[Enhancement] Ignore media based on user scripts (#330)

* Integrated pre-download callback for media items

* Refactored existing tests

* Docs, etc

lib/pinchflat/lifecycle/user_scripts/command_runner.ex

@@ -12,6 +12,7 @@ defmodule Pinchflat.Lifecycle.UserScripts.CommandRunner do
   @behaviour UserScriptCommandRunner
 
   @event_types [
+    :media_pre_download,
     :media_downloaded,
     :media_deleted
   ]
@@ -22,24 +23,25 @@ defmodule Pinchflat.Lifecycle.UserScripts.CommandRunner do
 
   This function will succeed in almost all cases, even if the user script command
   failed - this is because I don't want bad scripts to stop the whole process.
-  If something fails, it'll be logged.
+  If something fails, it'll be logged and returned BUT the tuple will always
+  start with {:ok, ...}.
 
   The only things that can cause a true failure are passing in an invalid event
   type or if the passed data cannot be encoded into JSON - both indicative of
   failures in the development process.
 
-  Returns :ok
+  Returns {:ok, :no_executable} | {:ok, output, exit_code}
   """
   @impl UserScriptCommandRunner
   def run(event_type, encodable_data) when event_type in @event_types do
     case backend_executable() do
       {:ok, :no_executable} ->
-        :ok
+        {:ok, :no_executable}
 
       {:ok, executable_path} ->
         {:ok, encoded_data} = Phoenix.json_library().encode(encodable_data)
 
-        {_output, _exit_code} =
+        {output, exit_code} =
           CliUtils.wrap_cmd(
             executable_path,
             [to_string(event_type), encoded_data],
@@ -47,7 +49,7 @@ defmodule Pinchflat.Lifecycle.UserScripts.CommandRunner do
             logging_arg_override: "[suppressed]"
           )
 
-        :ok
+        {:ok, output, exit_code}
     end
   end
 
@@ -62,7 +64,7 @@ defmodule Pinchflat.Lifecycle.UserScripts.CommandRunner do
     if FilesystemUtils.exists_and_nonempty?(filepath) do
       {:ok, filepath}
     else
-      Logger.warning("User scripts lifecyle file either not present or is empty. Skipping.")
+      Logger.info("User scripts lifecyle file either not present or is empty. Skipping.")
 
       {:ok, :no_executable}
     end