feat: introduce now transaction hash range scoping

[sborrazas]

refs #2075

[jyeshe]

Hi @sborrazas I was looking for the find_tx_location to catch up with the code again and came across with the fetch/3. It seems a good opportunity of reuse.

[sborrazas]

Not sure what you mean here, you mean fetching the full tx with the rendering by calling fetch/3?

[jyeshe]

Looking at the difference to the fetch/3, it would be only on the line of the {:ok, txt} return.

def fetch(state, tx_hash, opts) when is_binary(tx_hash) do
    encoded_tx_hash = :aeser_api_encoder.encode(:tx_hash, tx_hash)

    with mb_hash when is_binary(mb_hash) <- :aec_db.find_tx_location(tx_hash),
         {:ok, mb_height} <- Db.find_block_height(mb_hash) do
      state
      |> Blocks.fetch_txis_from_gen(mb_height)
      |> Stream.map(&State.fetch!(state, @table, &1))
      |> Enum.find_value(
        {:error, ErrInput.NotFound.exception(value: encoded_tx_hash)},
        fn
          Model.tx(id: ^tx_hash) = tx -> {:ok, render(state, tx, opts)}
          _tx -> nil
        end
      )
    else
      _no_block_or_header ->
        {:error, ErrInput.NotFound.exception(value: encoded_tx_hash)}
    end
  end

There would be multiple ways to refactor to reuse most of it in a way that only the rendering varies. Maybe a good reason to decouple the rendering from the fetching or would consider just rendering in another way as well.

[sborrazas]

Good call, I extracted it into the function that returns {:ok, Model.tx()} so it can be reused in both places

[jyeshe]

Brilliant!

[jyeshe]

an alternative suggest would be to pattern match with [_hash1, _hash2] = tx_hashes, similar, just another flavour

[sborrazas]

I can't pattern-match on this since it's valid for it to be a single element array too

[jyeshe]

I mean this format [_hash1 | _hash2] = tx_hashes for a more compact condition but it's fine the lengthy one (:

[jyeshe]

nvm, it would be lengthier checking the rest of the list

[jyeshe]

🔆

[jyeshe]

since this is the match for first = last, maybe instead of calling first and last just call it smth like gen?
It made me thinking about it after looking at the

      {:ok, :forward, {scope_type, last..first}}

while above we have

    {:ok, :forward, {scope_type, first..last}}

[sborrazas]

It's not always a gen, it can be txis and I think time too