// Assets/_Project/Scripts/Gameplay/EnemyUpgrades/EnemyUpgradeGroup.cs
using System;
using System.Collections.Generic;
using UnityEngine;
using TD.Core;

namespace TD.Gameplay.EnemyUpgrades
{
    /// <summary>
    /// One weighted candidate inside an <see cref="EnemyUpgradeGroup"/>.
    /// </summary>
    /// <remarks>
    /// Weight is relative and normalized at draw time — see <see cref="PoolWeightAttribute"/>.
    /// Kept on the entry rather than on the option asset for the same reason wave weights are:
    /// a card can be a staple of one phase's pool and a rarity in another's.
    /// </remarks>
    [Serializable]
    public class EnemyUpgradePoolEntry
    {
        [Tooltip("The enemy-buff card that may be offered from this group.")]
        public EnemyUpgradeOption Option;

        [Tooltip("Relative draw weight within the pool this group contributes to. Entries at " +
                 "equal weight are equally likely; 0.5 is half as likely as 1.0.")]
        [PoolWeight("buff")]
        public float Weight = 1f;
    }

    /// <summary>
    /// A named, reusable bag of enemy-buff cards. Groups are the unit designers move between
    /// phases: dragging a group into Phase 2's list makes every card in it votable from phase 2
    /// onward, without touching the cards themselves.
    /// </summary>
    /// <remarks>
    /// Buffs are gated by <b>phase</b>, not by cycle — every card a phase allows is votable from
    /// its very first wave. Gating by cycle was considered and rejected: the whole point of the
    /// cyclical structure is that players choose how hard to make their own next lap, and holding
    /// the interesting cards back until cycle 3 would flatten that decision into a formality.
    /// </remarks>
    [CreateAssetMenu(fileName = "EnemyUpgradeGroup",
                     menuName = "TD/Enemy Upgrades/Upgrade Group", order = 21)]
    public class EnemyUpgradeGroup : ScriptableObject
    {
        [Tooltip("Designer-facing name, shown in validation messages. Falls back to the asset name.")]
        public string DisplayName;

        [Tooltip("Cards in this group, each with a relative draw weight.")]
        public EnemyUpgradePoolEntry[] Options;

        /// <summary>Name used in validation and log messages. Falls back to the asset name.</summary>
        public string Label => string.IsNullOrWhiteSpace(DisplayName) ? name : DisplayName;

        /// <summary>
        /// Appends every non-null, non-zero-weight entry across <paramref name="groups"/> into
        /// <paramref name="into"/>. Zero-weight entries are filtered here so "weight 0 means it
        /// can never appear" lives in exactly one place.
        /// </summary>
        public static void CollectCandidates(EnemyUpgradeGroup[] groups, List<EnemyUpgradePoolEntry> into)
        {
            into.Clear();
            if (groups == null) return;

            foreach (var group in groups)
            {
                if (group?.Options == null) continue;
                foreach (var entry in group.Options)
                {
                    if (entry?.Option == null) continue;
                    if (entry.Weight <= 0f) continue;
                    into.Add(entry);
                }
            }
        }
    }
}