#include "src/Core/Maths.h"

namespace Nuake
{
    Quat LookAt(Vector3 sourcePoint, Vector3 destPoint)
    {
        Vector3 forwardVector = glm::normalize(destPoint - sourcePoint);

        float dot = glm::dot(Vector3(0, 0, 1), forwardVector);
        if (glm::abs(dot - (-1.0f)) < 0.000001f)
        {
            return Quat(0, 1, 0, 3.1415926535897932f);
        }
        if (glm::abs(dot - (1.0f)) < 0.000001f)
        {
            return Quat(); // identity
        }

        float rotAngle = acos(dot);
        Vector3 rotAxis = glm::cross(Vector3(0, 0, 1), forwardVector);
        rotAxis = glm::normalize(rotAxis);
        return CreateFromAxisAngle(rotAxis, rotAngle);
    }

    // just in case you need that function also
    Quat CreateFromAxisAngle(Vector3 axis, float angle)
    {
        float halfAngle = angle * .5f;
        float s = sin(halfAngle);
        Quat q;
        q.x = axis.x * s;
        q.y = axis.y * s;
        q.z = axis.z * s;
        q.w = cos(halfAngle);
        return q;
    }

    Quat QuatFromEuler(float x, float y, float z)
    {
        Quat pitchQuat = glm::angleAxis(Rad(x), Vector3(1.0f, 0.0f, 0.0f));
        Quat yawQuat = glm::angleAxis(Rad(y), Vector3(0.0f, 1.0f, 0.0f));
        Quat rollQuat = glm::angleAxis(Rad(z), Vector3(0.0f, 0.0f, -1.0f));
        Quat orientation = yawQuat * pitchQuat * rollQuat;

        return glm::normalize(orientation);
    }

    Vector3 QuatToDirection(const Quat& quat)
    {
        return glm::normalize(quat * Vector3(0, 0, -1));
    }

    void Decompose(const Matrix4& m, Vector3& pos, Quat& rot, Vector3& scale)
    {
        pos = m[3];
        for (int i = 0; i < 3; i++)
            scale[i] = glm::length(Vector3(m[i]));
        const Matrix3 rotMtx(
            Vector3(m[0]) / scale[0],
            Vector3(m[1]) / scale[1],
            Vector3(m[2]) / scale[2]);
        rot = glm::quat_cast(rotMtx);
    }

    float Distance(const Vector3& a, const Vector3& b)
    {
        return glm::distance(a, b);
    }

    const Matrix4& TransformToCameraTransform(const Matrix4& mat)
    {
        return mat;
    }
}
