// Copyright (c) Wojciech Figat. All rights reserved.

#pragma once

#include "Math.h"
#include "Mathd.h"
#include "Engine/Core/Formatting.h"
#include "Engine/Core/Templates.h"

/// <summary>
/// Represents a two dimensional mathematical vector.
/// </summary>
template<typename T>
API_STRUCT(Template) struct Vector2Base
{
    typedef T Real;
    static FLAXENGINE_API struct ScriptingTypeInitializer TypeInitializer;

    union
    {
        struct
        {
            /// <summary>
            /// The X component of the vector.
            /// </summary>
            API_FIELD() T X;

            /// <summary>
            /// The Y component of the vector.
            /// </summary>
            API_FIELD() T Y;
        };

        /// <summary>
        /// The raw vector values (in XY order).
        /// </summary>
        T Raw[2];
    };

public:
    // Vector with all components equal 0
    static FLAXENGINE_API const Vector2Base<T> Zero;

    // Vector with all components equal 1
    static FLAXENGINE_API const Vector2Base<T> One;

    // Vector with all components equal 0.5
    static FLAXENGINE_API const Vector2Base<T> Half;

    // Vector X=1, Y=0
    static FLAXENGINE_API const Vector2Base<T> UnitX;

    // Vector X=0, Y=1
    static FLAXENGINE_API const Vector2Base<T> UnitY;

    // Vector with all components equal maximum value.
    static FLAXENGINE_API const Vector2Base<T> Minimum;

    // Vector with all components equal minimum value.
    static FLAXENGINE_API const Vector2Base<T> Maximum;

public:
    /// <summary>
    /// Empty constructor.
    /// </summary>
    Vector2Base() = default;

    FORCE_INLINE Vector2Base(T xy)
        : X(xy)
        , Y(xy)
    {
    }

    FORCE_INLINE explicit Vector2Base(const T* xy)
        : X(xy[0])
        , Y(xy[1])
    {
    }

    FORCE_INLINE Vector2Base(T x, T y)
        : X(x)
        , Y(y)
    {
    }

    template<typename U = T, typename TEnableIf<TNot<TIsTheSame<T, U>>::Value>::Type...>
    FORCE_INLINE Vector2Base(const Vector2Base<U>& xy)
        : X((T)xy.X)
        , Y((T)xy.Y)
    {
    }

    FLAXENGINE_API explicit Vector2Base(const Int3& xy);
    FLAXENGINE_API explicit Vector2Base(const Int4& xy);
    FLAXENGINE_API explicit Vector2Base(const Float3& xy);
    FLAXENGINE_API explicit Vector2Base(const Float4& xy);
    FLAXENGINE_API explicit Vector2Base(const Double3& xy);
    FLAXENGINE_API explicit Vector2Base(const Double4& xy);
    FLAXENGINE_API explicit Vector2Base(const Color& color);

public:
    FLAXENGINE_API String ToString() const;

public:
    // Gets a value indicting whether this instance is normalized.
    bool IsNormalized() const
    {
        return Math::Abs((X * X + Y * Y) - 1.0f) < 1e-4f;
    }

    // Gets a value indicting whether this vector is zero.
    bool IsZero() const
    {
        return Math::IsZero(X) && Math::IsZero(Y);
    }

    // Gets a value indicting whether any vector component is zero.
    bool IsAnyZero() const
    {
        return Math::IsZero(X) || Math::IsZero(Y);
    }

    // Gets a value indicting whether this vector is zero.
    bool IsOne() const
    {
        return Math::IsOne(X) && Math::IsOne(Y);
    }

    // Calculates the length of the vector.
    T Length() const
    {
        return Math::Sqrt(X * X + Y * Y);
    }

    // Calculates the squared length of the vector.
    T LengthSquared() const
    {
        return X * X + Y * Y;
    }

    // Calculates inverted length of the vector (1 / length).
    T InvLength() const
    {
        return 1.0f / Length();
    }

    /// <summary>
    /// Returns the average arithmetic of all the components.
    /// </summary>
    T AverageArithmetic() const
    {
        return (X + Y) * 0.5f;
    }

    /// <summary>
    /// Gets the sum of all vector components values.
    /// </summary>
    T SumValues() const
    {
        return X + Y;
    }

    /// <summary>
    /// Gets the multiplication result of all vector components values.
    /// </summary>
    T MulValues() const
    {
        return X * Y;
    }

    /// <summary>
    /// Returns the minimum value of all the components.
    /// </summary>
    T MinValue() const
    {
        return Math::Min(X, Y);
    }

    /// <summary>
    /// Returns the maximum value of all the components.
    /// </summary>
    T MaxValue() const
    {
        return Math::Max(X, Y);
    }

    /// <summary>
    /// Returns true if vector has one or more components is not a number (NaN).
    /// </summary>
    bool IsNaN() const
    {
        return isnan(X) || isnan(Y);
    }

    /// <summary>
    /// Returns true if vector has one or more components equal to +/- infinity.
    /// </summary>
    bool IsInfinity() const
    {
        return isinf(X) || isinf(Y);
    }

    /// <summary>
    /// Returns true if vector has one or more components equal to +/- infinity or NaN.
    /// </summary>
    bool IsNanOrInfinity() const
    {
        return IsInfinity() || IsNaN();
    }

    /// <summary>
    /// Calculates a vector with values being absolute values of that vector.
    /// </summary>
    Vector2Base GetAbsolute() const
    {
        return Vector2Base(Math::Abs(X), Math::Abs(Y));
    }

    /// <summary>
    /// Calculates a vector with values being opposite to values of that vector.
    /// </summary>
    Vector2Base GetNegative() const
    {
        return Vector2Base(-X, -Y);
    }

    /// <summary>
    /// Calculates a normalized vector that has length equal to 1.
    /// </summary>
    Vector2Base GetNormalized() const
    {
        Vector2Base result(X, Y);
        result.Normalize();
        return result;
    }

public:
    /// <summary>
    /// Performs vector normalization (scales vector up to unit length).
    /// </summary>
    void Normalize()
    {
        const T length = Math::Sqrt(X * X + Y * Y);
        if (length >= ZeroTolerance)
        {
            const T invLength = (T)1.0f / length;
            X *= invLength;
            Y *= invLength;
        }
    }

public:
    Vector2Base operator+(const Vector2Base& b) const
    {
        return Vector2Base(X + b.X, Y + b.Y);
    }

    Vector2Base operator-(const Vector2Base& b) const
    {
        return Vector2Base(X - b.X, Y - b.Y);
    }

    Vector2Base operator*(const Vector2Base& b) const
    {
        return Vector2Base(X * b.X, Y * b.Y);
    }

    Vector2Base operator/(const Vector2Base& b) const
    {
        return Vector2Base(X / b.X, Y / b.Y);
    }

    Vector2Base operator-() const
    {
        return Vector2Base(-X, -Y);
    }

    Vector2Base operator+(T b) const
    {
        return Vector2Base(X + b, Y + b);
    }

    Vector2Base operator-(T b) const
    {
        return Vector2Base(X - b, Y - b);
    }

    Vector2Base operator*(T b) const
    {
        return Vector2Base(X * b, Y * b);
    }

    Vector2Base operator/(T b) const
    {
        return Vector2Base(X / b, Y / b);
    }

    Vector2Base operator+(typename TOtherFloat<T>::Type a) const
    {
        T b = (T)a;
        return Vector2Base(X + b, Y + b);
    }

    Vector2Base operator-(typename TOtherFloat<T>::Type a) const
    {
        T b = (T)a;
        return Vector2Base(X - b, Y - b);
    }

    Vector2Base operator*(typename TOtherFloat<T>::Type a) const
    {
        T b = (T)a;
        return Vector2Base(X * b, Y * b);
    }

    Vector2Base operator/(typename TOtherFloat<T>::Type a) const
    {
        T b = (T)a;
        return Vector2Base(X / b, Y / b);
    }

    Vector2Base& operator+=(const Vector2Base& b)
    {
        X += b.X;
        Y += b.Y;
        return *this;
    }

    Vector2Base& operator-=(const Vector2Base& b)
    {
        X -= b.X;
        Y -= b.Y;
        return *this;
    }

    Vector2Base& operator*=(const Vector2Base& b)
    {
        X *= b.X;
        Y *= b.Y;
        return *this;
    }

    Vector2Base& operator/=(const Vector2Base& b)
    {
        X /= b.X;
        Y /= b.Y;
        return *this;
    }

    Vector2Base& operator+=(T b)
    {
        X += b;
        Y += b;
        return *this;
    }

    Vector2Base& operator-=(T b)
    {
        X -= b;
        Y -= b;
        return *this;
    }

    Vector2Base& operator*=(T b)
    {
        X *= b;
        Y *= b;
        return *this;
    }

    Vector2Base& operator/=(T b)
    {
        X /= b;
        Y /= b;
        return *this;
    }

    bool operator==(const Vector2Base& b) const
    {
        return X == b.X && Y == b.Y;
    }

    bool operator!=(const Vector2Base& b) const
    {
        return X != b.X || Y != b.Y;
    }

    bool operator>(const Vector2Base& b) const
    {
        return X > b.X && Y > b.Y;
    }

    bool operator>=(const Vector2Base& b) const
    {
        return X >= b.X && Y >= b.Y;
    }

    bool operator<(const Vector2Base& b) const
    {
        return X < b.X && Y < b.Y;
    }

    bool operator<=(const Vector2Base& b) const
    {
        return X <= b.X && Y <= b.Y;
    }

public:
    static bool NearEqual(const Vector2Base& a, const Vector2Base& b)
    {
        return Math::NearEqual(a.X, b.X) && Math::NearEqual(a.Y, b.Y);
    }

    static bool NearEqual(const Vector2Base& a, const Vector2Base& b, T epsilon)
    {
        return Math::NearEqual(a.X, b.X, epsilon) && Math::NearEqual(a.Y, b.Y, epsilon);
    }

public:
    static T Dot(const Vector2Base& a, const Vector2Base& b)
    {
        return a.X * b.X + a.Y * b.Y;
    }

    static T Cross(const Vector2Base& a, const Vector2Base& b)
    {
        return a.X * b.Y - a.Y * b.X;
    }

    static void Add(const Vector2Base& a, const Vector2Base& b, Vector2Base& result)
    {
        result = Vector2Base(a.X + b.X, a.Y + b.Y);
    }

    static void Subtract(const Vector2Base& a, const Vector2Base& b, Vector2Base& result)
    {
        result = Vector2Base(a.X - b.X, a.Y - b.Y);
    }

    static void Multiply(const Vector2Base& a, const Vector2Base& b, Vector2Base& result)
    {
        result = Vector2Base(a.X * b.X, a.Y * b.Y);
    }

    static void Divide(const Vector2Base& a, const Vector2Base& b, Vector2Base& result)
    {
        result = Vector2Base(a.X / b.X, a.Y / b.Y);
    }

    static void Min(const Vector2Base& a, const Vector2Base& b, Vector2Base& result)
    {
        result = Vector2Base(a.X < b.X ? a.X : b.X, a.Y < b.Y ? a.Y : b.Y);
    }

    static void Max(const Vector2Base& a, const Vector2Base& b, Vector2Base& result)
    {
        result = Vector2Base(a.X > b.X ? a.X : b.X, a.Y > b.Y ? a.Y : b.Y);
    }

public:
    static Vector2Base Min(const Vector2Base& a, const Vector2Base& b)
    {
        return Vector2Base(a.X < b.X ? a.X : b.X, a.Y < b.Y ? a.Y : b.Y);
    }

    static Vector2Base Max(const Vector2Base& a, const Vector2Base& b)
    {
        return Vector2Base(a.X > b.X ? a.X : b.X, a.Y > b.Y ? a.Y : b.Y);
    }

    static Vector2Base Mod(const Vector2Base& a, const Vector2Base& b)
    {
        return Vector2Base(Math::Mod(a.X, b.X), Math::Mod(a.Y, b.Y));
    }

    static Vector2Base Floor(const Vector2Base& v)
    {
        return Vector2Base(Math::Floor(v.X), Math::Floor(v.Y));
    }

    static Vector2Base Frac(const Vector2Base& v)
    {
        return Vector2Base(v.X - (int32)v.X, v.Y - (int32)v.Y);
    }

    static Vector2Base Round(const Vector2Base& v)
    {
        return Vector2Base(Math::Round(v.X), Math::Round(v.Y));
    }

    static Vector2Base Ceil(const Vector2Base& v)
    {
        return Vector2Base(Math::Ceil(v.X), Math::Ceil(v.Y));
    }

    static Vector2Base Abs(const Vector2Base& v)
    {
        return Vector2Base(Math::Abs(v.X), Math::Abs(v.Y));
    }

public:
    // Restricts a value to be within a specified range (inclusive min/max).
    static Vector2Base Clamp(const Vector2Base& v, const Vector2Base& min, const Vector2Base& max)
    {
        Vector2Base result;
        Clamp(v, min, max, result);
        return result;
    }

    // Restricts a value to be within a specified range (inclusive min/max).
    static void Clamp(const Vector2Base& v, const Vector2Base& min, const Vector2Base& max, Vector2Base& result)
    {
        result = Vector2Base(Math::Clamp(v.X, min.X, max.X), Math::Clamp(v.Y, min.Y, max.Y));
    }

    // Calculates distance between two points in 2D.
    static T Distance(const Vector2Base& a, const Vector2Base& b)
    {
        const T x = a.X - b.X;
        const T y = a.Y - b.Y;
        return Math::Sqrt(x * x + y * y);
    }

    // Calculates the squared distance between two points in 2D.
    static T DistanceSquared(const Vector2Base& a, const Vector2Base& b)
    {
        const T x = a.X - b.X;
        const T y = a.Y - b.Y;
        return x * x + y * y;
    }

    // Performs vector normalization (scales vector up to unit length).
    static Vector2Base Normalize(const Vector2Base& v)
    {
        Vector2Base r = v;
        const T length = Math::Sqrt(r.X * r.X + r.Y * r.Y);
        if (length >= ZeroTolerance)
        {
            const T inv = (T)1.0f / length;
            r.X *= inv;
            r.Y *= inv;
        }
        return r;
    }

    // Performs a linear interpolation between two vectors.
    static void Lerp(const Vector2Base& start, const Vector2Base& end, T amount, Vector2Base& result)
    {
        result.X = Math::Lerp(start.X, end.X, amount);
        result.Y = Math::Lerp(start.Y, end.Y, amount);
    }

    // Performs a linear interpolation between two vectors.
    static Vector2Base Lerp(const Vector2Base& start, const Vector2Base& end, T amount)
    {
        Vector2Base result;
        Lerp(start, end, amount, result);
        return result;
    }

    // Performs a spherical linear interpolation between two vectors.
    static void Slerp(const Vector2Base& start, const Vector2Base& end, T amount, Vector2Base& result) 
    {
        T dot = Math::Clamp(Dot(start, end), -1.0f, 1.0f);
        T theta = Math::Acos(dot) * amount;
        Vector2Base relativeVector = end - start * dot;
        relativeVector.Normalize();
        result = ((start * Math::Cos(theta)) + (relativeVector * Math::Sin(theta)));
    }

    // Performs a spherical linear interpolation between two vectors.
    static Vector2Base Slerp(const Vector2Base& start, const Vector2Base& end, T amount) 
    {
        Vector2Base result;
        Slerp(start, end, amount, result);
        return result;
    }

public:
    /// <summary>
    /// Calculates the area of the triangle.
    /// </summary>
    /// <param name="v0">The first triangle vertex.</param>
    /// <param name="v1">The second triangle vertex.</param>
    /// <param name="v2">The third triangle vertex.</param>
    /// <returns>The triangle area.</returns>
    FLAXENGINE_API static T TriangleArea(const Vector2Base& v0, const Vector2Base& v1, const Vector2Base& v2);

    /// <summary>
    /// Calculates the angle (in radians) between from and to. This is always the smallest value.
    /// </summary>
    /// <param name="from">The first vector.</param>
    /// <param name="to">The second vector.</param>
    /// <returns>The angle (in radians).</returns>
    FLAXENGINE_API static T Angle(const Vector2Base& from, const Vector2Base& to);
};

template<typename T>
inline Vector2Base<T> operator+(T a, const Vector2Base<T>& b)
{
    return b + a;
}

template<typename T>
inline Vector2Base<T> operator-(T a, const Vector2Base<T>& b)
{
    return Vector2Base<T>(a) - b;
}

template<typename T>
inline Vector2Base<T> operator*(T a, const Vector2Base<T>& b)
{
    return b * a;
}

template<typename T>
inline Vector2Base<T> operator/(T a, const Vector2Base<T>& b)
{
    return Vector2Base<T>(a) / b;
}

template<typename T>
inline Vector2Base<T> operator+(typename TOtherFloat<T>::Type a, const Vector2Base<T>& b)
{
    return b + a;
}

template<typename T>
inline Vector2Base<T> operator-(typename TOtherFloat<T>::Type a, const Vector2Base<T>& b)
{
    return Vector2Base<T>(a) - b;
}

template<typename T>
inline Vector2Base<T> operator*(typename TOtherFloat<T>::Type a, const Vector2Base<T>& b)
{
    return b * a;
}

template<typename T>
inline Vector2Base<T> operator/(typename TOtherFloat<T>::Type a, const Vector2Base<T>& b)
{
    return Vector2Base<T>(a) / b;
}

template<typename T>
inline uint32 GetHash(const Vector2Base<T>& key)
{
    return (*(uint32*)&key.X * 397) ^ *(uint32*)&key.Y;
}

namespace Math
{
    template<typename T>
    FORCE_INLINE static bool NearEqual(const Vector2Base<T>& a, const Vector2Base<T>& b)
    {
        return Vector2Base<T>::NearEqual(a, b);
    }
}

template<>
struct TIsPODType<Float2>
{
    enum { Value = true };
};

DEFINE_DEFAULT_FORMATTING(Float2, "X:{0} Y:{1}", v.X, v.Y);

template<>
struct TIsPODType<Double2>
{
    enum { Value = true };
};

DEFINE_DEFAULT_FORMATTING(Double2, "X:{0} Y:{1}", v.X, v.Y);

template<>
struct TIsPODType<Int2>
{
    enum { Value = true };
};

DEFINE_DEFAULT_FORMATTING(Int2, "X:{0} Y:{1}", v.X, v.Y);

#if !defined(_MSC_VER) || defined(__clang__)
// Forward specializations for Clang
template<> FLAXENGINE_API const Float2 Float2::Zero;
template<> FLAXENGINE_API const Float2 Float2::One;
template<> FLAXENGINE_API const Float2 Float2::UnitX;
template<> FLAXENGINE_API const Float2 Float2::UnitY;
template<> FLAXENGINE_API const Float2 Float2::Minimum;
template<> FLAXENGINE_API const Float2 Float2::Maximum;
template<> FLAXENGINE_API ScriptingTypeInitializer Float2::TypeInitializer;

template<> FLAXENGINE_API const Double2 Double2::Zero;
template<> FLAXENGINE_API const Double2 Double2::One;
template<> FLAXENGINE_API const Double2 Double2::UnitX;
template<> FLAXENGINE_API const Double2 Double2::UnitY;
template<> FLAXENGINE_API const Double2 Double2::Minimum;
template<> FLAXENGINE_API const Double2 Double2::Maximum;
template<> FLAXENGINE_API ScriptingTypeInitializer Double2::TypeInitializer;

template<> FLAXENGINE_API const Int2 Int2::Zero;
template<> FLAXENGINE_API const Int2 Int2::One;
template<> FLAXENGINE_API const Int2 Int2::UnitX;
template<> FLAXENGINE_API const Int2 Int2::UnitY;
template<> FLAXENGINE_API const Int2 Int2::Minimum;
template<> FLAXENGINE_API const Int2 Int2::Maximum;
template<> FLAXENGINE_API ScriptingTypeInitializer Int2::TypeInitializer;
#endif
