<?php

/**
 * @file
 * The product kit module for Ubercart.
 *
 * Product kits are groups of products that are sold as a unit.
 */

define('UC_PRODUCT_KIT_UNMUTABLE_NO_LIST', -1);
define('UC_PRODUCT_KIT_UNMUTABLE_WITH_LIST', 0);
define('UC_PRODUCT_KIT_MUTABLE', 1);


/**
 * Implements hook_form_FORM_ID_alter() for uc_product_settings_form().
 */
function uc_product_kit_form_uc_product_settings_form_alter(&$form, &$form_state) {
  $form['product_kit'] = array(
    '#type' => 'fieldset',
    '#title' => 'Product kit settings',
    '#group' => 'product-settings',
    '#weight' => -5,
  );
  $form['product_kit']['uc_product_kit_mutable'] = array(
    '#type' => 'radios',
    '#title' => t('Product kit cart display'),
    '#options' => array(
      UC_PRODUCT_KIT_UNMUTABLE_NO_LIST => t('As a unit. Customers may only change how many kits they are buying. Do not list component products.'),
      UC_PRODUCT_KIT_UNMUTABLE_WITH_LIST => t('As a unit. Customers may only change how many kits they are buying. List component products.'),
      UC_PRODUCT_KIT_MUTABLE => t('As individual products. Customers may add or remove kit components at will. Discounts entered below are not applied to the kit price'),
    ),
    '#default_value' => variable_get('uc_product_kit_mutable', 0),
  );
}

/**
 * Implements hook_form_FORM_ID_alter() for node_delete_confirm().
 */
function uc_product_kit_form_node_delete_confirm_alter(&$form, &$form_state) {
  if (uc_product_is_product((integer)$form['nid']['#value'])) {
    $kits = db_query("SELECT COUNT(k.nid) FROM {node} n JOIN {uc_product_kits} k ON n.vid = k.vid WHERE k.vid IN (SELECT DISTINCT vid FROM {uc_product_kits} WHERE product_id = :nid) GROUP BY k.nid HAVING COUNT(product_id) = 1", array(':nid' => $form['nid']['#value']))->fetchField();

    if ($kits) {
      $description = $form['description']['#markup'];
      $form['description']['#markup'] = format_plural($kits, 'There is 1 product kit that consists of only this product. It will be deleted as well.', 'There are @count product kits that consist of only this products. They will be deleted as well.') . ' ' . $description;
    }
  }
}

/**
 * Implements hook_uc_form_alter().
 *
 * Puts a product list on the form, so product kit attributes will work on the
 * order admin edit form. See uc_attribute_form_alter().
 */
function uc_product_kit_uc_form_alter(&$form, &$form_state, $form_id) {
  if ($form_id == 'uc_order_add_product_form') {
    if (!isset($form['sub_products'])) {
      // We only want product kits.
      $kit = $form['node']['#value'];
      if ($kit->type !== 'product_kit') {
        return;
      }

      $products = array('#tree' => TRUE);
      foreach ($kit->products as $kit_product) {
        $products[$kit_product->nid] = array();
      }

      // Add the products to the beginning of the form for visual aesthetics.
      $form = array_merge(array('sub_products' => $products), $form);
    }
  }
}

/**
 * Implements hook_node_info().
 *
 * @return
 *   Node type information for product kits.
 */
function uc_product_kit_node_info() {
  return array(
    'product_kit' => array(
      'name' => t('Product kit'),
      'base' => 'uc_product_kit',
      'description' => t('Use <em>product kits</em> to list two or more products together, presenting a logical and convenient grouping of items to the customer.'),
      'title_label' => t('Name'),
      'body_label' => t('Description'),
    ),
  );
}

/**
 * Implements hook_prepare().
 */
function uc_product_kit_prepare($node) {
  $defaults = array(
    'mutable' => variable_get('uc_product_kit_mutable', UC_PRODUCT_KIT_UNMUTABLE_WITH_LIST),
    'products' => array(),
    'default_qty' => 1,
    'ordering' => 0,
  );

  foreach ($defaults as $key => $value) {
    if (!isset($node->$key)) {
      $node->$key = $value;
    }
  }
}

/**
 * Implements hook_insert().
 *
 * Adds a row to {uc_products} to make a product. Extra information about the
 * component products are stored in {uc_product_kits}.
 *
 * @param &$node
 *   The node object being saved.
 *
 * @see uc_product_insert()
 */
function uc_product_kit_insert(&$node) {
  $obj = new stdClass();
  $obj->vid = $node->vid;
  $obj->nid = $node->nid;
  $obj->model = '';
  $obj->list_price = 0;
  $obj->cost = 0;
  $obj->sell_price = 0;
  $obj->weight = 0;
  $obj->weight_units = variable_get('uc_weight_unit', 'lb');
  $obj->default_qty = $node->default_qty;
  $obj->ordering = $node->ordering;
  $obj->shippable = FALSE;

  $values = array();
  $placeholders = array();
  foreach ($node->products as $product) {
    if (is_numeric($product)) {
      $product = node_load($product);
    }

    $kit = array(
      'vid' => $node->vid,
      'nid' => $node->nid,
      'product_id' => $product->nid,
      'mutable' => $node->mutable,
      'qty' => 1,
      'synchronized' => 1,
    );

    drupal_write_record('uc_product_kits', $kit);

    $obj->model .= $product->model . ' / ';
    $obj->list_price += $product->list_price;
    $obj->cost += $product->cost;
    $obj->sell_price += $product->sell_price;
    $obj->weight += $product->weight * uc_weight_conversion($product->weight_units, $obj->weight_units);
    if ($product->shippable) {
      $obj->shippable = TRUE;
    }
  }

  $obj->model = rtrim($obj->model, ' / ');

  drupal_write_record('uc_products', $obj);
}

/**
 * Implements hook_update().
 *
 * Updates information in {uc_products} as well as {uc_product_kits}. Because
 * component products are known when the form is loaded, discount information
 * can be input and saved.
 *
 * @param &$node
 *   The node to be updated.
 *
 * @see uc_product_update()
 */
function uc_product_kit_update(&$node) {
  $obj = new stdClass();
  $obj->vid = $node->vid;
  $obj->nid = $node->nid;
  $obj->model = '';
  $obj->list_price = 0;
  $obj->cost = 0;
  $obj->sell_price = 0;
  $obj->weight = 0;
  $obj->weight_units = variable_get('uc_weight_unit', 'lb');
  $obj->default_qty = $node->default_qty;
  $obj->ordering = $node->ordering;
  $obj->shippable = FALSE;

  if (!isset($node->kit_total) && isset($node->synchronized) && isset($node->sell_price)) {
    $override_discounts = !$node->synchronized;
    $node->kit_total = $node->sell_price;
  }
  else {
    $override_discounts = isset($node->kit_total) && is_numeric($node->kit_total);
  }
  $product_count = count($node->products);

  // Get the price of all the products without any discounts. This number is
  // used if a total kit price was specified to calculate the individual
  // product discounts.
  if ($override_discounts) {
    $base_price = 0;
    foreach ($node->products as $nid) {
      // Usually, $node is $form_state['values'] cast as an object.
      // However, there could be times where node_save() is called with an
      // actual product kit node. $node->products is an array of objects and
      // $node->items doesn't exist then.
      if (is_numeric($nid)) {
        $product = node_load($nid, NULL, TRUE);
        if (!isset($node->items[$nid]['qty']) || $node->items[$nid]['qty'] === '') {
          $node->items[$nid]['qty'] = 1;
        }
      }
      else {
        $product = $nid;
        $nid = $product->nid;
        $node->items[$nid] = (array)$product;
      }
      $base_price += $product->sell_price * $node->items[$nid]['qty'];
    }
  }

  if (empty($node->revision)) {
    db_delete('uc_product_kits')
      ->condition('vid', $node->vid)
      ->execute();
  }
  foreach ($node->products as $nid) {
    if (is_numeric($nid)) {
      $product = node_load($nid);
    }
    else {
      $product = $nid;
      $nid = $product->nid;
    }

    // When a total kit price is specified, calculate the individual product
    // discounts needed to reach it, taking into account the product quantities
    // and their relative prices. More expensive products should be given a
    // proportionally higher discount.
    if ($override_discounts) {
      // After all the algebra that went into finding this formula, it's
      // surprising how simple it is.
      $discount = ($node->kit_total - $base_price) * $product->sell_price / $base_price;
    }
    elseif (isset($node->items[$nid]['discount'])) {
      $discount = (float) $node->items[$nid]['discount'];
    }
    elseif (isset($node->products[$nid]->discount)) {
      $discount = $node->products[$nid]->discount;
    }
    else {
      $discount = 0;
    }

    if (isset($node->items)) {
      if (!isset($node->items[$nid]['qty']) || $node->items[$nid]['qty'] === '') {
        $node->items[$nid]['qty'] = 1;
      }

      $product->qty = $node->items[$nid]['qty'];
      $product->ordering = isset($node->items[$nid]['ordering']) ? $node->items[$nid]['ordering'] : 0;
    }
    else {
      $product->qty = $node->products[$nid]->qty;
      $product->ordering = $node->products[$nid]->ordering;
    }
    // Discounts are always saved, but they are only applied if the kit can't
    // be changed by the customer.
    if ($node->mutable != UC_PRODUCT_KIT_MUTABLE) {
      $product->sell_price += $discount;
    }

    $obj->model .= $product->model . ' / ';
    $obj->list_price += $product->list_price * $product->qty;
    $obj->cost += $product->cost * $product->qty;
    $obj->sell_price += $product->sell_price * $product->qty;
    $obj->weight += $product->weight * $product->qty * uc_weight_conversion($product->weight_units, $obj->weight_units);
    if ($product->shippable) {
      $obj->shippable = TRUE;
    }

    db_insert('uc_product_kits')
      ->fields(array(
        'vid' => $node->vid,
        'nid' => $node->nid,
        'product_id' => $nid,
        'mutable' => $node->mutable,
        'qty' => $product->qty,
        'discount' => $discount,
        'ordering' => $product->ordering,
        'synchronized' => $override_discounts ? 0 : 1,
      ))
      ->execute();
  }

  $obj->model = rtrim($obj->model, ' / ');

  if ($node->mutable == UC_PRODUCT_KIT_MUTABLE && !empty($discount)) {
    drupal_set_message(t('Product kit discounts are not applied because the customer can remove components from their cart.'));
  }

  if (!empty($node->revision)) {
    drupal_write_record('uc_products', $obj);
  }
  else {
    db_merge('uc_products')
      ->key(array('vid' => $obj->vid))
      ->fields(array(
        'model' => $obj->model,
        'list_price' => $obj->list_price,
        'cost' => $obj->cost,
        'sell_price' => $obj->sell_price,
        'weight' => $obj->weight,
        'weight_units' => $obj->weight_units,
        'default_qty' => $obj->default_qty,
        'ordering' => $obj->ordering,
        'shippable' => $obj->shippable ? 1 : 0,
      ))
      ->execute();
  }

  // When a kit is updated, remove matching kits from the cart, as there is no
  // simple way to handle product addition or removal at this point.
  if (module_exists('uc_cart')) {
    db_delete('uc_cart_products')
      ->condition('data', '%' . db_like('s:6:"kit_id";s:' . strlen($node->nid) . ':"' . $node->nid . '";') . '%', 'LIKE')
      ->execute();
  }
}

/**
 * Implements hook_delete().
 */
function uc_product_kit_delete(&$node) {
  if (module_exists('uc_cart')) {
    db_delete('uc_cart_products')
      ->condition('data', '%' . db_like('s:6:"kit_id";s:' . strlen($node->nid) . ':"' . $node->nid . '";') . '%', 'LIKE')
      ->execute();
  }
  db_delete('uc_product_kits')
    ->condition('nid', $node->nid)
    ->execute();

  db_delete('uc_products')
    ->condition('nid', $node->nid)
    ->execute();
}

/**
 * Implements hook_load().
 */
function uc_product_kit_load($nodes) {
  $vids = array();
  foreach ($nodes as $nid => $node) {
    $vids[$nid] = $node->vid;
  }

  $all_products = array();
  $result = db_query("SELECT nid, product_id, mutable, qty, discount, ordering, synchronized FROM {uc_product_kits} WHERE vid IN (:vids) ORDER BY nid, ordering", array(':vids' => $vids));
  while ($prod = $result->fetchObject()) {
    $nodes[$prod->nid]->mutable = $prod->mutable;
    $nodes[$prod->nid]->synchronized = $prod->synchronized;

    // Add the component information.
    $data = array();
    if ($prod->mutable != UC_PRODUCT_KIT_MUTABLE) {
      $data = array('kit_id' => $prod->nid, 'kit_discount' => $prod->discount);
    }
    $product = uc_product_load_variant($prod->product_id, $data);
    $product->qty = $prod->qty;
    $product->discount = $prod->discount;
    $product->ordering = $prod->ordering;

    // Add product to the kit.
    $nodes[$prod->nid]->products[$product->nid] = $product;
  }

  // Add product data to kits.
  uc_product_load($nodes);
}

/**
 * Implements hook_module_implements_alter().
 *
 * Ensure that our component products have their discounts applied before any
 * other product alterations are made.
 */
function uc_product_kit_module_implements_alter(&$implementations, $hook) {
  if ($hook == 'uc_product_alter') {
    $group = $implementations['uc_product_kit'];
    unset($implementations['uc_product_kit']);
    $implementations =  array('uc_product_kit' => $group) + $implementations;
  }
}

/**
 * Implements hook_theme().
 */
function uc_product_kit_theme() {
  return array(
    'uc_product_kit_items_form' => array(
      'render element' => 'form',
      'file' => 'uc_product_kit.theme.inc',
    ),
    'uc_product_kit_add_to_cart' => array(
      'variables' => array('form' => NULL, 'view_mode' => 'full'),
      'file' => 'uc_product_kit.theme.inc',
    ),
    'uc_product_kit_list_item' => array(
      'arguments' => array('product' => NULL),
      'file' => 'uc_product_kit.theme.inc',
    ),
  );
}

/**
 * Implements hook_node_update().
 *
 * Ensures product kit discounts are updated if their component nodes are
 * updated or deleted.
 */
function uc_product_kit_node_update($node) {
  $result = db_query("SELECT DISTINCT nid FROM {uc_product_kits} WHERE product_id = :nid", array(':nid' => $node->nid));
  while ($nid = $result->fetchField()) {
    $kit = node_load($nid, NULL, TRUE);
    node_save($kit);
  }
}

/**
 * Implements hook_node_delete().
 *
 * Ensures product kit discounts are updated if their component nodes are
 * deleted.
 */
function uc_product_kit_node_delete($node) {
  $empty = array();
  $result = db_query("SELECT DISTINCT nid FROM {uc_product_kits} WHERE product_id = :nid", array(':nid' => $node->nid));
  while ($nid = $result->fetchField()) {
    $kit = node_load($nid, NULL, TRUE);
    unset($kit->products[$node->nid]);

    if (empty($kit->products)) {
      $empty[] = $kit->nid;
    }
    else {
      node_save($kit);
    }
  }

  if ($empty) {
    node_delete_multiple($empty);
  }
}

/**
 * Implements hook_forms().
 *
 * Registers an "Add to Cart" form for each product kit.
 *
 * @see uc_product_kit_add_to_cart_form()
 * @see uc_catalog_buy_it_now_form()
 */
function uc_product_kit_forms($form_id, $args) {
  $forms = array();
  if (isset($args[0]) && isset($args[0]->nid) && isset($args[0]->type)) {
    $product = $args[0];
    if ($product->type == 'product_kit') {
      $forms['uc_product_kit_add_to_cart_form_' . $product->nid] = array('callback' => 'uc_product_kit_add_to_cart_form');
      $forms['uc_product_add_to_cart_form_' . $product->nid] = array('callback' => 'uc_product_kit_add_to_cart_form');
      $forms['uc_catalog_buy_it_now_form_' . $product->nid] = array('callback' => 'uc_product_kit_buy_it_now_form');
    }
  }
  return $forms;
}

/**
 * Implements hook_form().
 *
 * @ingroup forms
 */
function uc_product_kit_form(&$node, $form_state) {
  $form['title'] = array(
    '#type' => 'textfield',
    '#title' => t('Name'),
    '#required' => TRUE,
    '#weight' => -5,
    '#default_value' => $node->title,
    '#description' => t('Name of the product kit')
  );

  // Create an array of products on the site for use in the product selector.
  $product_types = uc_product_types();
  $products = array();

  // Disregard other product kits.
  unset($product_types[array_search('product_kit', $product_types)]);

  // Query the database and loop through the results.
  $products = db_query("SELECT nid, title FROM {node} WHERE type IN (:types) ORDER BY title, nid", array(':types' => $product_types))->fetchAllKeyed();

  $form['base'] = array(
    '#type' => 'fieldset',
    '#title' => t('Product kit information'),
    '#collapsible' => TRUE,
    '#collapsed' => FALSE,
    '#weight' => -10,
    '#group' => 'additional_settings',
  );
  $form['base']['mutable'] = array(
    '#type' => 'radios',
    '#title' => t('How is this product kit handled by the cart?'),
    '#options' => array(
      UC_PRODUCT_KIT_UNMUTABLE_NO_LIST => t('As a unit. Customers may only change how many kits they are buying. Do not list component products.'),
      UC_PRODUCT_KIT_UNMUTABLE_WITH_LIST => t('As a unit. Customers may only change how many kits they are buying. List component products.'),
      UC_PRODUCT_KIT_MUTABLE => t('As individual products. Customers may add or remove kit components at will. Discounts entered below are not applied to the kit price'),
    ),
    '#default_value' => $node->mutable,
  );
  $form['base']['products'] = array(
    '#type' => 'select',
    '#multiple' => TRUE,
    '#required' => TRUE,
    '#title' => t('Products'),
    '#options' => $products,
    '#default_value' => array_keys($node->products),
  );
  $total = 0;
  $base_total = 0;
  $form['base']['items'] = array(
    '#tree' => TRUE,
    '#theme' => 'uc_product_kit_items_form',
    '#weight' => 1,
    '#description' => t('Enter a positive or negative discount to raise or lower the item price by that amount. The change is applied to each item in the kit.'),
  );
  if (!empty($node->products)) {
    foreach ($node->products as $i => $product) {
      $form['base']['items'][$i] = array(
        '#type' => 'fieldset',
      );
      $form['base']['items'][$i]['link'] = array(
        '#type' => 'item',
        '#markup' => l($product->title, 'node/' . $i),
      );
      $form['base']['items'][$i]['qty'] = array(
        '#type' => 'uc_quantity',
        '#title' => t('Quantity'),
        '#title_display' => 'invisible',
        '#default_value' => $product->qty,
      );
      $form['base']['items'][$i]['ordering'] = array(
        '#type' => 'weight',
        '#title' => t('List position'),
        '#title_display' => 'invisible',
        '#default_value' => isset($product->ordering) ? $product->ordering : 0,
        '#attributes' => array('class' => array('uc-product-kit-item-ordering')),
      );

      $form['base']['items'][$i]['discount'] = array(
        '#type' => 'textfield',
        '#title' => t('Discount'),
        '#title_display' => 'invisible',
        '#field_prefix' => uc_currency_format($product->sell_price) . ' + ',
        '#default_value' => isset($product->discount) ? number_format($product->discount, 3, '.', '') : 0,
        '#size' => 5,
      );
      $total += $product->sell_price * $product->qty;
      $base_total += $product->sell_price * $product->qty;
      if (isset($product->discount)) {
        $total += $product->discount * $product->qty;
      }
    }
    if (!$node->synchronized && $node->sell_price != $total) {
      // Component products have changed their prices. Recalculate discounts
      // to keep the same total.
      $total = $base_total;
      foreach ($node->products as $i => $product) {
        $discount = ($node->sell_price - $base_total) * $product->sell_price / $base_total;
        $total += $discount * $product->qty;
        $form['base']['items'][$i]['discount']['#default_value'] = number_format($discount, 3, '.', '');
      }
    }
    $form['base']['kit_total'] = array(
      '#type' => 'uc_price',
      '#title' => t('Total price'),
      '#default_value' => $node->synchronized ? '' : $total,
      '#description' => t('If this field is set, the discounts of the individual products will be recalculated to equal this value. Currently, the total sell price is %price.', array('%price' => uc_currency_format($total))),
      '#empty_zero' => FALSE,
    );
  }

  if (variable_get('uc_product_add_to_cart_qty', FALSE)) {
    $form['base']['default_qty'] = array(
      '#type' => 'uc_quantity',
      '#title' => t('Default quantity to add to cart'),
      '#default_value' => $node->default_qty,
      '#description' => t('Use 0 to disable the quantity field next to the add to cart button.'),
      '#weight' => 27,
      '#allow_zero' => TRUE,
    );
  }
  else {
    $form['base']['default_qty'] = array(
      '#type' => 'value',
      '#value' => $node->default_qty,
    );
  }

  $form['base']['ordering'] = array(
    '#type' => 'weight',
    '#title' => t('List position'),
    '#description' => t("Specify a value to set this product's position in product lists.<br />Products in the same position will be sorted alphabetically."),
    '#delta' => 25,
    '#default_value' => $node->ordering,
    '#weight' => 30,
  );

  // Disable all shipping related functionality.
  $form['shipping']['#access'] = FALSE;

  return $form;
}

/**
 * Implements hook_view().
 */
function uc_product_kit_view($node, $view_mode) {
  // Give modules a chance to alter this product.  If it is a variant, this
  // will have been done already by uc_product_load_variant(), so we check a
  // flag to be sure not to alter twice.
  $variant = empty($node->variant) ? uc_product_load_variant($node->nid) : $node;

  if (module_exists('uc_cart') && empty($variant->data['display_only'])) {
    $add_to_cart_form = drupal_get_form('uc_product_kit_add_to_cart_form_' . $variant->nid, clone $variant);
    if (variable_get('uc_product_update_node_view', FALSE)) {
      $variant = $add_to_cart_form['node']['#value'];
    }
  }

  // Calculate the display price.
  $display_price = 0;
  $suffixes = array();
  if ($node->mutable != UC_PRODUCT_KIT_MUTABLE) {
    // If this is a non-mutable kit, then sum the display price of each of the
    // component products.
    foreach ($variant->products as $product) {
      $build = node_view($product, $view_mode);
      $display_price += $build['display_price']['#value'] * $product->qty;
      $suffixes += $build['display_price']['#suffixes'];
    }
  }
  else {
    // For mutable, just use the price.
    $display_price = $variant->price;
    $suffixes = array();
  }

  $node->content['display_price'] = array(
    '#theme' => 'uc_product_price',
    '#value' => $display_price,
    '#suffixes' => $suffixes,
    '#attributes' => array(
      'class' => array(
        'product-kit',
        'display-price',
      ),
    ),
  );
  $node->content['model'] = array(
    '#theme' => 'uc_product_model',
    '#model' => $variant->model,
    '#view_mode' => $view_mode,
  );
  $node->content['list_price'] = array(
    '#theme' => 'uc_product_price',
    '#title' => t('List price:'),
    '#value' => $variant->list_price,
    '#attributes' => array(
      'class' => array(
        'product-kit',
        'list-price',
      ),
    ),
  );
  $node->content['cost'] = array(
    '#theme' => 'uc_product_price',
    '#title' => t('Cost:'),
    '#value' => $variant->cost,
    '#attributes' => array(
      'class' => array(
        'product-kit',
        'cost',
      ),
    ),
    '#access' => user_access('administer products'),
  );
  $node->content['sell_price'] = array(
    '#theme' => 'uc_product_price',
    '#title' => t('Price:'),
    '#value' => $variant->sell_price,
    '#attributes' => array(
      'class' => array(
        'product-kit',
        'sell-price',
      ),
    ),
  );
  $node->content['weight'] = array(
    '#theme' => 'uc_product_weight',
    '#amount' => $variant->weight,
    '#units' => $variant->weight_units,
    '#view_mode' => $view_mode,
  );

  if ($node->mutable != UC_PRODUCT_KIT_UNMUTABLE_NO_LIST) {
    $node->content['products'] = array('#weight' => 6);

    $i = 0;
    foreach ($node->products as $product) {
      $node->content['products'][$product->nid]['qty'] = array(
        '#markup' => '<div class="product-qty">' . theme('uc_product_kit_list_item', array('product' => $product)) . '</div>',
      );
      $node->content['products'][$product->nid]['#weight'] = $i++;
    }
  }

  if (isset($add_to_cart_form)) {
    $node->content['add_to_cart'] = array(
      '#theme' => 'uc_product_kit_add_to_cart',
      '#view_mode' => $view_mode,
      '#form' => $add_to_cart_form,
    );
  }

  $node->content['#node'] = $variant;

  return $node;
}

/**
 * Lets the cart know how many of which products are included in a kit.
 *
 * uc_attribute_form_alter() hooks into this form to add attributes to each
 * element in $form['products'].
 *
 * @see uc_product_kit_add_to_cart_form_validate()
 * @see uc_product_kit_add_to_cart_form_submit()
 * @ingroup forms
 */
function uc_product_kit_add_to_cart_form($form, &$form_state, $node) {
  $form['nid'] = array('#type' => 'value', '#value' => $node->nid);
  $form['products'] = array('#tree' => TRUE);
  foreach ($node->products as $i => $product) {
    $form['products'][$i] = array('#title' => check_plain($product->title));
    $form['products'][$i]['nid'] = array('#type' => 'hidden', '#value' => $product->nid);
    $form['products'][$i]['qty'] = array('#type' => 'hidden', '#value' => $product->qty);
  }
  if ($node->default_qty > 0 && variable_get('uc_product_add_to_cart_qty', FALSE)) {
    $form['qty'] = array(
      '#type' => 'uc_quantity',
      '#title' => t('Quantity'),
      '#default_value' => $node->default_qty,
    );
  }
  else {
    $form['qty'] = array('#type' => 'hidden', '#value' => $node->default_qty ? $node->default_qty : 1);
  }

  $form['actions'] = array('#type' => 'actions');
  $form['actions']['submit'] = array(
    '#type' => 'submit',
    '#value' => t('Add to cart'),
    '#id' => 'edit-submit-' . $node->nid,
    '#attributes' => array(
      'class' => array('node-add-to-cart'),
    ),
  );

  $form['node'] = array(
    '#type' => 'value',
    '#value' => isset($form_state['storage']['variant']) ? $form_state['storage']['variant'] : $node,
  );

  uc_form_alter($form, $form_state, __FUNCTION__);

  return $form;
}

/**
 * Form validation handler for uc_product_add_to_cart_form().
 *
 * @see uc_product_kit_add_to_cart_form()
 * @see uc_product_add_to_cart_form_validate()
 */
function uc_product_kit_add_to_cart_form_validate($form, &$form_state) {
  uc_product_add_to_cart_form_validate($form, $form_state);
  foreach ($form_state['storage']['variant']->products as &$product) {
    $data = module_invoke_all('uc_add_to_cart_data', $form_state['values']['products'][$product->nid]);
    $data += $product->data;
    $qty = $product->qty;
    $product = uc_product_load_variant($product->nid, $data);
    $product->qty = $qty;
  }
}

/**
 * Adds each product kit's component to the cart in the correct quantities.
 *
 * @see uc_product_kit_add_to_cart_form()
 */
function uc_product_kit_add_to_cart_form_submit($form, &$form_state) {
  if (variable_get('uc_cart_add_item_msg', TRUE)) {
    $node = node_load($form_state['values']['nid']);
    drupal_set_message(t('<strong>@product-title</strong> added to <a href="!url">your shopping cart</a>.', array('@product-title' => $node->title, '!url' => url('cart'))));
  }
  $form_state['redirect'] = uc_cart_add_item($form_state['values']['nid'], $form_state['values']['qty'], $form_state['values']);
}

/**
 * Add-to-cart button with any extra fields.
 *
 * @see uc_product_kit_buy_it_now_form_validate()
 * @see uc_product_kit_buy_it_now_form_submit()
 * @ingroup forms
 */
function uc_product_kit_buy_it_now_form($form, &$form_state, $node) {
  $form['nid'] = array(
    '#type' => 'hidden',
    '#value' => $node->nid,
    );
  if ($node->type == 'product_kit') {
    $form['products'] = array('#tree' => TRUE);
    foreach ($node->products as $i => $product) {
      $form['products'][$i] = array('#title' => check_plain($product->title));
      $form['products'][$i]['nid'] = array('#type' => 'hidden', '#value' => $product->nid);
      $form['products'][$i]['qty'] = array('#type' => 'hidden', '#value' => $product->qty);
    }
  }

  $form['actions'] = array('#type' => 'actions');
  $form['actions']['submit'] = array(
    '#type' => 'submit',
    '#value' => t('Add to cart'),
    '#id' => 'edit-submit-' . $node->nid,
    '#attributes' => array(
      'class' => array('list-add-to-cart'),
    ),
  );

  uc_form_alter($form, $form_state, __FUNCTION__);

  return $form;
}

/**
 * Redirects to the product kit page so attributes may be selected.
 *
 * @see uc_product_kit_buy_it_now_form()
 */
function uc_product_kit_buy_it_now_form_validate($form, &$form_state) {
  if (module_exists('uc_attribute')) {
    $node = node_load($form_state['values']['nid']);
    if (is_array($node->products)) {
      foreach ($node->products as $nid => $product) {
        $attributes = uc_product_get_attributes($nid);
        if (!empty($attributes)) {
          drupal_set_message(t('This product has options that need to be selected before purchase. Please select them in the form below.'), 'error');
          drupal_goto('node/' . $form_state['values']['nid']);
        }
      }
    }
  }
}

/**
 * Form submission handler for uc_product_kit_buy_it_now_form().
 *
 * @see uc_product_kit_buy_it_now_form()
 */
function uc_product_kit_buy_it_now_form_submit($form, &$form_state) {
  $node = node_load($form_state['values']['nid']);
  if (module_exists('uc_attribute')) {
    $attributes = uc_product_get_attributes($node->nid);
    if (!empty($attributes)) {
      drupal_set_message(t('This product has options that need to be selected before purchase. Please select them in the form below.'), 'error');
      $form_state['redirect'] = drupal_get_path_alias('node/' . $form_state['values']['nid']);
      return;
    }
    if (is_array($node->products)) {
      foreach ($node->products as $nid => $product) {
        $attributes = uc_product_get_attributes($nid);
        if (!empty($attributes)) {
          drupal_set_message(t('This product has options that need to be selected before purchase. Please select them in the form below.'), 'error');
          $form_state['redirect'] = drupal_get_path_alias('node/' . $form_state['values']['nid']);
          return;
        }
      }
    }
  }
  $form_state['redirect'] = uc_cart_add_item($form_state['values']['nid'], 1, $form_state['values'], NULL, variable_get('uc_cart_add_item_msg', TRUE));
}

/**
 * Implements hook_uc_product_types().
 */
function uc_product_kit_uc_product_types() {
  return array('product_kit');
}

/**
 * Implements hook_uc_store_status().
 */
function uc_product_kit_uc_store_status() {
  if (module_exists('filefield')) {
    module_load_include('inc', 'content', 'includes/content.crud');
    // Check for filefields on products.
    if ($field = variable_get('uc_image_product_kit', '')) {
      $instances = content_field_instance_read(array('field_name' => $field, 'type_name' => 'product_kit'));
    }
    else {
      $instances = array();
    }

    if (!count($instances)) {
      return array(array('status' => 'warning', 'title' => t('Images'), 'desc' => t('Product kits do not have an image field. You may add a %field_name at the <a href="!add_url">Add field page</a> and make sure it is set as the Ubercart image in the <a href="!edit_url">content type settings</a> under the Ubercart product settings fieldset.', array('%field_name' => $field, '!add_url' => url('admin/structure/types/manage/product-kit/fields'), '!edit_url' => url('admin/structure/types/manage/product-kit')))));
    }
  }

}

/**
 * Implements hook_uc_add_to_cart().
 */
function uc_product_kit_uc_add_to_cart($nid, $qty, $kit_data) {
  $node = node_load($nid);
  if ($node->type == 'product_kit') {
    $cart = uc_cart_get_contents();
    $unique = uniqid('', TRUE);
    $update = array();
    $product_data = array();

    foreach ($node->products as $product) {
      $data = array('kit_id' => $node->nid, 'module' => 'uc_product_kit') + module_invoke_all('uc_add_to_cart_data', $kit_data['products'][$product->nid]);
      $product_data[$product->nid] = $data;
      foreach ($cart as $item) {
        if ($item->nid == $product->nid && isset($item->data['kit_id']) && $item->data['kit_id'] == $node->nid) {
          // There is something in the cart like the product kit. Update
          // by default, but check that it's possible.
          $data['unique_id'] = $item->data['unique_id'];
          if ($item->data == $data) {
            // This product is a candidate for updating the cart quantity.
            // Make sure the data arrays will compare as equal when serialized.
            $product_data[$product->nid] = $item->data;
            $update[$product->nid] = TRUE;
          }
        }
      }

    }

    // The product kit can update its items only if they all can be updated.
    if (count($update) != count($node->products)) {
      foreach ($node->products as $product) {
        $data = $product_data[$product->nid];
        $data['unique_id'] = $unique;
        uc_cart_add_item($product->nid, $product->qty * $qty, $data, NULL, FALSE, FALSE, FALSE);
      }
    }
    else {
      foreach ($node->products as $product) {
        $data = $product_data[$product->nid];
        uc_cart_add_item($product->nid, $product->qty * $qty, $data, NULL, FALSE, FALSE, FALSE);
      }
    }

    // Rebuild the cart items cache.
    uc_cart_get_contents(NULL, 'rebuild');

    return array(array('success' => FALSE, 'silent' => TRUE, 'message' => ''));
  }
}

/**
 * Implements hook_uc_product_alter().
 */
function uc_product_kit_uc_product_alter(&$variant) {
  if (isset($variant->data['kit_id'])) {
    // If this is a kit component load, we would cause infinite recursion trying
    // to node_load() the parent, but we already have the discount available.
    if (isset($variant->data['kit_discount'])) {
      $discount = $variant->data['kit_discount'];
    }
    elseif (($kit = node_load($variant->data['kit_id'])) && $kit->mutable != UC_PRODUCT_KIT_MUTABLE) {
      $discount = $kit->products[$variant->nid]->discount;
    }
    else {
      $discount = 0;
    }
    $variant->price += $discount;
    $variant->data['module'] = 'uc_product_kit';
  }
}

/**
 * Implements hook_uc_order_product_alter().
 *
 * The hookups for making product kits work on the order edit admin screen.
 *
 * @param $product
 *   The order product being saved.
 * @param $order
 *   The order being edited.
 */
function uc_product_kit_uc_order_product_alter(&$product, $order) {
  if (empty($product->type) || $product->type !== 'product_kit') {
    return;
  }

  // Have to save each individual product if this is a kit.
  foreach ($product->products as $kit_product) {
    $qty = $kit_product->qty * $product->qty;
    $data = isset($kit_product->data) ? $kit_product->data : array();
    $data += module_invoke_all('uc_add_to_cart_data', $_POST['product_controls']['sub_products'][$kit_product->nid]);
    $data['shippable'] = $product->shippable;
    $kit_product = uc_product_load_variant($kit_product->nid, $data);
    $kit_product->qty = $qty;
    drupal_alter('uc_order_product', $kit_product, $order);

    // Save the individual item to the order.
    uc_order_product_save($order->order_id, $kit_product);
  }

  // Don't save the base kit node, though.
  $product->skip_save = TRUE;
}

/**
 * Implements hook_uc_cart_display().
 *
 * Displays either the kit as a whole, or each individual product based on the
 * store configuration. Each product in the cart that was added by
 * uc_product_kit was also given a unique kit id in order to help prevent
 * collisions. The side effect is that identical product kits are listed
 * separately if added separately. The customer may still change the quantity
 * of kits like other products.
 *
 * @param $item
 *   An item in the shopping cart.
 *
 * @return
 *   A form element array to be processed by uc_cart_view_form().
 */
function uc_product_kit_uc_cart_display($item) {
  static $elements = array();
  static $products;
  $unique_id = $item->data['unique_id'];
  $kit = node_load($item->data['kit_id']);
  if ($kit->mutable == UC_PRODUCT_KIT_MUTABLE) {
    return uc_product_uc_cart_display($item);
  }
  else {
    if (!isset($products[$unique_id])) {
      // Initialize table row.
      $kit_qty = $item->qty / $kit->products[$item->nid]->qty;
      $element = array();
      $element['nid'] = array('#type' => 'value', '#value' => $kit->nid);
      $element['module'] = array('#type' => 'value', '#value' => 'uc_product_kit');
      $element['remove'] = array('#type' => 'submit', '#value' => t('Remove'));
      $element['title'] = array('#markup' => l($kit->title, 'node/' . $kit->nid));
      $element['qty'] = array(
        '#type' => 'uc_quantity',
        '#title' => t('Quantity'),
        '#title_display' => 'invisible',
        '#default_value' => $kit_qty,
      );
      $element['description'] = array('#markup' => '');
      $element['#total'] = 0;
      $element['#suffixes'] = array();
      $element['#extra'] = array();
      $element['#entity'] = $kit; // Override the entity associated with this
                                  // render-array to be the kit itself.

      $elements[$unique_id] = $element;
    }
    // Add product specific information.
    $extra = uc_product_get_description($item);

    if ($kit->mutable == UC_PRODUCT_KIT_UNMUTABLE_WITH_LIST) {
      $elements[$unique_id]['#extra'][] = array(
        'data' => theme('uc_product_kit_list_item', array('product' => $item)) . $extra,
        'class' => array('kit-component-cart-desc'),
      );
    }

    // Build the kit item product variant.
    if (!isset($item->type)) {
      $node = node_load($item->nid);
      $item->type = $node->type;
    }
    $build = node_view($item);

    $elements[$unique_id]['#total'] += $build['display_price']['#value'] * $item->qty;
    $elements[$unique_id]['#suffixes'] += $build['display_price']['#suffixes'];
    $elements[$unique_id]['data'][$item->nid] = $item;
    $products[$unique_id][] = $item->nid;

    // Check if all products in this kit have been accounted for.
    $done = TRUE;
    foreach ($kit->products as $product) {
      if (!in_array($product->nid, $products[$unique_id])) {
        $done = FALSE;
        break;
      }
    }

    if ($done) {
      drupal_add_css(drupal_get_path('module', 'uc_product_kit') . '/uc_product_kit.css');
      $elements[$unique_id]['data'] = array('#type' => 'value', '#value' => serialize($elements[$unique_id]['data']));
      if ($kit->mutable == UC_PRODUCT_KIT_UNMUTABLE_WITH_LIST) {
        $elements[$unique_id]['description']['#markup'] .= theme('item_list', array('items' => $elements[$unique_id]['#extra'], 'attributes' => array('class' => array('product-description'))));
      }
      $element = $elements[$unique_id];
      unset($products[$unique_id]);
      unset($elements[$unique_id]);
      return $element;
    }
  }
  return array();
}

/**
 * Implements hook_uc_update_cart_item().
 *
 * Handles individual products or entire kits.
 */
function uc_product_kit_uc_update_cart_item($nid, $data = array(), $qty, $cid = NULL) {
  if (!$nid) return NULL;
  $cid = !(is_null($cid) || empty($cid)) ? $cid : uc_cart_get_id();

  if (isset($data['kit_id'])) {
    // Product was listed individually.
    uc_product_uc_update_cart_item($nid, $data, $qty, $cid);
  }
  else {
    $kit = node_load($nid);
    foreach ($data as $p_nid => $product) {
      uc_product_uc_update_cart_item($p_nid, $product->data, $qty * $kit->products[$p_nid]->qty, $cid);
    }
  }
}

/**
 * Implements hook_views_api().
 */
function uc_product_kit_views_api() {
  return array(
    'api' => 3,
    'path' => drupal_get_path('module', 'uc_product_kit') . '/views',
  );
}