module Stellar
  class TransactionEnvelope
    # Delegates any undefined method to the currently set arm
    def method_missing(method, *args, &block)
      value&.public_send(method, *args) || super
    end

    def respond_to_missing?(method, include_private = false)
      %w[tx signatures].include?(method) || super
    end

    # Checks to ensure that every signature for the envelope is
    # a valid signature of one of the provided `key_pairs`
    #
    # NOTE: this does not do any authorization checks, which requires access to
    # the current ledger state.
    #
    # @param key_pairs [Array<Stellar::KeyPair>] The key pairs to check the envelopes signatures against
    #
    # @return [Boolean] true if all signatures are from the provided key_pairs and validly sign the tx's hash
    def signed_correctly?(*key_pairs)
      hash = tx.hash
      return false if signatures.empty?

      key_index = key_pairs.index_by(&:signature_hint)

      signatures.all? do |sig|
        key_pair = key_index[sig.hint]
        break false if key_pair.nil?

        key_pair.verify(sig.signature, hash)
      end
    end

    def hash
      Digest::SHA256.digest(to_xdr)
    end

    def merge(other)
      merged_tx = tx.merge(other.tx)
      merged_tx.signatures = [signatures, other.signatures]
      merged_tx
    end
  end
end