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

namespace TD.Gameplay.EnemyAbilities
{
    /// <summary>
    /// Base class for one enemy ability (e.g. "split into smaller enemies on death"). Rolled
    /// at random for each spawned enemy by <see cref="EnemyAbilityPool.RollRandom"/> and applied
    /// via <see cref="EnemyAbility.InitializeServer"/>.
    /// </summary>
    /// <remarks>
    /// <para><b>One asset per kind.</b> <see cref="Kind"/> is fixed per subclass, same as
    /// <see cref="BuilderSpells.BuilderSpellDefinition"/>. <see cref="EnemyAbilityPool"/> uses
    /// it to build a fixed-size, enum-indexed lookup table.</para>
    ///
    /// <para><b>Server-only hooks.</b> All three hooks below only ever run on the server —
    /// <see cref="EnemyAbility"/> only calls them when <c>IsServer</c> is true. <see
    /// cref="ServerOnSpawn"/> and <see cref="ServerTick"/> are no-ops for abilities that don't
    /// need spawn-time setup or a per-frame timer (e.g. Split on Death uses neither); they exist
    /// so a future cooldown-driven ability (disable towers, teleport) doesn't need a base-class
    /// change.</para>
    /// </remarks>
    public abstract class EnemyAbilityDefinition : ScriptableObject
    {
        /// <summary>Which enemy ability this asset's data belongs to.</summary>
        public abstract EnemyAbilityKind Kind { get; }

        [Header("Presentation")]
        [Tooltip("Name shown in debug logs and future enemy-info UI.")]
        public string DisplayName;

        [Tooltip("Short description shown in future enemy-info UI.")]
        [TextArea(2, 4)]
        public string Description;

        [Header("Selection")]
        [Tooltip("Relative weight of this ability being rolled, vs. the pool's other abilities " +
                 "and its no-ability chance. Same semantics as DraftOption.Weight.")]
        [Min(0f)]
        public float Weight = 1f;

        /// <summary>Server-only: called once, right after this ability is assigned (before the
        /// enemy's NetworkObject is spawned to clients). Default no-op.</summary>
        public virtual void ServerOnSpawn(EnemyAbility instance) { }

        /// <summary>Server-only: called every frame this ability is active on a live enemy.
        /// Default no-op.</summary>
        public virtual void ServerTick(EnemyAbility instance, float dt) { }

        /// <summary>Server-only: called the instant the enemy's HP reaches zero, before the
        /// death animation/despawn sequence plays. Default no-op.</summary>
        public virtual void ServerOnDeath(EnemyAbility instance, EnemyHealth health) { }
    }
}