Render token transfers info according to the token's type

apps/explorer_web/lib/explorer_web.ex

@@ -41,7 +41,14 @@ defmodule ExplorerWeb do
       # Use all HTML functionality (forms, tags, etc)
       use Phoenix.HTML
 
-      import ExplorerWeb.{CurrencyHelpers, ErrorHelpers, Gettext, Router.Helpers, WeiHelpers}
+      import ExplorerWeb.{
+        CurrencyHelpers,
+        ErrorHelpers,
+        Gettext,
+        Router.Helpers,
+        TokenHelpers,
+        WeiHelpers
+      }
     end
   end
 

apps/explorer_web/lib/explorer_web/templates/address_transaction/_transaction.html.eex

@@ -77,7 +77,7 @@
           </span>
         </span>
         <span class="tile-title">
-          <%= format_according_to_decimals(token_transfer.amount, token_transfer.token.decimals) %> <%= token_transfer.token.symbol %>
+          <%= token_transfer_amount(token_transfer) %> <%= token_symbol(token_transfer.token) %>
         </span>
       </div>
       <div class="col-md-3 col-lg-2 d-flex flex-row flex-md-column align-items-end">

apps/explorer_web/lib/explorer_web/views/token_helpers.ex

@@ -0,0 +1,60 @@
+defmodule ExplorerWeb.TokenHelpers do
+  @moduledoc """
+  Helper functions for intereacting with `t:ExplorerWeb.Chain.Token` attributes.
+  """
+
+  alias Explorer.Chain.{Token, TokenTransfer}
+  alias ExplorerWeb.{CurrencyHelpers}
+
+  @doc """
+  Returns the token transfers' amount according to the token's type and decimails.
+
+  When the token's type is ERC-20, then we are going to format the amount according to the token's
+  decimals considering 0 when the decimals is nil. Case the amount is nil, this function will
+  return the symbol `--`.
+
+  When the token's type is ERC-721, the function will return a string with the token_id that
+  represents the ERC-721 token since this kind of token doesn't have amount and decimals.
+  """
+  def token_transfer_amount(%TokenTransfer{token: token, amount: amount, token_id: token_id}) do
+    do_token_transfer_amount(token, amount, token_id)
+  end
+
+  defp do_token_transfer_amount(%Token{type: "ERC-20"}, nil, _token_id) do
+    "--"
+  end
+
+  defp do_token_transfer_amount(%Token{type: "ERC-20", decimals: nil}, amount, _token_id) do
+    CurrencyHelpers.format_according_to_decimals(amount, 0)
+  end
+
+  defp do_token_transfer_amount(%Token{type: "ERC-20", decimals: decimals}, amount, _token_id) do
+    CurrencyHelpers.format_according_to_decimals(amount, decimals)
+  end
+
+  defp do_token_transfer_amount(%Token{type: "ERC-721"}, _amount, token_id) do
+    "TokenID [#{token_id}]"
+  end
+
+  defp do_token_transfer_amount(_token, _amount, _token_id) do
+    nil
+  end
+
+  @doc """
+  Returns the token's symbol.
+
+  When the token's symbol is nil, the function will return the contract address hash.
+  """
+  def token_symbol(%Token{symbol: nil, contract_address_hash: address_hash}) do
+    address_hash =
+      address_hash
+      |> to_string()
+      |> String.slice(0..6)
+
+    "#{address_hash}..."
+  end
+
+  def token_symbol(%Token{symbol: symbol}) do
+    symbol
+  end
+end

apps/explorer_web/test/explorer_web/views/address_transaction_view_test.exs

@@ -1,5 +0,0 @@
-defmodule ExplorerWeb.AddresstransactionViewTest do
-  use ExplorerWeb.ConnCase, async: true
-
-  doctest ExplorerWeb.AddressTransactionView
-end

apps/explorer_web/test/explorer_web/views/token_helpers_test.exs

@@ -0,0 +1,62 @@
+defmodule ExplorerWeb.TokenHelpersTest do
+  use ExplorerWeb.ConnCase, async: true
+
+  alias ExplorerWeb.{TokenHelpers}
+
+  describe "token_transfer_amount/1" do
+    test "returns the symbol -- with ERC-20 token and amount nil" do
+      token = build(:token, type: "ERC-20")
+      token_transfer = build(:token_transfer, token: token, amount: nil)
+
+      assert TokenHelpers.token_transfer_amount(token_transfer) == "--"
+    end
+
+    test "returns the formatted amount according to token decimals with ERC-20 token" do
+      token = build(:token, type: "ERC-20", decimals: 6)
+      token_transfer = build(:token_transfer, token: token, amount: Decimal.new(1_000_000))
+
+      assert TokenHelpers.token_transfer_amount(token_transfer) == "1"
+    end
+
+    test "returns the formatted amount when the decimals is nil with ERC-20 token" do
+      token = build(:token, type: "ERC-20", decimals: nil)
+      token_transfer = build(:token_transfer, token: token, amount: Decimal.new(1_000_000))
+
+      assert TokenHelpers.token_transfer_amount(token_transfer) == "1,000,000"
+    end
+
+    test "returns a string with the token_id with ERC-721 token" do
+      token = build(:token, type: "ERC-721", decimals: nil)
+      token_transfer = build(:token_transfer, token: token, amount: nil, token_id: 1)
+
+      assert TokenHelpers.token_transfer_amount(token_transfer) == "TokenID [1]"
+    end
+
+    test "returns nothing for unknow token's type" do
+      token = build(:token, type: "unknow")
+      token_transfer = build(:token_transfer, token: token)
+
+      assert TokenHelpers.token_transfer_amount(token_transfer) == nil
+    end
+  end
+
+  describe "token_symbol/1" do
+    test "returns the token symbol" do
+      token = build(:token, symbol: "BAT")
+
+      assert TokenHelpers.token_symbol(token) == "BAT"
+    end
+
+    test "returns the token contract address hash when the symbol is nil" do
+      address = build(:address)
+      token = build(:token, symbol: nil, contract_address_hash: address.hash)
+
+      address_hash =
+        address.hash
+        |> Explorer.Chain.Hash.to_string()
+        |> String.slice(0..6)
+
+      assert TokenHelpers.token_symbol(token) == "#{address_hash}..."
+    end
+  end
+end