using System;

namespace LinearAlgebra {

    public struct Vector2Int {
        public int horizontal;
        public int vertical;

        public Vector2Int(int horizontal, int vertical) {
            this.horizontal = horizontal;
            this.vertical = vertical;
        }

        /// <summary>
        /// A vector with zero for all axis
        /// </summary>
        public static readonly Vector2Int zero = new(0, 0);
        /// <summary>
        /// A vector with values (1, 1)
        /// </summary>
        public static readonly Vector2Int one = new(1, 1);
        /// <summary>
        /// A vector with values (0, 1)
        /// </summary>
        public static readonly Vector2Int up = new(0, 1);
        /// <summary>
        /// A vector with values (0, -1)
        /// </summary>
        public static readonly Vector2Int down = new(0, -1);
        /// <summary>
        /// A vector with values (0, 1)
        /// </summary>
        public static readonly Vector2Int forward = new(0, 1);
        /// <summary>
        /// A vector with values (0, -1)
        /// </summary>
        public static readonly Vector2Int back = new(0, -1);
        /// <summary>
        /// A vector3 with values (-1, 0)
        /// </summary>
        public static readonly Vector2Int left = new(-1, 0);
        /// <summary>
        /// A vector with values (1, 0)
        /// </summary>
        public static readonly Vector2Int right = new(1, 0);

        /*
        /// <summary>
        /// Get an hash code for the vector
        /// </summary>
        /// <returns>The hash code</returns>
        public override int GetHashCode() {
            return (this.horizontal, this.vertical).GetHashCode();
        }

        /// <summary>
        /// Tests if the vector has equal values as the given vector
        /// </summary>
        /// <param name="v1">The vector to compare to</param>
        /// <returns><em>true</em> if the vector values are equal</returns>
        public readonly bool Equals(Vector2Int v) => this.horizontal == v.horizontal && vertical == v.vertical;

        */

        /// <summary>
        /// Tests if the two vectors have equal values
        /// </summary>
        /// <param name="v1">The first vector</param>
        /// <param name="v2">The second vector</param>
        /// <returns><em>true</em>when the vectors have equal values</returns>
        /// Note that this uses a Float equality check which cannot be not exact in all cases.
        /// In most cases it is better to check if the Vector2.Distance between the vectors is smaller than Float.epsilon
        /// Or more efficient: (v1 - v2).sqrMagnitude < Float.sqrEpsilon
        public static bool operator ==(Vector2Int v1, Vector2Int v2) {
            return (v1.horizontal == v2.horizontal && v1.vertical == v2.vertical);
        }
        /// <summary>
        /// Tests if two vectors have different values
        /// </summary>
        /// <param name="v1">The first vector</param>
        /// <param name="v2">The second vector</param>
        /// <returns><em>true</em>when the vectors have different values</returns>
        /// Note that this uses a Float equality check which cannot be not exact in all case.
        /// In most cases it is better to check if the Vector2.Distance between the vectors is smaller than Float.epsilon.
        /// Or more efficient: (v1 - v2).sqrMagnitude < Float.sqrEpsilon
        public static bool operator !=(Vector2Int v1, Vector2Int v2) {
            return (v1.horizontal != v2.horizontal || v1.vertical != v2.vertical);
        }

        /// <summary>
        /// Tests if the vector is equal to the given object
        /// </summary>
        /// <param name="obj">The object to compare to</param>
        /// <returns><em>false</em> when the object is not a Vector2 or does not have equal values</returns>
        public override readonly bool Equals(object obj) {
            if (obj is not Vector2Int v)
                return false;

            return (this.horizontal == v.horizontal && this.vertical == v.vertical);
        }

        /// <summary>
        /// Get an hash code for the vector
        /// </summary>
        /// <returns>The hash code</returns>
        public override readonly int GetHashCode() {
            return HashCode.Combine(horizontal, vertical);
        }

        public readonly float sqrMagnitude => this.horizontal * this.horizontal + this.vertical * this.vertical;

        public static float SqrMagnitudeOf(Vector2Int v) {
            return v.sqrMagnitude;
        }

        public readonly float magnitude =>
                MathF.Sqrt(this.horizontal * this.horizontal + this.vertical * this.vertical);

        public static float MagnitudeOf(Vector2Int v) {
            return v.magnitude;
        }

        /// @brief Convert the vector to a length of 1
        /// @return The vector normalized to a length of 1
        public readonly Vector2Float normalized {
            get {
                float l = magnitude;
                Vector2Float v = Vector2Float.zero;
                if (l > Float.epsilon) 
                    v = new Vector2Float(this) / l;
                return v;
            }
        }
        /// @brief Convert the vector to a length of 1
        /// @param v The vector to convert
        /// @return The vector normalized to a length of 1
        public static Vector2Float Normalize(Vector2Int v) {
            float num = v.magnitude;
            Vector2Float result = Vector2Float.zero;
            if (num > Float.epsilon)
                result = new Vector2Float(v) / num;

            return result;
        }

        public static Vector2Int operator -(Vector2Int v) {
            return new Vector2Int(-v.horizontal, -v.vertical);    
        }
        
        public static Vector2Int operator -(Vector2Int v1, Vector2Int v2) {
            return new Vector2Int(v1.horizontal - v2.horizontal, v1.vertical - v2.vertical);
        }
        public static Vector2Int operator +(Vector2Int v1, Vector2Int v2) {
            return new Vector2Int(v1.horizontal + v2.horizontal, v1.vertical + v2.vertical);
        }

        public static Vector2Int operator /(Vector2Int v, int f) {
            return new Vector2Int(v.horizontal / f, v.vertical / f);
        }

        public static Vector2Int operator *(Vector2Int v1, int d) {
            return new Vector2Int(v1.horizontal * d, v1.vertical * d);
        }

        public static Vector2Int operator *(int d, Vector2Int v1) {
            return new Vector2Int(d * v1.horizontal, d * v1.vertical);
        }

        public static Vector2Int Scale(Vector2Int v1, Vector2Int v2) {
            return new Vector2Int(v1.horizontal * v2.horizontal, v1.vertical * v2.vertical);
        }

        /// @brief The dot product of two vectors
        /// @param v1 The first vector
        /// @param v2 The second vector
        /// @return The dot product of the two vectors
        public static int Dot(Vector2Int v1, Vector2Int v2) {
            return v1.horizontal * v2.horizontal + v1.vertical * v2.vertical;
        }

        public static float Distance(Vector2Int v1, Vector2Int v2) {
            return (v1 - v2).magnitude;
        }
    }
}