using System;
using System.Collections.Generic;
using Server.Targeting;

namespace Server.Spells.Mysticism
{
  public class SpellPlagueSpell : MysticSpell
  {
    private static SpellInfo m_Info = new SpellInfo(
      "Spell Plague", "Vas Rel Jux Ort",
      -1,
      9002,
      Reagent.DaemonBone,
      Reagent.DragonsBlood,
      Reagent.Nightshade,
      Reagent.SulfurousAsh
    );

    private static Dictionary<Mobile, SpellPlagueContext> m_Table = new Dictionary<Mobile, SpellPlagueContext>();

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

    public override TimeSpan CastDelayBase => TimeSpan.FromSeconds(2.25);

    public override double RequiredSkill => 70.0;
    public override int RequiredMana => 40;

    public static void Initialize()
    {
      EventSink.PlayerDeath += OnPlayerDeath;
    }

    public override void OnCast()
    {
      Caster.Target = new InternalTarget(this);
    }

    public void Target(Mobile targeted)
    {
      if (!Caster.CanSee(targeted))
      {
        Caster.SendLocalizedMessage(500237); // Target can not be seen.
      }
      else if (CheckHSequence(targeted))
      {
        SpellHelper.Turn(Caster, targeted);

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

        /* 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(targeted);

        int damage = GetNewAosDamage(33, 1, 5, targeted);
        SpellHelper.Damage(this, targeted, damage, 0, 0, 0, 0, 0);

        SpellPlagueContext context = new SpellPlagueContext(this, targeted);

        if (m_Table.TryGetValue(targeted, out SpellPlagueContext oldContext))
          oldContext.SetNext(context);
        else
        {
          m_Table[targeted] = context;
          context.Start();
        }
      }

      FinishSequence();
    }

    public static bool UnderEffect(Mobile m)
    {
      return m_Table.ContainsKey(m);
    }

    public static void RemoveEffect(Mobile m)
    {
      if (m_Table.TryGetValue(m, out SpellPlagueContext context))
        context.EndPlague(false);
    }

    public static void CheckPlague(Mobile m)
    {
      if (m_Table.TryGetValue(m, out SpellPlagueContext context))
        context.OnDamage();
    }

    private static void OnPlayerDeath(PlayerDeathEventArgs e)
    {
      RemoveEffect(e.Mobile);
    }

    protected 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 SpellPlagueContext
    {
      private int m_Explosions;
      private DateTime m_LastExploded;
      private SpellPlagueContext m_Next;
      private SpellPlagueSpell m_Owner;
      private Mobile m_Target;
      private Timer m_Timer;

      public SpellPlagueContext(SpellPlagueSpell owner, Mobile target)
      {
        m_Owner = owner;
        m_Target = target;
      }

      public void SetNext(SpellPlagueContext context)
      {
        if (m_Next == null)
          m_Next = context;
        else
          m_Next.SetNext(context);
      }

      public void Start()
      {
        m_Timer = Timer.DelayCall(TimeSpan.FromSeconds(8.0), EndPlague);
        m_Timer.Start();

        BuffInfo.AddBuff(m_Target,
          new BuffInfo(BuffIcon.SpellPlague, 1031690, 1080167, TimeSpan.FromSeconds(8.5), m_Target));
      }

      public void OnDamage()
      {
        if (DateTime.Now > m_LastExploded + TimeSpan.FromSeconds(2.0))
        {
          int exploChance = 90 - m_Explosions * 30;

          double resist = m_Target.Skills.MagicResist.Value;

          if (resist >= 70)
            exploChance -= (int)((resist - 70.0) * 3.0 / 10.0);

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

            int damage = m_Owner.GetNewAosDamage(15 + m_Explosions * 3, 1, 5, m_Target);

            m_Explosions++;
            m_LastExploded = DateTime.Now;

            SpellHelper.Damage(m_Owner, m_Target, damage, 0, 0, 0, 0, 0, 100);

            if (m_Explosions >= 3)
              EndPlague();
          }
        }
      }

      private void EndPlague()
      {
        EndPlague(true);
      }

      public void EndPlague(bool restart)
      {
        m_Timer?.Stop();

        if (restart && m_Next != null)
        {
          m_Table[m_Target] = m_Next;
          m_Next.Start();
        }
        else
        {
          m_Table.Remove(m_Target);

          BuffInfo.RemoveBuff(m_Target, BuffIcon.SpellPlague);
        }
      }
    }

    private class InternalTarget : Target
    {
      private SpellPlagueSpell m_Owner;

      public InternalTarget(SpellPlagueSpell owner)
        : base(12, false, TargetFlags.Harmful)
      {
        m_Owner = owner;
      }

      protected override void OnTarget(Mobile from, object o)
      {
        if (o is Mobile mobile)
          m_Owner.Target(mobile);
      }

      protected override void OnTargetFinish(Mobile from)
      {
        m_Owner.FinishSequence();
      }
    }
  }
}