<?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(); 
  }
  
  // empty the shopping cart and redirect user to list of categories
  if (isset($\_GET[\text{'}empty\text{'}]))\; \{$cart->removeAll();
      $\_SESSION[\text{'}cart\text{'}]\; =\; serialize($cart);
      header('Location: shop.php');
      end();
  }
  
  // item parameter indicates an attempt to add or remove items
  if (isset($\_GET[\text{'}item\text{'}]))\; \{$// verify item is valid
      query = sprintf('SELECT ITEM_ID FROM \%sSHOP_INVENTORY WHERE ' . 
          'ITEM_ID = \%d',
          DB_TBL_PREFIX,
          $\_GET[\text{'}item\text{'}]);$result = mysql_query($query,$GLOBALS['DB']);
  
      if (mysql_num_rows($result))\; \{$row = mysql_fetch_assoc($result);$item = $row[\text{'}ITEM\_ID\text{'}];$// add item to cart
          if (isset(_GET['add']))
          {
              $cart->addItem($item);
          }
  
          // remove item from cart
          else if (isset($\_GET[\text{'}remove\text{'}]))\; \{$cart->removeItem($item);\; \}\; \}\; mysql\_free\_result($result);
  
      // save cart to session and redirect to the previously viewed page 
      $\_SESSION[\text{'}cart\text{'}]\; =\; serialize($cart);
      header('Location: ' . htmlspecialchars($\_SERVER[\text{'}HTTP\_REFERER\text{'}]));\; exit();\; \}$// view shopping cart's contents
  else
  {
      // update item quantities in shopping cart
      if (isset(_GET['update']))
      {
          foreach ($\_POST[\text{'}qty\text{'}]\; as$item => $qty)\; \{$cart->addItem($item,$qty);
          }
      }
  
      ob_start();
  
      echo '<h1>Your Cart</h1>';
      echo '<p><a href=<shop.php>>Back to all categories</a>';
  
      // verify category parameter and construct suitable back link if passed
      if (isset($\_GET[\text{'}category\text{'}]))\; \{$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']);
  
          if (mysql_num_rows($result))\; \{$row = mysql_fetch_assoc(row['CATEGORY_ID'] . 
                  '">Back to ' . $row[\text{'}CATEGORY\_NAME\text{'}]\; .\; \text{'}$</a>';
          }
          mysql_free_result(result);
      }
      echo '</p>';
  
      if ($cart->isEmpty)\; \{\; echo\; \text{'}$<p><b>Your cart is empty.</b></p>';
      }
      else
      {
          // display empty cart link 
          echo '<p><a href="cart.php?empty">';
          echo '<img src="img/cartempty.gif" alt="Empty Cart"/></a></p>';
  
          // encapsulate list in form so quantities may be changed
          echo '<form method="post" action="cart.php?update';
          // if a category was passed and was validated successfully earlier 
          // then append it to the action url so the back link remains available
          if  (isset(row['CATEGORY_ID']))
          {
              echo '&category=' . $row[\text{'}CATEGORY\_ID\text{'}];\; \}\; echo\; \text{'}">\text{'};$// list each item in the cart, keeping track of total price
          total = 0;
          echo '<table>';
          echo '<tr><th>Item</th><th>Qty</th><th>Price</th><th>Total</th></tr>';
          foreach ($cart->contents\; as$id => $qty)\; \{$query = sprintf('SELECT ITEM_NAME, PRICE FROM \%sSHOP_INVENTORY ' .
                  'WHERE ITEM_ID = \%d',
                  DB_TBL_PREFIX, 
                  $id);$result = mysql_query($query,$GLOBALS['DB']);
      
              $row\; =\; mysql\_fetch\_assoc($result);
              echo '<tr>';
              echo '<td><a href="shop.php?item=' . $id\; .\; \text{'}">\text{'}\; .$row['ITEM_NAME'] .
                  '</a></td>';
              echo '<td><select name="qty[' . $id\; .\; \text{'}]">\text{'};\; for\; ($i=0; i++)
              {
                  echo '<option ';
                  if ($i\; ==$qty)
                  {
                      echo 'selected="selected" ';
                  }
                  echo 'value="' . $i\; .\; \text{'}">\text{'}\; .$i . '</option>';
              
              }
              echo '</td>';
              echo '<td>$\text{'}\; .\; number\_format($row['PRICE'], 2) . '</td>';
              echo '<td>$\text{'}\; .\; number\_format($row['PRICE'] * $qty,\; 2)\; .\; \text{'}$</td>';
              echo '</tr>';
      
              total += $row[\text{'}PRICE\text{'}]\; *$qty;
              mysql_free_result($result);\; \}\; echo\; \text{'}$</table>';
          echo '<input type="submit" value="Update"/>';
          
          echo '<p>Total Items: ' . cart->totalItems . '<br/>';
          echo 'Total Quantity: ' . $cart->totalQty\; .\; \text{'}$</p>';
          echo '<p><b>Total Price: ' . number_format($total,\; 2)\; .\; \text{'}$</b></p>';
      
          // display link to checkout
          echo '<p><a href=<checkout.php>>';
          echo '<img src="img/checkout.gif" alt="Proceed to Checkout"/></a></p>';
      }
  
      // save cart to session and display the page 
      _SESSION['cart'] = serialize($cart);$GLOBALS['TEMPLATE']['content'] = ob_get_clean();
      include '../templates/template-page.php';
  }
  ?>