Improve GetFirstPublicKey message

[ghost]

GetFirstPublicKey implementation is not clear about the behavior expected and how it's used.
Actually it should load the first public key, but finally its implementation:

archethic-node/lib/archethic/p2p/message.ex

Lines 1229 to 1237 in 819b8af

	def process(%GetFirstPublicKey{address: address}) do
	case TransactionChain.get_first_transaction(address, [:previous_public_key]) do
	{:ok, %Transaction{previous_public_key: key}} ->
	%FirstPublicKey{public_key: key}
	{:error, :transaction_not_exists} ->
	%NotFound{}
	end
	end

We are returning the first transaction public key or not found, but I think you should leverage more:

archethic-node/lib/archethic/transaction_chain.ex

Lines 70 to 74 in 819b8af

	@doc """
	Get the first public key from one the public key of the chain
	"""
	@spec get_first_public_key(Crypto.key()) :: Crypto.key()
	defdelegate get_first_public_key(previous_public_key), to: DB, as: :get_first_public_key

So we would not have not found return, but the just public key passed in case there are not previous public key.

As we are messing with first transaction and first public key concept.
Moreover, we are fetching the transaction data and fields, which will cause more I/O than just fetching the first public key from the indexing.

---

Related to #268

[internet-zero]

Hey team! Please add your planning poker estimate with ZenHub @blackode @imnik11 @roychowdhuryrohit-dev @samuel-uniris

[internet-zero]

Please add your planning poker estimate with ZenHub @apoorv-2204

[prix-uniris]

@samuel-uniris, @blackode
So, should i use only the Indexer to fetch details as per new db impl.

archethic-node/lib/archethic/db/embedded_impl/chain_index.ex

Lines 486 to 513 in b4e7d2c

	@spec get_first_public_key(Crypto.key(), String.t()) :: Crypto.key()
	def get_first_public_key(public_key, db_path) do
	# We derive the previous address from the public key to get the genesis address
	# and its relative file
	address = Crypto.derive_address(public_key)
	genesis_address = get_first_chain_address(address, db_path)
	filepath = chain_keys_path(db_path, genesis_address)
	case File.open(filepath, [:binary, :read]) do
	{:ok, fd} ->
	# We need to extract key metadata information to know how many bytes to decode
	# as keys can have different sizes based on the curve used
	with {:ok, <<_timestamp::32, curve_id::8, origin_id::8>>} <- :file.read(fd, 6),
	key_size <- Crypto.key_size(curve_id),
	{:ok, key} <- :file.read(fd, key_size) do
	# We then take the first public key registered
	:file.close(fd)
	<<curve_id::8, origin_id::8, key::binary>>
	else
	:eof ->
	:file.close(fd)
	public_key
	end
	{:error, _} ->
	public_key
	end
	end

Using this function

[ghost]

@samuel-uniris So, should i use only the Indexer to fetch details as per new db impl.

archethic-node/lib/archethic/db/embedded_impl/chain_index.ex

Lines 486 to 513 in b4e7d2c

	@spec get_first_public_key(Crypto.key(), String.t()) :: Crypto.key()
	def get_first_public_key(public_key, db_path) do
	# We derive the previous address from the public key to get the genesis address
	# and its relative file
	address = Crypto.derive_address(public_key)
	genesis_address = get_first_chain_address(address, db_path)
	filepath = chain_keys_path(db_path, genesis_address)
	case File.open(filepath, [:binary, :read]) do
	{:ok, fd} ->
	# We need to extract key metadata information to know how many bytes to decode
	# as keys can have different sizes based on the curve used
	with {:ok, <<_timestamp::32, curve_id::8, origin_id::8>>} <- :file.read(fd, 6),
	key_size <- Crypto.key_size(curve_id),
	{:ok, key} <- :file.read(fd, key_size) do
	# We then take the first public key registered
	:file.close(fd)
	<<curve_id::8, origin_id::8, key::binary>>
	else
	:eof ->
	:file.close(fd)
	public_key
	end
	{:error, _} ->
	public_key
	end
	end

Using this function

I guess you can use EmbeddedImpl.get_first_public_key​(​public_key​)​

[prix-uniris]

So Instead of using TransactionChain.get_first_transaction Here:

archethic-node/lib/archethic/p2p/message.ex

Lines 1229 to 1237 in 819b8af

	def process(%GetFirstPublicKey{address: address}) do
	case TransactionChain.get_first_transaction(address, [:previous_public_key]) do
	{:ok, %Transaction{previous_public_key: key}} ->
	%FirstPublicKey{public_key: key}
	{:error, :transaction_not_exists} ->
	%NotFound{}
	end
	end

Which eventually calls
DB.get_first_chain_address()

archethic-node/lib/archethic/transaction_chain.ex

Line 218 in 819b8af

|> DB.get_first_chain_address()

So we should use
TransactionChain.get_first_public_key() which calls
DB.get_first_public_key() which eventually calls
DB.get_first_chain_address()

So, what is required to do for this Issue.
@samuel-uniris @blackode @apoorv-2204

[prix-uniris]

Also not exactly sure , what "As we are messing with first transaction and first public key concept." this meant.

[apoorv-2204]

As we are messing with first transaction and first public key concept.
@prix-uniris

,

Thanks @blackode for verifying the diagram