package com.test24;

import java.nio.FloatBuffer;

import org.lwjgl.BufferUtils;
import org.lwjgl.opengl.GL11;
import org.lwjgl.util.vector.Vector3f;

public class Camera {
    private float DEG2RAD = 3.141592653589793f / 180.0f;
    private Vector3f pos;
    private Vector3f left, up, forward;
    private float[] rotationMat;
    private FloatBuffer rotation;

    public Camera() {
        pos = new Vector3f(0.0f, 0.0f, 0.0f);
        left = new Vector3f(1.0f, 0.0f, 0.0f);
        up = new Vector3f(0.0f, 1.0f, 0.0f);
        forward = new Vector3f(0.0f, 0.0f, 1.0f);
        rotationMat = new float[16];
        rotation = BufferUtils.createFloatBuffer(16);
    }

    public void moveForward(float amount) {
        pos.x += forward.x * amount;
        pos.y += forward.y * amount;
        pos.z += forward.z * amount;
    }

    public void rotateX(float delta) {
        delta *= DEG2RAD;
        Vector3f cross = new Vector3f();
        Vector3f.cross(up, forward, cross);
        calcRotationMat(delta, cross);
        Vector3f newVect1 = new Vector3f(rotationMat[0] * forward.x + rotationMat[4] * forward.y + rotationMat[8] * forward.z,
                rotationMat[1] * forward.x + rotationMat[5] * forward.y + rotationMat[9] * forward.z,
                rotationMat[2] * forward.x + rotationMat[6] * forward.y + rotationMat[10] * forward.z);
        forward = newVect1;

        Vector3f newVect2 = new Vector3f(rotationMat[0] * up.x + rotationMat[4] * up.y + rotationMat[8] * up.z,
                rotationMat[1] * up.x + rotationMat[5] * up.y + rotationMat[9] * up.z,
                rotationMat[2] * up.x + rotationMat[6] * up.y + rotationMat[10] * up.z);
        up = newVect2;
    }

    public void rotateY(float delta) {
        delta *= DEG2RAD;
        calcRotationMat(delta, up);
        Vector3f newVect = new Vector3f(rotationMat[0] * forward.x + rotationMat[4] * forward.y + rotationMat[8] * forward.z,
                rotationMat[1] * forward.x + rotationMat[5] * forward.y + rotationMat[9] * forward.z,
                rotationMat[2] * forward.x + rotationMat[6] * forward.y + rotationMat[10] * forward.z);
        forward = newVect;
    }

    public void rotateZ(float delta) {
        delta *= DEG2RAD;
        calcRotationMat(delta, forward);
        Vector3f newVect = new Vector3f(rotationMat[0] * up.x + rotationMat[4] * up.y + rotationMat[8] * up.z,
                rotationMat[1] * up.x + rotationMat[5] * up.y + rotationMat[9] * up.z,
                rotationMat[2] * up.x + rotationMat[6] * up.y + rotationMat[10] * up.z);
        up = newVect;
    }

    public void calcRotationMat(float angle, Vector3f v) {
        float x = v.x;
        float y = v.y;
        float z = v.z;
        float mag = (float) (1.0f / Math.sqrt(x * x + y * y + z * z));
        x *= mag;
        y *= mag;
        z *= mag;
        float c = (float) Math.cos(angle);
        float s = (float) Math.sin(angle);

        float xx = x * x;
        float yy = y * y;
        float zz = z * z;
        float xy = x * y;
        float yz = y * z;
        float zx = z * x;
        float xs = x * s;
        float ys = y * s;
        float zs = z * s;
        float one_c = 1.0f - c;

        rotationMat[0] = (one_c * xx) + c;
        rotationMat[4] = (one_c * xy) - zs;
        rotationMat[8] = (one_c * zx) + ys;
        rotationMat[12] = 0.0f;

        rotationMat[1] = (one_c * xy) + zs;
        rotationMat[5] = (one_c * yy) + c;
        rotationMat[9] = (one_c * yz) - xs;
        rotationMat[13] = 0.0f;

        rotationMat[2] = (one_c * zx) - ys;
        rotationMat[6] = (one_c * yz) + xs;
        rotationMat[10] = (one_c * zz) + c;
        rotationMat[14] = 0.0f;

        rotationMat[3] = 0.0f;
        rotationMat[7] = 0.0f;
        rotationMat[11] = 0.0f;
        rotationMat[15] = 1.0f;
    }

    public void applyCameraTransform() {
        Vector3f z = forward.negate(null);
        left = Vector3f.cross(up, z, null);
        rotation.clear();
        float[] orient = new float[] {
                left.x, up.x, z.x, 0.0f,
                left.y, up.y, z.y, 0.0f,
                left.z, up.z, z.z, 0.0f,
                0.0f, 0.0f, 0.0f, 1.0f
        };
        rotation.put(orient).flip();
        GL11.glMultMatrix(rotation);
        GL11.glTranslatef(-pos.x, -pos.y, -pos.z);
    }
}