// Assets/_Project/Scripts/Gameplay/Draft/DraftOption.cs
using UnityEngine;

namespace TD.Gameplay.Draft
{
    /// <summary>
    /// Base class for one authored draft choice. The draft system offers a player a
    /// weighted-random selection of these between waves; the player picks one and the
    /// server applies its effect.
    /// </summary>
    /// <remarks>
    /// <para><b>One asset per choice.</b> Concrete subclasses (e.g.
    /// <see cref="NewTowerDraftOption"/>) carry the payload and implement
    /// <see cref="ServerApply"/>. New choice types (systemic upgrade, builder ability,
    /// relic quest, enemy debuff) are added as new subclasses — the draft spine
    /// (<see cref="DraftService"/>, <see cref="PlayerDraft"/>, HUD) is type-agnostic.</para>
    ///
    /// <para><b>Identity.</b> Options live in <see cref="DraftPool"/> and are referenced
    /// over the network by their pool index (<c>DraftOptionId</c>) — the same
    /// stable-within-a-match index pattern used by the tower catalog.</para>
    ///
    /// <para><b>Server-only logic.</b> <see cref="IsValidFor"/> and
    /// <see cref="ServerApply"/> run on the server and operate on the target player's
    /// per-player components (deck, gold, etc.). The ScriptableObject holds no per-player
    /// state, so a single asset is shared across all players and matches.</para>
    /// </remarks>
    public abstract class DraftOption : ScriptableObject
    {
        [Header("Presentation")]
        [Tooltip("Name shown on the draft card.")]
        public string DisplayName;

        [Tooltip("Short description shown on the draft card.")]
        [TextArea(2, 4)]
        public string Description;

        [Tooltip("OPTIONAL override for the draft card icon. Leave empty to inherit the icon of " +
                 "the item this option grants (its tower / spell); assign one only when you want " +
                 "to override that inherited icon.")]
        public Sprite Icon;

        /// <summary>
        /// The icon actually shown on the draft card. Returns the explicit <see cref="Icon"/>
        /// override when one is assigned; otherwise subclasses fall back to the icon of the item
        /// they grant (tower, spell). The base class has no referenced item, so it just returns
        /// <see cref="Icon"/> (which may be null).
        /// </summary>
        public virtual Sprite ResolveIcon() => Icon;

        [Header("Generation")]
        [Tooltip("Relative draw weight. Higher = offered more often. Rarer rewards use " +
                 "lower weights. Must be > 0.")]
        [Min(0.0001f)]
        public float Weight = 1f;

        /// <summary>
        /// Server-only: can this option validly be OFFERED to the given player right now?
        /// Lets the generator skip options that would be a no-op (e.g. a tower the player
        /// already owns). Default true; override when an option has prerequisites.
        /// </summary>
        public virtual bool IsValidFor(ulong clientId) => true;

        /// <summary>
        /// Server-only: apply this option's effect to the given player. Returns false if
        /// it could not be applied (caller treats as a no-op and logs).
        /// </summary>
        public abstract bool ServerApply(ulong clientId);
    }
}