using System;
using Server.Items;

namespace Server.Spells
{
    public abstract class MagerySpell : Spell
    {
        private static readonly int[] _manaTable = { 4, 6, 9, 11, 14, 20, 40, 50 };

        /*
         * Starts at Circle -2 to account for scrolls
         * Mana requirements formula: (14 * (circle - 1)) + 2 = 50% probability
         * Add or subtract 20 for max or min limits
         */
        private static readonly double[] _requiredSkill = Core.ML ?
            new[] { -46.0, -32.0, -18.0, -4.0, 10.0, 24.0, 38.0, 52.0, 66.0, 80.0 } :
            new[] { -50.0, -30.0, 0.0, 10.0, 20.0, 30.0, 40.0, 50.0, 60.0, 70.0 };

        public MagerySpell(Mobile caster, Item scroll, SpellInfo info) : base(caster, scroll, info)
        {
        }

        public abstract SpellCircle Circle { get; }

        public override TimeSpan CastDelayBase => TimeSpan.FromSeconds((3 + (int)Circle) * CastDelaySecondsPerTick);

        public override bool ConsumeReagents() =>
            base.ConsumeReagents() || ArcaneGem.ConsumeCharges(Caster, Core.SE ? 1 : 1 + (int)Circle);

        public override void GetCastSkills(out double min, out double max)
        {
            // Original RunUO algorithm for required skill
            // const double chanceOffset = 20.0
            // const double chanceLength = 100.0 / 7.0
            // var avg = chanceLength * circle;
            // min = avg - chanceOffset;
            // max = avg + chanceOffset;

            // Correct algorithm according to OSI for UOR/UOML
            // TODO: Verify this algorithm on OSI for latest expansion.
            min = _requiredSkill[(int)(Scroll == null ? Circle + 2 : Circle)];
            max = min + 40;
        }

        public override int GetMana() => Scroll is BaseWand ? 0 : _manaTable[(int)Circle];

        public override double GetResistSkill(Mobile m)
        {
            var circle = (int)Circle;

            var maxSkill = 1 + circle * 10 + (1 + circle / 6) * 25;

            if (m.Skills.MagicResist.Value < maxSkill)
            {
                m.CheckSkill(SkillName.MagicResist, 0.0, m.Skills.MagicResist.Cap);
            }

            return m.Skills.MagicResist.Value;
        }

        public virtual bool CheckResisted(Mobile target)
        {
            var n = GetResistPercent(target) / 100.0;

            if (n <= 0.0)
            {
                return false;
            }

            if (n >= 1.0)
            {
                return true;
            }

            // Even though this calculation matches AOS+, we don't combine with GetResistSkills because of an assumption
            // about how it is used.
            var circle = (int)Circle;
            var maxSkill = (1 + circle) * 10 + (1 + circle / 6) * 25;

            if (target.Skills.MagicResist.Value < maxSkill)
            {
                target.CheckSkill(SkillName.MagicResist, 0.0, target.Skills.MagicResist.Cap);
            }

            return n >= Utility.RandomDouble();
        }

        public virtual double GetResistPercentForCircle(Mobile target, SpellCircle circle)
        {
            var magicResist = target.Skills.MagicResist.Value;
            var firstPercent = magicResist / 5.0;
            var secondPercent = magicResist -
                                ((Caster.Skills[CastSkill].Value - 20.0) / 5.0 + (1 + (int)circle) * 5.0);

            // Seems should be about half of what stratics says.
            return (firstPercent > secondPercent ? firstPercent : secondPercent) / 2.0;
        }

        public virtual double GetResistPercent(Mobile target) => GetResistPercentForCircle(target, Circle);

        public override TimeSpan GetCastDelay()
        {
            if (!Core.ML && Scroll is BaseWand)
            {
                return TimeSpan.Zero;
            }

            if (!Core.AOS)
            {
                return TimeSpan.FromSeconds(0.5 + 0.25 * (int)Circle);
            }

            return base.GetCastDelay();
        }
    }
}