alt-research · fyInALT · Oct 31, 2022 · Nov 1, 2022 · Nov 1, 2022 · Nov 1, 2022
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ### Features
 
+- [#6440](https://github.com/blockscout/blockscout/pull/6440) - Add support for base64 encoded NFT metadata
 - [#6407](https://github.com/blockscout/blockscout/pull/6407) - Indexed ratio for int txs fetching stage
 - [#6324](https://github.com/blockscout/blockscout/pull/6324) - Add verified contracts list page
 - [#6379](https://github.com/blockscout/blockscout/pull/6379) - API v2 for frontend

diff --git a/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex b/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
@@ -158,7 +158,7 @@ defmodule Explorer.Token.InstanceMetadataRetriever do
   def fetch_json(%{@uri => {:ok, ["data:application/json," <> json]}}, hex_token_id) do
     decoded_json = URI.decode(json)
 
-    fetch_json(%{@token_uri => {:ok, [decoded_json]}}, hex_token_id)
+    fetch_json(%{@uri => {:ok, [decoded_json]}}, hex_token_id)
   rescue
     e ->
       Logger.debug(["Unknown metadata format #{inspect(json)}. error #{inspect(e)}"],
@@ -168,6 +168,40 @@ defmodule Explorer.Token.InstanceMetadataRetriever do
       {:error, json}
   end
 
+  def fetch_json(%{@token_uri => {:ok, ["data:application/json;base64," <> base64_encoded_json]}}, hex_token_id) do
+    case Base.url_decode64(base64_encoded_json) do
+      {:ok, base64_decoded} ->
+        fetch_json(%{@token_uri => {:ok, [base64_decoded]}}, hex_token_id)
+
+      _ ->
+        {:error, base64_encoded_json}
+    end
+  rescue
+    e ->
+      Logger.debug(["Unknown metadata format base64 #{inspect(base64_encoded_json)}. error #{inspect(e)}"],
+        fetcher: :token_instances
+      )
+
+      {:error, base64_encoded_json}
+  end
+
+  def fetch_json(%{@uri => {:ok, ["data:application/json;base64," <> base64_encoded_json]}}, hex_token_id) do
+    case Base.url_decode64(base64_encoded_json) do
+      {:ok, base64_decoded} ->
+        fetch_json(%{@uri => {:ok, [base64_decoded]}}, hex_token_id)
+
+      _ ->
+        {:error, base64_encoded_json}
+    end
+  rescue
+    e ->
+      Logger.debug(["Unknown metadata format base64 #{inspect(base64_encoded_json)}. error #{inspect(e)}"],
+        fetcher: :token_instances
+      )
+
+      {:error, base64_encoded_json}
+  end
+
   def fetch_json(%{@token_uri => {:ok, ["ipfs://ipfs/" <> ipfs_uid]}}, hex_token_id) do
     ipfs_url = "https://ipfs.io/ipfs/" <> ipfs_uid
     fetch_metadata_inner(ipfs_url, hex_token_id)

diff --git a/apps/explorer/test/explorer/token/instance_metadata_retriever_test.exs b/apps/explorer/test/explorer/token/instance_metadata_retriever_test.exs
@@ -286,5 +286,26 @@ defmodule Explorer.Token.InstanceMetadataRetrieverTest do
                   }
                 }}
     end
+
+    test "decodes base64 encoded json file in tokenURI" do
+      data = %{
+        "c87b56dd" =>
+          {:ok,
+           [
+             "data:application/json;base64,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"
+           ]}
+      }
+
+      assert InstanceMetadataRetriever.fetch_json(data) ==
+               {:ok,
+                %{
+                  metadata: %{
+                    "name" => ".xdai",
+                    "description" => "Punk Domains digital identity. Visit https://punk.domains/",
+                    "image" =>
+                      "data:image/svg+xml;base64,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"
+                  }
+                }}
+    end
   end
 end