#region --- License ---
/*
Copyright (c) 2006 - 2008 The Open Toolkit library.

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
#endregion

using System;
using System.Runtime.InteropServices;
namespace OpenTK
{
    /// <summary>
    /// Defines a 2d box (rectangle).
    /// </summary>
    [StructLayout(LayoutKind.Sequential)]
    public struct Box2
    {
        /// <summary>
        /// The left boundary of the structure.
        /// </summary>
        public float Left;

        /// <summary>
        /// The right boundary of the structure.
        /// </summary>
        public float Right;

        /// <summary>
        /// The top boundary of the structure.
        /// </summary>
        public float Top;

        /// <summary>
        /// The bottom boundary of the structure.
        /// </summary>
        public float Bottom;

        /// <summary>
        /// Constructs a new Box2 with the specified dimensions.
        /// </summary>
        /// <param name="topLeft">An OpenTK.Vector2 describing the top-left corner of the Box2.</param>
        /// <param name="bottomRight">An OpenTK.Vector2 describing the bottom-right corner of the Box2.</param>
        public Box2(Vector2 topLeft, Vector2 bottomRight)
        {
            Left = topLeft.X;
            Top = topLeft.Y;
            Right = bottomRight.X;
            Bottom = bottomRight.Y;
        }

        /// <summary>
        /// Constructs a new Box2 with the specified dimensions.
        /// </summary>
        /// <param name="left">The position of the left boundary.</param>
        /// <param name="top">The position of the top boundary.</param>
        /// <param name="right">The position of the right boundary.</param>
        /// <param name="bottom">The position of the bottom boundary.</param>
        public Box2(float left, float top, float right, float bottom)
        {
            Left = left;
            Top = top;
            Right = right;
            Bottom = bottom;
        }

        /// <summary>
        /// Creates a new Box2 with the specified dimensions.
        /// </summary>
        /// <param name="top">The position of the top boundary.</param>
        /// <param name="left">The position of the left boundary.</param>
        /// <param name="right">The position of the right boundary.</param>
        /// <param name="bottom">The position of the bottom boundary.</param>
        /// <returns>A new OpenTK.Box2 with the specfied dimensions.</returns>
        public static Box2 FromTLRB(float top, float left, float right, float bottom)
        {
            return new Box2(left, top, right, bottom);
        }

        /// <summary>
        /// Creates a new Box2 with the specified dimensions.
        /// </summary>
        /// <param name="top">The position of the top boundary.</param>
        /// <param name="left">The position of the left boundary.</param>
        /// <param name="width">The width of the box.</param>
        /// <param name="height">The height of the box.</param>
        /// <returns>A new OpenTK.Box2 with the specfied dimensions.</returns>
        public static Box2 FromDimensions(float left, float top, float width, float height)
        {
            return new Box2(left, top, left + width, top + height);
        }

        /// <summary>
        /// Creates a new Box2 with the specified dimensions.
        /// </summary>
        /// <param name="position">The position of the top left corner.</param>
        /// <param name="size">The size of the box.</param>
        /// <returns>A new OpenTK.Box2 with the specfied dimensions.</returns>
        public static Box2 FromDimensions(Vector2 position, Vector2 size)
        {
            return FromDimensions(position.X, position.Y, size.X, size.Y);
        }

        /// <summary>
        /// Gets a float describing the width of the Box2 structure.
        /// </summary>
        public float Width { get { return (float)System.Math.Abs(Right - Left); } }

        /// <summary>
        /// Gets a float describing the height of the Box2 structure.
        /// </summary>
        public float Height { get { return (float)System.Math.Abs(Bottom - Top); } }

        /// <summary>
        /// Returns whether the box contains the specified point on the closed region described by this Box2.
        /// </summary>
        /// <param name="point">The point to query.</param>
        /// <returns>Whether this box contains the point.</returns>
        public bool Contains(Vector2 point)
        {
            return Contains(point, true);
        }

        /// <summary>
        /// Returns whether the box contains the specified point.
        /// </summary>
        /// <param name="point">The point to query.</param>
        /// <param name="closedRegion">Whether to include the box boundary in the test region.</param>
        /// <returns>Whether this box contains the point.</returns>
        public bool Contains(Vector2 point, bool closedRegion)
        {
            bool xOK = (closedRegion == Left <= Right) ?
                (point.X >= Left != point.X > Right) :
                (point.X > Left != point.X >= Right);

            bool yOK = (closedRegion == Top <= Bottom) ?
                (point.Y >= Top != point.Y > Bottom) :
                (point.Y > Top != point.Y >= Bottom);

            return xOK && yOK;
        }

        /// <summary>
        /// Returns a Box2 translated by the given amount.
        /// </summary>
        public Box2 Translated(Vector2 point)
        {
            return new Box2(Left + point.X, Top + point.Y, Right + point.X, Bottom + point.Y);
        }

        /// <summary>
        /// Translates this Box2 by the given amount.
        /// </summary>
        public void Translate(Vector2 point)
        {
            Left += point.X;
            Right += point.X;
            Top += point.Y;
            Bottom += point.Y;
        }

        /// <summary>
        /// Equality comparator.
        /// </summary>
        public static bool operator ==(Box2 left, Box2 right)
        {
            return left.Bottom == right.Bottom && left.Top == right.Top &&
                left.Left == right.Left && left.Right == right.Right;
        }

        /// <summary>
        /// Inequality comparator.
        /// </summary>
        public static bool operator !=(Box2 left, Box2 right)
        {
            return !(left == right);
        }

        /// <summary>
        /// Functional equality comparator.
        /// </summary>
        public bool Equals(Box2 other)
        {
            return this == other;
        }

        /// <summary>
        /// Implements Object.Equals.
        /// </summary>
        public override bool Equals(object obj)
        {
            return obj is Box2 && Equals((Box2) obj);
        }

        /// <summary>
        /// Gets the hash code for this Box2.
        /// </summary>
        /// <returns></returns>
        public override int GetHashCode()
        {
            return Left.GetHashCode() ^ Right.GetHashCode() ^ Top.GetHashCode() ^ Bottom.GetHashCode();
        }

        private static string listSeparator = System.Globalization.CultureInfo.CurrentCulture.TextInfo.ListSeparator;
        /// <summary>
        /// Returns a <see cref="System.String"/> describing the current instance.
        /// </summary>
        /// <returns></returns>
        public override string ToString()
        {
            return String.Format("({0}{4} {1}) - ({2}{4} {3})", Left, Top, Right, Bottom, listSeparator);
        }
    }
}