using System;

namespace Nanomesh
{
    public partial class DecimateModifier
    {
        public class EdgeCollapse : IComparable<EdgeCollapse>, IEquatable<EdgeCollapse>
        {
            public int posA;
            public int posB;
            public Vector3 result;
            public double error;

            private double _weight = -1;

            public ref double Weight => ref _weight;

            public void SetWeight(double weight)
            {
                _weight = weight;
            }

            public EdgeCollapse(int posA, int posB)
            {
                this.posA = posA;
                this.posB = posB;
            }

            public override int GetHashCode()
            {
                unchecked
                {
                    return posA + posB;
                }
            }

            public override bool Equals(object obj)
            {
                return Equals((EdgeCollapse)obj);
            }

            public bool Equals(EdgeCollapse pc)
            {
                if (ReferenceEquals(pc, null))
                    return false;

                if (ReferenceEquals(this, pc))
                {
                    return true;
                }
                else
                {
                    return (posA == pc.posA && posB == pc.posB) || (posA == pc.posB && posB == pc.posA);
                }
            }

            public int CompareTo(EdgeCollapse other)
            {
                return error > other.error ? 1 : error < other.error ? -1 : 0;
            }

            public static bool operator >(EdgeCollapse x, EdgeCollapse y)
            {
                return x.error > y.error;
            }

            public static bool operator >=(EdgeCollapse x, EdgeCollapse y)
            {
                return x.error >= y.error;
            }

            public static bool operator <(EdgeCollapse x, EdgeCollapse y)
            {
                return x.error < y.error;
            }

            public static bool operator <=(EdgeCollapse x, EdgeCollapse y)
            {
                return x.error <= y.error;
            }

            public override string ToString()
            {
                return $"<A:{posA} B:{posB} error:{error} topology:{_weight}>";
            }
        }
    }
}