1 files changed, 60 insertions, 0 deletions
diff --git a/lib/gitlab/metrics/dashboard/validator/errors.rb b/lib/gitlab/metrics/dashboard/validator/errors.rb
new file mode 100644
index 00000000000..0f6e687d291
--- /dev/null
+++ b/lib/gitlab/metrics/dashboard/validator/errors.rb
@@ -0,0 +1,60 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Metrics
+    module Dashboard
+      module Validator
+        module Errors
+          InvalidDashboardError = Class.new(StandardError)
+
+          class SchemaValidationError < InvalidDashboardError
+            def initialize(error = {})
+              super(error_message(error))
+            end
+
+            private
+
+            def error_message(error)
+              if error.is_a?(Hash) && error.present?
+                pretty(error)
+              else
+                "Dashboard failed schema validation"
+              end
+            end
+
+            # based on https://github.com/davishmcclurg/json_schemer/blob/master/lib/json_schemer/errors.rb
+            # with addition ability to translate error messages
+            def pretty(error)
+              data, data_pointer, type, schema = error.values_at('data', 'data_pointer', 'type', 'schema')
+              location = data_pointer.empty? ? 'root' : data_pointer
+
+              case type
+              when 'required'
+                keys = error.fetch('details').fetch('missing_keys').join(', ')
+                _("%{location} is missing required keys: %{keys}") % { location: location, keys: keys }
+              when 'null', 'string', 'boolean', 'integer', 'number', 'array', 'object'
+                _("'%{data}' at %{location} is not of type: %{type}") % { data: data, location: location, type: type }
+              when 'pattern'
+                _("'%{data}' at %{location} does not match pattern: %{pattern}") % { data: data, location: location, pattern: schema.fetch('pattern') }
+              when 'format'
+                _("'%{data}' at %{location} does not match format: %{format}") % { data: data, location: location, format: schema.fetch('format') }
+              when 'const'
+                _("'%{data}' at %{location} is not: %{const}") % { data: data, location: location, const: schema.fetch('const').inspect }
+              when 'enum'
+                _("'%{data}' at %{location} is not one of: %{enum}") % { data: data, location: location, enum: schema.fetch('enum') }
+              else
+                _("'%{data}' at %{location} is invalid: error_type=%{type}") % { data: data, location: location, type: type }
+              end
+            end
+          end
+
+          class DuplicateMetricIds < InvalidDashboardError
+            def initialize
+              super(_("metric_id must be unique across a project"))
+            end
+          end
+        end
+      end
+    end
+  end
+end