ModernUO/Projects/UOContent/Spells/Ninjitsu/SurpriseAttack.cs

using System;
using System.Collections.Generic;
using Server.SkillHandlers;

namespace Server.Spells.Ninjitsu
{
    public class SurpriseAttack : NinjaMove
    {
        private static readonly Dictionary<Mobile, SurpriseAttackInfo>
            m_Table = new();

        public override int BaseMana => 20;
        public override double RequiredSkill => Core.ML ? 60.0 : 30.0;

        public override TextDefinition AbilityMessage => new(1063128); // You prepare to surprise your prey.

        public override bool ValidatesDuringHit => false;

        public override bool Validate(Mobile from)
        {
            if (!from.Hidden || from.AllowedStealthSteps <= 0)
            {
                from.SendLocalizedMessage(1063087); // You must be in stealth mode to use this ability.
                return false;
            }

            return base.Validate(from);
        }

        public override bool OnBeforeSwing(Mobile attacker, Mobile defender)
        {
            var valid = Validate(attacker) && CheckMana(attacker, true);

            if (valid)
            {
                attacker.BeginAction<Stealth>();
                Timer.StartTimer(TimeSpan.FromSeconds(5.0), attacker.EndAction<Stealth>);
            }

            return valid;
        }

        public override void OnHit(Mobile attacker, Mobile defender, int damage)
        {
            // Validates before swing

            ClearCurrentMove(attacker);

            attacker.SendLocalizedMessage(1063129); // You catch your opponent off guard with your Surprise Attack!
            defender.SendLocalizedMessage(1063130); // Your defenses are lowered as your opponent surprises you!

            defender.FixedParticles(0x37B9, 1, 5, 0x26DA, 0, 3, EffectLayer.Head);

            attacker.RevealingAction();

            StopTimer(defender);

            var ninjitsu = attacker.Skills.Ninjitsu.Fixed;

            var malus = ninjitsu / 60 + (int)Tracking.GetStalkingBonus(attacker, defender);

            var info = new SurpriseAttackInfo(defender, malus);
            Timer.StartTimer(TimeSpan.FromSeconds(8.0), () => EndSurprise(info), out info._timerToken);

            m_Table[defender] = info;

            CheckGain(attacker);
        }

        public override void OnMiss(Mobile attacker, Mobile defender)
        {
            ClearCurrentMove(attacker);

            attacker.SendLocalizedMessage(1063161); // You failed to properly use the element of surprise.

            attacker.RevealingAction();
        }

        public static bool GetMalus(Mobile target, ref int malus)
        {
            if (!m_Table.TryGetValue(target, out var info))
            {
                return false;
            }

            malus = info.m_Malus;
            return true;
        }

        private static void StopTimer(Mobile m)
        {
            if (m_Table.Remove(m, out var info))
            {
                info._timerToken.Cancel();
            }
        }

        private static void EndSurprise(SurpriseAttackInfo info)
        {
            StopTimer(info.m_Target);
            info.m_Target.SendLocalizedMessage(1063131); // Your defenses have returned to normal.
        }

        private class SurpriseAttackInfo
        {
            public readonly int m_Malus;
            public readonly Mobile m_Target;
            public TimerExecutionToken _timerToken;

            public SurpriseAttackInfo(Mobile target, int effect)
            {
                m_Target = target;
                m_Malus = effect;
            }
        }
    }
}