append_content.php

<?php
/*
Plugin Name: Append Content
Description: Append content to your posts/pages, useful for repetitious messaging and calls to action. Apply template to all pages/posts, only to posts, or only to pages. 
Version: 1.0
Author URI: http://theandystratton.com
Author: Andy Stratton <theandystratton@gmail.com>
*/

class APContent {
	
	function APContent() {
		
	}
	
	function admin_menu() {
		add_submenu_page('options-general.php', 'Append Content', 'Append Content', 8, basename(__FILE__), array($this,'main'));
	}
	
	function admin_head() {
		if ( $_GET['page'] == basename(__FILE__) ) {
?>
<script type="text/javascript" src="../wp-includes/js/tinymce/tiny_mce.js"></script>
<script type="text/javascript">
<!--
tinyMCE.init({
theme : "advanced",
theme_advanced_toolbar_location:"top",
theme_advanced_buttons1:"bold,italic,strikethrough,|,bullist,numlist,blockquote,|,justifyleft,justifycenter,justifyright,|,link,unlink,wp_more,|,spellchecker,fullscreen,wp_adv|underline,justifyfull,forecolor,|,pastetext,pasteword,removeformat,|,media,charmap,|,outdent,indent,|,undo,redo,wp_help",
theme_advanced_buttons2:"",theme_advanced_buttons3:"", theme_advanced_buttons4:"", language:"en",
theme_advanced_toolbar_align:"left", theme_advanced_statusbar_location:"bottom", theme_advanced_resizing:"1",
mode : "exact",
elements : "content",
skin: "wp_theme",
width : "565",
height : "140"
});
-->
</script>
<?php 
		}
	}
	
	function the_content( $content ) {
		$publish = get_option('apc_publish');
		$apc_content = wpautop( get_option('apc_content') );
		switch ( $publish ) {
			case 'all':
				$content .= "\n\n" . $apc_content;
				break;
			case 'posts':
				if ( !is_page(get_the_ID()) ) {
					$content .= "\n\n" . $apc_content;
				}
				break;
			case 'pages':
				if ( is_page(get_the_ID()) ) {
					$content .= "\n\n" . $apc_content;
				}
				break;
			default:
				break;
		}
		return $content;
	}
	
	function main() {
?>
<div class="wrap">
	<h2>Append Content Plugin Settings</h2>
	
	<h3>Content Settings</h3>
	<?php 
		if ( sizeof($_POST['apc_content']) ) {
			$apc_content = stripslashes($_POST['apc_content']);
			update_option('apc_content', $apc_content);
			echo '<div class="message updated"><p>Content settings updated.</p></div>';
		}
	?>
	<form method="post" action="?<?php echo $_SERVER['QUERY_STRING']; ?>">
		<p>
			<label for="content">
				Content to Append:
			</label>
			<textarea id="content" name="apc_content" rows="8" cols="60"><?php 
				echo htmlentities(get_option('apc_content'));
			?></textarea>
		</p>
		<p>
			<input type="submit" value="Save Your Content" class="button-primary" />
		</p>
	</form>
	
	<h3>Publishing Settings</h3>
	<?php 
		if ( sizeof($_POST['apc_publish']) ) {
			if ( in_array($_POST['apc_publish'], array('all','posts','pages')) ) {
				update_option('apc_publish', $_POST['apc_publish']);
				echo '<div class="message updated"><p>Publishing settings updated.</p></div>';
			}
		}
		$apc_publish = get_option('apc_publish', 'all');
	?>
	<form method="post" action="?<?php echo $_SERVER['QUERY_STRING']; ?>">
		<p>
			Choose which posts/pages you'd like to apply content to:
		</p>
		<div style="margin-left: 1.5em;">
			<p>
				<label for="all_posts_pages">
					<input type="radio" id="all_posts_pages" name="apc_publish" value="all"<?php 
						if ( $apc_publish == 'all' ) echo 'checked="checked"';  
					?> />
					All posts/pages.
				</label>
			</p>
			<p>
				<label for="posts_only">
					<input type="radio" id="posts_only" name="apc_publish" value="posts"<?php 
						if ( $apc_publish == 'posts' ) echo 'checked="checked"';  
					?> />
					Only to posts.
				</label>
			</p>
			<p>
				<label for="pages_only">
					<input type="radio" id="pages_only" name="apc_publish" value="pages"<?php 
						if ( $apc_publish == 'pages' ) echo 'checked="checked"';  
					?> />
					Only to pages.
				</label>
			</p>
		</div>
		<p>
			<input type="submit" value="Save Publishing Settings" class="button-primary" />
		</p>
	</form>
</div>
<?php 
	}
	
}

$apcontent = new APContent();
add_action('admin_menu', array($apcontent, 'admin_menu'));
add_action('admin_head', array($apcontent, 'admin_head'));
add_filter('the_content', array($apcontent, 'the_content'));