require_once('data/data_util.php');

use \Tsugi\Core\LTIX;

use \Tsugi\Util\LTI;

use \Tsugi\Util\Mersenne_Twister;

if ( PHP_INT_SIZE == 8 ) {

$GLOBAL_PYTHON_DATA_URL = "http://py4e-data.dr-chuck.net/";

} else {

$GLOBAL_PYTHON_DATA_URL = false; // To serve locally

}

$sanity = array(

'urllib' => 'You should use urllib to retrieve the HTML Pages',

'BeautifulSoup' => 'You should use BeautifulSoup to parse the HTML'

);

$sample_pages = 4;

$sample_pos = 2;

$actual_pages = 7;

$actual_pos = 17;

$code = 12345;

$sample_names = array();

$names = getShuffledNames($code);

$name = $names[$sample_pos];

$sample_names[] = $name;

for($p=0;$p<$sample_pages;$p++) {

$code = array_search($name, $NAMES);

$names = getShuffledNames($code);

$name = $names[$sample_pos];

$sample_last = $name;

$sample_names[] = $name;

}

if ( isset($_SESSION['debug']) && is_string($_SESSION['debug']) ) {

$code = array_search($_SESSION['debug'], $NAMES);

$name = $_SESSION['debug'];

} else {

$code = $USER->id+$LINK->id+$CONTEXT->id;

$names = getShuffledNames($code);

$name = $names[$actual_pos];

}

$actual_names = array();

$actual_names[] = $name;

for($p=0;$p<$actual_pages;$p++) {

$code = array_search($name, $NAMES);

$names = getShuffledNames($code);

$name = $names[$actual_pos];

$actual_last = $name;

$actual_names[] = $name;

}

$oldgrade = $RESULT->grade;

if ( isset($_POST['name']) && isset($_POST['code']) ) {

if ( $USER->instructor && strpos($_POST['name'],'42') === 0 ) {

$pieces = explode(',',$_POST['name']);

$_SESSION['success'] = "Debug Mode Unlocked";

if ( count($pieces) == 2 ) {

$_SESSION['debug'] = $pieces[1];

} else {

$_SESSION['debug'] = true;

}

header('Location: '.addSession('index.php'));

return;

}

$RESULT->setJsonKey('code', $_POST['code']);

if ( $_POST['name'] != $actual_last ) {

$_SESSION['error'] = "Your name did not match";

header('Location: '.addSession('index.php'));

return;

}

$val = validate($sanity, $_POST['code']);

if ( is_string($val) ) {

$_SESSION['error'] = $val;

header('Location: '.addSession('index.php'));

return;

}

LTIX::gradeSendDueDate(1.0, $oldgrade, $dueDate);

// Redirect to ourself

header('Location: '.addSession('index.php'));

return;

}

if ( $RESULT->grade > 0 ) {

echo('<p class="alert alert-info">Your current grade on this assignment is: '.($RESULT->grade*100.0).'%</p>'."\n");

}

if ( $dueDate->message ) {

echo('<p style="color:red;">'.$dueDate->message.'</p>'."\n");

}

$sample_url = dataUrl('known_by_'.$sample_names[0].'.html');

$actual_url = dataUrl('known_by_'.$actual_names[0].'.html');

<p>

<b>Following Links in Python</b>

<p>

In this assignment you will write a Python program that expands on

<a href="http://www.py4e.com/code3/urllinks.py" target="_blank">http://www.py4e.com/code3/urllinks.py</a>.

The program will use <b>urllib</b> to read the HTML from the data files below,

extract the href= vaues from the anchor tags, scan for a tag that is in

a particular position relative to the first name in the list,

follow that link and repeat the process

a number of times and report the last name you find.

</p>

<p>

We provide two files for this assignment. One is a sample file where we give

you the name for your testing and the other is the actual data you need

to process for the assignment

<ul>

<li> Sample problem: Start at

<a href="<?= deHttps($sample_url) ?>" target="_blank"><?= deHttps($sample_url) ?></a> <br/>

Find the link at position <b><?= $sample_pos+1 ?></b> (the first name is 1).

Follow that link. Repeat this process <b><?= $sample_pages ?></b> times. The

answer is the last name that you retrieve.<br/>

Sequence of names:

foreach($sample_names as $name) {

echo($name.' ');

}

echo("<br/>\n");

Last name in sequence: <?= $sample_last ?><br/>

</li>

<li> Actual problem: Start at: <a href="<?= deHttps($actual_url) ?>" target="_blank"><?= deHttps($actual_url) ?></a> <br/>

Find the link at position <b><?= $actual_pos+1 ?></b> (the first name is 1).

Follow that link. Repeat this process <b><?= $actual_pages ?></b> times. The

answer is the last name that you retrieve.<br/>

Hint: The first character of the name of the last page

that you will load is: <?= substr($actual_last,0,1) ?><br/>

if ( isset($_SESSION['debug']) ) {

echo("<pre>\n");

echo("Debug sequence of names: \n");

foreach($actual_names as $name) {

echo(" $name\n");

}

echo("</pre>\n");

}

</li>

</ul>

<b>Strategy</b>

<p>

The web pages tweak the height between the links and hide the page after a few seconds

to make it difficult for you to do the assignment without writing a Python program.

But frankly with a little effort and patience you can overcome these attempts to make it

a little harder to complete the assignment without writing a Python program.

But that is not the point. The point is to write a clever Python program to solve the

program.

</p>

<p><b>Sample execution</b>

<p>

Here is a sample execution of a solution:

<pre>

$ python3 solution.py

Enter URL: <?= dataUrl('known_by_Fikret.html')."\n"; ?>

Enter count: 4

Enter position: 3

Retrieving: <?= dataUrl('known_by_Fikret.html')."\n"; ?>

Retrieving: <?= dataUrl('known_by_Montgomery.html')."\n"; ?>

Retrieving: <?= dataUrl('known_by_Mhairade.html')."\n"; ?>

Retrieving: <?= dataUrl('known_by_Butchi.html')."\n"; ?>

Retrieving: <?= dataUrl('known_by_Anayah.html')."\n"; ?>

</pre>

The answer to the assignment for this execution is "Anayah".

</p>

<?php httpsWarning($sample_url); ?>

<p><b>Turning in the Assignment</b>

<form method="post">

Enter the last name retrieved and your Python code below:<br/>

Name: <input type="text" size="20" name="name">

(name starts with <?= substr($actual_last,0,1) ?>)

<input type="submit" value="Submit Assignment"><br/>

if ( $USER->instructor ) {

echo("<b>Instructor Note:</b> If you want to test a student's data enter '42,Viki' with with starting name of the student's actual data.<br/>");

}

Python code:<br/>

<textarea rows="20" style="width: 90%" name="code"></textarea><br/>

</form>