defmodule Mix.Tasks.Porta.Gen.Migration do
  use Mix.Task

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

  @shortdoc "Generates a new migration for the repo"

  @moduledoc """
  Generates a migration.
  The repository must be set under `:ecto_repos` in the
  current app configuration or given via the `-r` option.
  ## Examples
      mix ecto.gen.migration add_posts_table
      mix ecto.gen.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
  """

  @doc false
  def run(args) do
    case OptionParser.parse(args) do
      {_opts, [name], _} ->
        migration_args = args ++ ["--change", sql_template(path(name))]
        Mix.Task.run("ecto.gen.migration", migration_args)
        create_directory "priv/sql_migrations"
        create_file path(name), ""
      {_, _, _} ->
        Mix.raise "expected porta.gen.migration to receive the migration file name, " <>
                  "got: #{inspect Enum.join(args, " ")}"
    end
  end

  def path(name), do: "priv/sql_migrations/#{underscore(name)}.sql"

  def sql_template(path) do
    """
        "#{path}"
        |> File.read!
        |> String.split(~r/\\n\\s*-----.*/, trim: true)
        |> Enum.each(&execute/1)
    """
  end
end