From 8027f19e82942ec08994e798e18431865733cedd Mon Sep 17 00:00:00 2001
From: Victor Baranov <baranov.viktor.27@gmail.com>
Date: Tue, 1 Sep 2020 12:48:11 +0300
Subject: [PATCH] Update token metadata at token transfer parsing

---
 CHANGELOG.md                                  |  1 +
 apps/explorer/lib/explorer/chain/address.ex   | 11 ++++++
 .../lib/explorer/chain/bridged_token.ex       |  8 +++++
 apps/explorer/lib/explorer/chain/token.ex     |  8 +++++
 .../lib/explorer/chain/transaction.ex         | 19 +++++++++++
 .../lib/indexer/transform/token_transfers.ex  | 34 ++++++++++++++++++-
 6 files changed, 80 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index e009ab9332..a600364ffe 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 ## Current
 
 ### Features
+- [#3273](https://github.com/poanetwork/blockscout/pull/3273) - Update token metadata at burn/mint events
 - [#3268](https://github.com/poanetwork/blockscout/pull/3268) - Token total supply on-demand fetcher
 - [#3261](https://github.com/poanetwork/blockscout/pull/3261) - Bridged tokens table
 
diff --git a/apps/explorer/lib/explorer/chain/address.ex b/apps/explorer/lib/explorer/chain/address.ex
index 1b167fbc78..0bf19330ac 100644
--- a/apps/explorer/lib/explorer/chain/address.ex
+++ b/apps/explorer/lib/explorer/chain/address.ex
@@ -71,6 +71,17 @@ defmodule Explorer.Chain.Address do
              :names
            ]}
 
+  @derive {Jason.Encoder,
+           except: [
+             :__meta__,
+             :smart_contract,
+             :decompiled_smart_contracts,
+             :token,
+             :contracts_creation_internal_transaction,
+             :contracts_creation_transaction,
+             :names
+           ]}
+
   @primary_key {:hash, Hash.Address, autogenerate: false}
   schema "addresses" do
     field(:fetched_coin_balance, Wei)
diff --git a/apps/explorer/lib/explorer/chain/bridged_token.ex b/apps/explorer/lib/explorer/chain/bridged_token.ex
index 15d13f4018..7399d46b21 100644
--- a/apps/explorer/lib/explorer/chain/bridged_token.ex
+++ b/apps/explorer/lib/explorer/chain/bridged_token.ex
@@ -31,6 +31,14 @@ defmodule Explorer.Chain.BridgedToken do
              :updated_at
            ]}
 
+  @derive {Jason.Encoder,
+           except: [
+             :__meta__,
+             :home_token_contract_address,
+             :inserted_at,
+             :updated_at
+           ]}
+
   @primary_key false
   schema "bridged_tokens" do
     field(:foreign_chain_id, :decimal)
diff --git a/apps/explorer/lib/explorer/chain/token.ex b/apps/explorer/lib/explorer/chain/token.ex
index e2b0c3fe62..e48ab5443b 100644
--- a/apps/explorer/lib/explorer/chain/token.ex
+++ b/apps/explorer/lib/explorer/chain/token.ex
@@ -57,6 +57,14 @@ defmodule Explorer.Chain.Token do
              :updated_at
            ]}
 
+  @derive {Jason.Encoder,
+           except: [
+             :__meta__,
+             :contract_address,
+             :inserted_at,
+             :updated_at
+           ]}
+
   @primary_key false
   schema "tokens" do
     field(:name, :string)
diff --git a/apps/explorer/lib/explorer/chain/transaction.ex b/apps/explorer/lib/explorer/chain/transaction.ex
index e4518c7349..607ad85e4c 100644
--- a/apps/explorer/lib/explorer/chain/transaction.ex
+++ b/apps/explorer/lib/explorer/chain/transaction.ex
@@ -185,6 +185,25 @@ defmodule Explorer.Chain.Transaction do
              :value
            ]}
 
+  @derive {Jason.Encoder,
+           only: [
+             :block_number,
+             :cumulative_gas_used,
+             :error,
+             :gas,
+             :gas_price,
+             :gas_used,
+             :index,
+             :created_contract_code_indexed_at,
+             :input,
+             :nonce,
+             :r,
+             :s,
+             :v,
+             :status,
+             :value
+           ]}
+
   @primary_key {:hash, Hash.Full, autogenerate: false}
   schema "transactions" do
     field(:block_number, :integer)
diff --git a/apps/indexer/lib/indexer/transform/token_transfers.ex b/apps/indexer/lib/indexer/transform/token_transfers.ex
index 303efa059e..33ca2e0136 100644
--- a/apps/indexer/lib/indexer/transform/token_transfers.ex
+++ b/apps/indexer/lib/indexer/transform/token_transfers.ex
@@ -6,7 +6,11 @@ defmodule Indexer.Transform.TokenTransfers do
   require Logger
 
   alias ABI.TypeDecoder
-  alias Explorer.Chain.TokenTransfer
+  alias Explorer.{Chain, Repo}
+  alias Explorer.Chain.{Token, TokenTransfer}
+  alias Explorer.Token.MetadataRetriever
+
+  @burn_address "0x0000000000000000000000000000000000000000"
 
   @doc """
   Returns a list of token transfers given a list of logs.
@@ -54,6 +58,8 @@ defmodule Indexer.Transform.TokenTransfers do
       type: "ERC-20"
     }
 
+    update_token(log.address_hash, token_transfer)
+
     {token, token_transfer}
   end
 
@@ -79,6 +85,8 @@ defmodule Indexer.Transform.TokenTransfers do
       type: "ERC-721"
     }
 
+    update_token(log.address_hash, token_transfer)
+
     {token, token_transfer}
   end
 
@@ -104,9 +112,33 @@ defmodule Indexer.Transform.TokenTransfers do
       type: "ERC-721"
     }
 
+    update_token(log.address_hash, token_transfer)
+
     {token, token_transfer}
   end
 
+  defp update_token(address_hash_string, token_transfer) do
+    if token_transfer.to_address_hash == @burn_address || token_transfer.from_address_hash == @burn_address do
+      {:ok, address_hash} = Chain.string_to_address_hash(address_hash_string)
+
+      token_params =
+        address_hash_string
+        |> MetadataRetriever.get_functions_of()
+
+      token = Repo.get_by(Token, contract_address_hash: address_hash)
+
+      if token do
+        token_to_update =
+          token
+          |> Repo.preload([:contract_address])
+
+        {:ok, _} = Chain.update_token(%{token_to_update | updated_at: DateTime.utc_now()}, token_params)
+      end
+    end
+
+    :ok
+  end
+
   defp truncate_address_hash(nil), do: "0x0000000000000000000000000000000000000000"
 
   defp truncate_address_hash("0x000000000000000000000000" <> truncated_hash) do