ModernUO/Projects/UOContent/Spells/Mysticism/SpellPlagueSpell.cs

using System;
using System.Collections.Generic;
using ModernUO.CodeGeneratedEvents;
using Server.Mobiles;
using Server.Targeting;

namespace Server.Spells.Mysticism;

public class SpellPlagueSpell : MysticSpell, ITargetingSpell<Mobile>
{
    private static readonly SpellInfo _info = new(
        "Spell Plague",
        "Vas Rel Jux Ort",
        -1,
        9002,
        Reagent.DaemonBone,
        Reagent.DragonsBlood,
        Reagent.Nightshade,
        Reagent.SulfurousAsh
    );

    private static readonly Dictionary<Mobile, SpellPlagueTimer> _table = new();

    public SpellPlagueSpell(Mobile caster, Item scroll = null) : base(caster, scroll, _info)
    {
    }

    public override SpellCircle Circle => SpellCircle.Seventh;

    public override void OnCast()
    {
        Caster.Target = new SpellTarget<Mobile>(this, TargetFlags.Harmful);
    }

    public void Target(Mobile m)
    {
        if (CheckHSequence(m))
        {
            SpellHelper.Turn(Caster, m);

            SpellHelper.CheckReflect(6, Caster, ref m);

            /* The target is hit with an explosion of chaos damage and then inflicted
             * with the spell plague curse. Each time the target is damaged while under
             * the effect of the spell plague, they may suffer an explosion of chaos
             * damage. The initial chance to trigger the explosion starts at 90% and
             * reduces by 30% every time an explosion occurs. Once the target is
             * afflicted by 3 explosions or 8 seconds have passed, that spell plague
             * is removed from the target. Spell Plague will stack with other spell
             * plagues so that they are applied one after the other.
             */

            VisualEffect(m);

            // Before Time of Legends, SDI was not applied to initial damage.
            var damage = GetNewAosDamage(33, 1, 5, Core.TOL, m);
            SpellHelper.Damage(this, m, damage, 0, 0, 0, 0, 0);

            var timer = new SpellPlagueTimer(this, m);

            if (_table.TryGetValue(m, out var oldtimer))
            {
                oldtimer.SetNext(timer);
            }
            else
            {
                _table[m] = timer;
                timer.StartPlague();
            }
        }
    }

    public static bool UnderEffect(Mobile m) => _table.ContainsKey(m);

    [OnEvent(nameof(PlayerMobile.PlayerDeathEvent))]
    public static bool RemoveEffect(Mobile m)
    {
        if (_table.Remove(m, out var timer))
        {
            timer.Stop();
            BuffInfo.RemoveBuff(m, BuffIcon.SpellPlague);
            return true;
        }

        return false;
    }

    public static void OnMobileDamaged(Mobile m)
    {
        if (m != null && _table.TryGetValue(m, out var context))
        {
            context.OnDamage();
        }
    }

    private static void VisualEffect(Mobile to)
    {
        to.PlaySound(0x658);

        to.FixedParticles(0x3728, 1, 13, 0x26B8, 0x47E, 7, EffectLayer.Head, 0);
        to.FixedParticles(0x3779, 1, 15, 0x251E, 0x43, 7, EffectLayer.Head, 0);
    }

    private class SpellPlagueTimer : Timer
    {
        private readonly SpellPlagueSpell _owner;
        private readonly Mobile _target;
        private int _explosions;
        private DateTime _nextExplosion;
        private SpellPlagueTimer _next;

        public SpellPlagueTimer(SpellPlagueSpell owner, Mobile target) : base(TimeSpan.FromSeconds(8.0))
        {
            _owner = owner;
            _target = target;
        }

        public void SetNext(SpellPlagueTimer timer)
        {
            if (_next == null)
            {
                _next = timer;
            }
            else
            {
                _next.SetNext(timer);
            }
        }

        public void StartPlague()
        {
            BuffInfo.AddBuff(
                _target,
                new BuffInfo(BuffIcon.SpellPlague, 1031690, 1080167, TimeSpan.FromSeconds(8.5), _target)
            );

            _nextExplosion = Core.Now + TimeSpan.FromSeconds(1);
            Start();
        }

        public void OnDamage()
        {
            if (Core.Now < _nextExplosion)
            {
                return;
            }

            var exploChance = 90 - _explosions * 30;

            var resist = _target.Skills.MagicResist.Fixed - 700;

            if (resist > 0)
            {
                exploChance -= resist / 100 * 3;
            }

            if (exploChance > Utility.Random(100))
            {
                VisualEffect(_target);

                var damage = _owner.GetNewAosDamage(15 + _explosions * 3, 1, 5, false, _target);

                _explosions++;
                _nextExplosion = Core.Now + TimeSpan.FromSeconds(1);

                SpellHelper.Damage(_owner, _target, damage, 0, 0, 0, 0, 0, 100);

                if (_explosions >= 3)
                {
                    DoNextPlague();
                }
            }
        }

        protected override void OnTick() => DoNextPlague();

        private void DoNextPlague()
        {
            if (_next != null)
            {
                _table[_target] = _next;
                _next.StartPlague();
            }
            else
            {
                _table.Remove(_target);
                BuffInfo.RemoveBuff(_target, BuffIcon.SpellPlague);
            }

            _next = null;
            Stop();
        }
    }
}