// -----------------------------------------------------------------------
// <copyright file="Size.cs" company="Steven Kirk">
// Copyright 2014 MIT Licence. See licence.md for more information.
// </copyright>
// -----------------------------------------------------------------------

namespace Perspex
{
    using System;
    using System.Globalization;

    /// <summary>
    /// Defines a size.
    /// </summary>
    public struct Size
    {
        /// <summary>
        /// A size representing infinity.
        /// </summary>
        public static readonly Size Infinity = new Size(double.PositiveInfinity, double.PositiveInfinity);

        /// <summary>
        /// The width.
        /// </summary>
        private double width;

        /// <summary>
        /// The height.
        /// </summary>
        private double height;

        /// <summary>
        /// Initializes a new instance of the <see cref="Size"/> structure.
        /// </summary>
        /// <param name="width">The width.</param>
        /// <param name="height">The height.</param>
        public Size(double width, double height)
        {
            this.width = width;
            this.height = height;
        }

        /// <summary>
        /// Gets the width.
        /// </summary>
        public double Width
        {
            get { return this.width; }
        }

        /// <summary>
        /// Gets the height.
        /// </summary>
        public double Height
        {
            get { return this.height; }
        }

        /// <summary>
        /// Checks for equality between two <see cref="Size"/>s.
        /// </summary>
        /// <param name="left">The first size.</param>
        /// <param name="right">The second size.</param>
        /// <returns>True if the sizes are equal; otherwise false.</returns>
        public static bool operator ==(Size left, Size right)
        {
            return left.width == right.width && left.height == right.height;
        }

        /// <summary>
        /// Checks for unequality between two <see cref="Size"/>s.
        /// </summary>
        /// <param name="left">The first size.</param>
        /// <param name="right">The second size.</param>
        /// <returns>True if the sizes are unequal; otherwise false.</returns>
        public static bool operator !=(Size left, Size right)
        {
            return !(left == right);
        }

        /// <summary>
        /// Scales a size.
        /// </summary>
        /// <param name="rect">The size</param>
        /// <param name="scale">The scaling factor.</param>
        /// <returns>The scaled size.</returns>
        public static Size operator *(Size size, Vector scale)
        {
            return new Size(size.width * scale.X, size.height * scale.Y);
        }

        /// <summary>
        /// Scales a size.
        /// </summary>
        /// <param name="rect">The size</param>
        /// <param name="scale">The scaling factor.</param>
        /// <returns>The scaled size.</returns>
        public static Size operator /(Size size, Vector scale)
        {
            return new Size(size.width / scale.X, size.height / scale.Y);
        }

        /// <summary>
        /// Constrains the size.
        /// </summary>
        /// <param name="constraint">The size to constrain to.</param>
        /// <returns>The constrained size.</returns>
        public Size Constrain(Size constraint)
        {
            return new Size(
                Math.Min(this.width, constraint.width),
                Math.Min(this.height, constraint.height));
        }

        /// <summary>
        /// Deflates the size by a <see cref="Thickness"/>.
        /// </summary>
        /// <param name="thickness">The thickness.</param>
        /// <returns>The deflated size.</returns>
        /// <remarks>The deflated size cannot be less than 0.</remarks>
        public Size Deflate(Thickness thickness)
        {
            return new Size(
                Math.Max(0, this.width - thickness.Left - thickness.Right),
                Math.Max(0, this.height - thickness.Top - thickness.Bottom));
        }

        public override bool Equals(object obj)
        {
            if (obj is Size)
            {
                var other = (Size)obj;
                return this.Width == other.Width && this.Height == other.Height;
            }

            return false;
        }

        public override int GetHashCode()
        {
            unchecked
            {
                int hash = 17;
                hash = (hash * 23) + this.Width.GetHashCode();
                hash = (hash * 23) + this.Height.GetHashCode();
                return hash;
            }
        }

        /// <summary>
        /// Inflates the size by a <see cref="Thickness"/>.
        /// </summary>
        /// <param name="thickness">The thickness.</param>
        /// <returns>The inflated size.</returns>
        public Size Inflate(Thickness thickness)
        {
            return new Size(
                this.width + thickness.Left + thickness.Right,
                this.height + thickness.Top + thickness.Bottom);
        }

        /// <summary>
        /// Returns a new <see cref="Size"/> with the same height and the specified width.
        /// </summary>
        /// <param name="width">The width.</param>
        /// <returns>The new <see cref="Size"/>.</returns>
        public Size WithWidth(double width)
        {
            return new Size(width, this.height);
        }

        /// <summary>
        /// Returns a new <see cref="Size"/> with the same width and the specified height.
        /// </summary>
        /// <param name="height">The height.</param>
        /// <returns>The new <see cref="Size"/>.</returns>
        public Size WithHeight(double height)
        {
            return new Size(this.width, height);
        }

        /// <summary>
        /// Returns the string representation of the size.
        /// </summary>
        /// <returns>The string representation of the size</returns>
        public override string ToString()
        {
            return string.Format(CultureInfo.InvariantCulture, "{0}, {1}", this.width, this.height);
        }
    }
}