<?php

/**

 * @file

 * Batch processing API for processes to run in multiple HTTP requests.

 *

 * Note that batches are usually invoked by form submissions, which is

 * why the core interaction functions of the batch processing API live in

 * form.inc.

 *

 * @see form.inc

 * @see batch_set()

 * @see batch_process()

 * @see batch_get()

 */

/**

 * Loads a batch from the database.

 *

 * @param $id

 *   The ID of the batch to load. When a progressive batch is being processed,

 *   the relevant ID is found in $_REQUEST['id'].

 *

 * @return

 *   An array representing the batch, or FALSE if no batch was found.

 */

function batch_load($id) {

  $batch = db_query("SELECT batch FROM {batch} WHERE bid = :bid AND token = :token", array(

    ':bid' => $id,

    ':token' => drupal_get_token($id),

  ))->fetchField();

  if ($batch) {

    return unserialize($batch);

  }

  return FALSE;

}

/**

 * Renders the batch processing page based on the current state of the batch.

 *

 * @see _batch_shutdown()

 */

function _batch_page() {

  $batch = &batch_get();

  if (!isset($_REQUEST['id'])) {

    return FALSE;

  }

  // Retrieve the current state of the batch.

  if (!$batch) {

    $batch = batch_load($_REQUEST['id']);

    if (!$batch) {

      drupal_set_message(t('No active batch.'), 'error');

      drupal_goto();

    }

  }

  // Register database update for the end of processing.

  drupal_register_shutdown_function('_batch_shutdown');

  // Add batch-specific CSS.

  foreach ($batch['sets'] as $batch_set) {

    if (isset($batch_set['css'])) {

      foreach ($batch_set['css'] as $css) {

        drupal_add_css($css);

      }

    }

  }

  $op = isset($_REQUEST['op']) ? $_REQUEST['op'] : '';

  $output = NULL;

  switch ($op) {

    case 'start':

      $output = _batch_start();

      break;

    case 'do':

      // JavaScript-based progress page callback.

      _batch_do();

      break;

    case 'do_nojs':

      // Non-JavaScript-based progress page.

      $output = _batch_progress_page_nojs();

      break;

    case 'finished':

      $output = _batch_finished();

      break;

  }

  return $output;

}

/**

 * Initializes the batch processing.

 *

 * JavaScript-enabled clients are identified by the 'has_js' cookie set in

 * drupal.js. If no JavaScript-enabled page has been visited during the current

 * user's browser session, the non-JavaScript version is returned.

 */

function _batch_start() {

  if (isset($_COOKIE['has_js']) && $_COOKIE['has_js']) {

    return _batch_progress_page_js();

  }

  else {

    return _batch_progress_page_nojs();

  }

}

/**

 * Outputs a batch processing page with JavaScript support.

 *

 * This initializes the batch and error messages. Note that in JavaScript-based

 * processing, the batch processing page is displayed only once and updated via

 * AHAH requests, so only the first batch set gets to define the page title.

 * Titles specified by subsequent batch sets are not displayed.

 *

 * @see batch_set()

 * @see _batch_do()

 */

function _batch_progress_page_js() {

  $batch = batch_get();

  $current_set = _batch_current_set();

  drupal_set_title($current_set['title'], PASS_THROUGH);

  // Merge required query parameters for batch processing into those provided by

  // batch_set() or hook_batch_alter().

  $batch['url_options']['query']['id'] = $batch['id'];

  $js_setting = array(

    'batch' => array(

      'errorMessage' => $current_set['error_message'] . '<br />' . $batch['error_message'],

      'initMessage' => $current_set['init_message'],

      'uri' => url($batch['url'], $batch['url_options']),

    ),

  );

  drupal_add_js($js_setting, 'setting');

  drupal_add_library('system', 'drupal.batch');

  return '<div id="progress"></div>';

}

/**

 * Does one execution pass with JavaScript and returns progress to the browser.

 *

 * @see _batch_progress_page_js()

 * @see _batch_process()

 */

function _batch_do() {

  // HTTP POST required.

  if ($_SERVER['REQUEST_METHOD'] != 'POST') {

    drupal_set_message(t('HTTP POST is required.'), 'error');

    drupal_set_title(t('Error'));

    return '';

  }

  // Perform actual processing.

  list($percentage, $message) = _batch_process();

  drupal_json_output(array('status' => TRUE, 'percentage' => $percentage, 'message' => $message));

}

/**

 * Outputs a batch processing page without JavaScript support.

 *

 * @see _batch_process()

 */

function _batch_progress_page_nojs() {

  $batch = &batch_get();

  $current_set = _batch_current_set();

  drupal_set_title($current_set['title'], PASS_THROUGH);

  $new_op = 'do_nojs';

  if (!isset($batch['running'])) {

    // This is the first page so we return some output immediately.

    $percentage       = 0;

    $message          = $current_set['init_message'];

    $batch['running'] = TRUE;

  }

  else {

    // This is one of the later requests; do some processing first.

    // Error handling: if PHP dies due to a fatal error (e.g. a nonexistent

    // function), it will output whatever is in the output buffer, followed by

    // the error message.

    ob_start();

    $fallback = $current_set['error_message'] . '<br />' . $batch['error_message'];

    $fallback = theme('maintenance_page', array('content' => $fallback, 'show_messages' => FALSE));

    // We strip the end of the page using a marker in the template, so any

    // additional HTML output by PHP shows up inside the page rather than below

    // it. While this causes invalid HTML, the same would be true if we didn't,

    // as content is not allowed to appear after </html> anyway.

    list($fallback) = explode('<!--partial-->', $fallback);

    print $fallback;

    // Perform actual processing.

    list($percentage, $message) = _batch_process($batch);

    if ($percentage == 100) {

      $new_op = 'finished';

    }

    // PHP did not die; remove the fallback output.

    ob_end_clean();

  }

  // Merge required query parameters for batch processing into those provided by

  // batch_set() or hook_batch_alter().

  $batch['url_options']['query']['id'] = $batch['id'];

  $batch['url_options']['query']['op'] = $new_op;

  $url = url($batch['url'], $batch['url_options']);

  $element = array(

    '#tag' => 'meta',

    '#attributes' => array(

      'http-equiv' => 'Refresh',

      'content' => '0; URL=' . $url,

    ),

  );

  drupal_add_html_head($element, 'batch_progress_meta_refresh');

  return theme('progress_bar', array('percent' => $percentage, 'message' => $message));

}

/**

 * Processes sets in a batch.

 *

 * If the batch was marked for progressive execution (default), this executes as

 * many operations in batch sets until an execution time of 1 second has been

 * exceeded. It will continue with the next operation of the same batch set in

 * the next request.

 *

 * @return

 *   An array containing a completion value (in percent) and a status message.

 */

function _batch_process() {

  $batch       = &batch_get();

  $current_set = &_batch_current_set();

  // Indicate that this batch set needs to be initialized.

  $set_changed = TRUE;

  // If this batch was marked for progressive execution (e.g. forms submitted by

  // drupal_form_submit()), initialize a timer to determine whether we need to

  // proceed with the same batch phase when a processing time of 1 second has

  // been exceeded.

  if ($batch['progressive']) {

    timer_start('batch_processing');

  }

  if (empty($current_set['start'])) {

    $current_set['start'] = microtime(TRUE);

  }

  $queue = _batch_queue($current_set);

  while (!$current_set['success']) {

    // If this is the first time we iterate this batch set in the current

    // request, we check if it requires an additional file for functions

    // definitions.

    if ($set_changed && isset($current_set['file']) && is_file($current_set['file'])) {

      include_once DRUPAL_ROOT . '/' . $current_set['file'];

    }

    $task_message = '';

    // Assume a single pass operation and set the completion level to 1 by

    // default.

    $finished = 1;

    if ($item = $queue->claimItem()) {

      list($function, $args) = $item->data;

      // Build the 'context' array and execute the function call.

      $batch_context = array(

        'sandbox'  => &$current_set['sandbox'],

        'results'  => &$current_set['results'],

        'finished' => &$finished,

        'message'  => &$task_message,

      );

      call_user_func_array($function, array_merge($args, array(&$batch_context)));

      if ($finished >= 1) {

        // Make sure this step is not counted twice when computing $current.

        $finished = 0;

        // Remove the processed operation and clear the sandbox.

        $queue->deleteItem($item);

        $current_set['count']--;

        $current_set['sandbox'] = array();

      }

    }

    // When all operations in the current batch set are completed, browse

    // through the remaining sets, marking them 'successfully processed'

    // along the way, until we find a set that contains operations.

    // _batch_next_set() executes form submit handlers stored in 'control'

    // sets (see form_execute_handlers()), which can in turn add new sets to

    // the batch.

    $set_changed = FALSE;

    $old_set = $current_set;

    while (empty($current_set['count']) && ($current_set['success'] = TRUE) && _batch_next_set()) {

      $current_set = &_batch_current_set();

      $current_set['start'] = microtime(TRUE);

      $set_changed = TRUE;

    }

    // At this point, either $current_set contains operations that need to be

    // processed or all sets have been completed.

    $queue = _batch_queue($current_set);

    // If we are in progressive mode, break processing after 1 second.

    if ($batch['progressive'] && timer_read('batch_processing') > 1000) {

      // Record elapsed wall clock time.

      $current_set['elapsed'] = round((microtime(TRUE) - $current_set['start']) * 1000, 2);

      break;

    }

  }

  if ($batch['progressive']) {

    // Gather progress information.

    // Reporting 100% progress will cause the whole batch to be considered

    // processed. If processing was paused right after moving to a new set,

    // we have to use the info from the new (unprocessed) set.

    if ($set_changed && isset($current_set['queue'])) {

      // Processing will continue with a fresh batch set.

      $remaining        = $current_set['count'];

      $total            = $current_set['total'];

      $progress_message = $current_set['init_message'];

      $task_message     = '';

    }

    else {

      // Processing will continue with the current batch set.

      $remaining        = $old_set['count'];

      $total            = $old_set['total'];

      $progress_message = $old_set['progress_message'];

    }

    // Total progress is the number of operations that have fully run plus the

    // completion level of the current operation.

    $current    = $total - $remaining + $finished;

    $percentage = _batch_api_percentage($total, $current);

    $elapsed    = isset($current_set['elapsed']) ? $current_set['elapsed'] : 0;

    $values     = array(

      '@remaining'  => $remaining,

      '@total'      => $total,

      '@current'    => floor($current),

      '@percentage' => $percentage,

      '@elapsed'    => format_interval($elapsed / 1000),

      // If possible, estimate remaining processing time.

      '@estimate'   => ($current > 0) ? format_interval(($elapsed * ($total - $current) / $current) / 1000) : '-',

    );

    $message = strtr($progress_message, $values);

    if (!empty($message)) {

      $message .= '<br />';

    }

    if (!empty($task_message)) {

      $message .= $task_message;

    }

    return array($percentage, $message);

  }

  else {

    // If we are not in progressive mode, the entire batch has been processed.

    return _batch_finished();

  }

}

/**

 * Formats the percent completion for a batch set.

 *

 * @param $total

 *   The total number of operations.

 * @param $current

 *   The number of the current operation. This may be a floating point number

 *   rather than an integer in the case of a multi-step operation that is not

 *   yet complete; in that case, the fractional part of $current represents the

 *   fraction of the operation that has been completed.

 *

 * @return

 *   The properly formatted percentage, as a string. We output percentages

 *   using the correct number of decimal places so that we never print "100%"

 *   until we are finished, but we also never print more decimal places than

 *   are meaningful.

 *

 * @see _batch_process()

 */

function _batch_api_percentage($total, $current) {

  if (!$total || $total == $current) {

    // If $total doesn't evaluate as true or is equal to the current set, then

    // we're finished, and we can return "100".

    $percentage = "100";

  }

  else {

    // We add a new digit at 200, 2000, etc. (since, for example, 199/200

    // would round up to 100% if we didn't).

    $decimal_places = max(0, floor(log10($total / 2.0)) - 1);

    do {

      // Calculate the percentage to the specified number of decimal places.

      $percentage = sprintf('%01.' . $decimal_places . 'f', round($current / $total * 100, $decimal_places));

      // When $current is an integer, the above calculation will always be

      // correct. However, if $current is a floating point number (in the case

      // of a multi-step batch operation that is not yet complete), $percentage

      // may be erroneously rounded up to 100%. To prevent that, we add one

      // more decimal place and try again.

      $decimal_places++;

    } while ($percentage == '100');

  }

  return $percentage;

}

/**

 * Returns the batch set being currently processed.

 */

function &_batch_current_set() {

  $batch = &batch_get();

  return $batch['sets'][$batch['current_set']];

}

/**

 * Retrieves the next set in a batch.

 *

 * If there is a subsequent set in this batch, assign it as the new set to

 * process and execute its form submit handler (if defined), which may add

 * further sets to this batch.

 *

 * @return

 *   TRUE if a subsequent set was found in the batch.

 */

function _batch_next_set() {

  $batch = &batch_get();

  if (isset($batch['sets'][$batch['current_set'] + 1])) {

    $batch['current_set']++;

    $current_set = &_batch_current_set();