Pagination only inside CATEGORY

Hello all!

Please somebody can help me change the code below to navigate (next/previous) only inside the category the user are in. I’m using JustWrite theme.

funcitions.php

/*  Post pagination
/* ------------------------------------ */
if ( ! function_exists( 'ac_post_nav_arrows' ) ) {

	function ac_post_nav_arrows() {
		global $post;

		$prev_post = get_next_post();
		$next_post = get_previous_post();

		if( $prev_post ) {
			$prev_post_id = $prev_post->ID;
			$prev_post_url = get_permalink($prev_post_id);
		};
		if( $next_post ) {
			$next_post_id = $next_post->ID;
			$next_post_url = get_permalink($next_post_id);
		};

		echo '<div class="post-navigation clearfix">';

		if( $prev_post ) {
			echo '<a href="' . esc_url( $prev_post_url ) . '" class="prev-post" title="' . __( 'Previous Post', 'justwrite' ) . '">' . ac_icon('angle-left', false) . '</a>';
		} else {
			echo '<span class="prev-post">' . ac_icon('angle-left', false) . '</span>';
		}

		if( $next_post ) {
			echo '<a href="' . esc_url( $next_post_url ) . '" class="next-post" title="' . __( 'Next Post', 'justwrite' ) . '">' . ac_icon('angle-right', false) . '</a>';
		} else {
			echo '<span class="next-post">' . ac_icon('angle-right', false) . '</span>';
		}

		echo '</div>';
	}

}

single.php

// Next - Previous Post
ac_post_nav_arrows();

Thanks!
Kind regards!