Pin encoding into aeser

src/aeser_hc.erl

@@ -0,0 +1,65 @@
+%%%-----------------------------------------------------------------------------
+%%% @copyright (C) 2024, Aeternity Anstalt
+%%% @doc
+%%% Module for various Hypoerchain-related encoding tasks
+%%% @end
+%%%-----------------------------------------------------------------------------
+
+-module(aeser_hc).
+
+-export([encode_parent_pin_payload/1,
+         decode_parent_pin_payload/1,
+         encode_child_pin_payload/1,
+         decode_child_pin_payload/1]).
+
+%%%=============================================================================
+%%% Global Definitions
+%%%=============================================================================
+
+%%%=============================================================================
+%%% Pinning
+%%%=============================================================================
+
+%%=============================================================================
+%% Encode an Epoch info map to a <80 bytes binary to use in payload when pinning
+%% Hyperchain state to the parent chain
+%% =============================================================================
+-spec encode_parent_pin_payload(#{epoch => integer(), height => integer(), block_hash => binary()}) -> binary().
+encode_parent_pin_payload(#{epoch := Epoch, height := Height, block_hash := BlockHash}) ->
+    EpochHex = list_to_binary(erlang:integer_to_list(Epoch, 16)),
+    HeightHex = list_to_binary(erlang:integer_to_list(Height, 16)),
+    EncBlockHash = aeser_api_encoder:encode(key_block_hash, BlockHash),
+    <<EpochHex/binary, ":", HeightHex/binary, " ", EncBlockHash/binary>>.
+
+%%=============================================================================
+%% Decode a bionary payload to an Epoch info map when fetching pinning info
+%% from the parent chain
+%% =============================================================================
+-spec decode_parent_pin_payload(binary()) ->
+    {ok, #{epoch => integer(), height => integer(), block_hash => term()}} | {error, term()}.
+decode_parent_pin_payload(Binary) ->
+    try
+        [HexEpoch, HexHeight, EncBlockHash] = binary:split(Binary, [<<":">>, <<" ">>], [global]),
+        Epoch = erlang:list_to_integer(binary_to_list(HexEpoch), 16),
+        Height = erlang:list_to_integer(binary_to_list(HexHeight), 16),
+        {ok, BlockHash} = aeser_api_encoder:safe_decode(key_block_hash, EncBlockHash),
+        {ok, #{epoch => Epoch, height => Height, block_hash => BlockHash}}
+    catch
+        _ -> {error, {bad_parent_pin_payload, Binary}}
+    end.
+
+%%=============================================================================
+%% Encode the transaction hash returned when pinning to the parent chain to be
+%% easily findable when notarized (in a spend tx to the leader of the last
+%% epoch block) to the hyper chain.
+%%=============================================================================
+encode_child_pin_payload(TxHash) ->
+    <<"pin", TxHash/binary>>.
+
+%%=============================================================================
+%% Decode a pinning transacation notarization payload
+%% =============================================================================
+decode_child_pin_payload(<<"pin", TxHash/binary>>) ->
+    {ok, TxHash};
+decode_child_pin_payload(BadTxHash) ->
+    {error, {bad_child_pin_payload, BadTxHash}}.