feat: add like/unlike system for podcasts and episodes (Closes #154)

apps/balados_sync_core/lib/balados_sync_core/aggregates/like.ex

@@ -0,0 +1,193 @@
+defmodule BaladosSyncCore.Aggregates.Like do
+  @moduledoc """
+  Like aggregate for the CQRS/Event Sourcing system.
+
+  Handles user likes for podcasts and episodes.
+
+  ## Bounded Context
+
+  This aggregate is part of the like bounded context, separate from
+  subscriptions, play tracking, playlists, and collections.
+
+  ## State
+
+  - `user_id` - Unique identifier for the user
+  - `podcast_likes` - Map of `%{feed => %{liked_at, unliked_at}}`
+  - `episode_likes` - Map of `%{item => %{liked_at, unliked_at, rss_source_feed}}`
+  """
+
+  defstruct [
+    :user_id,
+    # %{rss_source_feed => %{liked_at, unliked_at}}
+    podcast_likes: %{},
+    # %{rss_source_item => %{liked_at, unliked_at, rss_source_feed}}
+    episode_likes: %{}
+  ]
+
+  alias BaladosSyncCore.Commands.{
+    LikePodcast,
+    UnlikePodcast,
+    LikeEpisode,
+    UnlikeEpisode,
+    SnapshotLike
+  }
+
+  alias BaladosSyncCore.Events.{
+    PodcastLiked,
+    PodcastUnliked,
+    EpisodeLiked,
+    EpisodeUnliked,
+    LikeCheckpoint
+  }
+
+  alias BaladosSyncCore.LikeNormalizer
+
+  # LikePodcast - idempotent: no-op if already liked
+  def execute(%__MODULE__{} = state, %LikePodcast{} = cmd) do
+    case Map.get(state.podcast_likes, cmd.rss_source_feed) do
+      %{liked_at: liked_at, unliked_at: unliked_at}
+      when not is_nil(liked_at) and is_nil(unliked_at) ->
+        []
+
+      _ ->
+        %PodcastLiked{
+          user_id: cmd.user_id,
+          rss_source_feed: cmd.rss_source_feed,
+          liked_at: cmd.liked_at || DateTime.utc_now() |> DateTime.truncate(:second),
+          timestamp: DateTime.utc_now() |> DateTime.truncate(:second),
+          event_infos: cmd.event_infos || %{}
+        }
+    end
+  end
+
+  # UnlikePodcast - idempotent: no-op if not currently liked
+  def execute(%__MODULE__{} = state, %UnlikePodcast{} = cmd) do
+    case Map.get(state.podcast_likes, cmd.rss_source_feed) do
+      %{liked_at: liked_at, unliked_at: unliked_at}
+      when not is_nil(liked_at) and is_nil(unliked_at) ->
+        %PodcastUnliked{
+          user_id: cmd.user_id,
+          rss_source_feed: cmd.rss_source_feed,
+          unliked_at: cmd.unliked_at || DateTime.utc_now() |> DateTime.truncate(:second),
+          timestamp: DateTime.utc_now() |> DateTime.truncate(:second),
+          event_infos: cmd.event_infos || %{}
+        }
+
+      _ ->
+        []
+    end
+  end
+
+  # LikeEpisode - idempotent
+  def execute(%__MODULE__{} = state, %LikeEpisode{} = cmd) do
+    case Map.get(state.episode_likes, cmd.rss_source_item) do
+      %{liked_at: liked_at, unliked_at: unliked_at}
+      when not is_nil(liked_at) and is_nil(unliked_at) ->
+        []
+
+      _ ->
+        %EpisodeLiked{
+          user_id: cmd.user_id,
+          rss_source_feed: cmd.rss_source_feed,
+          rss_source_item: cmd.rss_source_item,
+          liked_at: cmd.liked_at || DateTime.utc_now() |> DateTime.truncate(:second),
+          timestamp: DateTime.utc_now() |> DateTime.truncate(:second),
+          event_infos: cmd.event_infos || %{}
+        }
+    end
+  end
+
+  # UnlikeEpisode - idempotent
+  def execute(%__MODULE__{} = state, %UnlikeEpisode{} = cmd) do
+    case Map.get(state.episode_likes, cmd.rss_source_item) do
+      %{liked_at: liked_at, unliked_at: unliked_at}
+      when not is_nil(liked_at) and is_nil(unliked_at) ->
+        %EpisodeUnliked{
+          user_id: cmd.user_id,
+          rss_source_feed: cmd.rss_source_feed,
+          rss_source_item: cmd.rss_source_item,
+          unliked_at: cmd.unliked_at || DateTime.utc_now() |> DateTime.truncate(:second),
+          timestamp: DateTime.utc_now() |> DateTime.truncate(:second),
+          event_infos: cmd.event_infos || %{}
+        }
+
+      _ ->
+        []
+    end
+  end
+
+  # SnapshotLike — skip if aggregate has never been initialized
+  def execute(%__MODULE__{user_id: nil}, %SnapshotLike{}), do: []
+
+  def execute(%__MODULE__{} = state, %SnapshotLike{}) do
+    %LikeCheckpoint{
+      user_id: state.user_id,
+      podcast_likes: state.podcast_likes,
+      episode_likes: state.episode_likes,
+      timestamp: DateTime.utc_now() |> DateTime.truncate(:second)
+    }
+  end
+
+  # Apply events
+
+  def apply(%__MODULE__{} = state, %PodcastLiked{} = event) do
+    updated = %{
+      liked_at: event.liked_at,
+      unliked_at: nil
+    }
+
+    %{
+      state
+      | user_id: event.user_id,
+        podcast_likes: Map.put(state.podcast_likes, event.rss_source_feed, updated)
+    }
+  end
+
+  def apply(%__MODULE__{} = state, %PodcastUnliked{} = event) do
+    case Map.get(state.podcast_likes, event.rss_source_feed) do
+      nil ->
+        state
+
+      like ->
+        updated = Map.put(like, :unliked_at, event.unliked_at)
+        %{state | podcast_likes: Map.put(state.podcast_likes, event.rss_source_feed, updated)}
+    end
+  end
+
+  def apply(%__MODULE__{} = state, %EpisodeLiked{} = event) do
+    updated = %{
+      liked_at: event.liked_at,
+      unliked_at: nil,
+      rss_source_feed: event.rss_source_feed
+    }
+
+    %{
+      state
+      | user_id: event.user_id,
+        episode_likes: Map.put(state.episode_likes, event.rss_source_item, updated)
+    }
+  end
+
+  def apply(%__MODULE__{} = state, %EpisodeUnliked{} = event) do
+    case Map.get(state.episode_likes, event.rss_source_item) do
+      nil ->
+        state
+
+      like ->
+        updated = Map.put(like, :unliked_at, event.unliked_at)
+        %{state | episode_likes: Map.put(state.episode_likes, event.rss_source_item, updated)}
+    end
+  end
+
+  def apply(%__MODULE__{} = state, %LikeCheckpoint{} = event) do
+    # Normalize keys: after JSON deserialization, nested map keys may be strings
+    %{
+      state
+      | user_id: event.user_id,
+        podcast_likes: LikeNormalizer.normalize(event.podcast_likes || %{}),
+        episode_likes: LikeNormalizer.normalize(event.episode_likes || %{})
+    }
+  end
+
+  def apply(%__MODULE__{} = state, _event), do: state
+end

apps/balados_sync_core/lib/balados_sync_core/commands/like_episode.ex

@@ -0,0 +1,21 @@
+defmodule BaladosSyncCore.Commands.LikeEpisode do
+  @moduledoc """
+  Command to like an episode.
+  """
+
+  @type t :: %__MODULE__{
+          user_id: String.t(),
+          rss_source_feed: String.t(),
+          rss_source_item: String.t(),
+          liked_at: DateTime.t() | nil,
+          event_infos: map()
+        }
+
+  defstruct [
+    :user_id,
+    :rss_source_feed,
+    :rss_source_item,
+    :liked_at,
+    :event_infos
+  ]
+end

apps/balados_sync_core/lib/balados_sync_core/commands/like_podcast.ex

@@ -0,0 +1,19 @@
+defmodule BaladosSyncCore.Commands.LikePodcast do
+  @moduledoc """
+  Command to like a podcast feed.
+  """
+
+  @type t :: %__MODULE__{
+          user_id: String.t(),
+          rss_source_feed: String.t(),
+          liked_at: DateTime.t() | nil,
+          event_infos: map()
+        }
+
+  defstruct [
+    :user_id,
+    :rss_source_feed,
+    :liked_at,
+    :event_infos
+  ]
+end

apps/balados_sync_core/lib/balados_sync_core/commands/snapshot_like.ex

@@ -0,0 +1,4 @@
+defmodule BaladosSyncCore.Commands.SnapshotLike do
+  @moduledoc "Command to snapshot the Like aggregate state."
+  defstruct [:user_id]
+end

apps/balados_sync_core/lib/balados_sync_core/commands/unlike_episode.ex

@@ -0,0 +1,21 @@
+defmodule BaladosSyncCore.Commands.UnlikeEpisode do
+  @moduledoc """
+  Command to unlike an episode.
+  """
+
+  @type t :: %__MODULE__{
+          user_id: String.t(),
+          rss_source_feed: String.t(),
+          rss_source_item: String.t(),
+          unliked_at: DateTime.t() | nil,
+          event_infos: map()
+        }
+
+  defstruct [
+    :user_id,
+    :rss_source_feed,
+    :rss_source_item,
+    :unliked_at,
+    :event_infos
+  ]
+end

apps/balados_sync_core/lib/balados_sync_core/commands/unlike_podcast.ex

@@ -0,0 +1,19 @@
+defmodule BaladosSyncCore.Commands.UnlikePodcast do
+  @moduledoc """
+  Command to unlike a podcast feed.
+  """
+
+  @type t :: %__MODULE__{
+          user_id: String.t(),
+          rss_source_feed: String.t(),
+          unliked_at: DateTime.t() | nil,
+          event_infos: map()
+        }
+
+  defstruct [
+    :user_id,
+    :rss_source_feed,
+    :unliked_at,
+    :event_infos
+  ]
+end

apps/balados_sync_core/lib/balados_sync_core/dispatcher/router.ex

@@ -5,6 +5,7 @@ defmodule BaladosSyncCore.Dispatcher.Router do
   alias BaladosSyncCore.Aggregates.PlayTracking
   alias BaladosSyncCore.Aggregates.Playlist
   alias BaladosSyncCore.Aggregates.Collection
+  alias BaladosSyncCore.Aggregates.Like
   alias BaladosSyncCore.Middleware.ValidateSubscription
 
   alias BaladosSyncCore.Commands.{
@@ -32,7 +33,12 @@ defmodule BaladosSyncCore.Dispatcher.Router do
     UpdateCollection,
     DeleteCollection,
     ReorderCollectionFeed,
-    ChangeCollectionVisibility
+    ChangeCollectionVisibility,
+    LikePodcast,
+    UnlikePodcast,
+    LikeEpisode,
+    UnlikeEpisode,
+    SnapshotLike
   }
 
   # Registered globally (runs for all commands) because Commanded doesn't support
@@ -104,4 +110,18 @@ defmodule BaladosSyncCore.Dispatcher.Router do
     ],
     to: Collection
   )
+
+  # Like aggregate (podcast and episode likes)
+  identify(Like, by: :user_id, prefix: "like-")
+
+  dispatch(
+    [
+      LikePodcast,
+      UnlikePodcast,
+      LikeEpisode,
+      UnlikeEpisode,
+      SnapshotLike
+    ],
+    to: Like
+  )
 end

apps/balados_sync_core/lib/balados_sync_core/events/episode_liked.ex

@@ -0,0 +1,11 @@
+defmodule BaladosSyncCore.Events.EpisodeLiked do
+  @derive Jason.Encoder
+  defstruct [
+    :user_id,
+    :rss_source_feed,
+    :rss_source_item,
+    :liked_at,
+    :timestamp,
+    :event_infos
+  ]
+end

apps/balados_sync_core/lib/balados_sync_core/events/episode_unliked.ex

@@ -0,0 +1,11 @@
+defmodule BaladosSyncCore.Events.EpisodeUnliked do
+  @derive Jason.Encoder
+  defstruct [
+    :user_id,
+    :rss_source_feed,
+    :rss_source_item,
+    :unliked_at,
+    :timestamp,
+    :event_infos
+  ]
+end

apps/balados_sync_core/lib/balados_sync_core/events/like_checkpoint.ex

@@ -0,0 +1,9 @@
+defmodule BaladosSyncCore.Events.LikeCheckpoint do
+  @derive Jason.Encoder
+  defstruct [
+    :user_id,
+    :podcast_likes,
+    :episode_likes,
+    :timestamp
+  ]
+end

apps/balados_sync_core/lib/balados_sync_core/events/podcast_liked.ex

@@ -0,0 +1,10 @@
+defmodule BaladosSyncCore.Events.PodcastLiked do
+  @derive Jason.Encoder
+  defstruct [
+    :user_id,
+    :rss_source_feed,
+    :liked_at,
+    :timestamp,
+    :event_infos
+  ]
+end

apps/balados_sync_core/lib/balados_sync_core/events/podcast_unliked.ex

@@ -0,0 +1,10 @@
+defmodule BaladosSyncCore.Events.PodcastUnliked do
+  @derive Jason.Encoder
+  defstruct [
+    :user_id,
+    :rss_source_feed,
+    :unliked_at,
+    :timestamp,
+    :event_infos
+  ]
+end