-- Notifications table
CREATE TABLE notifications (
  id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
  user_id uuid NOT NULL REFERENCES auth.users(id) ON DELETE CASCADE,
  type text NOT NULL CHECK (type IN ('new_podcast', 'like', 'comment')),
  data jsonb NOT NULL DEFAULT '{}',
  read boolean NOT NULL DEFAULT false,
  created_at timestamptz NOT NULL DEFAULT now()
);

CREATE INDEX idx_notifications_user ON notifications(user_id, created_at DESC);

ALTER TABLE notifications ENABLE ROW LEVEL SECURITY;

CREATE POLICY "Users can view their own notifications"
  ON notifications FOR SELECT
  USING (user_id = auth.uid());

CREATE POLICY "Users can update their own notifications"
  ON notifications FOR UPDATE
  USING (user_id = auth.uid())
  WITH CHECK (user_id = auth.uid());

-- Trigger: notify followers when a new podcast is created
CREATE OR REPLACE FUNCTION notify_new_podcast()
RETURNS TRIGGER AS $$
DECLARE
  creator_username text;
  follower_record RECORD;
BEGIN
  -- Skip scheduled podcasts
  IF NEW.published_at IS NOT NULL AND NEW.published_at > now() THEN
    RETURN NEW;
  END IF;

  SELECT username INTO creator_username FROM profiles WHERE id = NEW.creator_id;

  FOR follower_record IN
    SELECT follower_id FROM follows WHERE following_id = NEW.creator_id
  LOOP
    INSERT INTO notifications (user_id, type, data)
    VALUES (
      follower_record.follower_id,
      'new_podcast',
      jsonb_build_object(
        'podcast_id', NEW.id,
        'podcast_title', NEW.title,
        'username', COALESCE(creator_username, 'Quelqu''un')
      )
    );
  END LOOP;

  RETURN NEW;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;

CREATE TRIGGER on_podcast_created
  AFTER INSERT ON podcasts
  FOR EACH ROW
  EXECUTE FUNCTION notify_new_podcast();

-- Trigger: notify podcast creator when someone likes their podcast
CREATE OR REPLACE FUNCTION notify_like()
RETURNS TRIGGER AS $$
DECLARE
  liker_username text;
  podcast_record RECORD;
BEGIN
  SELECT username INTO liker_username FROM profiles WHERE id = NEW.user_id;
  SELECT id, title, creator_id INTO podcast_record FROM podcasts WHERE id = NEW.podcast_id;

  -- Don't notify if user likes their own podcast
  IF podcast_record.creator_id = NEW.user_id THEN
    RETURN NEW;
  END IF;

  INSERT INTO notifications (user_id, type, data)
  VALUES (
    podcast_record.creator_id,
    'like',
    jsonb_build_object(
      'podcast_id', podcast_record.id,
      'podcast_title', podcast_record.title,
      'username', COALESCE(liker_username, 'Quelqu''un')
    )
  );

  RETURN NEW;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;

CREATE TRIGGER on_like_created
  AFTER INSERT ON likes
  FOR EACH ROW
  EXECUTE FUNCTION notify_like();

-- Trigger: notify podcast creator when someone comments
CREATE OR REPLACE FUNCTION notify_comment()
RETURNS TRIGGER AS $$
DECLARE
  commenter_username text;
  podcast_record RECORD;
BEGIN
  SELECT username INTO commenter_username FROM profiles WHERE id = NEW.user_id;
  SELECT id, title, creator_id INTO podcast_record FROM podcasts WHERE id = NEW.podcast_id;

  -- Don't notify if user comments on their own podcast
  IF podcast_record.creator_id = NEW.user_id THEN
    RETURN NEW;
  END IF;

  INSERT INTO notifications (user_id, type, data)
  VALUES (
    podcast_record.creator_id,
    'comment',
    jsonb_build_object(
      'podcast_id', podcast_record.id,
      'podcast_title', podcast_record.title,
      'username', COALESCE(commenter_username, 'Quelqu''un')
    )
  );

  RETURN NEW;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;

CREATE TRIGGER on_comment_created
  AFTER INSERT ON comments
  FOR EACH ROW
  EXECUTE FUNCTION notify_comment();