<?php
  include '../lib/common.php';
  include '../lib/db.php';
  include '../lib/ShoppingCart.php';
  
  // create or resume session and retrieve shopping cart
  session_start();
  if (isset($\_SESSION[\text{'}cart\text{'}]))\; \{$cart = unserialize($\_SESSION[\text{'}cart\text{'}]);\; \}\; else\; \{$cart = new ShoppingCart(); 
  }
  
  // display sales page for a particular item
  if (isset($\_GET[\text{'}item\text{'}]))\; \{$// verify item exists
      query = sprintf('
          SELECT
              ITEM_ID, ITEM_NAME, ITEM_DESCRIPTION, PRICE, ITEM_IMAGE,
              C.CATEGORY_ID, CATEGORY_NAME
          FROM
             \%sSHOP_INVENTORY I
                 JOIN \%sSHOP_CATEGORY C ON I.CATEGORY_ID = C.CATEGORY_ID
          WHERE
              ITEM_ID = \%d',
          DB_TBL_PREFIX,
          DB_TBL_PREFIX,
          $\_GET[\text{'}item\text{'}]);$result = mysql_query($query,$GLOBALS['DB']);
  
      // item does not exist so redirect to main categories list
      if (!mysql_num_rows($result))\; \{\; mysql\_free\_result($result);
          header('Location: shop.php');
          exit();
      }
  
      $row\; =\; mysql\_fetch\_assoc($result);
  
      ob_start();
      echo '<p><a href="cart.php?category=' . $row[\text{'}CATEGORY\_ID\text{'}]\; .\; \text{'}">\text{'};\; echo\; \text{'}$<img src="img/cartview.gif" alt="View Cart"/></a></p>';
  
      echo '<h1>' . row['ITEM_NAME'] . '</h1>';
  
      echo '<p><a href=<shop.php>>Back to all categories</a> / ';
      echo '<a href="shop.php?category=' . $row[\text{'}CATEGORY\_ID\text{'}].\; \text{'}">Back\; to\; \text{'}\; .$row['CATEGORY_NAME'] . '</a></p>'; 
  
      echo '<table>';
      echo '<tr><td rowspan="3">';
      echo '<img src="' . $row[\text{'}ITEM\_IMAGE\text{'}]\; .\; \text{'}"/>$</td>';
      echo '<td><b>' . row['ITEM_NAME'] . '</b></td></tr>';
      echo '<tr><td>' . nl2br($row[\text{'}ITEM\_DESCRIPTION\text{'}])\; .\; \text{'}$</td></tr>';
      echo '<tr><td>' . number_format($row[\text{'}PRICE\text{'}],\; 2)\; .\; \text{'}$<br/>';
  
      // show link to either add or remove item from cart
      if (!cart->qtyItem(row['ITEM_ID'] . '">';
          echo '<img src="img/cartadd.gif" alt="Add to Cart"/></a>';
      }
      else
      {
          echo '<a href="cart.php?remove&item=' . $row[\text{'}ITEM\_ID\text{'}]\; .\; \text{'}">\text{'};\; echo\; \text{'}$<img src="img/cartremove.gif" alt="Remove from Cart"/></a>';
      }
      echo '</td></tr>';
      echo '</table>';
  
      GLOBALS['TEMPLATE']['content'] = ob_get_clean();
  }
  
  // display list of items in category
  else if (isset($\_GET[\text{'}category\text{'}]))\; \{$// verify if category parameter is valid
      query = sprintf('SELECT CATEGORY_ID, CATEGORY_NAME FROM ' .
          '\%sSHOP_CATEGORY WHERE CATEGORY_ID = \%d',
          DB_TBL_PREFIX,
          $\_GET[\text{'}category\text{'}]);$result = mysql_query($query,$GLOBALS['DB']);
  
      // category does not exist so redirect to main categories list
      if (!mysql_num_rows($result))\; \{\; mysql\_free\_result($result);
          header('Location: shop.php');
          exit();
      }
  
      $row\; =\; mysql\_fetch\_assoc($result);
      $id\; =$row['CATEGORY_ID'];
      $name\; =$row['CATEGORY_NAME'];
      mysql_free_result($result);\; ob\_start();\; echo\; \text{'}$<p><a href="cart.php?category=' . id . '">';
      echo '<img src="img/cartview.gif" alt="View Cart"/></a></p>';
  
      echo '<h1>Products in ' . $name\; .\; \text{'}$</h1>';
  
      echo '<p><a href=<shop.php>>Back to all categories</a></p>';
  
      // retrieve items
      query = sprintf('SELECT ITEM_ID, ITEM_NAME, ITEM_IMAGE ' . 
          'FROM \%sSHOP_INVENTORY WHERE CATEGORY_ID = \%d ORDER BY ITEM_NAME ASC',
          DB_TBL_PREFIX,
          $id);$result = mysql_query($query,$GLOBALS['DB']);
  
      while ($row\; =\; mysql\_fetch\_assoc($result))
      {
          echo '<table>';
          echo '<tr><td><img src="' . $row[\text{'}ITEM\_IMAGE\text{'}]\; .\; \text{'}"\; style="width:50px;height:50px;"/>$</td>';
          echo '<td><a href="shop.php?item=' . row['ITEM_ID'] . '">' .
              $row[\text{'}ITEM\_NAME\text{'}]\; .\; \text{'}$</a>' . '</td></tr>';
          echo '</table>';
      }
  
      GLOBALS['TEMPLATE']['content'] = ob_get_clean();
  }
  
  // display main list of categories and the number of products within each
  else
  {
      ob_start();
      echo '<p><a href=<cart.php>>' . 
          '<img src="img/cartview.gif" alt="View Cart"/></a></p>';
  
      echo '<h1>All Categories</h1>';
  
      // Note: LEFT JOIN not specified so any categories without products will
      // not be included in the results
      $query\; =\; sprintf(\text{'}\; SELECT\; C.CATEGORY\_ID,\; CATEGORY\_NAME,\; COUNT(ITEM\_ID)\; AS\; ITEM\_COUNT\; FROM$\%sSHOP_CATEGORY C
                  JOIN \%sSHOP_INVENTORY I ON C.CATEGORY_ID = I.CATEGORY_ID
          GROUP BY
              C.CATEGORY_ID
          ORDER BY
              CATEGORY_NAME ASC',
          DB_TBL_PREFIX,
          DB_TBL_PREFIX);
      result = mysql_query($query,$GLOBALS['DB']);
  
      echo '<ul>';
      while ($row\; =\; mysql\_fetch\_assoc($result))
      {
          printf('<li><a href="shop.php?category=\%d">\%s</a> (\%d \%s)</li>',
              $row[\text{'}CATEGORY\_ID\text{'}],$row['CATEGORY_NAME'], 
              $row[\text{'}ITEM\_COUNT\text{'}],\; (($row['ITEM_COUNT'] == 1) ? 'product' : 'products'));
      }
      mysql_free_result($result);\; echo\; \text{'}$</ul>';
  
      GLOBALS['TEMPLATE']['content'] = ob_get_clean();
  }
  
  // display the page
  include '../templates/template-page.php';
  ?>