1}, netmask: 32}
+  @wipe_fp "ffff"
+
+  def erase_permanently!(user, moderator) do
+    # Erase avatar
+    {:ok, user} = Users.remove_avatar(user)
+
+    # Erase "about me" and personal title
+    {:ok, user} = Users.update_description(user, %{description: "", personal_title: ""})
+
+    # Delete all forum posts
+    Post
+    |> where(user_id: ^user.id)
+    |> Repo.all()
+    |> Enum.each(fn post ->
+      {:ok, post} = Posts.hide_post(post, %{deletion_reason: @reason}, moderator)
+      {:ok, _post} = Posts.destroy_post(post)
+    end)
+
+    # Delete all comments
+    Comment
+    |> where(user_id: ^user.id)
+    |> Repo.all()
+    |> Enum.each(fn comment ->
+      {:ok, comment} = Comments.hide_comment(comment, %{deletion_reason: @reason}, moderator)
+      {:ok, _comment} = Comments.destroy_comment(comment)
+    end)
+
+    # Delete all galleries
+    Gallery
+    |> where(creator_id: ^user.id)
+    |> Repo.all()
+    |> Enum.each(fn gallery ->
+      {:ok, _gallery} = Galleries.delete_gallery(gallery)
+    end)
+
+    # Delete all posted topics
+    Topic
+    |> where(user_id: ^user.id)
+    |> Repo.all()
+    |> Enum.each(fn topic ->
+      {:ok, _topic} = Topics.hide_topic(topic, @reason, moderator)
+    end)
+
+    # Revert all source changes
+    SourceChange
+    |> where(user_id: ^user.id)
+    |> order_by(desc: :created_at)
+    |> preload(:image)
+    |> Repo.all()
+    |> Enum.each(fn source_change ->
+      if source_change.added do
+        revert_added_source_change(source_change, user)
+      else
+        revert_removed_source_change(source_change, user)
+      end
+    end)
+
+    # Delete all source changes
+    SourceChange
+    |> where(user_id: ^user.id)
+    |> Repo.delete_all()
+
+    # Ban the user
+    {:ok, _ban} =
+      Bans.create_user(
+        moderator,
+        %{
+          "user_id" => user.id,
+          "reason" => @reason,
+          "valid_until" => "permanent"
+        }
+      )
+
+    # We succeeded
+    :ok
+  end
+
+  defp revert_removed_source_change(source_change, user) do
+    old_sources = %{}
+    new_sources = %{"0" => %{"source" => source_change.source_url}}
+
+    revert_source_change(source_change, user, old_sources, new_sources)
+  end
+
+  defp revert_added_source_change(source_change, user) do
+    old_sources = %{"0" => %{"source" => source_change.source_url}}
+    new_sources = %{}
+
+    revert_source_change(source_change, user, old_sources, new_sources)
+  end
+
+  defp revert_source_change(source_change, user, old_sources, new_sources) do
+    attrs = %{"old_sources" => old_sources, "sources" => new_sources}
+
+    attribution = [
+      user: user,
+      ip: @wipe_ip,
+      fingerprint: @wipe_fp,
+      user_agent: "",
+      referrer: ""
+    ]
+
+    {:ok, _} = Images.update_sources(source_change.image, attribution, attrs)
+  end
+end

lib/philomena/workers/user_erase_worker.ex

@@ -0,0 +1,11 @@
+defmodule Philomena.UserEraseWorker do
+  alias Philomena.Users.Eraser
+  alias Philomena.Users
+
+  def perform(user_id, moderator_id) do
+    moderator = Users.get_user!(moderator_id)
+    user = Users.get_user!(user_id)
+
+    Eraser.erase_permanently!(user, moderator)
+  end
+end

lib/philomena_web/controllers/admin/user/erase_controller.ex

@@ -0,0 +1,74 @@
+defmodule PhilomenaWeb.Admin.User.EraseController do
+  use PhilomenaWeb, :controller
+
+  alias Philomena.Users.User
+  alias Philomena.Users
+
+  plug :verify_authorized
+
+  plug :load_resource,
+    model: User,
+    id_name: "user_id",
+    id_field: "slug",
+    persisted: true,
+    preload: [:roles]
+
+  plug :prevent_deleting_privileged_users
+  plug :prevent_deleting_verified_users
+  plug :prevent_deleting_old_users
+
+  def new(conn, _params) do
+    render(conn, "new.html", title: "Erase user")
+  end
+
+  def create(conn, _params) do
+    {:ok, user} = Users.erase_user(conn.assigns.user, conn.assigns.current_user)
+
+    conn
+    |> put_flash(:info, "User erase started")
+    |> redirect(to: ~p"/profiles/#{user}")
+  end
+
+  defp verify_authorized(conn, _opts) do
+    case Canada.Can.can?(conn.assigns.current_user, :index, User) do
+      true -> conn
+      _false -> PhilomenaWeb.NotAuthorizedPlug.call(conn)
+    end
+  end
+
+  defp prevent_deleting_privileged_users(conn, _opts) do
+    if conn.assigns.user.role != "user" do
+      conn
+      |> put_flash(:error, "Cannot erase a privileged user")
+      |> redirect(to: ~p"/profiles/#{conn.assigns.user}")
+      |> Plug.Conn.halt()
+    else
+      conn
+    end
+  end
+
+  defp prevent_deleting_verified_users(conn, _opts) do
+    if conn.assigns.user.verified do
+      conn
+      |> put_flash(:error, "Cannot erase a verified user")
+      |> redirect(to: ~p"/profiles/#{conn.assigns.user}")
+      |> Plug.Conn.halt()
+    else
+      conn
+    end
+  end
+
+  defp prevent_deleting_old_users(conn, _opts) do
+    now = DateTime.utc_now(:second)
+    two_weeks = 1_209_600
+
+    if DateTime.compare(now, DateTime.add(conn.assigns.user.created_at, two_weeks)) == :gt do
+      conn
+      |> put_flash(:error, "Cannot erase a user older than two weeks")
+      |> redirect(to: ~p"/profiles/#{conn.assigns.user}")
+      |> Plug.Conn.halt()
+    else
+      conn
+    end
+  end
+end

lib/philomena_web/router.ex

@@ -398,6 +398,7 @@ defmodule PhilomenaWeb.Router do
           singleton: true
 
         resources "/unlock", User.UnlockController, only: [:create], singleton: true
+        resources "/erase", User.EraseController, only: [:new, :create], singleton: true
         resources "/api_key", User.ApiKeyController, only: [:delete], singleton: true
         resources "/downvotes", User.DownvoteController, only: [:delete], singleton: true
         resources "/votes", User.VoteController, only: [:delete], singleton: true

lib/philomena_web/templates/admin/user/erase/new.html.slime

@@ -0,0 +1,16 @@
+h1
+  ' Deleting all changes for user
+  = @user.name
+
+.block.block--fixed.block--warning
+  p This is IRREVERSIBLE.
+  p All user details will be destroyed.
+  p Are you really sure?
+
+.field
+  => button_to "Abort", ~p"/profiles/#{@user}", class: "button"
+  => button_to "Erase user", ~p"/admin/users/#{@user}/erase", method: "post", class: "button button--state-danger", data: [confirm: "Are you really, really sure?"]
+
+p
+  ' This automatically creates user and IP bans but does not create a fingerprint ban.
+  ' Check to see if one is necessary after erasing.

lib/philomena_web/templates/profile/_admin_block.html.slime

@@ -171,6 +171,12 @@ a.label.label--primary.label--block href="#" data-click-toggle=".js-admin__optio
           i.fa.fa-fw.fa-arrow-down
           span.admin__button Remove All Downvotes
 
+      = if @user.role == "user" do
+        li
+          = link to: ~p"/admin/users/#{@user}/erase/new", data: [confirm: "Are you really, really sure?"] do
+            i.fa.fa-fw.fa-warning
+            span.admin__button Erase for spam
+
     = if @user.role == "user" and can?(@conn, :revert, Philomena.TagChanges.TagChange) do
       li
         = link to: ~p"/tag_changes/full_revert?#{[user_id: @user.id]}", data: [confirm: "Are you really, really sure?", method: "create"] do

lib/philomena_web/views/admin/user/erase_view.ex

@@ -0,0 +1,3 @@
+defmodule PhilomenaWeb.Admin.User.EraseView do
+  use PhilomenaWeb, :view
+end