// Assets/_Project/Scripts/Gameplay/WaveDefinition.cs
using System;
using UnityEngine;

namespace TD.Gameplay
{
    /// <summary>
    /// A single spawn group within a wave: one enemy type and how many of them.
    /// </summary>
    [Serializable]
    public struct WaveEntry
    {
        [Tooltip("The enemy type to spawn for this group.")]
        public EnemyDefinition EnemyType;

        [Tooltip("How many enemies of this type to spawn.")]
        public int Count;
    }

    /// <summary>
    /// Defines the composition of a single wave. One asset per wave; referenced in
    /// order by <see cref="WaveManager.waveDefinitions"/>.
    /// </summary>
    /// <remarks>
    /// Entries are processed in array order. Multiple entries let designers mix enemy
    /// types within one wave (e.g. 10 fast scouts followed by 3 armoured brutes).
    /// All enemies spawn held at wave start; they are released in 10% chunks separated
    /// by <see cref="ReleaseInterval"/> seconds. The wave is not complete until all
    /// enemies are dead or have leaked.
    /// </remarks>
    [CreateAssetMenu(fileName = "WaveDefinition", menuName = "TD/Wave Definition", order = 4)]
    public class WaveDefinition : ScriptableObject
    {
        [Tooltip("Seconds between the wave-number advancing (start of prep) and the " +
                 "first enemies becoming visible. Gives players time to build before the horde appears.")]
        public float PrepTime = 10f;

        [Tooltip("Seconds between each chunk release. All enemies spawn held at wave " +
                 "start and are released 10% at a time on this interval.")]
        public float ReleaseInterval = 2f;

        [Tooltip("Enemy groups that make up this wave. Processed in order.")]
        public WaveEntry[] Entries;

        /// <summary>
        /// The enemy type this wave is "about" — the first assigned entry's type. Null if the
        /// wave has no usable entries.
        /// </summary>
        /// <remarks>
        /// The 2.0 design gives each wave a single enemy type, and enemy upgrades are keyed to a
        /// wave slot, so this is the identity the phase draw uses to keep slots distinct and the
        /// HUD uses to label an upcoming wave. <see cref="Entries"/> still supports multiple
        /// groups (useful for staggering counts of the same type), but mixing <i>types</i> within
        /// one wave makes this ambiguous — see <see cref="HasSingleEnemyType"/>.
        /// </remarks>
        public EnemyDefinition PrimaryEnemyType
        {
            get
            {
                if (Entries == null) return null;
                foreach (var e in Entries)
                {
                    if (e.EnemyType != null && e.Count > 0) return e.EnemyType;
                }
                return null;
            }
        }

        /// <summary>
        /// True if every usable entry in this wave spawns the same enemy type. False means
        /// <see cref="PrimaryEnemyType"/> is only telling part of the story — the run validator
        /// warns on these rather than rejecting them, since a mixed wave still plays fine, it
        /// just labels and upgrades oddly.
        /// </summary>
        public bool HasSingleEnemyType
        {
            get
            {
                var first = PrimaryEnemyType;
                if (first == null) return false;
                foreach (var e in Entries)
                {
                    if (e.EnemyType != null && e.Count > 0 && e.EnemyType != first) return false;
                }
                return true;
            }
        }

        /// <summary>Total enemies spawned per zone by this wave, across all entries.</summary>
        /// <remarks>
        /// Also the divisor for the encounter's health budget — see
        /// <see cref="EnemyScalingConfig.ResolvePerEnemyHp"/>. That makes count a <i>texture</i>
        /// knob rather than a difficulty one: a wave of 8 spawns eight tanks, a wave of 150 spawns
        /// a fragile swarm, and both present the same total health for their slot in the run.
        /// </remarks>
        public int TotalEnemyCount
        {
            get
            {
                if (Entries == null) return 0;
                int total = 0;
                foreach (var e in Entries)
                {
                    if (e.EnemyType != null && e.Count > 0) total += e.Count;
                }
                return total;
            }
        }
    }
}