using { /Fortnite.com/Devices }
using { /Verse.org/Simulation }
using { /UnrealEngine.com/Temporary/Diagnostics }

# SPAWNER WAVES — a survival horde driven by the NPC Spawner device.
#
# The npc_spawner_device is the front door to putting characters in your world
# from Verse. You pick WHO it spawns in the editor (its NPC Character Definition);
# Verse decides WHEN and HOW MANY. Here a button starts a wave, the device fires
# SpawnedEvent for every character it creates, EliminatedEvent every time one
# falls, and when the whole wave is down we roll the next one — bigger each time.
wave_horde_device := class(creative_device):

    # Drop your NPC Spawner here. Choose its character (zombie, husk, custom) in
    # the editor — Verse just commands the spawns.
    @editable
    Spawner : npc_spawner_device = npc_spawner_device{}

    # Press to begin the horde.
    @editable
    StartButton : button_device = button_device{}

    # How many enemies the FIRST wave spawns. Each wave adds one more.
    @editable
    FirstWaveSize : int = 3

    # Which wave we're on (0 = not started).
    var WaveNumber : int = 0

    # How many of the current wave are still alive.
    var AliveCount : int = 0

    OnBegin<override>()<suspends> : void =
        # Listen to the spawner's own lifecycle events.
        Spawner.SpawnedEvent.Subscribe(OnSpawned)
        Spawner.EliminatedEvent.Subscribe(OnEliminated)
        StartButton.InteractedWithEvent.Subscribe(OnStart)

    # First press kicks off wave 1.
    OnStart(Presser : agent) : void =
        if (WaveNumber = 0):
            StartNextWave()

    # Roll the next wave: enable the device and spawn (WaveNumber + base) enemies.
    StartNextWave() : void =
        set WaveNumber += 1
        Count := FirstWaveSize + WaveNumber - 1
        Print("=== WAVE {WaveNumber} — spawning {Count} ===")
        Spawner.Enable()
        # Reset the spawn count so a new batch is allowed, then spawn each one.
        Spawner.Reset()
        var I : int = 0
        loop:
            if (I >= Count):
                break
            Spawner.Spawn()
            set I += 1

    # Every character the device spawns bumps the alive counter.
    OnSpawned(Spawned : agent) : void =
        set AliveCount += 1
        Print("Enemy spawned — {AliveCount} alive")

    # device_ai_interaction_result carries Source (killer) and Target (the dead).
    OnEliminated(Result : device_ai_interaction_result) : void =
        set AliveCount -= 1
        Print("Enemy down — {AliveCount} left")
        # Wave cleared? Roll the next, tougher one.
        if (AliveCount <= 0):
            Print("Wave {WaveNumber} cleared!")
            StartNextWave()