using NeonSprawl.Server.Game.PositionState;
using NeonSprawl.Server.Game.World;

namespace NeonSprawl.Server.Game.Npc;

/// <summary>Deterministic prototype aggro acquire and leash-clear rules (NEO-92).</summary>
public static class AggroOperations
{
    /// <summary>
    /// Sets aggro holder to <paramref name="playerId"/> when the NPC row is empty.
    /// Returns <c>true</c> only when holder was empty and is now set.
    /// </summary>
    public static bool TryAcquire(string npcInstanceId, string playerId, IThreatStateStore threatStore)
    {
        var npcKey = NormalizeId(npcInstanceId);
        var playerKey = NormalizeId(playerId);
        if (npcKey.Length == 0 || playerKey.Length == 0 || !PrototypeNpcRegistry.TryGet(npcKey, out _))
        {
            return false;
        }

        if (!threatStore.TryGet(npcKey, out var current))
        {
            return false;
        }

        if (!string.IsNullOrEmpty(current.AggroHolderPlayerId))
        {
            return false;
        }

        return threatStore.TrySetHolder(npcKey, playerKey);
    }

    /// <summary>
    /// Clears aggro on every prototype NPC instance where <paramref name="playerId"/> is holder
    /// and horizontal distance from the NPC anchor exceeds catalog <c>leashRadius</c>.
    /// </summary>
    public static void TryClearOnLeashForPlayer(
        string playerId,
        IPositionStateStore positions,
        INpcBehaviorDefinitionRegistry behaviorRegistry,
        IThreatStateStore threatStore)
    {
        var playerKey = NormalizeId(playerId);
        if (playerKey.Length == 0 || !positions.TryGetPosition(playerKey, out var playerSnap))
        {
            return;
        }

        foreach (var npcInstanceId in PrototypeNpcRegistry.GetInstanceIdsInOrder())
        {
            TryClearOnLeashForNpc(
                npcInstanceId,
                playerKey,
                in playerSnap,
                behaviorRegistry,
                threatStore);
        }
    }

    /// <summary>Clears aggro for one NPC when the holder is outside that NPC's leash radius.</summary>
    public static void TryClearOnLeashForNpc(
        string npcInstanceId,
        string playerIdLowercase,
        in PositionSnapshot playerSnap,
        INpcBehaviorDefinitionRegistry behaviorRegistry,
        IThreatStateStore threatStore)
    {
        var npcKey = NormalizeId(npcInstanceId);
        if (npcKey.Length == 0 ||
            !PrototypeNpcRegistry.TryGet(npcKey, out var entry) ||
            !threatStore.TryGet(npcKey, out var threat) ||
            string.IsNullOrEmpty(threat.AggroHolderPlayerId) ||
            !string.Equals(threat.AggroHolderPlayerId, playerIdLowercase, StringComparison.Ordinal))
        {
            return;
        }

        if (!behaviorRegistry.TryGetDefinition(entry.BehaviorDefId, out var behavior))
        {
            return;
        }

        var distance = HorizontalReach.HorizontalDistance(
            playerSnap.X,
            playerSnap.Z,
            entry.X,
            entry.Z);

        if (distance > behavior.LeashRadius)
        {
            threatStore.TryClearHolder(npcKey);
        }
    }

    /// <summary>Clears aggro holders on all prototype NPC instances (dev fixture).</summary>
    public static void ClearAllPrototypeHolders(IThreatStateStore threatStore)
    {
        foreach (var npcInstanceId in PrototypeNpcRegistry.GetInstanceIdsInOrder())
        {
            threatStore.TryClearHolder(npcInstanceId);
        }
    }

    private static string NormalizeId(string? raw) =>
        raw?.Trim().ToLowerInvariant() ?? string.Empty;
}