using { /Fortnite.com/AI }
using { /Fortnite.com/Characters }
using { /Fortnite.com/Playspaces }
using { /Verse.org/Simulation }
using { /Verse.org/SceneGraph }
using { /UnrealEngine.com/Temporary/Diagnostics }

# SIDEKICK COMPANION — a pet that follows you and emotes how it feels.
#
# Sidekicks are NPC companions with their own moods and reactions. You spawn one
# from an NPC Spawner using a Sidekick character definition, then drive it with
# an npc_behavior. The Sidekick API lives on the npc_sidekick_component, which
# you read off the behavior's ENTITY (GetEntity[].GetComponent[...]).
#
# This companion locks onto its owner, follows them around, and plays a Happy
# reaction the moment it catches up — then forces a permanent cheerful mood so
# it never sulks. You cannot BUILD a sidekick_component in Verse (it's
# epic_internal), but once the spawner gives you one, every method here is public.
sidekick_companion := class(npc_behavior):

    # How close the pet tries to get to its owner (centimeters).
    FollowRadius : float = 300.0

    OnBegin<override>()<suspends> : void =
        if:
            Agent := GetAgent[]
            Character := Agent.GetFortCharacter[]
            Entity := GetEntity[]
            # Pull the sidekick component off our own entity.
            Sidekick := Entity.GetComponent[npc_sidekick_component]
        then:
            Print("Sidekick reporting for duty!")
            # Lock it into a cheerful mood and react to its own mood swings.
            set Sidekick.MoodOverride = option{ sidekick_mood.Neutral }
            Sidekick.ChangeMoodEvent.Subscribe(OnMoodChanged)
            # Find a player to adopt as our owner, then follow forever.
            if (Owner := FindOwner[Entity]):
                spawn{ FollowOwner(Character, Owner, Sidekick) }

    # Grab the first player in the match as the companion's owner. We reach the
    # playspace through our own entity (npc_behavior.GetPlayspace is epic_internal).
    FindOwner(Entity : entity)<transacts><decides> : agent =
        Playspace := Entity.GetPlayspaceForEntity[]
        Players := Playspace.GetPlayers()
        Players[0]

    # Chase the owner forever, celebrating each time we reach them.
    FollowOwner(Character : fort_character, Owner : agent, Sidekick : npc_sidekick_component)<suspends> : void =
        if (Navigatable := Character.GetNavigatable[]):
            loop:
                Target := MakeNavigationTarget(Owner)
                Result := Navigatable.NavigateTo(Target, ?ReachRadius := FollowRadius)
                if (Result = navigation_result.Reached):
                    # Caught up — play a happy emote (failable: may be busy).
                    if (Sidekick.PlayReaction[sidekick_reaction.Happy]):
                        Print("Sidekick caught up — playing Happy!")
                    Navigatable.Wait(?Duration := 1.5)

    # Log mood transitions so you can see the system tick.
    OnMoodChanged(Moods : tuple(sidekick_mood, sidekick_mood)) : void =
        Print("Sidekick mood changed.")