multi_tenancex.gen.tenant_migration.ex

defmodule Mix.Tasks.MultiTenancex.Gen.TenantMigration do
  use Mix.Task

  import Macro, only: [camelize: 1, underscore: 1]
  import Mix.Generator
  import Mix.Ecto

  @migrations_folder "tenant_migrations"

  @shortdoc "Generates a new tenant migration for the repo"

  @moduledoc """
  Generates a tenant migration.

  The repository must be set under `:ecto_repos` in the
  current app configuration or given via the `-r` option.

  ## Examples

      mix multi_tenancex.gen.tenant_migration add_posts_table
      mix multi_tenancex.gen.tenant_migration add_posts_table -r Custom.Repo

  By default, the migration will be generated to the
  "priv/YOUR_REPO/migrations" directory of the current application
  but it can be configured to be any subdirectory of `priv` by
  specifying the `:priv` key under the repository configuration.

  This generator will automatically open the generated file if
  you have `ECTO_EDITOR` set in your environment variable.

  ## Command line options

    * `-r`, `--repo` - the repo to generate migration for

  """

  @switches [change: :string]

  @doc false
  def run(args) do
    no_umbrella!("multi_tenancex.gen.tenant_migration")
    repos = parse_repo(args)

    Enum.each(repos, fn repo ->
      case OptionParser.parse(args, switches: @switches) do
        {opts, [name], _} ->
          ensure_repo(repo, args)

          path =
            Path.relative_to(
              tenant_migrations_path(repo),
              Mix.Project.app_path()
            )

          file = Path.join(path, "#{timestamp()}_#{underscore(name)}.exs")
          create_directory(path)

          assigns = [
            mod: Module.concat([repo, Migrations, camelize(name)]),
            change: opts[:change]
          ]

          create_file(file, migration_template(assigns))

          if open?(file) and
               Mix.shell().yes?("Do you want to run this migration?") do
            Mix.Task.run("ecto.migrate", [repo])
          end

        {_, _, _} ->
          Mix.raise(
            "expected multi_tenancex.gen.migration to receive the migration file name, " <>
              "got: #{inspect(Enum.join(args, " "))}"
          )
      end
    end)
  end

  defp timestamp do
    {{y, m, d}, {hh, mm, ss}} = :calendar.universal_time()
    "#{y}#{pad(m)}#{pad(d)}#{pad(hh)}#{pad(mm)}#{pad(ss)}"
  end

  defp pad(i) when i < 10, do: <<?0, ?0 + i>>
  defp pad(i), do: to_string(i)

  defp tenant_migrations_path(repo) do
    priv_path_for(repo, @migrations_folder)
  end

  defp priv_dir(app), do: "#{:code.priv_dir(app)}"

  defp priv_path_for(repo, filename) do
    repo_underscore =
      repo
      |> Module.split()
      |> List.last()
      |> Macro.underscore()

    Path.join([priv_dir(:multi_tenancex), repo_underscore, filename])
  end

  embed_template(:migration, """
  defmodule <%= inspect @mod %> do
    use Ecto.Migration

    def change do
  <%= @change %>
    end
  end
  """)
end