Provide a link to existing domain block when trying to block an already-blocked domain (#10663)

* When trying to block an already-blocked domain, provide a link to the block

* Fix styling for links in flash messages

* Allow blocks to be upgraded but not downgraded

3 files changed, 35 insertions, 5 deletions

diff --git a/app/controllers/admin/domain_blocks_controller.rb b/app/controllers/admin/domain_blocks_controller.rb
index 5f307ddee..dd3f83389 100644
--- a/app/controllers/admin/domain_blocks_controller.rb
+++ b/app/controllers/admin/domain_blocks_controller.rb
@@ -13,13 +13,25 @@ module Admin
       authorize :domain_block, :create?
 
       @domain_block = DomainBlock.new(resource_params)
+      existing_domain_block = resource_params[:domain].present? ? DomainBlock.find_by(domain: resource_params[:domain]) : nil
 
-      if @domain_block.save
-        DomainBlockWorker.perform_async(@domain_block.id)
-        log_action :create, @domain_block
-        redirect_to admin_instances_path(limited: '1'), notice: I18n.t('admin.domain_blocks.created_msg')
-      else
+      if existing_domain_block.present? && !@domain_block.stricter_than?(existing_domain_block)
+        @domain_block.save
+        flash[:alert] = I18n.t('admin.domain_blocks.existing_domain_block_html', name: existing_domain_block.domain, unblock_url: admin_domain_block_path(existing_domain_block)).html_safe # rubocop:disable Rails/OutputSafety
+        @domain_block.errors[:domain].clear
         render :new
+      else
+        if existing_domain_block.present?
+          @domain_block = existing_domain_block
+          @domain_block.update(resource_params)
+        end
+        if @domain_block.save
+          DomainBlockWorker.perform_async(@domain_block.id)
+          log_action :create, @domain_block
+          redirect_to admin_instances_path(limited: '1'), notice: I18n.t('admin.domain_blocks.created_msg')
+        else
+          render :new
+        end
       end
     end
 
diff --git a/app/javascript/styles/mastodon/forms.scss b/app/javascript/styles/mastodon/forms.scss
index 91888d305..2b8d7a682 100644
--- a/app/javascript/styles/mastodon/forms.scss
+++ b/app/javascript/styles/mastodon/forms.scss
@@ -533,6 +533,17 @@ code {
     color: $error-value-color;
   }
 
+  a {
+    display: inline-block;
+    color: $darker-text-color;
+    text-decoration: none;
+
+    &:hover {
+      color: $primary-text-color;
+      text-decoration: underline;
+    }
+  }
+
   p {
     margin-bottom: 15px;
   }
diff --git a/app/models/domain_block.rb b/app/models/domain_block.rb
index 069cda367..0b12617c6 100644
--- a/app/models/domain_block.rb
+++ b/app/models/domain_block.rb
@@ -29,4 +29,11 @@ class DomainBlock < ApplicationRecord
   def self.blocked?(domain)
     where(domain: domain, severity: :suspend).exists?
   end
+
+  def stricter_than?(other_block)
+    return true if suspend?
+    return false if other_block.suspend? && (silence? || noop?)
+    return false if other_block.silence? && noop?
+    (reject_media || !other_block.reject_media) && (reject_reports || !other_block.reject_reports)
+  end
 end