From 3a6751c3cce2f4d9beff82a9f10dcc27b682d000 Mon Sep 17 00:00:00 2001
From: Gustavo Santos Ferreira <gustavosantosfe@gmail.com>
Date: Fri, 21 Dec 2018 11:39:24 -0200
Subject: [PATCH] importer module to import batches of block rewards

---
 .../block/uncataloged_rewards/importer.ex     | 112 ++++++++++++++++++
 .../uncataloged_rewards/importer_test.exs     |  64 ++++++++++
 2 files changed, 176 insertions(+)
 create mode 100644 apps/indexer/lib/indexer/block/uncataloged_rewards/importer.ex
 create mode 100644 apps/indexer/test/indexer/block/uncataloged_rewards/importer_test.exs

diff --git a/apps/indexer/lib/indexer/block/uncataloged_rewards/importer.ex b/apps/indexer/lib/indexer/block/uncataloged_rewards/importer.ex
new file mode 100644
index 0000000000..8c544f2837
--- /dev/null
+++ b/apps/indexer/lib/indexer/block/uncataloged_rewards/importer.ex
@@ -0,0 +1,112 @@
+defmodule Indexer.Block.UncatalogedRewards.Importer do
+  @moduledoc """
+  a module to fetch and import the rewards for blocks that were indexed without the reward
+  """
+
+  alias Ecto.Multi
+  alias EthereumJSONRPC.FetchedBeneficiaries
+  alias Explorer.Chain
+  alias Explorer.Chain.{Block.Reward, Wei}
+
+  # max number of blocks in a single request
+  # higher numbers may cause the requests to time out
+  # lower numbers will generate more requests
+  @chunk_size 10
+
+  @doc """
+  receives a list of blocks and tries to fetch and insert rewards for them
+  """
+  def fetch_and_import_rewards(blocks_batch) do
+    result =
+      blocks_batch
+      |> break_into_chunks_of_block_numbers()
+      |> Enum.reduce([], fn chunk, acc ->
+        chunk
+        |> fetch_beneficiaries()
+        |> fetch_block_rewards()
+        |> insert_reward_group()
+        |> case do
+          :empty -> acc
+          insert -> [insert | acc]
+        end
+      end)
+
+    {:ok, result}
+  rescue
+    e in RuntimeError -> {:error, %{exception: e}}
+  end
+
+  defp fetch_beneficiaries(chunk) do
+    {chunk_start, chunk_end} = Enum.min_max(chunk)
+
+    {:ok, %FetchedBeneficiaries{params_set: result}} =
+      with :ignore <- EthereumJSONRPC.fetch_beneficiaries(chunk_start..chunk_end, json_rpc_named_arguments()) do
+        {:ok, %FetchedBeneficiaries{params_set: MapSet.new()}}
+      end
+
+    result
+  end
+
+  defp fetch_block_rewards(beneficiaries) do
+    Enum.map(beneficiaries, fn beneficiary ->
+      beneficiary_changes =
+        case beneficiary.address_type do
+          :validator ->
+            validation_reward = fetch_validation_reward(beneficiary)
+
+            {:ok, reward} = Wei.cast(beneficiary.reward)
+
+            %{beneficiary | reward: Wei.sum(reward, validation_reward)}
+
+          _ ->
+            beneficiary
+        end
+
+      Reward.changeset(%Reward{}, beneficiary_changes)
+    end)
+  end
+
+  defp fetch_validation_reward(beneficiary) do
+    {:ok, accumulator} = Wei.cast(0)
+
+    beneficiary.block_number
+    |> Chain.get_transactions_of_block_number()
+    |> Enum.reduce(accumulator, fn t, acc ->
+      {:ok, price_as_wei} = Wei.cast(t.gas_used)
+      price_as_wei |> Wei.mult(t.gas_price) |> Wei.sum(acc)
+    end)
+  end
+
+  defp break_into_chunks_of_block_numbers(blocks) do
+    Enum.chunk_while(
+      blocks,
+      [],
+      fn block, acc ->
+        if (acc == [] || hd(acc) + 1 == block.number) && length(acc) < @chunk_size do
+          {:cont, [block.number | acc]}
+        else
+          {:cont, acc, [block.number]}
+        end
+      end,
+      fn
+        [] -> {:cont, []}
+        acc -> {:cont, acc, []}
+      end
+    )
+  end
+
+  defp insert_reward_group([]), do: :empty
+
+  defp insert_reward_group(rewards) do
+    rewards
+    |> Enum.reduce({Multi.new(), 0}, fn changeset, {multi, index} ->
+      {Multi.insert(multi, "insert_#{index}", changeset), index + 1}
+    end)
+    |> elem(0)
+    |> Explorer.Repo.transaction()
+  end
+
+  defp json_rpc_named_arguments do
+    Application.get_env(:explorer, :json_rpc_named_arguments)
+  end
+end
diff --git a/apps/indexer/test/indexer/block/uncataloged_rewards/importer_test.exs b/apps/indexer/test/indexer/block/uncataloged_rewards/importer_test.exs
new file mode 100644
index 0000000000..1422f7f70d
--- /dev/null
+++ b/apps/indexer/test/indexer/block/uncataloged_rewards/importer_test.exs
@@ -0,0 +1,64 @@
+defmodule Indexer.Block.UncatalogedRewards.ImporterTest do
+  use EthereumJSONRPC.Case, async: false
+  use Explorer.DataCase
+
+  import Mox
+  import EthereumJSONRPC, only: [integer_to_quantity: 1]
+  import EthereumJSONRPC.Case
+
+  alias Explorer.Chain
+  alias Indexer.Block.UncatalogedRewards.Importer
+
+  describe "fetch_and_import_rewards/1" do
+    test "return `{:ok, []}` when receiving an empty list" do
+      assert Importer.fetch_and_import_rewards([]) == {:ok, []}
+    end
+
+    @tag :no_geth
+    test "return `{:ok, [transactions executed]}`" do
+      address = insert(:address)
+      block = insert(:block, number: 1234, miner: address)
+
+      expect(EthereumJSONRPC.Mox, :json_rpc, fn [%{id: id, method: "trace_block", params: _params}], _options ->
+        {:ok,
+         [
+           %{
+             id: id,
+             result: [
+               %{
+                 "action" => %{
+                   "author" => to_string(address.hash),
+                   "rewardType" => "external",
+                   "value" => "0xde0b6b3a7640000"
+                 },
+                 "blockHash" => to_string(block.hash),
+                 "blockNumber" => 1234,
+                 "result" => nil,
+                 "subtraces" => 0,
+                 "traceAddress" => [],
+                 "transactionHash" => nil,
+                 "transactionPosition" => nil,
+                 "type" => "reward"
+               }
+             ]
+           }
+         ]}
+      end)
+
+      expected =
+        {:ok,
+         [
+           ok: %{
+             "insert_0" => %Explorer.Chain.Block.Reward{
+               address_hash: address.hash,
+               block_hash: block.hash,
+               address_type: :validator
+             }
+           }
+         ]}
+
+      result = Importer.fetch_and_import_rewards([block])
+      assert result = expected
+    end
+  end
+end