P2 Q&A Comments

p2-qa-comments.php

<?php
/* Plugin Name: P2 Q&A Comments
 * Description: Allows you to mark P2 comments as +1/-1 and as answered. Ideal for live Q&A sessions.
 * Author: Andrew Nacin
 * Author URI: http://andrewnacin.com/
 */

/* WARNING about studying and copying this code:
 * 
 * P2 is not currently an ideal platform for developing extensions. Some of this
 * plugin is hacky and may make kittens and core developers cry. It is not
 * guaranteed to work as-is in a future version of P2. While I'll keep it updated
 * to work, please do your best to avoid these techniques. Do as I say, not as I do.
 *
 * -- Nacin
 */

/**
 * @package P2_QA_Comments
 */
class P2_QA_Comments {

	static $instance;

	/**
	 * Constructor. Saves instance and sets up initial hook.
	 */
	function __construct() {
		self::$instance = $this;
		add_action( 'after_setup_theme', array( $this, 'after_setup_theme' ) );
	}

	/**
	 * Sets up initial hooks, if the P2 theme is in play.
	 */
	function after_setup_theme() {
		if ( ! class_exists( 'P2' ) )
			return;
		add_action( 'wp_head', array( $this, 'wp_head' ) );
		add_action( 'wp_footer', array( $this, 'wp_footer' ) );
		add_filter( 'comment_text', array( $this, 'comment_text' ), 9 );
		add_filter( 'comment_class', array( $this, 'comment_class' ), 10, 3 );
		add_action( 'admin_post_p2_qa_comments', array( $this, 'admin_post_p2_qa_comments' ) );
		add_action( 'wp_ajax_p2_qa_polling', array( $this, 'wp_ajax_p2_qa_polling' ) );
	}

	function wp_ajax_p2_qa_polling() {
		global $wpdb;
		$post_id = absint( $_GET['p'] );
		$results = $wpdb->get_results( $wpdb->prepare( "SELECT m.comment_id, m.meta_value FROM $wpdb->commentmeta m INNER JOIN $wpdb->comments c ON c.comment_ID = m.comment_id WHERE c.comment_post_ID = %d", $post_id ) );
		echo json_encode( $results );
		die();
	}

	/**
	 * Adds voting options to comments.
	 */
	function comment_text( $text, $comment = null ) {
		if ( $comment === null )
			$comment = $GLOBALS['comment'];
		$id = $comment->comment_ID;

		$meta = get_comment_meta( $id, '_p2_qa_comments', true );

		if ( ! current_user_can( 'edit_published_posts' ) ) {
			if ( 'answered' == $meta )
				$text .= "\n\n" . '<div class="p2_qa_comments_links"><strong>Answered</strong></div>';
			return $text;
		}

		$go = add_query_arg( array(
				'action' => 'p2_qa_comments',
				'comment' => $id,
				'_wp_http_referer' => urlencode( stripslashes( $_SERVER['REQUEST_URI'] ) )
			), admin_url( 'admin-post.php' ) );

		$go = wp_nonce_url( $go, 'p2_qa_comments-' . $id );

		$text .= "\n\n" . '<div class="p2_qa_comments_links"><a class="promote' . ( 'promote' == $meta ? ' current' : '' ) . '" href="' . esc_url( add_query_arg( array( 'qa' => 'promote' ), $go ) ) . '">Promote</a> ';
		$text .= '<a class="demote' . ( 'demote' == $meta ? ' current' : '' ) . '" href="' . esc_url( add_query_arg( array( 'qa' => 'demote' ), $go ) ) . '">Demote</a> ';
		$text .= '<a class="answered' . ( 'answered' == $meta ? ' current' : '' ) . '" href="' . esc_url( add_query_arg( array( 'qa' => 'answered' ), $go ) ) . '">Answered</a> ';
		$text .= '<a class="zero" href="' . esc_url( add_query_arg( array( 'qa' => '0' ), $go ) ) . '">(Clear)</a></div>';
		return $text;
	}

	function comment_class( $classes, $class, $comment_id = null ) {
		if ( $comment_id === null )
			$comment_id = $GLOBALS['comment']->comment_ID;
		if ( ! is_single() )
			return $classes;
		$meta = get_comment_meta( $comment_id, '_p2_qa_comments', true );
		if ( $meta !== false && $meta !== '0' )
			$classes[] = 'p2-qa-' . $meta;
		return $classes;
	}

	function admin_post_p2_qa_comments() {
		$comment_id = absint( $_GET['comment'] );

		if ( ! current_user_can( 'edit_published_posts' ) )
			wp_die( __( "You can't do that.", 'p2-qa-comments' ) );

		if ( ! wp_verify_nonce( $_GET['_wpnonce'], 'p2_qa_comments-' . $comment_id ) )
			wp_die( __( 'Did you intend to do this?', 'p2-qa-comments' ) );

		$do = $_GET['qa'];
		if ( ! in_array( $do, array( 'promote', 'demote', 'answered' ) ) )
			$do = '0';

		update_comment_meta( $comment_id, '_p2_qa_comments', $do );

		if ( ! defined( 'DOING_AJAX' ) || ! DOING_AJAX )
			wp_safe_redirect( wp_get_referer() );
		die();
	}

	/**
	 * Drop in some CSS.
	 */
	function wp_head() {
		echo "<style>
.p2_qa_comments_links a { margin: 0 5px }
.p2_qa_comments_links { margin-bottom: 10px; font-size: 13px }
.p2_qa_comments_links a.current { font-weight: bold; color: #000 }

.p2-qa-promote {
	background: #eef9fc;
}
	.p2-qa-promote > .children {
		background: white;
	}

.p2-qa-demote > *,
.p2-qa-answered > * {
	opacity: 0.5;
}

.p2-qa-demote > .children,
.p2-qa-answered > .children {
	opacity: 1;
}

</style>\n";
	}

	/**
	 * Drop in some JS.
	 */
	function wp_footer() {
?>
<script>
(function($){
	$(document).ready( function() {
		$('.p2_qa_comments_links a').click( function(e) {
			e.preventDefault();
			$.ajax({
				url : $(this).attr('href'),
				context : $(this),
				success : function() {
					$(this).parent().find('a').removeClass('current'); // self included, not siblings
					$(this).closest('li').removeClass('p2-qa-promote p2-qa-demote p2-qa-answered').addClass( 'p2-qa-' + this[0].className );
					if ( ! $(this).hasClass('zero') )
						$(this).addClass('current');
				}
			});
		});
<?php if ( is_single() ) : ?>
		var p2QAPollForFormatting = function() {
			$.ajax({
				url : ajaxurl + '?action=p2_qa_polling&p=' + <?php echo get_the_ID(); ?>,
				context : $(this),
				success : function(data) {
					data = $.parseJSON(data);
					$.each( data, function ( index, value ) {
						$('#comment-' + value.comment_id)
							.removeClass('p2-qa-promote p2-qa-demote p2-qa-answered')
							.addClass('p2-qa-' + value.meta_value)
							.find('.p2_qa_comments_links').first()
							.find('a').removeClass('current')
							.filter('.' + value.meta_value)
							.addClass('current');
					});
				}
			});
		};
		window.setInterval( p2QAPollForFormatting, 10000 );
<?php endif; ?>
	});
})(jQuery);
</script>
<?php
	}

}
new P2_QA_Comments;