socialsecurity popularnames technical test

gistfile1.aw

<?php

// queries http://www.socialsecurity.gov/cgi-bin/popularnames.cgi
// allows user to enter years to aggregate stats over, allows user to limit thei  caches if possible


// Given the extra time
// * Functions would have doxygen documentation around them
// * All functions would assert clearly and bail early if they weren't given expected variables
// * Rationalise mixed use of camelCase and snake_case
// * More comments
// * More helper functions and abstract the page function into a separate one when there is a $_GET submission
// * Maybe written an abstraction of the apc read/writes so it could fall back to serialised file writes
// * Make the previously selected values display in the inputs
// * Use selects rather than inputs
// * Make the table sortable in php/javascript
// * Made it more obvious that if you don't specify a limit it will display all it can
// * Written some css to make it more readable
// * Made the table semantic
// * Allowed the user to retrieve the response in different formats
// * Used a pear class to help write and validate the form elements e.g http://pear.php.net/manual/en/package.html.html-quickform.tutorial.php
// In hindsight
// * I probably wouldn't have written the dom entirely in php as I spent far to long on it and the code isn't as readable as I wanted it to be
// * There might be a faster way to traverse the dom than xpath, I just went with what I knew I could do quickly
// * I could/should have written what processes the xpath into something safer than what it is
// * While I've limited exposure to Symfony I should have used that to do some of the leg work rather than reinventing the wheel in a few places
// * I presume the test was written a while ago, but since you specified the year as 2010 I made it restrict to that rather than the relative last year since 2011 data is available


class mytest {

  public static $entrypoint = "http://www.socialsecurity.gov/cgi-bin/popularnames.cgi";
  public static $apc_prefix = "mytest_";
  public static $apc_ttl = 360; // cache responses for 5 mins

  function __construct() {
    // check for some basics
    if (!function_exists("apc_fetch"))
      die("We need apc");
    if (!function_exists("curl_init"))
      die("We need curl");
  }

  private function make_http_request($year) {
    $ch = curl_init();
    $query['year'] = $year;
    $query['top'] = 1000;
    $query['number'] = "n";
    curl_setopt($ch, CURLOPT_URL, self::$entrypoint);
    curl_setopt($ch, CURLOPT_POST, TRUE);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
    curl_setopt($ch, CURLOPT_FAILONERROR, TRUE);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 0);
    curl_setopt($ch, CURLOPT_TIMEOUT, 180);
    curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($query));
    $return = curl_exec($ch);
    curl_close($ch);
    if (!$return) {
      $http_error_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
      die($http_error_code . ': Unable to connect to server');
    }
    return $return;
  }

  private function get_and_make_array_of_year($year) {
    $rawresponse = self::make_http_request($year);
    $doc = new DOMDocument();
    $doc->loadHTML($rawresponse);
    // @todo insert error handling if dom is not parsed correctly
    $xpath = new DOMXpath($doc); // create an xpath addressable object
    // @todo insert error handling if we can't get an xpath handler on dom
    // @todo refactor this xpath with something that dosen't require the gross stuff beneath
    // @todo maybe allow you to select women too
    $elements = $xpath->query("//table[@summary='Popularity for top 1000']/tr[position() >= 2]/td[position() = 2 or position() = 3 ]");
    $data = array();
    foreach ($elements as $node) {
      if (!$key) { // if we're dealing with the name just take that and clear it later
        $key = $node->nodeValue;
        continue;
      }
      // todo insert some error handling if we don't get an integer back or they change their formatting
      $data[$key] = str_replace(',', '', $node->nodeValue) * 1; // remove commas and make sure its stored as an int
      unset($key);
    }
    return $data;
  }

  private function fetch_year_data($year) {
    if (!is_numeric($year))
      die("year is not numeric");
    $data = apc_fetch(self::$apc_prefix . $year);
    if ($data)
      return $data; // if we have this year cached then just return it

    $data = self::get_and_make_array_of_year($year);

    apc_store(self::$apc_prefix . $year, $data, self::$apc_ttl);
    return $data;
  }

  private function merge_year_data($start_year, $end_year, $limit) {
    if (!$limit) unset($limit);
    $alldata = array_fill($start_year, $end_year - $start_year + 1, array());
    // first just get some full big formed data array to work with
    foreach ($alldata as $year => &$data) {
      $data = self::fetch_year_data($year);
    }
    unset($data);
    $merged_data = array();

    foreach ($alldata as $year) { // process a year
      foreach ($year as $name => $count) { // merge all the years data together
        // if we've already seen this name
        if (isset($merged_data[$name])) {
          $merged_data[$name] += $count;
        }
        else {
          $merged_data[$name] = $count;
        }
      }
    }
    arsort($merged_data);
    // now we've got a massive correct dataset make it manageable and delete a load of it if a limit has been set
    if ($limit)
      array_splice($merged_data, $limit);
    return $merged_data;
  }

  public function page() {
    $document = DOMImplementation::createDocument(null, 'html', DOMImplementation::createDocumentType("html", "-//W3C//DTD XHTML 1.0 Transitional//EN", "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"));
    $document->formatOutput = true;

    $html = $document->documentElement;
    $head = $document->createElement('head');
    $title = $document->createElement('title');
    $text = $document->createTextNode('CNS Test');
    $body = $document->createElement('body');

    $title->appendChild($text);
    $head->appendChild($title);
    $html->appendChild($head);
    $html->appendChild($body);

    $form = $document->createElement('form');

    $form_inputs = array(
      "limit" => "Limit",
      "startyear" => "Start Year",
      "endyear" => "End Year",
    );
    $value_attribute = $document->createAttribute('value');
    $label_attribute = $document->createAttribute('for');

    foreach ($form_inputs as $name => $label) {
      $label = $document->createElement('label', $label);
      $label_attribute->value = $name;
      $label->appendChild($label_attribute);
      $form->appendChild($label);
      $input = $document->createElement('input');
      $name_attribute = $document->createAttribute('name');
      $name_attribute->value = $name;
      $input->appendChild($name_attribute);
      $form->appendChild($input);
    }
    $submit_button = $document->createElement('input');
    $type_attribute = $document->createAttribute('type');
    $type_attribute->value = "submit";
    $value_attribute->value = "submit";
    $submit_button->appendChild($type_attribute);
    $submit_button->appendChild($value_attribute);
    $form->appendChild($submit_button);
    $body->appendChild($form);

    $limit = $_GET['limit'] * 1;
    $startyear = $_GET['startyear'] * 1;
    $endyear = $_GET['endyear'] * 1;
    if (empty($_GET)) {
      return $document->saveHTML();
    }
    if ($startyear < 1880 || $endyear < 1180 || $startyear > 2010 || $endyear > 2010 || $startyear > $endyear) {
      die("invalid date range");
    }
      $table = $document->createElement("table");
      $table_head = $document->createElement("thead");
      $rowheads = array("Rank", "Name", "Total");
      foreach ($rowheads as $text) {
      $table_head_th = $document->createElement("th", $text);
      $table_head->appendChild($table_head_th);
      }

      $table->appendChild($table_head);

      $table_body = $document->createElement("tbody");
      $table->appendChild($table_body);

      $data = self::merge_year_data($startyear, $endyear, $limit);
      $rank = 1;
      foreach ($data as $name => $total) {
      $tr = $document->createElement('tr');
      $table_body->appendChild($tr);
      $td_rank = $document->createElement('td', $rank);
      $td_name = $document->createElement('td', $name);
      $td_total = $document->createElement('td', number_format($total));
      $tr->appendChild($td_rank);
      $tr->appendChild($td_name);
      $tr->appendChild($td_total);
      $rank++;
      }
      $body->appendChild($table);

    return $document->saveHTML();
  }

}

$documentcontroler = new mytest();
print $documentcontroler->page();