Overhauled version of Drupal's Commerce Checkout Redirect module

commerce_checkout_redirect.module

<?php
/**
 * @file
 * Force anonymous users to login before being able to checkout.
 */

/**
 * Implements hook_menu().
 */
function commerce_checkout_redirect_menu() {
  $items = array();
  $items['admin/commerce/config/checkout_redirect'] = array(
    'title' => t('Checkout Redirect'),
    'description' => t('Checkout redirect module settings'),
    'page callback' => 'drupal_get_form',
    'page arguments' => array('commerce_checkout_redirect_settings'),
    'access arguments' => array('configure store'),
    'type' => MENU_NORMAL_ITEM,
  );
  return $items;
}

/**
 * Implements hook_entity_property_info_alter().
 */
function commerce_checkout_redirect_entity_property_info_alter(&$info) {
  // Add the commerce_checkout_redirect property to the user, useful for
  // resolving redirect conflicts.
  $info['user']['properties']['commerce_checkout_redirect'] = array(
    'label' => t('User is in the checkout redirect process'),
    'description' => t('The user is in the checkout redirect process.'),
    'type' => 'boolean',
    'computed' => TRUE,
  );
}

/**
 * Creates settings form for module.
 */
function commerce_checkout_redirect_settings($form, &$form_state) {
  $form = array();
  $form['commerce_checkout_redirect_path'] = array(
    '#type' => 'textfield',
    '#title' => t('Checkout redirect path'),
    '#description' => t("Set the checkout redirect path for anonymous users. Leave blank to use the default 'user/login' page. If you redirect to another page, make sure you add a user login block to that page."),
    '#default_value' => variable_get('commerce_checkout_redirect_path')
  );
  $form['commerce_checkout_redirect_message'] = array(
    '#type' => 'textarea',
    '#title' => t('Checkout redirect message'),
    '#description' => t('The optional message that will be displayed at the login page in the checkout process.'),
    '#default_value' => variable_get('commerce_checkout_redirect_message', t('You need to be logged in to be able to checkout.')),
    '#rows' => 2,
  );
  $form['commerce_checkout_redirect_anonymous'] = array(
    '#type' => 'checkbox',
    '#title' => t('Continue without register'),
    '#description' => t('Allow anonymous checkout.'),
    '#default_value' => variable_get('commerce_checkout_redirect_anonymous', FALSE),
  );
  $form['commerce_checkout_redirect_username_as_order_email'] = array(
    '#type' => 'checkbox',
    '#title' => t('Require an e-mail address'),
    '#description' => t("The username field will be turned into an e-mail field. It's value will be used as the order's e-mail address and at login forms the user can login using his e-mail address."),
    '#default_value' => variable_get('commerce_checkout_redirect_username_as_order_email', FALSE),
    '#states' => array (
      'visible' => array(
       ':input[name="commerce_checkout_redirect_anonymous"]' => array('checked' => true),
      ),
    ),
  );
  $form['commerce_checkout_redirect_anonymous_as_login_option'] = array(
    '#type' => 'checkbox',
    '#title' => t('Hide fields'),
    '#description' => t('Initially hide fields that are irrelevant for anonymous checkout.'),
    '#default_value' => variable_get('commerce_checkout_redirect_anonymous_as_login_option', FALSE),
    '#states' => array (
      'visible' => array(
       ':input[name="commerce_checkout_redirect_anonymous"]' => array('checked' => true),
      ),
    ),
  );

  // Setting which holds the keys of user forms that may contain anonymous
  // checkout functionality.
  $form['commerce_checkout_redirect_user_forms'] = array(
    '#type' => 'checkboxes',
    '#title' => t('User forms that may contain anonymous checkout functionality.'),
    '#description' => t('Select the forms which should contain the option to checkout anonymously.'),
    '#default_value' => variable_get('commerce_checkout_redirect_user_forms', array_keys(commerce_checkout_redirect_get_user_forms())),
    '#options' => commerce_checkout_redirect_get_user_forms(),
    '#states' => array (
      'visible' => array(
       ':input[name="commerce_checkout_redirect_anonymous"]' => array('checked' => true),
      ),
    ),
  );

  // Chekout button help text for e-mail verification when a visitor creates an account.
  if (variable_get('user_email_verification', TRUE)) {
    $form['commerce_checkout_redirect_reset_password_message'] = array(
      '#type' => 'textarea',
      '#title' => t('Reset password checkout redirect message'),
      '#description' => t('The message that should be displayed for the reset password page for new account in the checkout process.'),
      '#default_value' => variable_get('commerce_checkout_redirect_reset_password_message', t('You can also continue with the checkout process.')),
      '#rows' => 2,
    );
  }

  return system_settings_form($form);
}

/**
 * Implements hook_commerce_checkout_router().
 */
function commerce_checkout_redirect_commerce_checkout_router($order, $checkout_page) {
  // Get keys of first and last checkout pages.
  $checkout_pages = array_keys(commerce_checkout_pages());
  $first_checkout_page = $checkout_pages[0];
  $last_checkout_page = end($checkout_pages);

  // If user is at the first checkout page.
  if ($checkout_page['page_id'] == $first_checkout_page) {
    // If user is anonymous, does not have an empty cart and has not chosen to
    // checkout anonymously.
    if (user_is_anonymous() && !commerce_checkout_redirect_is_cart_empty() && empty($_SESSION['commerce_checkout_redirect_bypass'])) {
      // Unset session variable that indicates that the user is being
      // redirected.
      $_SESSION['commerce_checkout_redirect_anonymous'] = TRUE;

      // Show redirect message.
      if (variable_get('commerce_checkout_redirect_message')) {
        drupal_set_message(variable_get('commerce_checkout_redirect_message', t('You need to be logged in to be able to checkout.')));
      }

      // If no redirect path has been set.
      if (!($redirect_path = variable_get('commerce_checkout_redirect_path', 'user/login'))) {
        // Set default redirect path.
        $redirect_path = 'user/login';
      }

      // Redirect user.
      return drupal_goto($redirect_path);
    }
  }
  // If user is at the last checkout page.
  elseif ($checkout_page['page_id'] == $last_checkout_page) {
    // Unset bypass session variable.
    unset($_SESSION['commerce_checkout_redirect_bypass']);
  }
}

/**
 * Implements hook_commerce_checkout_pane_info_alter().
 *
 */
function commerce_checkout_redirect_commerce_checkout_pane_info_alter(&$checkout_panes) {
  // If the user is anonymous and an e-mail address is required to checkout
  // anonymously.
  if (user_is_anonymous() && variable_get('commerce_checkout_redirect_username_as_order_email', FALSE)) {
    // Disable the Account Information pane if the username it will be used for order email.
    $checkout_panes['account']['page'] = 'disabled';
    $checkout_panes['account']['enabled'] = FALSE;
  }
}

/**
 * Implements hook_module_implements_alter().
 */
function commerce_checkout_redirect_module_implements_alter(&$implementations, $hook) {
  // Return if the hook is not for hook_user_login.
  if ($hook !== 'user_login') {
    return;
  }

  // Move our hook implementation to the top, so the commerce_checkout_redirect
  // user property could be used by other hook implementations.
  $module = 'commerce_checkout_redirect';
  $group = array($module => $implementations[$module]);
  unset($implementations[$module]);
  $implementations = $group + $implementations;
}

/**
 * Implements hook_user_login().
 */
function commerce_checkout_redirect_user_login(&$edit, &$account) {
  // If the user has been redirected.
  if (!empty($_SESSION['commerce_checkout_redirect_anonymous'])) {
    // Add the commerce_checkout_redirect property to the account object.
    $account->commerce_checkout_redirect = TRUE;
  }
}

/**
 * Implements hook_form_alter().
 */
function commerce_checkout_redirect_form_alter(&$form, &$form_state, $form_id) {
  // If form is one of the user forms that could be anonymous checkout enabled.
  if (in_array($form_id, array_keys(commerce_checkout_redirect_get_user_forms()))) {
    // Return if the cart is empty, the user has chosen to checkout anonymously
    // or the user has already been redirected.
    if (commerce_checkout_redirect_is_cart_empty() || !empty($_SESSION['commerce_checkout_redirect_bypass']) || empty($_SESSION['commerce_checkout_redirect_anonymous'])) {
      return;
    }

    // Get some settings to improve readability of this script.
    $setting_anonymous_checkout_enabled = variable_get('commerce_checkout_redirect_anonymous', FALSE);
    $setting_email_required = variable_get('commerce_checkout_redirect_username_as_order_email', FALSE);
    $setting_initially_hide_fields = variable_get('commerce_checkout_redirect_anonymous_as_login_option', FALSE);

    // If this is the first time this form is being built.
    if (!isset($form_state['build_info']['ajax_options'])) {
      // Define AJAX options and store them in build_info so we can re-use the
      // random wrapper ID.
      $form_state['build_info']['ajax_options'] = array(
        'effect' => 'fade',
        'callback' => 'commerce_checkout_redirect_form_ajax_callback',
        'wrapper' => drupal_html_class($form_state['build_info']['form_id'] . '-wrapper-' . user_password()),
      );

      // Store the form's original path.
      $form_state['build_info']['original_path'] = url(current_path());
    }

    // Append the checkout redirect function to all user forms.
    $form['#submit'][] = 'commerce_checkout_redirect_redirect_anonymous_submit';

    // We used to unset the action property to use submit form functions
    // instead. Now we set the form's original path to prevent Drupal from
    // setting an AJAX path when no path is provided on an AJAX call.
    $form['#action'] = $form_state['build_info']['original_path'];

    // Get anonymous checkout enabled user forms.
    $anonymous_checkout_enabled_user_form_keys = variable_get('commerce_checkout_redirect_user_forms', commerce_checkout_redirect_get_user_forms());

    // Return if form is not anonymous checkout enabled.
    if (empty($anonymous_checkout_enabled_user_form_keys[$form_id])) {
      return;
    }

    // If form is not the password reset form (it is a login, register or user
    // profile form) and anonymous checkout is enabled.
    if ($form_id != 'user_pass_reset' && $setting_anonymous_checkout_enabled) {
      // Store order in form state array.
      $form_state['#order'] = commerce_cart_order_load();

      // Set flag: hide fields?
      $hide_fields = FALSE;

      // Get parent form element.
      if (isset($form['account'])) $parent_form_element = &$form['account'];
      else $parent_form_element = &$form;

      // Get key of name or mail field.
      $name_or_mail_field_key = empty($parent_form_element['mail']) ? 'name' : 'mail';

      // If irrelevant fields are supposed to be hidden initially.
      if ($setting_initially_hide_fields) {
        // Wrap form (while respecting possible earlier set prefix and suffix
        // properties) so AJAX can replace the wrapper's contents.
        $form['#prefix'] = '<div id="' . $form_state['build_info']['ajax_options']['wrapper'] . '">' . (empty($form['#prefix']) ? '' : $form['#prefix']);
        $form['#suffix'] = (empty($form['#suffix']) ? '' : $form['#suffix']) . '</div>';

        // Add radio buttons that show / hide irrelevant fields.
        $parent_form_element['have_pass'] = array(
          '#type' => 'radios',
          '#title' => t('Do you have an account?'),
          '#options' => array(
            0 => t('No (You can create an account later)'),
            1 => t('Yes'),
          ),
          '#default_value' => 0,
          '#weight' => -1000,
          '#ajax' => $form_state['build_info']['ajax_options'],
        );

        // Alter hide fields flag depending on user input or have_pass's default
        // value.
        $hide_fields = (isset($form_state['values']['have_pass']) ? $form_state['values']['have_pass'] : $parent_form_element['have_pass']['#default_value']) == 0;
      }

      // Add continue anonymously button.
      $form['actions']['continue_button'] = array(
        '#name' => 'continue_button',
        '#type' => 'submit',
        '#value' => t('Checkout without an account'),
        '#limit_validation_errors' => array(),
        '#submit' => array('commerce_checkout_redirect_anonymous_continue_checkout'),
        '#access' => !$setting_initially_hide_fields || $hide_fields,
      );

      // If fields need to be hidden.
      if ($hide_fields) {
        // Show / hide the name or mail and password fields on login forms.
        // @todo: Add alter hook to easily hide other fields?
        if (strpos($form_id, 'user_login') === 0) {
          // Show / hide the name or mail field depending on whether an e-mail
          // address is required to continue anonymous checkout.
          $parent_form_element[$name_or_mail_field_key]['#access'] = $setting_email_required;
          $parent_form_element['pass']['#access'] = FALSE;
        }
        elseif ($form_id === 'user_register_form') {
          // Show / hide the name or mail field depending on whether an e-mail
          // address is required to continue anonymous checkout.
          $parent_form_element['name']['#access'] = FALSE;
          $parent_form_element['mail']['#access'] = $setting_email_required;
        }

        // Hide the default submit button.
        $form['actions']['submit']['#access'] = FALSE;

        // Alter the continue anonymously button's title.
        $form['actions']['continue_button']['#value'] = strpos($form_id, 'user_login') === 0 ? t('Continue without logging in') : t('Continue without an account');
      }

      // If an e-mail address is required.
      if ($setting_email_required) {
        // If the form does not have a dedicated e-mail field and the Email
        // Registration module is not enabled.
        if ($name_or_mail_field_key === 'name') {
          // Alter name and pass fields' properties.
          $parent_form_element['name']['#title'] = t('E-mail');
          $parent_form_element['name']['#description'] = t('Enter your e-mail address.');
        }

        // Set weight of name or mail field to move it to top of the form.
        $parent_form_element[$name_or_mail_field_key]['#weight'] = -1001;

        // Set validation options for continue anonymously button.
        $form['actions']['continue_button']['#limit_validation_errors'] = array(array($name_or_mail_field_key));
        $form['actions']['continue_button']['#validate'][] = 'commerce_checkout_redirect_username_as_order_email_form_validate';

        // Add separate element validation callback that is also called when the
        // form has not been submitted by continue anonymously button.
        $parent_form_element[$name_or_mail_field_key]['#element_validate'][] = 'commerce_checkout_redirect_username_as_order_email_element_validate';

        // If an e-mail address has already been defined for this order.
        if ($form_state['#order']->mail) {
          // Set the order's e-mail address as a default value.
          $parent_form_element[$name_or_mail_field_key]['#default_value'] = $form_state['#order']->mail;
        }
      }
    }
    // If form is a password reset form and any actions are defined, provide the
    // option to checkout anonymously.
    elseif ($form_id == 'user_pass_reset' && !empty($form['actions'])) {
      // Add help text for continue anonymously button.
      if (variable_get('commerce_checkout_redirect_reset_password_message')) {
        $form['actions']['checkout_message']['#markup'] = '<p>' . variable_get('commerce_checkout_redirect_reset_password_message', t('You can also continue with the checkout process.')) . '</p>';
      }

      // Add continue anonymously button.
      $form['actions']['checkout'] = array(
        '#type' => 'submit',
        '#value' => t('Continue with checkout'),
      );
    }
  }
  // For resetting the session variables for back to cart checkout button.
  elseif (strpos($form_id, 'commerce_checkout_form_') === 0 && !empty($form['buttons']['cancel'])) {
    $form['buttons']['cancel']['#submit'][] = 'commerce_checkout_redirect_checkout_form_cancel_submit';
  }
}

/**
 * AJAX form callback function.
 */
function commerce_checkout_redirect_form_ajax_callback($form, &$form_state) {
  // Return the full form.
  return $form;
}

/**
 * Submit callback for the user forms that will perform the redirection.
 */
function commerce_checkout_redirect_redirect_anonymous_submit($form, &$form_state) {
  // Because the user in the order may have been updated (from uid 0 to the real
  // uid for example), clear static cache before trying to get the order.
  drupal_static_reset('commerce_cart_order_id');

  // If the user has been redirected.
  if (!empty($_SESSION['commerce_checkout_redirect_anonymous'])) {
    // If form is password reset form (after e-mail verification for new
    // accounts or after an existing user requested to change his password.
    if ($form['#form_id'] == 'user_pass_reset') {
      // Login to account to continue with the checkout process.
      // @see user_pass_reset()
      if ($form_state['clicked_button']['#id'] == 'edit-checkout') {
        global $user;
        $users = user_load_multiple(array($form_state['build_info']['args'][0]), array('status' => '1'));
        $user = reset($users);
        $GLOBALS['user'] = $user;
        // User login with user_login_finalize().
        user_login_finalize();
        // Let the user's password be changed without the current password check.
        $token = drupal_random_key();
        $_SESSION['pass_reset_' . $GLOBALS['user']->uid] = $token;
      }
      // Continue the reset password process.
      else {
        drupal_goto('user/reset/' . implode('/', $form_state['build_info']['args']) . '/login');
      }
    }

    // If user is logged in and an order ID can be retrieved.
    if (user_is_logged_in() && ($order_id = commerce_cart_order_id($GLOBALS['user']->uid))) {
      // Unset session variable and user property.
      unset($_SESSION['commerce_checkout_redirect_anonymous']);
      unset($GLOBALS['user']->commerce_checkout_redirect);

      // Set redirect path.
      $form_state['redirect'] = 'checkout/' . $order_id;
    }
  }
}

/**
 * Validation callback for name field when it is used as a mail field.
 *
 * This function is solely used to trim the user input and swap the e-mail
 * address for an actual username if the form has not been submitted by the
 * anonymous checkout button (inspired by the Email Registration module).
 */
function commerce_checkout_redirect_username_as_order_email_element_validate($element, &$form_state, $form) {
  // Get parent form element.
  if (isset($form['account'])) $parent_form_element = &$form['account'];
  else $parent_form_element = &$form;

  // Get key of name or mail field.
  $name_or_mail_field_key = empty($parent_form_element['mail']) ? 'name' : 'mail';

  // Return if the field contains an actual mail field or if the field has no
  // value.
  if ($name_or_mail_field_key === 'mail' || empty($form_state['values']['name'])) {
    return;
  }

  // Store the field's trimmed value.
  form_set_value($parent_form_element['name'], trim($form_state['values']['name']), $form_state);

  // Swap the e-mail address for an actual username if the form has not been
  // submitted by the anonymous checkout button.
  if ($form_state['triggering_element']['#name'] !== 'continue_button' && !module_exists('email_registration')) {
    // Keep the e-mail value in form state for possible further validation.
    $form_state['values']['mail'] = $form_state['values']['name'];

    // Try to find the actual username.
    if ($name = db_query('SELECT name FROM {users} WHERE LOWER(mail) = LOWER(:name)', array(':name' => $form_state['values']['mail']))->fetchField()) {
      $form_state['values']['name'] = $name;
    }
  }
}

/**
 * Validation callback for anonymous checkout enabled user forms when an e-mail
 * address is required.
 */
function commerce_checkout_redirect_username_as_order_email_form_validate($form, &$form_state) {
  // Get parent form element.
  if (isset($form['account'])) $parent_form_element = &$form['account'];
  else $parent_form_element = &$form;

  // Get key of name or mail field.
  $name_or_mail_field_key = empty($parent_form_element['mail']) ? 'name' : 'mail';

  // The Email Registration module might have looked up the user's actual
  // username and set it as the name field's value. Set the e-mail address as
  // the name field's value if the form was submitted by the checkout anonymous
  // button.
  if ($form_state['triggering_element']['#name'] === 'continue_button' && module_exists('email_registration') && $name_or_mail_field_key == 'name') {
    // If mail value exists.
    if (isset($form_state['values']['mail'])) {
      $form_state['values']['name'] = $form_state['values']['mail'];
    }
    // If email value exists (Email Registration sets the email value which
    // seems errornous since Drupal only uses the mail property).
    // @link https://www.drupal.org/node/2393189
    elseif (isset($form_state['values']['email'])) {
      $form_state['values']['name'] = $form_state['values']['email'];
    }
  }

  // Return if the field has no value.
  if (empty($form_state['values'][$name_or_mail_field_key])) {
    return;
  }

  // Validate the e-mail address.
  if ($error = user_validate_mail($form_state['values'][$name_or_mail_field_key])) {
    form_set_error($name_or_mail_field_key, $error);
    return;
  }

  // Check if the e-mail address is taken by an existing user.
  if ($form_state['triggering_element']['#name'] === 'continue_button') {
    // Try to look up the user ID for a user with the given e-mail address.
    $mail_taken = db_select('users')
      ->fields('users', array('uid'))
      ->condition('uid', $GLOBALS['user']->uid, '<>')
      // Why was a like pattern used? Couldn't this return a false positive if
      // e-mail address joe@gmail.com was given and superjoe@gmail.com existed
      // in the database?
      // ->condition('mail', db_like($form_state['values'][$name_or_mail_field_key]), 'LIKE')
      ->condition('mail', $form_state['values'][$name_or_mail_field_key])
      ->range(0, 1)
      ->execute()
      ->fetchField();

    // If an account exists with the givern e-mail address.
    if ($mail_taken) {
      // Format error message depending on whether the user is logged in.
      if (user_is_logged_in()) {
        form_set_error($name_or_mail_field_key, t('The e-mail address %email is already taken.', array('%email' => $form_state['values'][$name_or_mail_field_key])));
      }
      else {
        form_set_error($name_or_mail_field_key, t('The e-mail address %email is already registered. <a href="@password">Have you forgotten your password?</a>', array('%email' => $form_state['values'][$name_or_mail_field_key], '@password' => url('user/password'))));
      }
    }
  }
}

/**
 * Submit callback to allow anonymous users to continue without logging in.
 */
function commerce_checkout_redirect_anonymous_continue_checkout($form, &$form_state) {
  // Get parent form element.
  if (isset($form['account'])) $parent_form_element = &$form['account'];
  else $parent_form_element = &$form;

  // Get key of name or mail field.
  $name_or_mail_field_key = empty($parent_form_element['mail']) ? 'name' : 'mail';

  // If the user chooses to continue without an account, set this variable so user
  // is only redirected once per order (or once per session if the session expires first).
  $_SESSION['commerce_checkout_redirect_bypass'] = TRUE;

  // Using the username as order email.
  if (variable_get('commerce_checkout_redirect_username_as_order_email', FALSE)) {
    // Set order's e-mail address.
    $form_state['#order']->mail = $form_state['values'][$name_or_mail_field_key];

    // Save order.
    commerce_order_save($form_state['#order']);
  }

  // Set redirect path.
  $form_state['redirect'] = 'checkout';
}

/**
 * Submit callback for the cancel checkout button.
 */
function commerce_checkout_redirect_checkout_form_cancel_submit($form, &$form_state) {
  unset($_SESSION['commerce_checkout_redirect_anonymous']);
  unset($_SESSION['commerce_checkout_redirect_bypass']);
}

/**
 * Helper function to check if the current user's cart is empty.
 *
 * Based on proposal for commerce_cart_is_cart_empty().
 * @link https://www.drupal.org/node/2372223
 */
function commerce_checkout_redirect_is_cart_empty() {
  global $user;

  if ($order = commerce_cart_order_load($user->uid)) {
    $wrapper = entity_metadata_wrapper('commerce_order', $order);

    // If there are one or more products in the cart...
    if (commerce_line_items_quantity($wrapper->commerce_line_items, commerce_product_line_item_types()) > 0) {
      return FALSE;
    }
  }

  return TRUE;
}

/**
 * Helper function to get user forms which can be anonymous checkout enabled.
 */
function commerce_checkout_redirect_get_user_forms() {
  return array(
    'user_login' => t('Login form'),
    'user_login_block' => t('Login form block'),
    'user_register_form' => t('Registration form'),
    'user_profile_form' => t('User profile form'),
    'user_pass_reset' => t('Password reset form'),
  );
}