libdir.'/blocklib.php');
    require_once($CFG->libdir.'/tablelib.php');
    $confirm  = optional_param('confirm', 0, PARAM_INT);
    $hide     = optional_param('hide', 0, PARAM_INT);
    $show     = optional_param('show', 0, PARAM_INT);
    $delete   = optional_param('delete', 0, PARAM_INT);
    $multiple = optional_param('multiple', 0, PARAM_INT);
    require_login();
    if (!isadmin()) {
        error("Only administrators can use this page!");
    }
    if (!$site = get_site()) {
        error("Site isn't defined!");
    }
/// Print headings
    $stradministration = get_string('administration');
    $strconfiguration = get_string('configuration');
    $strmanageblocks = get_string('manageblocks');
    $strdelete = get_string('delete');
    $strversion = get_string('version');
    $strhide = get_string('hide');
    $strshow = get_string('show');
    $strsettings = get_string('settings');
    $strcourses = get_string('blockinstances', 'admin');
    $strname = get_string('name');
    $strmultiple = get_string('blockmultiple', 'admin');
    print_header("$site->shortname: $strmanageblocks", "$site->fullname",
                 "$stradministration -> ".
                 "$strconfiguration -> $strmanageblocks");
    print_heading($strmanageblocks);
/// If data submitted, then process and store.
    if (!empty($hide) && confirm_sesskey()) {
        if (!$block = get_record('block', 'id', $hide)) {
            error("Block doesn't exist!");
        }
        set_field('block', 'visible', '0', 'id', $block->id);      // Hide block
    }
    if (!empty($show) && confirm_sesskey() ) {
        if (!$block = get_record('block', 'id', $show)) {
            error("Block doesn't exist!");
        }
        set_field('block', 'visible', '1', 'id', $block->id);      // Show block
    }
    if (!empty($multiple) && confirm_sesskey()) {
        if (!$block = blocks_get_record($multiple)) {
            error("Block doesn't exist!");
        }
        $block->multiple = !$block->multiple;
        update_record('block', $block);
    }
    if (!empty($delete) && confirm_sesskey()) {
        if (!$block = blocks_get_record($delete)) {
            error("Block doesn't exist!");
        }
        if (!block_is_compatible($block->name)) {
            $strblockname = $block->name;
        }
        else {
            $blockobject = block_instance($block->name);
            $strblockname = $blockobject->get_title();
        }
        if (!$confirm) {
            notice_yesno(get_string('blockdeleteconfirm', '', $strblockname),
                         'blocks.php?delete='.$block->id.'&confirm=1&sesskey='.$USER->sesskey,
                         'blocks.php');
            print_footer();
            exit;
        } else {
            // Delete block
            if (!delete_records('block', 'id', $block->id)) {
                notify("Error occurred while deleting the $strblockname record from blocks table");
            }
            $instances = get_records('block_instance', 'blockid', $block->id);
            if(!empty($instances)) {
                foreach($instances as $instance) {
                    blocks_delete_instance($instance);
                }
            }
            // Then the tables themselves
            if ($tables = $db->Metatables()) {
                $prefix = $CFG->prefix.$block->name;
                foreach ($tables as $table) {
                    if (strpos($table, $prefix) === 0) {
                        if (!execute_sql("DROP TABLE $table", false)) {
                            notify("ERROR: while trying to drop table $table");
                        }
                    }
                }
            }
            $a->block = $strblockname;
            $a->directory = $CFG->dirroot.'/blocks/'.$block->name;
            notice(get_string('blockdeletefiles', '', $a), 'blocks.php');
        }
    }
/// Main display starts here
/// Get and sort the existing blocks
    if (false === ($blocks = get_records('block'))) {
        error('No blocks found!');  // Should never happen
    }
    $incompatible = array();
    foreach ($blocks as $block) {
        if(!block_is_compatible($block->name)) {
            notify('Block '. $block->name .' is not compatible with the current version of Mooodle and needs to be updated by a programmer.');
            $incompatible[] = $block;
            continue;
        }
        if(($blockobject = block_instance($block->name)) === false) {
            // Failed to load
            continue;
        }
        $blockbyname[$blockobject->get_title()] = $block->id;
        $blockobjects[$block->id] = $blockobject;
    }
    if(empty($blockbyname)) {
        error('One or more blocks are registered in the database, but they all failed to load!');
    }
    ksort($blockbyname);
/// Print the table of all blocks
    $table = new flexible_table('admin-blocks-compatible');
    $table->define_columns(array('name', 'instances', 'version', 'hideshow', 'multiple', 'delete', 'settings'));
    $table->define_headers(array($strname, $strcourses, $strversion, $strhide.'/'.$strshow, $strmultiple, $strdelete, $strsettings));
    $table->define_baseurl($CFG->wwwroot.'/admin/blocks.php');
    $table->set_attribute('cellspacing', '0');
    $table->set_attribute('id', 'blocks');
    $table->set_attribute('class', 'generaltable generalbox');
    $table->setup();
    foreach ($blockbyname as $blockname => $blockid) {
        $blockobject = $blockobjects[$blockid];
        $delete = ''.$strdelete.'';
        $settings = ''; // By default, no configuration
        if($blockobject->has_config()) {
            $settings = ''.$strsettings.'';
        }
        $count = count_records('block_instance', 'blockid', $blockid);
        $class = ''; // Nothing fancy, by default
        if ($blocks[$blockid]->visible) {
            $visible = ''.
                       '
';
        } else {
            $visible = ''.
                       '
';
            $class = ' class="dimmed_text"'; // Leading space required!
        }
        if ($blockobject->instance_allow_multiple()) {
            if($blocks[$blockid]->multiple) {
                $multiple = ''.get_string('yes').' ('.get_string('change', 'admin').')';
            }
            else {
                $multiple = ''.get_string('no').' ('.get_string('change', 'admin').')';
            }
        }
        else {
            $multiple = '';
        }
        $table->add_data(array(
            ''.$blockobject->get_title().'',
            $count,
            $blockobject->get_version(),
            $visible,
            $multiple,
            $delete,
            $settings
        ));
    }
    $table->print_html();
    if(!empty($incompatible)) {
        print_heading(get_string('incompatibleblocks', 'admin'));
        $table = new flexible_table('admin-blocks-incompatible');
        
        $table->define_columns(array('block', 'delete'));
        $table->define_headers(array($strname, $strdelete));
        $table->define_baseurl($CFG->wwwroot.'/admin/blocks.php');
    
        $table->set_attribute('cellspacing', '0');
        $table->set_attribute('id', 'incompatible');
        $table->set_attribute('class', 'generaltable generalbox');
    
        $table->setup();
        foreach ($incompatible as $block) {
            $table->add_data(array(
                $block->name,
                ''.$strdelete.'',
            ));
        }
        $table->print_html();
    }
    print_footer();
?>