moved CAPTCHA plugin to a helper
diff --git a/user_guide/helpers/captcha_helper.html b/user_guide/helpers/captcha_helper.html
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+CAPTCHA Helper
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+<div id="content">
+
+
+<h1>CAPTCHA Helper</h1>
+
+<p>The CAPTCHA Helper file contains functions that assist in creating CAPTCHA images.</p>
+
+
+<h2>Loading this Helper</h2>
+
+<p>This helper is loaded using the following code:</p>
+<code>$this->load->helper('captcha');</code>
+
+<p>The following functions are available:</p>
+
+<h2>captcha_create(<var>$data</var>)</h2>
+
+<p>Takes an array of information to generate the CAPTCHA as input and creates the image to your specifications, returning an array of associative data about the image.</p>
+
+<code>[array]<br />
+(<br />
+ 'image' => IMAGE TAG<br />
+ 'time' => TIMESTAMP (in microtime)<br />
+ 'word' => CAPTCHA WORD<br />
+)</code>
+
+ <p>The "image" is the actual image tag:
+<code><img src="http://example.com/captcha/12345.jpg" width="140" height="50" /></code></p>
+
+ <p>The "time" is the micro timestamp used as the image name without the file
+ extension. It will be a number like this: 1139612155.3422</p>
+
+ <p>The "word" is the word that appears in the captcha image, which if not
+ supplied to the function, will be a random string.</p>
+
+ <h3>Using the CAPTCHA plugin</h3>
+
+ <p>Once loaded you can generate a captcha like this:</p>
+
+<code>$vals = array(<br />
+ 'word' => 'Random word',<br />
+ 'img_path' => './captcha/',<br />
+ 'img_url' => 'http://example.com/captcha/',<br />
+ 'font_path' => './path/to/fonts/texb.ttf',<br />
+ 'img_width' => '150',<br />
+ 'img_height' => 30,<br />
+ 'expiration' => 7200<br />
+ );<br />
+<br />
+$cap = create_captcha($vals);<br />
+echo $cap['image'];</code>
+
+ <ul>
+ <li>The captcha function requires the GD image library.</li>
+ <li>Only the img_path and img_url are required.</li>
+ <li>If a "word" is not supplied, the function will generate a random
+ ASCII string. You might put together your own word library that
+ you can draw randomly from.</li>
+ <li>If you do not specify a path to a TRUE TYPE font, the native ugly GD
+ font will be used.</li>
+ <li>The "captcha" folder must be writable (666, or 777)</li>
+ <li>The "expiration" (in seconds) signifies how long an image will
+ remain in the captcha folder before it will be deleted. The default
+ is two hours.</li>
+ </ul>
+
+ <h3>Adding a Database</h3>
+
+ <p>In order for the captcha function to prevent someone from submitting, you will need
+ to add the information returned from <kbd>create_captcha()</kbd> function to your database.
+ Then, when the data from the form is submitted by the user you will need to verify
+ that the data exists in the database and has not expired.</p>
+
+ <p>Here is a table prototype:</p>
+
+<code>CREATE TABLE captcha (<br />
+ captcha_id bigint(13) unsigned NOT NULL auto_increment,<br />
+ captcha_time int(10) unsigned NOT NULL,<br />
+ ip_address varchar(16) default '0' NOT NULL,<br />
+ word varchar(20) NOT NULL,<br />
+ PRIMARY KEY `captcha_id` (`captcha_id`),<br />
+ KEY `word` (`word`)<br />
+)</code>
+
+ <p>Here is an example of usage with a database. On the page where the CAPTCHA will be shown you'll have something like this:</p>
+
+<code>$this->load->plugin('captcha');<br />
+$vals = array(<br />
+ 'img_path' => './captcha/',<br />
+ 'img_url' => 'http://example.com/captcha/'<br />
+ );<br />
+<br />
+$cap = create_captcha($vals);<br />
+<br />
+$data = array(<br />
+ 'captcha_time' => $cap['time'],<br />
+ 'ip_address' => $this->input->ip_address(),<br />
+ 'word' => $cap['word']<br />
+ );<br />
+<br />
+$query = $this->db->insert_string('captcha', $data);<br />
+$this->db->query($query);<br />
+<br />
+echo 'Submit the word you see below:';<br />
+echo $cap['image'];<br />
+echo '<input type="text" name="captcha" value="" />';</code>
+
+ <p>Then, on the page that accepts the submission you'll have something like this:</p>
+
+<code>// First, delete old captchas<br />
+$expiration = time()-7200; // Two hour limit<br />
+$this->db->query("DELETE FROM captcha WHERE captcha_time < ".$expiration); <br />
+<br />
+// Then see if a captcha exists:<br />
+$sql = "SELECT COUNT(*) AS count FROM captcha WHERE word = ? AND ip_address = ? AND date > ?";<br />
+$binds = array($_POST['captcha'], $this->input->ip_address(), $expiration);<br />
+$query = $this->db->query($sql, $binds);<br />
+$row = $query->row();<br />
+<br />
+if ($row->count == 0)<br />
+{<br />
+ echo "You must submit the word that appears in the image";<br />
+}</code>
+
+</div>
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