public class FPCamera {
    private Vector3f position;
    private float pitch = 0f;
    private float yaw = 0f;
    private float roll = 0f;

    private float movementSpeed = 10f;
    private float mouseSensitivity = 0f;
    private float movementMultiplier = 1f;

    public FPCamera(float x, float y, float z, float pitch, float yaw, float roll, float sensitivity, float movementSpeed) {
        this.position = new Vector3f(x, y, z);
        this.pitch = pitch;
        this.yaw = yaw;
        this.roll = roll;
        this.mouseSensitivity = sensitivity;
        this.movementSpeed = movementSpeed;

        Mouse.setGrabbed(true);
    }

    public void tick(float delta) {
        int dx = Mouse.getDX();
        int dy = Mouse.getDY();

        yaw(dx * mouseSensitivity);
        pitch(dy * mouseSensitivity);

        if(Keyboard.isKeyDown(Keyboard.KEY_W) || Keyboard.isKeyDown(Keyboard.KEY_UP)) {
            forward(movementSpeed * movementMultiplier * delta);
        }

        if(Keyboard.isKeyDown(Keyboard.KEY_S) || Keyboard.isKeyDown(Keyboard.KEY_DOWN)) {
            backward(movementSpeed * movementMultiplier * delta);
        }

        if(Keyboard.isKeyDown(Keyboard.KEY_A) || Keyboard.isKeyDown(Keyboard.KEY_LEFT)) {
            strafeLeft(movementSpeed * movementMultiplier * delta);
        }

        if(Keyboard.isKeyDown(Keyboard.KEY_D) || Keyboard.isKeyDown(Keyboard.KEY_RIGHT)) {
            strafeRight(movementSpeed * movementMultiplier * delta);
        }

        if(Keyboard.isKeyDown(Keyboard.KEY_D) || Keyboard.isKeyDown(Keyboard.KEY_RIGHT)) {
            strafeRight(movementSpeed * movementMultiplier * delta);
        }

        if(Keyboard.isKeyDown(Keyboard.KEY_SPACE)) {
            up(movementSpeed * movementMultiplier * delta);
        }

        if(Keyboard.isKeyDown(Keyboard.KEY_LCONTROL)) {
            down(movementSpeed * movementMultiplier * delta);
        }

        // Hold LSHIFT to move faster
        movementMultiplier = Keyboard.isKeyDown(Keyboard.KEY_LSHIFT) ? 10f : 1f;

        glLoadIdentity();
        glRotatef(pitch, 1f, 0f, 0f);
        glRotatef(yaw, 0f, 1f, 0f);
        glRotatef(roll, 0f, 0f, 1f);
        glTranslatef(position.x, position.y, position.z);
    }

    private void forward(float distance) {
        double y = Math.toRadians(yaw);
        double p = Math.toRadians(pitch);

        position.x -= (float) (distance * Math.sin(y));
        position.y += (float) (distance * Math.cos(p) * Math.sin(y));
        position.z += (float) (distance * Math.cos(p) * Math.cos(y));
    }

    private void backward(float distance) {
        double y = Math.toRadians(yaw);
        double p = Math.toRadians(pitch);

        position.x += (float) (distance * Math.sin(y));
        position.y -= (float) (distance * Math.cos(p) * Math.sin(y));
        position.z -= (float) (distance * Math.cos(p) * Math.cos(y));
    }

    private void up(float distance) {
        position.y -= distance;
    }

    private void down(float distance) {
        position.y += distance;
    }

    private void strafeLeft(float distance) {
        position.x -= distance * Math.sin(Math.toRadians(yaw - 90));
        position.z += distance * Math.cos(Math.toRadians(yaw - 90));
    }

    private void strafeRight(float distance) {
        position.x += distance * Math.sin(Math.toRadians(yaw - 90));
        position.z -= distance * Math.cos(Math.toRadians(yaw - 90));
    }

    public void pitch(float amount) {
        pitch -= amount;

        if(pitch > 90f)
            pitch = 90f;
        else if(pitch < -90f)
            pitch = -90f;
    }

    public void yaw(float amount) {
        yaw += amount;
    }

    public void rollLeft(float amount) {
        roll(amount);
    }

    public void rollRight(float amount) {
        roll(-amount);
    }

    public void roll(float amount) {
        roll += amount;
    }
}