<?php
  /*
   * CSE 154
   * Week 9 Section
   * API to handle update queries for adding to MyCart
   */
  include("common.php");
  
  if (isset($_POST["mode"]) && isset($_POST["pid"]) && isset($_POST["qty"])) {
    $db = get_PDO();
    $mode = strtolower($_POST["mode"]);
    if ($mode === "add") {
      add_product_to_cart($db, $_POST["pid"], $_POST["qty"]);
    } else {
      handle_error("Mode parameter must be passed as 'add'");
    }
  } else {
    handle_error("Missing required 'mode', 'pid', and 'qty' POST parameters.");
  }

  # Exercise 4
  function add_product_to_cart($db, $pid, $qty) {
    try {
      # Looking to see if product exists in Inventory
      $qry = "SELECT name FROM Inventory WHERE id=:pid";
      $stmt = $db->prepare($qry);
      $params = array("pid" => $pid);
      $stmt->execute($params);
      $row = $stmt->fetch();

      if ($row) {
        $name = $row["name"];
        $qry = "SELECT qty FROM MyCart WHERE pid=:pid";
        $stmt = $db->prepare($qry);
        $stmt->execute($params);
        $cart_row = $stmt->fetch();

        header("Content-type: application/json");
        if ($cart_row) {
          $old_qty = $cart_row["qty"];
          $qty += $old_qty;
          $qry = "UPDATE MyCart SET qty=:qty, lastupdated=NOW() WHERE pid=:pid";
        } else { # No product found with the given $pid
          $qry = "INSERT INTO MyCart (pid, qty, lastupdated) VALUES(:pid, :qty, NOW())";
        }
        $stmt = $db->prepare($qry);
        $params = array("qty" => $qty, "pid" => $pid);
        $stmt->execute($params);

        print(json_encode(array("success" => "{$qty} of {$name} added to your shopping cart!")));
      } else {
        handle_error("Product not found in our inventory");
      }
    } catch (PDOException $ex) {
      handle_error("Error adding product into database. Please try again later.", $ex);
    }
  }
?>