Add client generator mix task

lib/mix/tasks/xogmios.gen.client.ex

@@ -0,0 +1,213 @@
+defmodule Mix.Tasks.Xogmios.Gen.Client do
+  @shortdoc "Generates a Xogmios client module"
+
+  @moduledoc """
+  Generates a new Xogmios client module.
+
+    $ mix xogmios.gen.client -p chain_sync MyClientModule
+
+  The following CLI flags are required:
+  ```md
+  -p, --protocol        The Ouroboros mini-protocol for which the client module
+                        will be working with. This can be one of: chain_sync,
+                        mempool_txs, state_query, tx_submission.
+  ```
+  """
+
+  use Mix.Task
+  alias Mix.Shell.IO
+
+  @impl true
+  def run(args) do
+    otp_app =
+      Mix.Project.config()
+      |> Keyword.get(:app)
+      |> Atom.to_string()
+
+    case parse_options(args) do
+      %{protocol: protocol, client_module_name: client_module_name} ->
+        generate_client(otp_app, protocol, client_module_name)
+
+      _ ->
+        raise "Missing required arguments. Run mix help xogmios.gen.client for usage instructions"
+    end
+  end
+
+  defp generate_client(otp_app, protocol, client_module_name) do
+    project_root = File.cwd!()
+    filename = Macro.underscore(client_module_name)
+    path = Path.join([project_root, "lib", otp_app, "#{filename}.ex"])
+    dirname = Path.dirname(path)
+
+    unless File.exists?(dirname) do
+      raise "Required directory path #{dirname} does not exist. "
+    end
+
+    write_file =
+      if File.exists?(path) do
+        IO.yes?("File already exists at #{path}. Overwrite?")
+      else
+        true
+      end
+
+    if write_file do
+      create_client_file(path, otp_app, protocol, client_module_name)
+      IO.info("Successfully wrote out #{path}")
+    else
+      IO.info("Did not write file out to #{path}")
+    end
+  end
+
+  defp parse_options(args) do
+    cli_options = [protocol: :string]
+    cli_aliases = [p: :protocol]
+
+    parsed_args = OptionParser.parse(args, aliases: cli_aliases, strict: cli_options)
+
+    case parsed_args do
+      {options, [client_module_name], [] = _errors} ->
+        options
+        |> Map.new()
+        |> Map.merge(%{client_module_name: client_module_name})
+
+      {_options, _remaining_args, errors} ->
+        raise "Invalid CLI args were provided: #{inspect(errors)}"
+    end
+  end
+
+  defp create_client_file(path, otp_app, protocol, client_module_name) do
+    app_module_name = Macro.camelize(otp_app)
+
+    assigns = [
+      app_module_name: app_module_name,
+      protocol: protocol,
+      client_module_name: client_module_name
+    ]
+
+    module_template =
+      xogmios_module_template(protocol)
+      |> EEx.eval_string(assigns: assigns)
+
+    path
+    |> File.write!(module_template)
+  end
+
+  defp xogmios_module_template("chain_sync") do
+    """
+    defmodule <%= @app_module_name %>.<%= @client_module_name %> do
+      @moduledoc \"\"\"
+      This module syncs with the chain and reads new blocks.
+
+      Be sure to add this module to your app's supervision tree like so:
+
+      def start(_type, _args) do
+        children = [
+          ...,
+          {<%= @app_module_name %>.<%= @client_module_name %>, url: System.fetch_env!("OGMIOS_URL")}
+        ]
+        ...
+      end
+      \"\"\"
+
+      use Xogmios, :chain_sync
+
+      def start_link(opts) do
+        # Syncs from current tip by default
+        initial_state = []
+        ### See examples below on how to sync
+        ### from different points of the chain:
+        # initial_state = [sync_from: :babbage]
+        # initial_state = [
+        #   sync_from: %{
+        #     point: %{
+        #       slot: 114_127_654,
+        #       id: "b0ff1e2bfc326a7f7378694b1f2693233058032bfb2798be2992a0db8b143099"
+        #     }
+        #   }
+        # ]
+        opts = Keyword.merge(opts, initial_state)
+        Xogmios.start_chain_sync_link(__MODULE__, opts)
+      end
+
+      @impl true
+      def handle_block(block, state) do
+        IO.puts("handle_block \#{block["height"]}")
+        {:ok, :next_block, state}
+      end
+    end
+    """
+  end
+
+  defp xogmios_module_template("state_query") do
+    """
+    defmodule <%= @app_module_name %>.<%= @client_module_name %> do
+      @moduledoc \"\"\"
+      This module queries against the known tip of the chain.
+
+      Be sure to add this module to your app's supervision tree like so:
+
+      def start(_type, _args) do
+        children = [
+          ...,
+          {<%= @app_module_name %>.<%= @client_module_name %>, url: System.fetch_env!("OGMIOS_URL")}
+        ]
+        ...
+      end
+
+      Then invoke functions:
+       * <%= @client_module_name %>.send_query("eraStart")
+       * <%= @client_module_name %>.send_query("queryNetwork/blockHeight")
+      \"\"\"
+
+      use Xogmios, :state_query
+      alias Xogmios.StateQuery
+
+      def start_link(opts) do
+        Xogmios.start_state_link(__MODULE__, opts)
+      end
+
+      def send_query(pid \\\\\ __MODULE__, query_name) do
+        StateQuery.send_query(pid, query_name)
+      end
+    end
+    """
+  end
+
+  defp xogmios_module_template("mempool_txs") do
+    """
+    defmodule <%= @app_module_name %>.<%= @client_module_name %> do
+      @moduledoc \"\"\"
+      This module prints transactions as they become available in the mempool.
+
+      Be sure to add this module to your app's supervision tree like so:
+
+      def start(_type, _args) do
+        children = [
+          ...,
+          {<%= @app_module_name %>.<%= @client_module_name %>, url: System.fetch_env!("OGMIOS_URL")}
+        ]
+        ...
+      end
+      \"\"\"
+
+      use Xogmios, :mempool_txs
+
+      def start_link(opts) do
+        # set include_details: false (default) to retrieve
+        # only transaction id.
+        # set include_details: true to retrieve
+        # complete information about the transaction.
+        opts = Keyword.merge(opts, include_details: false)
+        Xogmios.start_mempool_txs_link(__MODULE__, opts)
+      end
+
+      @impl true
+      def handle_transaction(transaction, state) do
+        IO.puts("transaction \#{\inspect(transaction)}")
+
+        {:ok, :next_transaction, state}
+      end
+    end
+    """
+  end
+end