1 files changed, 113 insertions, 0 deletions
diff --git a/activestorage/lib/active_storage/service/gcs_service.rb b/activestorage/lib/active_storage/service/gcs_service.rb
new file mode 100644
index 0000000000..6f6f4105fe
--- /dev/null
+++ b/activestorage/lib/active_storage/service/gcs_service.rb
@@ -0,0 +1,113 @@
+# frozen_string_literal: true
+
+gem "google-cloud-storage", "~> 1.8"
+
+require "google/cloud/storage"
+require "active_support/core_ext/object/to_query"
+
+module ActiveStorage
+  # Wraps the Google Cloud Storage as an Active Storage service. See ActiveStorage::Service for the generic API
+  # documentation that applies to all services.
+  class Service::GCSService < Service
+    def initialize(**config)
+      @config = config
+    end
+
+    def upload(key, io, checksum: nil)
+      instrument :upload, key: key, checksum: checksum do
+        begin
+          # The official GCS client library doesn't allow us to create a file with no Content-Type metadata.
+          # We need the file we create to have no Content-Type so we can control it via the response-content-type
+          # param in signed URLs. Workaround: let the GCS client create the file with an inferred
+          # Content-Type (usually "application/octet-stream") then clear it.
+          bucket.create_file(io, key, md5: checksum).update do |file|
+            file.content_type = nil
+          end
+        rescue Google::Cloud::InvalidArgumentError
+          raise ActiveStorage::IntegrityError
+        end
+      end
+    end
+
+    # FIXME: Download in chunks when given a block.
+    def download(key)
+      instrument :download, key: key do
+        io = file_for(key).download
+        io.rewind
+
+        if block_given?
+          yield io.read
+        else
+          io.read
+        end
+      end
+    end
+
+    def delete(key)
+      instrument :delete, key: key do
+        begin
+          file_for(key).delete
+        rescue Google::Cloud::NotFoundError
+          # Ignore files already deleted
+        end
+      end
+    end
+
+    def delete_prefixed(prefix)
+      instrument :delete_prefixed, prefix: prefix do
+        bucket.files(prefix: prefix).all(&:delete)
+      end
+    end
+
+    def exist?(key)
+      instrument :exist, key: key do |payload|
+        answer = file_for(key).exists?
+        payload[:exist] = answer
+        answer
+      end
+    end
+
+    def url(key, expires_in:, filename:, content_type:, disposition:)
+      instrument :url, key: key do |payload|
+        generated_url = file_for(key).signed_url expires: expires_in, query: {
+          "response-content-disposition" => content_disposition_with(type: disposition, filename: filename),
+          "response-content-type" => content_type
+        }
+
+        payload[:url] = generated_url
+
+        generated_url
+      end
+    end
+
+    def url_for_direct_upload(key, expires_in:, content_type:, content_length:, checksum:)
+      instrument :url, key: key do |payload|
+        generated_url = bucket.signed_url key, method: "PUT", expires: expires_in,
+          content_type: content_type, content_md5: checksum
+
+        payload[:url] = generated_url
+
+        generated_url
+      end
+    end
+
+    def headers_for_direct_upload(key, content_type:, checksum:, **)
+      { "Content-Type" => content_type, "Content-MD5" => checksum }
+    end
+
+    private
+      attr_reader :config
+
+      def file_for(key)
+        bucket.file(key, skip_lookup: true)
+      end
+
+      def bucket
+        @bucket ||= client.bucket(config.fetch(:bucket))
+      end
+
+      def client
+        @client ||= Google::Cloud::Storage.new(config.except(:bucket))
+      end
+  end
+end