using UnityEngine;
using TD.Core;

namespace TD.Towers
{
    /// <summary>
    /// Data definition for a single tower type. One asset per tower type; shared across all
    /// instances of that tower in a match. Consumed by tower placement, construction, and
    /// (eventually) combat systems.
    /// </summary>
    /// <remarks>
    /// TowerDefinitions are authored as ScriptableObject assets and referenced by
    /// <see cref="RaceDefinition"/> (tower roster) and <see cref="TowerInstance"/> (which
    /// definition this placed tower corresponds to). Clients load the full asset locally
    /// from the project's ScriptableObject pool; only the asset reference (not the full data)
    /// is replicated over the network.
    ///
    /// Fields marked STUBBED are defined here to lock in the data shape but are not yet
    /// consumed by any runtime system. They will be wired in during the sessions noted.
    /// </remarks>
    [CreateAssetMenu(fileName = "TowerDefinition", menuName = "TD/Tower Definition", order = 2)]
    public class TowerDefinition : ScriptableObject
    {
        // -------------------------------------------------------------------
        // Identity
        // -------------------------------------------------------------------

        [Header("Identity")]
        [Tooltip("Human-readable name shown in the HUD tower grid and context panel.")]
        public string DisplayName;

        [Tooltip("Short description shown in the HUD context panel when this tower is selected.")]
        [TextArea(2, 4)]
        public string Description;

        // -------------------------------------------------------------------
        // Placement
        // -------------------------------------------------------------------

        [Header("Placement")]
        [Tooltip("Footprint size in tiles. Default 2×2. The anchor tile is the south-west corner " +
                 "of the footprint (minimum x, minimum y). Every tile in the footprint must be " +
                 "Buildable and owned by the placing player for placement to succeed.")]
        public Vector2Int FootprintSize = new Vector2Int(2, 2);

        [Tooltip("Gold cost to place this tower. Deducted from the placing player's pool on " +
                 "successful server-side placement validation.")]
        public int GoldCost;

        // -------------------------------------------------------------------
        // Construction
        // -------------------------------------------------------------------

        [Header("Construction")]
        [Tooltip("STUBBED — not consumed until Path D (Builder system). " +
                 "Time in seconds from construction start to tower becoming active. " +
                 "A Builder must be within build range for construction to proceed. " +
                 "Set to 0 for instant construction (placeholder behaviour during Path B testing).")]
        public float BuildTime = 0f;

        // -------------------------------------------------------------------
        // Visuals
        // -------------------------------------------------------------------

        [Header("Visuals")]
        [Tooltip("Prefab instantiated in the world when this tower is placed. Must have a " +
                 "TowerInstance component at its root. During Path B this is a colored cube; " +
                 "replace with a real mesh when art is available.")]
        public GameObject TowerPrefab;

        // -------------------------------------------------------------------
        // Combat
        // -------------------------------------------------------------------

        [Header("Combat — Targeting")]
        [Tooltip("How the tower's damage is typed. Determines lingering effects and enemy " +
                 "resistance/weakness interactions.")]
        public DamageType DamageType;

        [Tooltip("Which enemy in range the tower prioritizes.")]
        public TargetPriority TargetPriority;

        [Tooltip("How damage is distributed: Single (one enemy), Splash (primary + radius), " +
                 "Chain (primary then N nearest neighbours).")]
        public TargetType TargetType;

        [Tooltip("When true, this tower can only target grounded enemies. " +
                 "Default false = targets both grounded and flying units.")]
        public bool GroundedOnly;

        [Header("Combat — Attack")]
        [Tooltip("Damage dealt per hit to the primary target, before resistances.")]
        public float Damage;

        [Tooltip("Attack range in world units. Enemies within this radius are targetable. " +
                 "Displayed as a translucent decal circle when the tower is selected.")]
        public float Range;

        [Tooltip("Attacks per second.")]
        public float FireRate;

        [Header("Combat — Area")]
        [Tooltip("Radius of splash damage around the primary impact point. " +
                 "Only used when TargetType = Splash.")]
        public float SplashRadius;

        [Tooltip("Number of additional enemies damage chains to after the primary target. " +
                 "Only used when TargetType = Chain.")]
        public int ChainCount;

        [Tooltip("Maximum world-unit distance each chain jump can travel. " +
                 "Only used when TargetType = Chain.")]
        public float ChainRange;

        [Header("Combat — Effects")]
        [Tooltip("For Cold towers: fraction of movement speed retained on hit. " +
                 "1.0 = no slow, 0.5 = half speed. Ignored for other damage types.")]
        [Range(0f, 1f)]
        public float SlowFactor = 1f;

        [Tooltip("For Fire / Poison towers: damage per second applied as a damage-over-time tick. " +
                 "Ignored for other damage types.")]
        public float DotDamagePerSecond;

        [Tooltip("Duration in seconds that any lingering effect (slow, burn, poison) persists " +
                 "after the hit. 0 = no lingering effect.")]
        public float EffectDuration;

        [Header("Combat — Projectile")]
        [Tooltip("Prefab fired at targets. Must have a Projectile component, NetworkObject, " +
                 "and NetworkTransform at its root. Null = hitscan (instant hit, no travel).")]
        public GameObject ProjectilePrefab;

        [Tooltip("World-units per second the projectile travels. Ignored when ProjectilePrefab is null.")]
        public float ProjectileSpeed = 10f;

        // -------------------------------------------------------------------
        // Upgrades
        // -------------------------------------------------------------------

        [Header("Upgrades")]
        [Tooltip("Tower definitions this tower can upgrade into. Leave empty for no upgrades. " +
                 "Multiple entries create branching paths — the player chooses one.")]
        public TowerDefinition[] UpgradePaths;
    }
}