Add a sync_with_file mix task

Other changes:

* Changed the genesis block nonce to a raw binary instead of an integer.
I compared our implementation with the genesis block from SyncWithInfura
which had it as a raw binary.

.dialyzer.ignore-warnings

@@ -163,6 +163,10 @@ apps/blockchain/lib/blockchain/transaction.ex
 -------------------------------
 apps/blockchain/lib/blockchain/application.ex:14: The call 'Elixir.EVM.Debugger':break_on([{'address',binary()},...]) will never return since the success typing is (['address']) -> integer() and the contract is (elixir:keyword('Elixir.EVM.Debugger.Breakpoint':conditions())) -> 'Elixir.EVM.Debugger.Breakpoint':id()
 
+-------------------------------
+# apps/blockchain/lib/mix/tasks/sync/from_file.ex
+-------------------------------
+apps/blockchain/lib/mix/tasks/sync/from_file.ex
 -------------------------------
 # Ignores the whole contract and account_interface file
 -------------------------------

apps/blockchain/lib/blockchain/chain.ex

@@ -246,7 +246,7 @@ defmodule Blockchain.Chain do
 
   defp get_genesis_seal(map) do
     %{
-      nonce: map["ethereum"]["nonce"] |> load_hex(),
+      nonce: map["ethereum"]["nonce"] |> load_raw_hex(),
       mix_hash: map["ethereum"]["mixHash"] |> load_raw_hex()
     }
   end

apps/blockchain/lib/blockchain/genesis.ex

@@ -50,7 +50,7 @@ defmodule Blockchain.Genesis do
           receipts_root: <<86, 232, 31, 23, 27, 204, 85, 166, 255, 131, 69, 230, 146, 192, 248, 110, 91, 72, 224, 27, 153, 108, 173, 192, 1, 98, 47, 181, 227, 99, 180, 33>>,
           ommers_hash: <<29, 204, 77, 232, 222, 199, 93, 122, 171, 133, 181, 103, 182, 204, 212, 26, 211, 18, 69, 27, 148, 138, 116, 19, 240, 161, 66, 253, 64, 212, 147, 71>>,
           mix_hash: <<0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0>>,
-          nonce: 66
+          nonce: <<0, 0, 0, 0, 0, 0, 0, 66>>
         },
         ommers: [],
         transactions: []

apps/blockchain/lib/mix/tasks/sync/from_file.ex

@@ -0,0 +1,86 @@
+defmodule Mix.Tasks.Sync.FromFile do
+  @shortdoc "Allows users to sync the blockchain from a file exported by parity"
+  @moduledoc """
+  SyncFromFile allows users to sync the blockchain from a file exported by parity.
+
+  You can make an export with the following command:
+
+  `parity export blocks ./export-blocks-mainnet.bin`
+
+  And then run `sync_with_file` to verify the chain:
+
+  `mix run apps/blockchain/scripts/sync_from_file.ex export-blocks-mainnet.bin`
+  """
+  use Mix.Task
+  require Logger
+
+  def run(args) do
+    {db, chain} = setup()
+
+    current_block_number =
+      case MerklePatriciaTree.DB.get(db, "current_block_number") do
+        {:ok, current_block_number} ->
+          current_block_number
+
+        _ ->
+          0
+      end
+
+    tree =
+      case MerklePatriciaTree.DB.get(db, "current_block_tree") do
+        {:ok, current_block_tree} ->
+          :erlang.binary_to_term(current_block_tree)
+
+        _ ->
+          Blockchain.Blocktree.new_tree()
+      end
+
+    {first_block_data, blocks_data} =
+      args
+      |> File.read!()
+      |> ExRLP.decode()
+      |> Enum.split(3)
+
+    first_block = Blockchain.Block.deserialize(first_block_data)
+
+    blocks =
+      [Blockchain.Genesis.create_block(chain, db), first_block] ++
+        (blocks_data
+         |> Enum.map(&Blockchain.Block.deserialize/1))
+
+    add_block_to_tree(db, chain, tree, blocks, current_block_number)
+  end
+
+  def setup() do
+    db = MerklePatriciaTree.DB.RocksDB.init(db_name())
+    chain = Blockchain.Chain.load_chain(:foundation)
+
+    {db, chain}
+  end
+
+  def add_block_to_tree(db, chain, tree, blocks, n) do
+    next_block = Enum.at(blocks, n)
+
+    if is_nil(next_block) do
+      Logger.info("Validation complete")
+      MerklePatriciaTree.DB.put!(db, "current_block_number", 0)
+    else
+      case Blockchain.Blocktree.verify_and_add_block(tree, chain, next_block, db) do
+        {:ok, next_tree} ->
+          Logger.info("Verified Block #{n}")
+          MerklePatriciaTree.DB.put!(db, "current_block_number", next_block.header.number)
+          add_block_to_tree(db, chain, next_tree, blocks, n + 1)
+
+        {:invalid, error} ->
+          Logger.info("Failed to Verify Block #{n}")
+          Logger.error(inspect(error))
+          MerklePatriciaTree.DB.put!(db, "current_block_tree", :erlang.term_to_binary(tree))
+      end
+    end
+  end
+
+  defp db_name() do
+    env = Mix.env() |> to_string()
+    "db/mana-" <> env
+  end
+end