using UnityEngine.TestTools;

/// <summary>
/// Represents an edge constraint between two vertices in the triangulation
/// </summary>
public class EdgeConstraint
{
    /// <summary>
    /// Index of the first end point of the constraint
    /// </summary>
    public int v1;
    
    /// <summary>
    /// Index of the second end point of the constraint
    /// </summary>
    public int v2;

    /// <summary>
    /// Index of the triangle prior to the edge crossing (v1 -> v2)
    /// </summary>
    public int t1;

    /// <summary>
    /// Index of the triangle after the edge crossing (v1 -> v2)
    /// </summary>
    public int t2;

    /// <summary>
    /// Index of the edge on the t1 side
    /// </summary>
    public int t1Edge;

    /// <summary>
    /// Creates a new edge constraint with the given end points
    /// </summary>
    public EdgeConstraint(int v1, int v2)
    {
        this.v1 = v1;
        this.v2 = v2;
        this.t1 = -1;
        this.t2 = -1;
    }

    /// <summary>
    /// Creates a new edge constraint and defines triangles on either side of the edge
    /// </summary>
    public EdgeConstraint(int v1, int v2, int triangle1, int triangle2, int edge1)
    {
        this.v1 = v1;
        this.v2 = v2;
        this.t1 = triangle1;
        this.t2 = triangle2;
        this.t1Edge = edge1;
    }

    public override bool Equals(object obj)
    {
        if (obj is EdgeConstraint)
        {
            var other = (EdgeConstraint)obj;
            return (this.v1 == other.v1 && this.v2 == other.v2) ||
                   (this.v1 == other.v2 && this.v2 == other.v1);
        }
        return false;
    }

    public override int GetHashCode()
    {
        return new { v1, v2 }.GetHashCode() + new { v2, v1 }.GetHashCode();
    }

    public static bool operator ==(EdgeConstraint lhs, EdgeConstraint rhs)
    {
        return lhs.Equals(rhs);
    }

    public static bool operator !=(EdgeConstraint lhs, EdgeConstraint rhs)
    {
        return !lhs.Equals(rhs);
    }

    [ExcludeFromCoverage]
    public override string ToString()
    {
        return $"Edge: T{t1}->T{t2} (V{v1}->V{v2})";
    }
}