feat: gas prices with base fee if no transactions (#11132)

* feat: gas prices with base fee if no transactions

* Replace wildcard with exact error

Co-authored-by: Victor Baranov <baranov.viktor.27@gmail.com>

---------

Co-authored-by: Victor Baranov <baranov.viktor.27@gmail.com>

apps/explorer/lib/explorer/chain/cache/gas_price_oracle.ex

@@ -92,11 +92,7 @@ defmodule Explorer.Chain.Cache.GasPriceOracle do
 
     from_block_query = max(from_block_acc, from_block_actual)
 
-    average_block_time =
-      case AverageBlockTime.average_block_time() do
-        {:error, _} -> nil
-        average_block_time -> average_block_time |> Duration.to_milliseconds()
-      end
+    average_block_time = get_average_block_time()
 
     fee_query =
       from(
@@ -186,11 +182,26 @@ defmodule Explorer.Chain.Cache.GasPriceOracle do
   defp merge_gas_prices(new, acc, from_block), do: Enum.take_while(new ++ acc, &(&1.block_number > from_block))
 
   defp process_fee_data_from_db([]) do
-    %{
-      slow: nil,
-      average: nil,
-      fast: nil
-    }
+    case Block.next_block_base_fee_per_gas() do
+      %Decimal{} = base_fee ->
+        base_fee_wei = base_fee |> Wei.from(:wei)
+        exchange_rate = Market.get_coin_exchange_rate()
+
+        average_block_time = get_average_block_time()
+
+        %{
+          slow: compose_gas_price(base_fee_wei, average_block_time, exchange_rate, base_fee_wei, 0),
+          average: compose_gas_price(base_fee_wei, average_block_time, exchange_rate, base_fee_wei, 0),
+          fast: compose_gas_price(base_fee_wei, average_block_time, exchange_rate, base_fee_wei, 0)
+        }
+
+      _ ->
+        %{
+          slow: nil,
+          average: nil,
+          fast: nil
+        }
+    end
   end
 
   defp process_fee_data_from_db(fees) do
@@ -223,13 +234,12 @@ defmodule Explorer.Chain.Cache.GasPriceOracle do
           {gas_price(slow_gas_price), gas_price(average_gas_price), gas_price(fast_gas_price), nil}
       end
 
-    exchange_rate_from_db = Market.get_coin_exchange_rate()
+    exchange_rate = Market.get_coin_exchange_rate()
 
     %{
-      slow: compose_gas_price(slow_fee, slow_time, exchange_rate_from_db, base_fee_wei, slow_priority_fee_per_gas),
-      average:
-        compose_gas_price(average_fee, average_time, exchange_rate_from_db, base_fee_wei, average_priority_fee_per_gas),
-      fast: compose_gas_price(fast_fee, fast_time, exchange_rate_from_db, base_fee_wei, fast_priority_fee_per_gas)
+      slow: compose_gas_price(slow_fee, slow_time, exchange_rate, base_fee_wei, slow_priority_fee_per_gas),
+      average: compose_gas_price(average_fee, average_time, exchange_rate, base_fee_wei, average_priority_fee_per_gas),
+      fast: compose_gas_price(fast_fee, fast_time, exchange_rate, base_fee_wei, fast_priority_fee_per_gas)
     }
   end
 
@@ -251,15 +261,27 @@ defmodule Explorer.Chain.Cache.GasPriceOracle do
       {key, value} ->
         value = if is_list(value), do: value, else: [value]
         count = Enum.count(value)
-        {key, value |> Enum.reduce(Decimal.new(0), &Decimal.add/2) |> Decimal.div(count)}
+
+        value =
+          value
+          |> Enum.reduce(Decimal.new(0), fn
+            fee, sum when is_float(fee) ->
+              fee |> Decimal.from_float() |> Decimal.add(sum)
+
+            fee, sum ->
+              Decimal.add(sum, fee)
+          end)
+          |> Decimal.div(count)
+
+        {key, value}
     end)
   end
 
-  defp compose_gas_price(fee, time, exchange_rate_from_db, base_fee, priority_fee) do
+  defp compose_gas_price(fee, time, exchange_rate, base_fee, priority_fee) do
     %{
       price: fee |> format_wei(),
       time: time && time |> Decimal.to_float(),
-      fiat_price: fiat_fee(fee, exchange_rate_from_db),
+      fiat_price: fiat_fee(fee, exchange_rate),
       base_fee: base_fee |> format_wei(),
       priority_fee: base_fee && priority_fee && priority_fee |> Decimal.new() |> Wei.from(:wei) |> format_wei(),
       priority_fee_wei: base_fee && priority_fee && priority_fee |> Decimal.new() |> Decimal.round(),
@@ -358,4 +380,11 @@ defmodule Explorer.Chain.Cache.GasPriceOracle do
   end
 
   defp async_task_on_deletion(_data), do: nil
+
+  defp get_average_block_time do
+    case AverageBlockTime.average_block_time() do
+      {:error, :disabled} -> nil
+      average_block_time -> average_block_time |> Duration.to_milliseconds()
+    end
+  end
 end

apps/explorer/test/explorer/chain/cache/gas_price_oracle_test.exs

@@ -90,6 +90,53 @@ defmodule Explorer.Chain.Cache.GasPriceOracleTest do
                }}, []} = GasPriceOracle.get_average_gas_price(2, 35, 60, 90)
     end
 
+    test "returns base fee only gas estimation if there is no recent transactions with non-zero gas price" do
+      block1 =
+        insert(:block,
+          number: 100,
+          hash: "0x3e51328bccedee581e8ba35190216a61a5d67fd91ca528f3553142c0c7d18391",
+          base_fee_per_gas: 100
+        )
+
+      block2 =
+        insert(:block,
+          number: 101,
+          hash: "0x76c3da57334fffdc66c0d954dce1a910fcff13ec889a13b2d8b0b6e9440ce729",
+          base_fee_per_gas: 100
+        )
+
+      :transaction
+      |> insert(
+        status: :ok,
+        block_hash: block1.hash,
+        block_number: block1.number,
+        cumulative_gas_used: 884_322,
+        gas_used: 106_025,
+        index: 0,
+        gas_price: 0,
+        hash: "0xac2a7dab94d965893199e7ee01649e2d66f0787a4c558b3118c09e80d4df8269"
+      )
+
+      :transaction
+      |> insert(
+        status: :ok,
+        block_hash: block2.hash,
+        block_number: block2.number,
+        cumulative_gas_used: 884_322,
+        gas_used: 106_025,
+        index: 0,
+        gas_price: 0,
+        hash: "0x5d5c2776f96704e7845f7d3c1fbba6685ab6efd6f82b6cd11d549f3b3a46bd03"
+      )
+
+      assert {{:ok,
+               %{
+                 average: %{base_fee: 0.01, priority_fee: +0.0, price: 0.01},
+                 fast: %{base_fee: 0.01, priority_fee: +0.0, price: 0.01},
+                 slow: %{base_fee: 0.01, priority_fee: +0.0, price: 0.01}
+               }}, []} = GasPriceOracle.get_average_gas_price(2, 35, 60, 90)
+    end
+
     test "returns the same percentile values if gas price is the same over transactions" do
       block1 = insert(:block, number: 100, hash: "0x3e51328bccedee581e8ba35190216a61a5d67fd91ca528f3553142c0c7d18391")
       block2 = insert(:block, number: 101, hash: "0x76c3da57334fffdc66c0d954dce1a910fcff13ec889a13b2d8b0b6e9440ce729")