From 46098f2970528ca711827a3ccfeaabbc2c14535a Mon Sep 17 00:00:00 2001
From: Sojan Jose <sojan@pepalo.com>
Date: Mon, 26 Oct 2020 00:31:19 +0530
Subject: [PATCH] chore: Monkey patch Azure Storage Service (#1366)

Monkey patch azure storage service until the changes come into rails stable versions
---
 .rubocop.yml                                  |   1 +
 .../azure_storage_service_patch.rb            | 170 ++++++++++++++++++
 lib/azure/storage.rb                          |   2 +
 .../core/auth/shared_access_signature.rb      |   2 +
 4 files changed, 175 insertions(+)
 create mode 100644 config/initializers/azure_storage_service_patch.rb
 create mode 100644 lib/azure/storage.rb
 create mode 100644 lib/azure/storage/core/auth/shared_access_signature.rb

diff --git a/.rubocop.yml b/.rubocop.yml
index c27b9651b..9cd50a44f 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -124,3 +124,4 @@ AllCops:
     - 'tmp/**/*'
     - 'storage/**/*'
     - 'db/migrate/20200225162150_init_schema.rb'
+    - 'config/initializers/azure_storage_service_patch.rb'
diff --git a/config/initializers/azure_storage_service_patch.rb b/config/initializers/azure_storage_service_patch.rb
new file mode 100644
index 000000000..82a0cbd14
--- /dev/null
+++ b/config/initializers/azure_storage_service_patch.rb
@@ -0,0 +1,170 @@
+# TODO: Remove this once the changes comes into rails version
+# https://github.com/Azure/azure-storage-ruby/issues/166#issuecomment-637696565 
+# Remove this once the changes comes into rails version
+
+# code from current master : https://github.com/rails/rails/blob/8520cc77133d9ff642e2c393b4ee5eae2a2a28b6/activestorage/lib/active_storage/service/azure_storage_service.rb
+
+require 'azure/storage/blob'
+require 'active_storage/service/azure_storage_service'
+module ActiveStorage
+  # Wraps the Microsoft Azure Storage Blob Service as an Active Storage service.
+  # See ActiveStorage::Service for the generic API documentation that applies to all services.
+  class Service::AzureStorageService < Service
+    attr_reader :client, :container, :signer
+
+    def initialize(storage_account_name:, storage_access_key:, container:, public: false, **options)
+      @client = Azure::Storage::Blob::BlobService.create(storage_account_name: storage_account_name, storage_access_key: storage_access_key, **options)
+      @signer = Azure::Storage::Common::Core::Auth::SharedAccessSignature.new(storage_account_name, storage_access_key)
+      @container = container
+      @public = public
+    end
+
+    def upload(key, io, checksum: nil, filename: nil, content_type: nil, disposition: nil, **)
+      instrument :upload, key: key, checksum: checksum do
+        handle_errors do
+          content_disposition = content_disposition_with(filename: filename, type: disposition) if disposition && filename
+
+          client.create_block_blob(container, key, IO.try_convert(io) || io, content_md5: checksum, content_type: content_type, content_disposition: content_disposition)
+        end
+      end
+    end
+
+    def download(key, &block)
+      if block_given?
+        instrument :streaming_download, key: key do
+          stream(key, &block)
+        end
+      else
+        instrument :download, key: key do
+          handle_errors do
+            _, io = client.get_blob(container, key)
+            io.force_encoding(Encoding::BINARY)
+          end
+        end
+      end
+    end
+
+    def download_chunk(key, range)
+      instrument :download_chunk, key: key, range: range do
+        handle_errors do
+          _, io = client.get_blob(container, key, start_range: range.begin, end_range: range.exclude_end? ? range.end - 1 : range.end)
+          io.force_encoding(Encoding::BINARY)
+        end
+      end
+    end
+
+    def delete(key)
+      instrument :delete, key: key do
+        client.delete_blob(container, key)
+      rescue Azure::Core::Http::HTTPError => e
+        raise unless e.type == "BlobNotFound"
+        # Ignore files already deleted
+      end
+    end
+
+    def delete_prefixed(prefix)
+      instrument :delete_prefixed, prefix: prefix do
+        marker = nil
+
+        loop do
+          results = client.list_blobs(container, prefix: prefix, marker: marker)
+
+          results.each do |blob|
+            client.delete_blob(container, blob.name)
+          end
+
+          break unless marker = results.continuation_token.presence
+        end
+      end
+    end
+
+    def exist?(key)
+      instrument :exist, key: key do |payload|
+        answer = blob_for(key).present?
+        payload[:exist] = answer
+        answer
+      end
+    end
+
+    def url_for_direct_upload(key, expires_in:, content_type:, content_length:, checksum:)
+      instrument :url, key: key do |payload|
+        generated_url = signer.signed_uri(
+          uri_for(key), false,
+          service: "b",
+          permissions: "rw",
+          expiry: format_expiry(expires_in)
+        ).to_s
+
+        payload[:url] = generated_url
+
+        generated_url
+      end
+    end
+
+    def headers_for_direct_upload(key, content_type:, checksum:, filename: nil, disposition: nil, **)
+      content_disposition = content_disposition_with(type: disposition, filename: filename) if filename
+
+      { "Content-Type" => content_type, "Content-MD5" => checksum, "x-ms-blob-content-disposition" => content_disposition, "x-ms-blob-type" => "BlockBlob" }
+    end
+
+    private
+      def private_url(key, expires_in:, filename:, disposition:, content_type:, **)
+        signer.signed_uri(
+          uri_for(key), false,
+          service: "b",
+          permissions: "r",
+          expiry: format_expiry(expires_in),
+          content_disposition: content_disposition_with(type: disposition, filename: filename),
+          content_type: content_type
+        ).to_s
+      end
+
+      def public_url(key, **)
+        uri_for(key).to_s
+      end
+
+
+      def uri_for(key)
+        client.generate_uri("#{container}/#{key}")
+      end
+
+      def blob_for(key)
+        client.get_blob_properties(container, key)
+      rescue Azure::Core::Http::HTTPError
+        false
+      end
+
+      def format_expiry(expires_in)
+        expires_in ? Time.now.utc.advance(seconds: expires_in).iso8601 : nil
+      end
+
+      # Reads the object for the given key in chunks, yielding each to the block.
+      def stream(key)
+        blob = blob_for(key)
+
+        chunk_size = 5.megabytes
+        offset = 0
+
+        raise ActiveStorage::FileNotFoundError unless blob.present?
+
+        while offset < blob.properties[:content_length]
+          _, chunk = client.get_blob(container, key, start_range: offset, end_range: offset + chunk_size - 1)
+          yield chunk.force_encoding(Encoding::BINARY)
+          offset += chunk_size
+        end
+      end
+
+      def handle_errors
+        yield
+      rescue Azure::Core::Http::HTTPError => e
+        case e.type
+        when "BlobNotFound"
+          raise ActiveStorage::FileNotFoundError
+        when "Md5Mismatch"
+          raise ActiveStorage::IntegrityError
+        else
+          raise
+        end
+      end
+  end
+end
\ No newline at end of file
diff --git a/lib/azure/storage.rb b/lib/azure/storage.rb
new file mode 100644
index 000000000..f0bb9129a
--- /dev/null
+++ b/lib/azure/storage.rb
@@ -0,0 +1,2 @@
+# https://github.com/Azure/azure-storage-ruby/issues/166#issuecomment-637696565
+# Remove this once the changes comes into rails
diff --git a/lib/azure/storage/core/auth/shared_access_signature.rb b/lib/azure/storage/core/auth/shared_access_signature.rb
new file mode 100644
index 000000000..ba10b61c0
--- /dev/null
+++ b/lib/azure/storage/core/auth/shared_access_signature.rb
@@ -0,0 +1,2 @@
+# TODO: Remove this once the changes comes into rails version
+# https://github.com/Azure/azure-storage-ruby/issues/166#issuecomment-637696565