using System;

namespace Gwen
{
    /// <summary>
    /// Represents inner spacing.
    /// </summary>
    public struct Padding : IEquatable<Padding>
    {
        public readonly int Top;
        public readonly int Bottom;
        public readonly int Left;
        public readonly int Right;

        // common values
        public static Padding Zero = new Padding(0, 0, 0, 0);
        public static Padding One = new Padding(1, 1, 1, 1);
        public static Padding Two = new Padding(2, 2, 2, 2);
        public static Padding Three = new Padding(3, 3, 3, 3);
        public static Padding Four = new Padding(4, 4, 4, 4);
        public static Padding Five = new Padding(5, 5, 5, 5);

        public Padding(int left, int top, int right, int bottom)
        {
            Top = top;
            Bottom = bottom;
            Left = left;
            Right = right;
        }

        public bool Equals(Padding other)
        {
            return other.Top == Top && other.Bottom == Bottom && other.Left == Left && other.Right == Right;
        }

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

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

        public override bool Equals(object obj)
        {
            if (ReferenceEquals(null, obj)) return false;
            if (obj.GetType() != typeof (Padding)) return false;
            return Equals((Padding) obj);
        }

        public override int GetHashCode()
        {
            unchecked
            {
                int result = Top;
                result = (result*397) ^ Bottom;
                result = (result*397) ^ Left;
                result = (result*397) ^ Right;
                return result;
            }
        }
    }
}