Merge branch 'master' into glitch-soc/merge-upstream

Conflicts:
- `app/services/resolve_url_service.rb`:
  The private toot search by URL hack has been revamped upstream.
  Took upstream's version.

app/validators/import_validator.rb

@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+class ImportValidator < ActiveModel::Validator
+  KNOWN_HEADERS = [
+    'Account address',
+    '#domain',
+    '#uri',
+  ].freeze
+
+  def validate(import)
+    return if import.type.blank? || import.data.blank?
+
+    # We parse because newlines could be part of individual rows. This
+    # runs on create so we should be reading the local file here before
+    # it is uploaded to object storage or moved anywhere...
+    csv_data = CSV.parse(import.data.queued_for_write[:original].read)
+
+    row_count  = csv_data.size
+    row_count -= 1 if KNOWN_HEADERS.include?(csv_data.first&.first)
+
+    import.errors.add(:data, I18n.t('imports.errors.over_rows_processing_limit', count: ImportService::ROWS_PROCESSING_LIMIT)) if row_count > ImportService::ROWS_PROCESSING_LIMIT
+
+    case import.type
+    when 'following'
+      validate_following_import(import, row_count)
+    end
+  end
+
+  private
+
+  def validate_following_import(import, row_count)
+    base_limit = FollowLimitValidator.limit_for_account(import.account)
+
+    limit = begin
+      if import.overwrite?
+        base_limit
+      else
+        base_limit - import.account.following_count
+      end
+    end
+
+    import.errors.add(:data, I18n.t('users.follow_limit_reached', limit: base_limit)) if row_count > limit
+  end
+end