feat: Celo API updates (#10629)

* fix: use atom for matching the `:chain_type`

* feat: add celo epoch number to `/api/v2/stats` response

* chore: display base fee in wei

* feat: add token info to base fee section

* fix: process review comments

apps/block_scout_web/lib/block_scout_web/controllers/api/v2/stats_controller.ex

@@ -190,12 +190,18 @@ defmodule BlockScoutWeb.API.V2.StatsController do
         end
       end
 
-    "optimism" ->
+    :optimism ->
       defp add_chain_type_fields(response) do
         import Explorer.Counters.LastOutputRootSizeCounter, only: [fetch: 1]
         response |> Map.put("last_output_root_size", fetch(@api_true))
       end
 
+    :celo ->
+      defp add_chain_type_fields(response) do
+        import Explorer.Chain.Celo.Reader, only: [last_block_epoch_number: 0]
+        response |> Map.put("celo", %{"epoch_number" => last_block_epoch_number()})
+      end
+
     _ ->
       defp add_chain_type_fields(response), do: response
   end

apps/block_scout_web/lib/block_scout_web/views/api/v2/celo_view.ex

@@ -14,7 +14,7 @@ defmodule BlockScoutWeb.API.V2.CeloView do
   alias Explorer.Chain.Celo.Helper, as: CeloHelper
   alias Explorer.Chain.Celo.{ElectionReward, EpochReward}
   alias Explorer.Chain.Hash
-  alias Explorer.Chain.{Block, Transaction}
+  alias Explorer.Chain.{Block, Token, Transaction, Wei}
 
   @address_params [
     necessity_by_association: %{
@@ -97,20 +97,26 @@ defmodule BlockScoutWeb.API.V2.CeloView do
   end
 
   def render("celo_base_fee.json", %Block{} = block) do
-    # For the blocks, where both FeeHandler and Governance contracts aren't
-    # deployed, the base fee is not burnt, but refunded to transaction sender,
-    # so we return nil in this case.
-
-    base_fee = Block.burnt_fees(block.transactions, block.base_fee_per_gas)
-
-    fee_handler_base_fee_breakdown(
-      base_fee,
-      block.number
-    ) ||
-      governance_base_fee_breakdown(
-        base_fee,
-        block.number
-      )
+    block.transactions
+    |> Block.burnt_fees(block.base_fee_per_gas)
+    |> Wei.cast()
+    |> case do
+      {:ok, base_fee} ->
+        # For the blocks, where both FeeHandler and Governance contracts aren't
+        # deployed, the base fee is not burnt, but refunded to transaction sender,
+        # so we return nil in this case.
+        fee_handler_base_fee_breakdown(
+          base_fee,
+          block.number
+        ) ||
+          governance_base_fee_breakdown(
+            base_fee,
+            block.number
+          )
+
+      _ ->
+        nil
+    end
   end
 
   def render("celo_election_rewards.json", %{
@@ -246,7 +252,7 @@ defmodule BlockScoutWeb.API.V2.CeloView do
 
   # Get the breakdown of the base fee for the case when FeeHandler is a contract
   # that receives the base fee.
-  @spec fee_handler_base_fee_breakdown(Decimal.t(), Block.block_number()) ::
+  @spec fee_handler_base_fee_breakdown(Wei.t(), Block.block_number()) ::
           %{
             :recipient => %{optional(String.t()) => any()},
             :amount => float(),
@@ -265,13 +271,14 @@ defmodule BlockScoutWeb.API.V2.CeloView do
          {:ok, %{"address" => fee_beneficiary_address_hash}} <-
            CeloCoreContracts.get_event(:fee_handler, :fee_beneficiary_set, block_number),
          {:ok, %{"value" => burn_fraction_fixidity_lib}} <-
-           CeloCoreContracts.get_event(:fee_handler, :burn_fraction_set, block_number) do
+           CeloCoreContracts.get_event(:fee_handler, :burn_fraction_set, block_number),
+         {:ok, celo_token_address_hash} <- CeloCoreContracts.get_address(:celo_token, block_number) do
       burn_fraction = burn_fraction_decimal(burn_fraction_fixidity_lib)
 
-      burnt_amount = Decimal.mult(base_fee, burn_fraction)
+      burnt_amount = Wei.mult(base_fee, burn_fraction)
       burnt_percentage = Decimal.mult(burn_fraction, 100)
 
-      carbon_offsetting_amount = Decimal.sub(base_fee, burnt_amount)
+      carbon_offsetting_amount = Wei.sub(base_fee, burnt_amount)
       carbon_offsetting_percentage = Decimal.sub(100, burnt_percentage)
 
       celo_burn_address_hash_string = dead_address_hash_string()
@@ -311,18 +318,25 @@ defmodule BlockScoutWeb.API.V2.CeloView do
           }
         )
 
+      celo_token = Token.get_by_contract_address_hash(celo_token_address_hash, api?: true)
+
       %{
         recipient: fee_handler_contract_address_info,
         amount: base_fee,
+        token:
+          TokenView.render("token.json", %{
+            token: celo_token,
+            contract_address_hash: celo_token.contract_address_hash
+          }),
         breakdown: [
           %{
             address: burn_address_info,
-            amount: Decimal.to_float(burnt_amount),
+            amount: burnt_amount,
             percentage: Decimal.to_float(burnt_percentage)
           },
           %{
             address: fee_beneficiary_address_info,
-            amount: Decimal.to_float(carbon_offsetting_amount),
+            amount: carbon_offsetting_amount,
             percentage: Decimal.to_float(carbon_offsetting_percentage)
           }
         ]
@@ -337,7 +351,7 @@ defmodule BlockScoutWeb.API.V2.CeloView do
   #
   # Note that the base fee is not burnt in this case, but simply kept on the
   # contract balance.
-  @spec governance_base_fee_breakdown(Decimal.t(), Block.block_number()) ::
+  @spec governance_base_fee_breakdown(Wei.t(), Block.block_number()) ::
           %{
             :recipient => %{optional(String.t()) => any()},
             :amount => float(),
@@ -353,7 +367,8 @@ defmodule BlockScoutWeb.API.V2.CeloView do
   defp governance_base_fee_breakdown(base_fee, block_number) do
     with {:ok, address_hash_string} when not is_nil(address_hash_string) <-
            CeloCoreContracts.get_address(:governance, block_number),
-         {:ok, address_hash} <- Chain.string_to_address_hash(address_hash_string) do
+         {:ok, address_hash} <- Chain.string_to_address_hash(address_hash_string),
+         {:ok, celo_token_address_hash} <- CeloCoreContracts.get_address(:celo_token, block_number) do
       address =
         address_hash
         # todo: Querying database in the view is not a good practice. Consider
@@ -370,9 +385,16 @@ defmodule BlockScoutWeb.API.V2.CeloView do
           address_hash
         )
 
+      celo_token = Token.get_by_contract_address_hash(celo_token_address_hash, api?: true)
+
       %{
         recipient: address_with_info,
         amount: base_fee,
+        token:
+          TokenView.render("token.json", %{
+            token: celo_token,
+            contract_address_hash: celo_token.contract_address_hash
+          }),
         breakdown: []
       }
     else

apps/explorer/lib/explorer/chain.ex

@@ -2105,11 +2105,11 @@ defmodule Explorer.Chain do
       {:error, :not_found}
 
   """
-  @spec max_consensus_block_number() :: {:ok, Block.block_number()} | {:error, :not_found}
-  def max_consensus_block_number do
+  @spec max_consensus_block_number(Keyword.t()) :: {:ok, Block.block_number()} | {:error, :not_found}
+  def max_consensus_block_number(options \\ []) do
     Block
     |> where(consensus: true)
-    |> Repo.aggregate(:max, :number)
+    |> select_repo(options).aggregate(:max, :number)
     |> case do
       nil -> {:error, :not_found}
       number -> {:ok, number}

apps/explorer/lib/explorer/chain/celo/reader.ex

@@ -9,11 +9,13 @@ defmodule Explorer.Chain.Celo.Reader do
     only: [
       select_repo: 1,
       join_associations: 2,
-      default_paging_options: 0
+      default_paging_options: 0,
+      max_consensus_block_number: 1
     ]
 
-  alias Explorer.Chain.Cache.CeloCoreContracts
-  alias Explorer.Chain.Celo.ElectionReward
+  alias Explorer.Chain.Block
+  alias Explorer.Chain.Cache.{Blocks, CeloCoreContracts}
+  alias Explorer.Chain.Celo.{ElectionReward, Helper}
   alias Explorer.Chain.{Hash, Token, Wei}
 
   @election_reward_types ElectionReward.types()
@@ -190,4 +192,24 @@ defmodule Explorer.Chain.Celo.Reader do
       {reward_type_atom, Map.get(token_atom_to_token, token_atom)}
     end)
   end
+
+  @doc """
+  Retrieves the epoch number of the last fetched block.
+  """
+  @spec last_block_epoch_number(Keyword.t()) :: Block.block_number() | nil
+  def last_block_epoch_number(options \\ []) do
+    block_number =
+      1
+      |> Blocks.atomic_take_enough()
+      |> case do
+        [%Block{number: number}] -> {:ok, number}
+        nil -> max_consensus_block_number(options)
+      end
+      |> case do
+        {:ok, number} -> number
+        _ -> nil
+      end
+
+    block_number && Helper.block_number_to_epoch_number(block_number)
+  end
 end