[Enhancement] Redownload new media after a delay (#173)

* Added redownload-related columns

* Added methods for fetching re-downloadable media items

* Filled out redownload worker + tests

* Added redownload worker to config.exs cron

* Added to UI and README

lib/pinchflat/media/media.ex

@@ -31,15 +31,39 @@ defmodule Pinchflat.Media do
   def list_cullable_media_items do
     MediaQuery.new()
     |> MediaQuery.with_media_filepath()
-    |> MediaQuery.with_passed_retention_period()
-    |> MediaQuery.with_no_culling_prevention()
+    |> MediaQuery.where_past_retention_period()
+    |> MediaQuery.where_culling_not_prevented()
+    |> Repo.all()
+  end
+
+  @doc """
+  Returns a list of media_items that are redownloadable based on the redownload delay
+  of the media_profile their source belongs to.
+
+  The logic is that a media_item is past_redownload_delay if the media_item's
+  upload_date is at least redownload_delay_days ago AND
+  `media_downloaded_at` - `redownload_delay_days` is before the media_item's `upload_date`.
+  This logic grabs media that we've recently downloaded AND is recently uploaded, but
+  doesn't grab media that we've recently downloaded and was uploaded a long time ago.
+  This also makes things work as expected when downloading media from a source for the
+  first time.
+
+  Returns [%MediaItem{}, ...]
+  """
+  def list_redownloadable_media_items do
+    MediaQuery.new()
+    |> MediaQuery.with_media_downloaded_at()
+    |> MediaQuery.where_download_not_prevented()
+    |> MediaQuery.where_not_culled()
+    |> MediaQuery.where_media_not_redownloaded()
+    |> MediaQuery.where_past_redownload_delay()
     |> Repo.all()
   end
 
   @doc """
   Returns a list of pending media_items for a given source, where
   pending means the `media_filepath` is `nil` AND the media_item
-  matches satisfies `MediaQuery.with_media_pending_download`. You
+  matches satisfies `MediaQuery.where_pending_download`. You
   should really check out that function if you need to know more
   because it has a lot going on.
 
@@ -48,7 +72,7 @@ defmodule Pinchflat.Media do
   def list_pending_media_items_for(%Source{} = source) do
     MediaQuery.new()
     |> MediaQuery.for_source(source)
-    |> MediaQuery.with_media_pending_download()
+    |> MediaQuery.where_pending_download()
     |> Repo.all()
   end
 
@@ -66,7 +90,7 @@ defmodule Pinchflat.Media do
 
     MediaQuery.new()
     |> MediaQuery.with_id(media_item.id)
-    |> MediaQuery.with_media_pending_download()
+    |> MediaQuery.where_pending_download()
     |> Repo.exists?()
   end
 

lib/pinchflat/media/media_item.ex

@@ -34,7 +34,8 @@ defmodule Pinchflat.Media.MediaItem do
     # These are user or system controlled fields
     :prevent_download,
     :prevent_culling,
-    :culled_at
+    :culled_at,
+    :media_redownloaded_at
   ]
   # Pretty much all the fields captured at index are required.
   @required_fields ~w(
@@ -61,6 +62,7 @@ defmodule Pinchflat.Media.MediaItem do
     field :livestream, :boolean, default: false
     field :short_form_content, :boolean, default: false
     field :media_downloaded_at, :utc_datetime
+    field :media_redownloaded_at, :utc_datetime
     field :upload_date, :date
     field :duration_seconds, :integer
 

lib/pinchflat/media/media_query.ex

@@ -15,7 +15,7 @@ defmodule Pinchflat.Media.MediaQuery do
   # Prefixes:
   # - for_* - belonging to a certain record
   # - join_* - for joining on a certain record
-  # - with_* - for filtering based on full, concrete attributes
+  # - with_*, where_* - for filtering based on full, concrete attributes
   # - matching_* - for filtering based on partial attributes (e.g. LIKE, regex, full-text search)
   #
   # Suffixes:
@@ -33,24 +33,46 @@ defmodule Pinchflat.Media.MediaQuery do
     from(mi in query, join: s in assoc(mi, :source), as: :sources)
   end
 
-  def with_passed_retention_period(query) do
+  def where_past_retention_period(query) do
     query
     |> require_assoc(:source)
     |> where(
       [mi, source],
-      fragment(
-        "IFNULL(?, 0) > 0 AND DATETIME('now', '-' || ? || ' day') > ?",
-        source.retention_period_days,
-        source.retention_period_days,
-        mi.media_downloaded_at
-      )
+      fragment("""
+      IFNULL(retention_period_days, 0) > 0 AND
+      DATETIME('now', '-' || retention_period_days || ' day') > media_downloaded_at
+      """)
     )
   end
 
-  def with_no_culling_prevention(query) do
+  def where_past_redownload_delay(query) do
+    query
+    |> require_assoc(:source)
+    |> require_assoc(:media_profile)
+    |> where(
+      [_mi, _source, _media_profile],
+      # Returns media items where the upload_date is at least redownload_delay_days ago AND
+      # downloaded_at minus the redownload_delay_days is before the upload date
+      fragment("""
+        IFNULL(redownload_delay_days, 0) > 0 AND
+        DATETIME('now', '-' || redownload_delay_days || ' day') > upload_date AND
+        DATETIME(media_downloaded_at, '-' || redownload_delay_days || ' day') < upload_date
+      """)
+    )
+  end
+
+  def where_culling_not_prevented(query) do
     where(query, [mi], mi.prevent_culling == false)
   end
 
+  def where_not_culled(query) do
+    where(query, [mi], is_nil(mi.culled_at))
+  end
+
+  def where_media_not_redownloaded(query) do
+    where(query, [mi], is_nil(mi.media_redownloaded_at))
+  end
+
   def with_id(query, id) do
     where(query, [mi], mi.id == ^id)
   end
@@ -59,6 +81,10 @@ defmodule Pinchflat.Media.MediaQuery do
     where(query, [mi], mi.media_id in ^media_ids)
   end
 
+  def with_media_downloaded_at(query) do
+    where(query, [mi], not is_nil(mi.media_downloaded_at))
+  end
+
   def with_media_filepath(query) do
     where(query, [mi], not is_nil(mi.media_filepath))
   end
@@ -73,7 +99,7 @@ defmodule Pinchflat.Media.MediaQuery do
     |> where([mi, source], is_nil(source.download_cutoff_date) or mi.upload_date >= source.download_cutoff_date)
   end
 
-  def with_no_prevented_download(query) do
+  def where_download_not_prevented(query) do
     where(query, [mi], mi.prevent_download == false)
   end
 
@@ -129,9 +155,9 @@ defmodule Pinchflat.Media.MediaQuery do
     )
   end
 
-  def with_media_pending_download(query) do
+  def where_pending_download(query) do
     query
-    |> with_no_prevented_download()
+    |> where_download_not_prevented()
     |> with_no_media_filepath()
     |> with_upload_date_after_source_cutoff()
     |> with_format_matching_profile_preference()