When user starts watching season N, start to monitor season N+1

[mmgoodnow]

I want to make it clear that I'm submitting this issue with no expectations that it will ever be implemented. I recognize this would be a pretty significant expansion of scope, but just throwing it out there to get some opinions.

Problem

Watchlistarr monitors based on the SONARR_SEASON_MONITORING environment variable, but the only really viable one is all if you want people to be able to watch an entire series just by watchlisting. However, if they request something like NCIS and then decide they don't like it in season 1, we're left downloading the other 19 seasons.

Proposal

As part of the Discover Together features, friends can share their watch history with each other (of course, we could get this from something like Tautulli or PMS itself as well).

With this information, I think it'd be possible to monitor series incrementally. The monitoring criteria could look like something along these lines:

function shouldMonitorSeason(series: Series, seasonNumber: number) {
  const maxViewedSeason = getAllEpisodeWatchEventsFromPlex(series, peopleThatWatchlistedIt).map(h => h.seasonNumber).reduce(Math.max)
  return seasonNumber <= maxViewedSeason + 1
}

Potential problems

• If someone watchlists something like SNL and they just want to watch the current season, not start from season 1, this would not work. But it doesn't really work within the current behavior either.