Add scr.delete mix task

lib/mix/tasks/scr.delete.ex

@@ -0,0 +1,60 @@
+defmodule Mix.Tasks.Scr.Delete do
+  @moduledoc """
+  Removes an existing secret in specified environment and under specified
+  name.
+
+  It uses configuration of current application to retrieve keys and
+  so on.
+
+  ## Usage
+      mix scr.delete prod database_url
+  """
+
+  @shortdoc "Delete an existing secret"
+
+  use Mix.Task
+
+  alias SecretVault.{CLI, Config}
+
+  @impl true
+  def run(args)
+
+  def run([environment, name | rest]) do
+    otp_app = Mix.Project.config()[:app]
+    prefix = CLI.find_option(rest, "p", "prefix") || "default"
+
+    config_opts =
+      Config.available_options()
+      |> Enum.map(&{&1, CLI.find_option(rest, nil, "#{&1}")})
+      |> Enum.reject(fn {_, value} -> is_nil(value) end)
+
+    with {:ok, config} <-
+           Config.fetch_from_env(otp_app, environment, prefix, config_opts),
+         :ok <- ensure_secret_exists(config, name) do
+      SecretVault.delete(config, name)
+    else
+      {:error, :secret_does_not_exist} ->
+        Mix.shell().error("Secret with name #{name} does not exist")
+
+      {:error, {:no_configuration_for_prefix, prefix}} ->
+        message = "No configuration for prefix #{inspect(prefix)} found"
+        Mix.shell().error(message)
+
+      {:error, {:no_configuration_for_app, otp_app}} ->
+        Mix.shell().error("No configuration for otp_app #{otp_app} found")
+    end
+  end
+
+  def run(_args) do
+    msg = "Invalid number of arguments. Use `mix help scr.delete`."
+    Mix.shell().error(msg)
+  end
+
+  defp ensure_secret_exists(config, name) do
+    if SecretVault.exists?(config, name) do
+      :ok
+    else
+      {:error, :secret_does_not_exist}
+    end
+  end
+end