commerce_tax.module

<?php

/**
 * @file
 * Defines tax rates and Rules integration for configuring tax rules for
 *   applicability and display.
 */


/**
 * Implements hook_hook_info().
 */
function commerce_tax_hook_info() {
  $hooks = array(
    'commerce_tax_type_info' => array(
      'group' => 'commerce',
    ),
    'commerce_tax_type_info_alter' => array(
      'group' => 'commerce',
    ),
    'commerce_tax_type_insert' => array(
      'group' => 'commerce',
    ),
    'commerce_tax_type_update' => array(
      'group' => 'commerce',
    ),
    'commerce_tax_type_delete' => array(
      'group' => 'commerce',
    ),
    'commerce_tax_rate_info' => array(
      'group' => 'commerce',
    ),
    'commerce_tax_rate_info_alter' => array(
      'group' => 'commerce',
    ),
    'commerce_tax_rate_insert' => array(
      'group' => 'commerce',
    ),
    'commerce_tax_rate_update' => array(
      'group' => 'commerce',
    ),
    'commerce_tax_rate_delete' => array(
      'group' => 'commerce',
    ),
    'commerce_tax_type_calculate_rates' => array(
      'group' => 'commerce',
    ),
  );

  return $hooks;
}

/**
 * Returns an array of tax type objects keyed by name.
 */
function commerce_tax_types() {
  // First check the static cache for a tax types array.
  $tax_types = &drupal_static(__FUNCTION__);

  // If it did not exist, fetch the types now.
  if (!isset($tax_types)) {
    $tax_types = array();

    // Find tax types defined by hook_commerce_tax_type_info().
    foreach (module_implements('commerce_tax_type_info') as $module) {
      foreach (module_invoke($module, 'commerce_tax_type_info') as $name => $tax_type) {
        // Initialize tax rate properties if necessary.
        $defaults = array(
          'name' => $name,
          'display_title' => $tax_type['title'],
          'description' => '',
          'display_inclusive' => FALSE,
          'module' => $module,
        );

        $tax_types[$name] = array_merge($defaults, $tax_type);
      }
    }

    // Last allow the info to be altered by other modules.
    drupal_alter('commerce_tax_type_info', $tax_types);
  }

  return $tax_types;
}

/**
 * Resets the cached list of tax types.
 */
function commerce_tax_types_reset() {
  $tax_types = &drupal_static('commerce_tax_types');
  $tax_types = NULL;
}

/**
 * Returns a single tax type object.
 *
 * @param $name
 *   The name of the tax type to return.
 *
 * @return
 *   The specified tax type object or FALSE if it did not exist.
 */
function commerce_tax_type_load($name) {
  $tax_types = commerce_tax_types();
  return empty($tax_types[$name]) ? FALSE : $tax_types[$name];
}

/**
 * Returns the titles of every tax type keyed by name.
 */
function commerce_tax_type_titles() {
  $titles = array();

  foreach (commerce_tax_types() as $name => $tax_type) {
    $titles[$name] = $tax_type['title'];
  }

  return $titles;
}

/**
 * Implements hook_commerce_price_component_type_info().
 */
function commerce_tax_commerce_price_component_type_info() {
  $components = array();

  // Add a price component type for each tax rate that specifies it.
  foreach (commerce_tax_rates() as $name => $tax_rate) {
    if ($tax_rate['price_component']) {
      $components[$tax_rate['price_component']] = array(
        'title' => $tax_rate['title'],
        'display_title' => $tax_rate['display_title'],
      );
    }
  }

  return $components;
}

/**
 * Returns an array of tax rate objects keyed by name.
 */
function commerce_tax_rates() {
  // First check the static cache for a tax rates array.
  $tax_rates = &drupal_static(__FUNCTION__);

  // If it did not exist, fetch the types now.
  if (!isset($tax_rates)) {
    $tax_rates = array();

    // Find tax rates defined by hook_commerce_tax_rate_info().
    foreach (module_implements('commerce_tax_rate_info') as $module) {
      foreach (module_invoke($module, 'commerce_tax_rate_info') as $name => $tax_rate) {
        // Initialize tax rate properties if necessary.
        $defaults = array(
          'name' => $name,
          'display_title' => $tax_rate['title'],
          'description' => '',
          'rate' => 0,
          'type' => '',
          'rules_component' => TRUE,
          'price_component' => 'tax|' . $name,
          'calculation_callback' => 'commerce_tax_rate_calculate',
          'module' => $module,
        );

        $tax_rates[$name] = array_merge($defaults, $tax_rate);
      }
    }

    // Last allow the info to be altered by other modules.
    drupal_alter('commerce_tax_rate_info', $tax_rates);
  }

  return $tax_rates;
}

/**
 * Resets the cached list of tax rates.
 */
function commerce_tax_rates_reset() {
  $tax_rates = &drupal_static('commerce_tax_rates');
  $tax_rates = NULL;
}

/**
 * Returns a single tax rate object.
 *
 * @param $name
 *   The name of the tax rate to return.
 *
 * @return
 *   The specified tax rate object or FALSE if it did not exist.
 */
function commerce_tax_rate_load($name) {
  $tax_rates = commerce_tax_rates();
  return empty($tax_rates[$name]) ? FALSE : $tax_rates[$name];
}

/**
 * Returns the titles of every tax rate keyed by name.
 */
function commerce_tax_rate_titles() {
  $titles = array();

  foreach (commerce_tax_rates() as $name => $tax_rate) {
    $titles[$name] = $tax_rate['title'];
  }

  return $titles;
}

/**
 * Calculates taxes of a particular type by invoking any components that match
 *   the tax type.
 *
 * @param $tax_type
 *   The tax type object whose rates should be calculated.
 * @param $line_item
 *   The line item to which the taxes should be applied.
 */
function commerce_tax_type_calculate_rates($tax_type, $line_item) {
  // Load all the rule components.
  $components = rules_get_components(FALSE, 'action');

  // Loop over each tax rate in search of matching components.
  foreach (commerce_tax_rates() as $name => $tax_rate) {
    // If the current rate matches the type and specifies a default component...
    if ($tax_rate['type'] == $tax_type['name'] && $tax_rate['rules_component']) {
      $component_name = 'commerce_tax_rate_' . $name;

      // If we can load the current rate's component...
      if (!empty($components[$component_name])) {
        // Invoke it with the line item.
        rules_invoke_component($component_name, $line_item);
      }
    }
  }

  // Allow modules handling tax application on their own to apply rates of the
  // current type as well.
  module_invoke_all('commerce_tax_type_calculate_rates', $tax_type, $line_item);
}

/**
 * Applies a tax rate to the unit price of a line item.
 *
 * @param $tax_rate
 *   The tax rate to apply to the line item.
 * @param $line_item
 *   The line item whose unit price will be modified to include the tax.
 */
function commerce_tax_rate_apply($tax_rate, $line_item) {
  // If a valid rate is specified...
  if (is_numeric($tax_rate['rate'])) {
    $wrapper = entity_metadata_wrapper('commerce_line_item', $line_item);

    // Invoke the tax rate's calculation callback and apply the returned tax
    // price to the line item.
    if ($tax_price = $tax_rate['calculation_callback']($tax_rate, $wrapper)) {
      // Add the tax to the unit price's data array along with a display inclusive
      // property used to track whether or not the tax is included in the price.
      $included = FALSE;

      // If the rate specifies a valid tax type that is display inclusive...
      if (($tax_type = commerce_tax_type_load($tax_rate['type'])) &&
        $tax_type['display_inclusive']) {
        // Include the tax amount in the displayed unit price.
        $wrapper->commerce_unit_price->amount = $wrapper->commerce_unit_price->amount->value() + $tax_price['amount'];
        $included = TRUE;
      }

      // Update the data array with the tax component.
      $wrapper->commerce_unit_price->data = commerce_price_component_add(
        $wrapper->commerce_unit_price->value(),
        $tax_rate['price_component'],
        $tax_price,
        $included
      );
    }
  }
}

/**
 * Calculates a price array for the tax on the unit price of a line item.
 *
 * @param $tax_rate
 *   The tax rate array for the tax to calculate.
 * @param $line_item_wrapper
 *   An entity_metadata_wrapper() for the line item whose unit price should be
 *     used in the tax calculation.
 *
 * @return
 *   The tax price array or FALSE if the tax is already applied.
 */
function commerce_tax_rate_calculate($tax_rate, $line_item_wrapper) {
  // By default, do not duplicate a tax that's already on the line item.
  if (!commerce_price_component_load($line_item_wrapper->commerce_unit_price->value(), $tax_rate['price_component'])) {
    return array(
      'amount' => $line_item_wrapper->commerce_unit_price->amount->value() * $tax_rate['rate'],
      'currency_code' => $line_item_wrapper->commerce_unit_price->currency_code->value(),
      'data' => array(
        'tax_rate' => $tax_rate,
      ),
    );
  }

  return FALSE;
}

/**
 * Implements hook_field_attach_form().
 */
function commerce_tax_field_attach_form($entity_type, $entity, &$form, &$form_state, $langcode) {
  // Alter price widgets on the product form to have tax inclusive price entry.
  if ($entity_type == 'commerce_product') {
    // Build an array of tax types that are display inclusive.
    $inclusive_types = array();

    foreach (commerce_tax_types() as $name => $tax_type) {
      if ($tax_type['display_inclusive']) {
        $inclusive_types[$name] = $tax_type['title'];
      }
    }

    // Build an options array of tax rates of these types.
    $options = array();

    foreach (commerce_tax_rates() as $name => $tax_rate) {
      if (in_array($tax_rate['type'], array_keys($inclusive_types))) {
        $options[$inclusive_types[$tax_rate['type']]][$name] = t('Including @title', array('@title' => $tax_rate['title']));
      }
    }

    // Only alter the form if there are available tax rates...
    if (!empty($options)) {
      // Get an array of price fields attached to products.
      $fields = commerce_info_fields('commerce_price', 'commerce_product');

      // Loop over each child element of the form.
      foreach (element_children($form) as $key) {
        // If the current element is for a price field...
        if (in_array($key, array_keys($fields))) {
          // Loop over each of its child items...
          foreach (element_children($form[$key][$form[$key]['#language']]) as $delta) {
            // Find the default value for the tax included element.
            $default = '';

            if (!empty($form[$key][$form[$key]['#language']][$delta]['data']['#default_value']['components'])) {
              foreach (array_keys($options) as $optgroup) {
                foreach ($options[$optgroup] as $name => $title) {
                  $tax_rate = commerce_tax_rate_load($name);

                  // If this tax rate's component is included in the price, it
                  // must be the default!
                  foreach ($form[$key][$form[$key]['#language']][$delta]['data']['#default_value']['components'] as $component) {
                    if ($component['included'] && $component['name'] == $tax_rate['price_component']) {
                      $default = $name;
                    }
                  }
                }
              }
            }

            $form[$key][$form[$key]['#language']][$delta]['currency_code']['#title'] = '&nbsp;';

            $form[$key][$form[$key]['#language']][$delta]['include_tax'] = array(
              '#type' => 'select',
              '#title' => t('Include tax in this price'),
              '#description' => t('Saving prices tax inclusive will bypass later calculations for the specified tax.'),
              '#options' => count($options) == 1 ? reset($options) : $options,
              '#default_value' => $default,
              '#required' => FALSE,
              '#empty_value' => '',
              '#suffix' => '<div class="commerce-price-tax-included-clearfix"></div>',
              '#attached' => array(
                'css' => array(drupal_get_path('module', 'commerce_tax') . '/theme/commerce_tax.css'),
              ),
            );

            // Append a validation handler to the price field's element validate
            // array to add the included tax price component after the price has
            // been converted from a decimal.
            $form[$key][$form[$key]['#language']][$delta]['#element_validate'][] = 'commerce_tax_price_field_validate';
          }
        }
      }
    }
  }
}

/**
 * Validate callback for the tax inclusion select list that serves to reset the
 *   data array based on the selected tax.
 */
function commerce_tax_price_field_validate($element, &$form_state) {
  // Build an array of form parents to the price array.
  $parents = $element['#parents'];

  // Get the price array from the form state.
  $price = $form_state['values'];

  foreach ($parents as $parent) {
    $price = $price[$parent];
  }

  // If a tax was specified...
  if (!empty($element['include_tax']['#value'])) {
    // Remove the include_tax value from the price array and reset the components.
    unset($price['include_tax']);
    $price['data']['components'] = array();

    // Load and reverse apply the tax.
    $tax_rate = commerce_tax_rate_load($element['include_tax']['#value']);
    $amount = $price['amount'] / (1 + $tax_rate['rate']);

    // Add a base price to the data array.
    $component = array(
      'amount' => $amount,
      'currency_code' => $price['currency_code'],
      'data' => array(),
    );

    $price['data'] = commerce_price_component_add($price, 'base_price', $component, TRUE);

    // Add the tax to the data array.
    $component['amount'] = $price['amount'] - $amount;

    $price['data'] = commerce_price_component_add($price, $tax_rate['price_component'], $component, TRUE);
  }
  else {
    // Otherwise reset the components array.
    unset($price['data']['components']);
  }

  // Add the data array to the form state.
  $parents[] = 'data';

  form_set_value(array('#parents' => $parents), $price['data'], $form_state);
}