// Assets/_Project/Scripts/Gameplay/EnemyAbilities/BlinkAbilityDefinition.cs
using UnityEngine;
using TD.Core;

namespace TD.Gameplay.EnemyAbilities
{
    /// <summary>
    /// Every few seconds, the enemy teleports a short distance further along its path — skipping
    /// tiles, and the towers covering them.
    /// </summary>
    /// <remarks>
    /// Blinks follow the path rather than cutting toward the goal, so the maze still shapes the
    /// route; the buff shortens time-under-fire rather than bypassing walls. See
    /// <c>EnemyMovement.ServerBlinkForward</c>.
    ///
    /// <para>The cooldown lives in this enemy's own timer slot rather than on the asset. A field
    /// here would be shared by every enemy carrying the buff, so the whole wave would blink in
    /// perfect unison — which looks like a bug even when the timing is right.</para>
    /// </remarks>
    [CreateAssetMenu(fileName = "BlinkAbility", menuName = "TD/Enemy Abilities/Blink")]
    public class BlinkAbilityDefinition : EnemyAbilityDefinition
    {
        public override EnemyAbilityKind Kind => EnemyAbilityKind.Blink;

        [Header("Blink")]
        [Tooltip("Seconds between blinks.")]
        [Min(0.1f)]
        public float IntervalSeconds = 8f;

        [Tooltip("World units to advance along the path per blink.")]
        [Min(0.1f)]
        public float BlinkDistanceMeters = 4f;

        public override void ServerOnSpawn(EnemyAbility instance, int abilityIndex)
        {
            // Seed each enemy's cooldown with a random point within the full interval, as if it
            // spawned already partway through a cooldown. A small jitter window near zero would
            // still let a burst of enemies spawned together sync up and blink as a visible cluster
            // every cycle; spreading across the whole interval avoids that regardless of how
            // IntervalSeconds is tuned. Done once, here, rather than on the first tick — a tick-time
            // check would have to distinguish "never started" from "just blinked", and both
            // states read as a zero timer.
            instance.TimerFor(abilityIndex) = -Random.Range(0f, IntervalSeconds);
        }

        public override void ServerTick(EnemyAbility instance, int abilityIndex, float dt)
        {
            ref float timer = ref instance.TimerFor(abilityIndex);
            timer += dt;
            if (timer < IntervalSeconds) return;

            timer = 0f;
            instance.GetComponent<EnemyMovement>()?.ServerBlinkForward(BlinkDistanceMeters);
        }
    }
}