1 files changed, 94 insertions, 0 deletions
diff --git a/app/services/namespaces/check_storage_size_service.rb b/app/services/namespaces/check_storage_size_service.rb
new file mode 100644
index 00000000000..b3cf17681ee
--- /dev/null
+++ b/app/services/namespaces/check_storage_size_service.rb
@@ -0,0 +1,94 @@
+# frozen_string_literal: true
+
+module Namespaces
+  class CheckStorageSizeService
+    include ActiveSupport::NumberHelper
+    include Gitlab::Allowable
+    include Gitlab::Utils::StrongMemoize
+
+    def initialize(namespace, user)
+      @root_namespace = namespace.root_ancestor
+      @root_storage_size = Namespace::RootStorageSize.new(root_namespace)
+      @user = user
+    end
+
+    def execute
+      return ServiceResponse.success unless Feature.enabled?(:namespace_storage_limit, root_namespace)
+      return ServiceResponse.success if alert_level == :none
+
+      if root_storage_size.above_size_limit?
+        ServiceResponse.error(message: above_size_limit_message, payload: payload)
+      else
+        ServiceResponse.success(payload: payload)
+      end
+    end
+
+    private
+
+    attr_reader :root_namespace, :root_storage_size, :user
+
+    USAGE_THRESHOLDS = {
+      none: 0.0,
+      info: 0.5,
+      warning: 0.75,
+      alert: 0.95,
+      error: 1.0
+    }.freeze
+
+    def payload
+      return {} unless can?(user, :admin_namespace, root_namespace)
+
+      {
+        explanation_message: explanation_message,
+        usage_message: usage_message,
+        alert_level: alert_level
+      }
+    end
+
+    def explanation_message
+      root_storage_size.above_size_limit? ? above_size_limit_message : below_size_limit_message
+    end
+
+    def usage_message
+      s_("You reached %{usage_in_percent} of %{namespace_name}'s capacity (%{used_storage} of %{storage_limit})" % current_usage_params)
+    end
+
+    def alert_level
+      strong_memoize(:alert_level) do
+        usage_ratio = root_storage_size.usage_ratio
+        current_level = USAGE_THRESHOLDS.each_key.first
+
+        USAGE_THRESHOLDS.each do |level, threshold|
+          current_level = level if usage_ratio >= threshold
+        end
+
+        current_level
+      end
+    end
+
+    def below_size_limit_message
+      s_("If you reach 100%% storage capacity, you will not be able to: %{base_message}" % { base_message: base_message } )
+    end
+
+    def above_size_limit_message
+      s_("%{namespace_name} is now read-only. You cannot: %{base_message}" % { namespace_name: root_namespace.name, base_message: base_message })
+    end
+
+    def base_message
+      s_("push to your repository, create pipelines, create issues or add comments. To reduce storage capacity, delete unused repositories, artifacts, wikis, issues, and pipelines.")
+    end
+
+    def current_usage_params
+      {
+        usage_in_percent: number_to_percentage(root_storage_size.usage_ratio * 100, precision: 0),
+        namespace_name: root_namespace.name,
+        used_storage: formatted(root_storage_size.current_size),
+        storage_limit: formatted(root_storage_size.limit)
+      }
+    end
+
+    def formatted(number)
+      number_to_human_size(number, delimiter: ',', precision: 2)
+    end
+  end
+end