<?php

/**
 * Implements hook_menu().
 */
function multiblock_menu() {
  $items = array();
  $items['admin/structure/block/instances'] = array(
    'title' => 'Instances',
    'description' => 'Create and delete instances of blocks.',
    'page callback' =>  'multiblock_general',
    'access callback' => 'user_access',
    'access arguments' => array('administer blocks'),
    'type' => MENU_LOCAL_TASK,
    'weight' => -15,
  );
  $items['admin/structure/block/instances/delete'] = array(
    'title' => 'Delete Block Instance',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('multiblock_delete_form'),
    'access callback' => 'user_access',
    'access arguments' => array('administer blocks'),
    'type' => MENU_CALLBACK,
  );
  return $items;
}

/**
 * Implements hook_block_info().
 */
function multiblock_block_info() {
  // Get all of the block instances that exist.
  $blocks = array();
  $blocks = multiblock_get_block(NULL);
  foreach ($blocks as $block) {
    $blocks[$block->delta] = array('info' => $block->title,'cache'=>DRUPAL_NO_CACHE);
  }
  return $blocks;
}

/**
 * Implements hook_block_view().
 */
function multiblock_block_view($delta = 0, $edit = array()) {
  return multiblock_call_block($delta, 'view', $edit);
}

/**
 * Implements hook_block_save().
 */
function multiblock_block_save($delta = 0, $edit = array()) {
  return multiblock_call_block($delta, 'save', $edit);
}

/**
 * Implements hook_block_configure().
 */
function multiblock_block_configure($delta = 0, $edit = array()) {
  return multiblock_call_block($delta, 'configure', $edit);
}

/**
 * Fetch a given block from the multiblock database table.
 * 
 * @param $delta
 *   Optional. Retreive a single block based on this delta. If none specified,
 *   all multiblock instances are returned.
 * @param $reset
 *   Optional. Boolean value to reset the interal cache of this function.
 */
function multiblock_get_block($delta = NULL, $reset = FALSE) {
  static $blocks;

  if (!isset($blocks) || $reset) {
    $blocks = array();
    $result = db_query("SELECT * FROM {multiblock}");
    foreach ($result as $row) {
      $blocks[$row->delta] = $row;
    }
  }

  return is_numeric($delta) ? $blocks[$delta] : $blocks;
}

/**
 * Dispatch a hook_block call to it's respective module. Paramater $delta
 * is the new multiblock delta that we're using and $op is the op we are
 * dispatching.
 */
function multiblock_call_block($delta, $op, $edit) {
  $result = db_query("SELECT module, orig_delta, delta, multi_settings FROM {multiblock} WHERE delta = :delta", array(
    ':delta' => $delta,
  ));
  if ($block_info = $result->fetchObject()) {
    // If this block is multiblock enabled, send it the delta of the block we're using.
    if ($block_info->multi_settings == 1 ) {
      $edit['multiblock_delta'] = array(
        '#type' => 'value',
        '#value' => $block_info->delta,
        );
    }
    if ($op == 'save') {
      $block = module_invoke($block_info->module, 'block_'. $op, $block_info->orig_delta, $edit);
    }
    else {
      $block = module_invoke($block_info->module, 'block_'. $op, $block_info->orig_delta);
    }
    return $block;
  }
  // No such multiblock, shouldn't ever happen.
  return;
}

/**
 * Page callback for the "Manage Block Instances page".
 */
function multiblock_general() {
  if (func_num_args() && func_get_arg(0) == 'edit' && is_numeric($instance = func_get_arg(1))) {
    $req_block = multiblock_get_block($instance);
  }
  // Fetch blocks directly from modules using block.module function.
  $blocks = _block_rehash();
  // Sort blocks how we want them.
  usort($blocks, 'multiblock_block_sort');

  // Fetch "Add Instance" form.
  if (isset($req_block)) {
    $form = drupal_render(drupal_get_form('multiblock_add_form', $blocks, $req_block));
  }
  else {
    $form = drupal_render(drupal_get_form('multiblock_add_form', $blocks));
  }

  // Get an array of existing blocks.
  $multiblocks = multiblock_get_block(NULL, TRUE);
  return theme('multiblock_general', array(
    'add_block_form' => $form,
    'multiblocks' => $multiblocks,
    'edit' => isset($req_block),
  ));
}

/**
 * "Add Instance" form.
 */
function multiblock_add_form($form, &$form_state, $blocks, $update = NULL) {
  $form['title'] = array(
    '#type' => 'textfield',
    '#title' => t('Instance Title'),
    '#maxlength' => 256,
    '#required' => TRUE,
    '#default_value' => (isset($update->title) ? $update->title : NULL),
    );
  if ($update) {
    $form['instance'] = array('#type' => 'value', '#value' => $update->delta);
  }
  else {
    // Turn $blocks into form options of block types.
    // Remember we need the module and delta to be able to tell what kind of
    // blocks we're talking about. 
    $options = array();
    foreach ($blocks as $block) {
      // Don't include multiblock module blocks in the list.
      if ($block['module'] != 'multiblock') {
        $options[$block['module'] .'***MB***'. $block['delta']] = $block['info'];
      }
    }
  
    $form['block'] = array(
      '#type' => 'select',
      '#title' => t('Block type'),
      '#options' => $options,
      '#required' => TRUE,
    );
  }
  $form['submit'] = array(
    '#type' => 'submit',
    '#value' => t('Save'),
  );
  return $form;
}

function multiblock_delete_form($form, $form_state, $delta) {
  $block = multiblock_get_block($delta);

  if (empty($block)) {
    drupal_set_message(t('The multiblock with the delta @delta was not found.', array('@delta' => $delta)), 'error');
    return array();
  }

  $form['delta'] = array('#type' => 'value', '#value' => $delta);
  return confirm_form($form,
    t('Delete the block instance %title?', array('%title' => $block->title)),
    'admin/structure/block/instances',
    t('This will delete the instance of the block %title.', array('%title' => $block->title)),
    t('Delete'), t('Cancel'));
}

function multiblock_delete_form_submit($form, &$form_state) {
  if (multiblock_delete($form_state['values']['delta'])) {
    drupal_set_message(t('Block successfully deleted!'));
  }
  else {
    drupal_set_message(t('There was a problem deleting the block'));
  }
  $form_state['redirect'] = 'admin/structure/block/instances';
}


/**
 * Add a multiblock instance.
 *
 * @param $original_block
 *   The original block for which an instance is being created.
 * @param $block_instance
 *   An object contain information about the particular block instance.
 * @return
 *   The delta of the newly added block.
 */
function multiblock_add($original_block, $block_instance) {
  // Create new delta for block instance.
  $record = array(
    'title' => $block_instance->title,
    'module' => $original_block->module,
    'orig_delta' => $original_block->delta,
    'multi_settings' => $block_instance->mb_enabled,
  );
  drupal_write_record('multiblock', $record);
  return $record['delta'];
}

/**
 * Delete a multiblock instance.
 */
function multiblock_delete($multiblock_delta) {
  // Remove instance from multiblock's storage.
  $num_deleted = db_delete('multiblock')
    ->condition('delta', (int) $multiblock_delta)
    ->execute();
  // Remove block instances from the block modules tables to avoid orphans.
  db_delete('block')
    ->condition('module', 'multiblock')
    ->condition('delta', (int) $multiblock_delta)
    ->execute();
  db_delete('block_role')
    ->condition('module', 'multiblock')
    ->condition('delta', (int) $multiblock_delta)
    ->execute();
  if (ctype_digit($multiblock_delta) && $num_deleted) {
    _block_rehash();
    return TRUE;
  }
  else {
    return FALSE;
  }
}

/**
 * Validate "Add Block Instance" form.
 */
function multiblock_add_form_validate($form, &$form_state) {
  if (!isset($form_state['values']['instance'])) {
    // Make sure we are getting a valid block to add.
    if (!preg_match('/^.+\*\*\*MB\*\*\*.+$/', $form_state['values']['block'])) {
      form_set_error('block', t('Bad block module input, contact administrator'));
      return;
    }
    // Make sure the block and delta exist.
    $orig_block = multiblock_blockinfo_from_form($form_state['values']['block']);
    if (!module_hook($orig_block['module'], 'block_info') ||
      !array_key_exists($orig_block['delta'], module_invoke($orig_block['module'], 'block_info'))) {
      form_set_error('block', t('Module or block doesn\'t exist, contact administrator'));
    }
  }
}

/**
 * Add block instance to database from "Add Block Instance" form.
 */
function multiblock_add_form_submit($form, &$form_state) {
  if (isset($form_state['values']['instance'])) {
    $num_updated = db_update('multiblock')
      ->fields(array(
        'title' => $form_state['values']['title'],
      ))
      ->condition('delta', $form_state['values']['instance'], '=')
      ->execute();

    $form_state['redirect'] = 'admin/structure/block/instances';
    return;
  }

  // Get the original block info.
  $orig_block = multiblock_blockinfo_from_form($form_state['values']['block']);
  // Check whether this module is multiblock enabled.
  $block_info = module_invoke($orig_block['module'], 'block_info');
  $mb_enabled = (int) (!empty($block_info[$orig_block['delta']]['mb_enabled']) && $block_info[$orig_block['delta']]['mb_enabled'] == TRUE);
  // Create block instance information.
  $orig_block = (object) $orig_block;
  $instance = (object) array('title' => $form_state['values']['title'], 'mb_enabled' => $mb_enabled);
  // Add the block instance.
  multiblock_add($orig_block, $instance);
  drupal_set_message(t('Block instance %instance created.', array('%instance' => $form_state['values']['title'])));
}

/**
 * Custom sort based on info element of array.
 */
function multiblock_block_sort($a, $b) {
  return strcmp($a['info'], $b['info']);
}

/**
 * Get the module and delta from the "Add Block Instance" block form element.
 */
function multiblock_blockinfo_from_form($form_value) {
  $matches = array();
  preg_match('/^(.+)\*\*\*MB\*\*\*(.+)$/', $form_value, $matches);
  return array('module' => $matches[1], 'delta' => $matches[2]);
}

/**
 * Get title of a block by its module and delta.
 */
function multiblock_get_block_title($module, $delta) {
  $block_info = module_invoke($module, 'block_info', $delta);
  return $block_info[$delta]['info'];
}

/**
 * Implementation of hook_theme().
 */
function multiblock_theme() {
  return array(
    'multiblock_general' => array(
      'arguments' => array('add_block_form' => NULL, 'multiblocks' => NULL, 'edit' => NULL),
      ),
    );
}

/**
 * Theme function for the "Manage Block Instances" page.
 */
function theme_multiblock_general($variables) {
  extract($variables, EXTR_SKIP);
  $output = '';
  $noyes = array('misc/watchdog-error.png', 'misc/watchdog-ok.png');
  
  $output .= '<p><h3>'. ($edit ? t('Edit Instance') : t('Add Instance')) .'</h3>'. $add_block_form .'</p>';
  
  $header = array(t('Title'), t('Original Block Title'), t('Original Module'), t('MultiBlock Enabled'), t('Original Delta'), t('Action'));
  
  $rows = array();
  foreach ($multiblocks as $row) {
    $ops_link = l(t('Edit'), 'admin/structure/block/instances/edit/'. $row->delta)
      .' '. l(t('Delete'), 'admin/structure/block/instances/delete/'. $row->delta);
    $title = multiblock_get_block_title($row->module, $row->orig_delta);
    $mb_enabled = $noyes[$row->multi_settings];
    $alt = t('Not Multiblock enabled');
    if ($row->multi_settings) {
      $alt = t('Multiblock enabled');
    }
    $rows[] = array(
      check_plain($row->title),
      check_plain($title),
      $row->module,
      array('data' => theme('image', array(
        'path' => $mb_enabled,
        'alt' => $alt,
        'title' => $alt)), 'align' => 'center'),
      $row->orig_delta, $ops_link,
      );
  }

  $output .= '<p><h3>'. t('Manage Instances') .'</h3>';
  if (!empty($rows)) {
    $output .= theme('table', array('header' => $header, 'rows' => $rows));
  }
  else {
    $output .= t('No instances defined yet.');
  }
  $output .= '</p>';

  return $output;
}