using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using UnityEngine;

namespace TransportGame.Model
{
    public struct Vector2
    {
        /// <summary>
        /// Zero vector
        /// </summary>
        public static readonly Vector2 Zero = new Vector2(0, 0);

        /// <summary>
        /// Unit vector
        /// </summary>
        public static readonly Vector2 Unit = new Vector2(1, 0);

        /// <summary>
        /// Gets the X component
        /// </summary>
        public float X { get; private set; }

        /// <summary>
        /// Gets the Y component
        /// </summary>
        public float Y { get; private set; }

        /// <summary>
        /// Initializes a vector2
        /// </summary>
        /// <param name="x">X component</param>
        /// <param name="y">Y component</param>
        public Vector2(float x, float y)
            : this()
        {
            X = x;
            Y = y; 
        }

        /// <summary>
        /// Gets the length of the vector
        /// </summary>
        public float Length
        {
            get
            {
                return (float)Math.Sqrt(LengthSq);
            }
        }

        /// <summary>
        /// Gets the length of the vector squared
        /// </summary>
        public float LengthSq
        {
            get
            {
                return X * X + Y * Y;
            }
        }

        /// <summary>
        /// Gets the normalized vector
        /// </summary>
        /// <returns>Normalized vector</returns>
        public Vector2 Normalized
        {
            get
            {
                float len = Length;
                return new Vector2(X / len, Y / len);
            }
        }

        /// <summary>
        /// Rotates vector by given number of radians
        /// </summary>
        /// <param name="radians"></param>
        /// <returns></returns>
        public Vector2 Rotate(float radians)
        {
            float sin = (float)Math.Sin(radians);
            float cos = (float)Math.Cos(radians);

            return new Vector2(X * cos - Y * sin, X * sin + Y * cos);
        }

        /// <summary>
        /// Rotates vector by given number of degrees
        /// </summary>
        /// <param name="degrees"></param>
        /// <returns></returns>
        public Vector2 RotateDeg(float degrees)
        {
            return Rotate(degrees * (float)Math.PI / 180f);
        }

        /// <summary>
        /// Sum operator
        /// </summary>
        /// <param name="a">First vector</param>
        /// <param name="b">Second vector</param>
        /// <returns>Result of addition</returns>
        public static Vector2 operator +(Vector2 a, Vector2 b)
        {
            return new Vector2(a.X + b.X, a.Y + b.Y);
        }

        /// <summary>
        /// Subtract operator
        /// </summary>
        /// <param name="a">First vector</param>
        /// <param name="b">Second vector</param>
        /// <returns>Result of subtraction</returns>
        public static Vector2 operator -(Vector2 a, Vector2 b)
        {
            return new Vector2(a.X - b.X, a.Y - b.Y);
        }

        /// <summary>
        /// Multiply by constant
        /// </summary>
        /// <param name="a">Vector</param>
        /// <param name="c">Constant</param>
        /// <returns>Result</returns>
        public static Vector2 operator *(Vector2 a, float c)
        {
            return new Vector2(a.X * c, a.Y * c);
        }

        /// <summary>
        /// Multiply by constant
        /// </summary>
        /// <param name="c">Constant</param>
        /// <param name="a">Vector</param>
        /// <returns>Result</returns>
        public static Vector2 operator *(float c, Vector2 a)
        {
            return new Vector2(a.X * c, a.Y * c);
        }

        /// <summary>
        /// Divide by constant
        /// </summary>
        /// <param name="a">Vector</param>
        /// <param name="c">Constant</param>
        /// <returns>Result</returns>
        public static Vector2 operator /(Vector2 a, float c)
        {
            return new Vector2(a.X / c, a.Y / c);
        }

        /// <summary>
        /// Equality operator
        /// </summary>
        /// <param name="a">First vector</param>
        /// <param name="b">Second vector</param>
        /// <returns>True if vectors are equal</returns>
        public static bool operator ==(Vector2 a, Vector2 b)
        {
            return a.X == b.X && a.Y == b.Y;
        }
        /// <summary>
        /// Inequality operator
        /// </summary>
        /// <param name="a">First vector</param>
        /// <param name="b">Second vector</param>
        /// <returns>True if vectors are not equal</returns>
        public static bool operator !=(Vector2 a, Vector2 b)
        {
            return a.X != b.X || a.Y != b.Y;
        }

        /// <summary>
        /// Calculates dot product of two vectors
        /// </summary>
        /// <param name="a">First vector</param>
        /// <param name="b">Second vector</param>
        /// <returns>Dot product</returns>
        public static float Dot(Vector2 a, Vector2 b)
        {
            return a.X * b.X + a.Y * b.Y;
        }

        /// <summary>
        /// Gets the vector corresponding with specified angle (in radians)
        /// </summary>
        /// <param name="rads">Radians</param>
        /// <returns>Vector</returns>
        public static Vector2 FromRadians(float rads)
        {
            return new Vector2((float)Math.Cos(rads), (float)Math.Sin(rads));
        }

        /// <summary>
        /// Gets the vector corresponding with specified angle (in degrees)
        /// </summary>
        /// <param name="degs">Degrees</param>
        /// <returns>Vector</returns>
        public static Vector2 FromDegrees(float degs)
        {
            float rads = (degs * (float)Math.PI / 180f);
            return FromRadians(rads);
        }

        public override string ToString()
        {
            return String.Format("({0}, {1})", X, Y);
        }

        public override bool Equals(object obj)
        {
            if (obj is Vector2)
            {
                Vector2 other = (Vector2)obj;
                return X == other.X && Y == other.Y;
            }

            return false;
        }

        public override int GetHashCode()
        {
            return X.GetHashCode() * 7 + Y.GetHashCode();
        }
    }
}