<?php

/**
 * The standard render pipeline for a Panels display object.
 *
 * Given a fully-loaded panels_display object, this class will turn its
 * combination of layout, panes, and styles into HTML, invoking caching
 * appropriately along the way. Interacting with the renderer externally is
 * very simple - just pass it the display object and call the render() method:
 *
 * @code
 *   // given that $display is a fully loaded Panels display object
 *   $renderer = panels_get_renderer_handler('standard', $display)
 *   $html_output = $renderer->render();
 * @endcode
 *
 * Internally, the render pipeline is divided into two phases, prepare and
 * render:
 *   - The prepare phase transforms the skeletal data on the provided
 *     display object into a structure that is expected by the render phase.
 *     It is divided into a series of discrete sub-methods and operates
 *     primarily by passing parameters, all with the intention of making
 *     subclassing easier.
 *   - The render phase relies primarily on data stored in the renderer object's
 *     properties, presumably set in the prepare phase. It iterates through the
 *     rendering of each pane, pane styling, placement in panel regions, region
 *     styling, and finally the arrangement of rendered regions in the layout.
 *     Caching, if in use, is triggered per pane, or on the entire display.
 *
 * In short: prepare builds conf, render renders conf. Subclasses should respect
 * this separation of responsibilities by adhering to these loose guidelines,
 * given a loaded display object:
 *   - If your renderer needs to modify the datastructure representing what is
 *     to be rendered (panes and their conf, styles, caching, etc.), it should
 *     use the prepare phase.
 *   - If your renderer needs to modify the manner in which that renderable
 *     datastructure data is rendered, it should use the render phase.
 *
 * In the vast majority of use cases, this standard renderer will be sufficient
 * and need not be switched out/subclassed; style and/or layout plugins can
 * accommodate nearly every use case. If you think you might need a custom
 * renderer, consider the following criteria/examples:
 *   - Some additional markup needs to be added to EVERY SINGLE panel.
 *   - Given a full display object, just render one pane.
 *   - Show a Panels admin interface.
 *
 * The system is almost functionally identical to the old procedural approach,
 * with some exceptions (@see panels_renderer_legacy for details). The approach
 * here differs primarily in its friendliness to tweaking in subclasses.
 */
class panels_renderer_standard {
  /**
   * The fully-loaded Panels display object that is to be rendered. "Fully
   * loaded" is defined as:
   *   1. Having been produced by panels_load_displays(), whether or this page
   *      request or at some time in the past and the object was exported.
   *   2. Having had some external code attach context data ($display->context),
   *      in the exact form expected by panes. Context matching is delicate,
   *      typically relying on exact string matches, so special attention must
   *      be taken.
   *
   * @var panels_display
   */
  var $display;

  /**
   * An associative array of loaded plugins. Used primarily as a central
   * location for storing plugins that require additional loading beyond
   * reading the plugin definition, which is already statically cached by
   * ctools_get_plugins(). An example is layout plugins, which can optionally
   * have a callback that determines the set of panel regions available at
   * runtime.
   *
   * @var array
   */
  var $plugins = array();

  /**
   * A multilevel array of rendered data. The first level of the array
   * indicates the type of rendered data, typically with up to three keys:
   * 'layout', 'regions', and 'panes'. The relevant rendered data is stored as
   * the value for each of these keys as it is generated:
   *  - 'panes' are an associative array of rendered output, keyed on pane id.
   *  - 'regions' are an associative array of rendered output, keyed on region
   *    name.
   *  - 'layout' is the whole of the rendered output.
   *
   * @var array
   */
  var $rendered = array();

  /**
   * A multilevel array of data prepared for rendering. The first level of the
   * array indicates the type of prepared data. The standard renderer populates
   * and uses two top-level keys, 'panes' and 'regions':
   *  - 'panes' are an associative array of pane objects to be rendered, keyed
   *    on pane id and sorted into proper rendering order.
   *  - 'regions' are an associative array of regions, keyed on region name,
   *    each of which is itself an indexed array of pane ids in the order in
   *    which those panes appear in that region.
   *
   * @var array
   */
  var $prepared = array();

  /**
   * Boolean state variable, indicating whether or not the prepare() method has
   * been run.
   *
   * This state is checked in panels_renderer_standard::render_layout() to
   * determine whether the prepare method should be automatically triggered.
   *
   * @var bool
   */
  var $prep_run = FALSE;

  /**
   * The plugin that defines this handler.
   */
  var $plugin = FALSE;

  /**
   * TRUE if this renderer is rendering in administrative mode
   * which will allow layouts to have extra functionality.
   *
   * @var bool
   */
  var $admin = FALSE;

  /**
   * Where to add standard meta information. There are three possibilities:
   * - standard: Put the meta information in the normal location. Default.
   * - inline: Put the meta information directly inline. This will
   *   not work for javascript.
   *
   * @var string
   */
  var $meta_location = 'standard';

  /**
   * Include rendered HTML prior to the layout.
   *
   * @var string
   */
  var $prefix = '';

  /**
   * Include rendered HTML after the layout.
   *
   * @var string
   */
  var $suffix = '';

  /**
   * Receive and store the display object to be rendered.
   *
   * This is a psuedo-constructor that should typically be called immediately
   * after object construction.
   *
   * @param array $plugin
   *   The definition of the renderer plugin.
   * @param panels_display $display
   *   The panels display object to be rendered.
   */
  function init($plugin, &$display) {
    $this->plugin = $plugin;
    $layout = panels_get_layout($display->layout);
    $this->display = &$display;
    $this->plugins['layout'] = $layout;
    if (!isset($layout['regions'])) {
      $this->plugins['layout']['regions'] = panels_get_regions($layout, $display);
    }

    if (empty($this->plugins['layout'])) {
      watchdog('panels', "Layout: @layout couldn't been found, maybe the theme is disabled.", array('@layout' => $display->layout));
    }
  }

  /**
   * Prepare the attached display for rendering.
   *
   * This is the outermost prepare method. It calls several sub-methods as part
   * of the overall preparation process. This compartmentalization is intended
   * to ease the task of modifying renderer behavior in child classes.
   *
   * If you override this method, it is important that you either call this
   * method via parent::prepare(), or manually set $this->prep_run = TRUE.
   *
   * @param mixed $external_settings
   *  An optional parameter allowing external code to pass in additional
   *  settings for use in the preparation process. Not used in the default
   *  renderer, but included for interface consistency.
   */
  function prepare($external_settings = NULL) {
    $this->prepare_panes($this->display->content);
    $this->prepare_regions($this->display->panels, $this->display->panel_settings);
    $this->prep_run = TRUE;
  }

  /**
   * Prepare the list of panes to be rendered, accounting for visibility/access
   * settings and rendering order.
   *
   * This method represents the standard approach for determining the list of
   * panes to be rendered that is compatible with all parts of the Panels
   * architecture. It first applies visibility & access checks, then sorts panes
   * into their proper rendering order, and returns the result as an array.
   *
   * Inheriting classes should override this method if that renderer needs to
   * regularly make additions to the set of panes that will be rendered.
   *
   * @param array $panes
   *  An associative array of pane data (stdClass objects), keyed on pane id.
   * @return array
   *  An associative array of panes to be rendered, keyed on pane id and sorted
   *  into proper rendering order.
   */
  function prepare_panes($panes) {
    ctools_include('content');
    // Use local variables as writing to them is very slightly faster
    $first = $normal = $last = array();

    // Prepare the list of panes to be rendered
    foreach ($panes as $pid => $pane) {
      if (empty($this->admin)) {
        // TODO remove in 7.x and ensure the upgrade path weeds out any stragglers; it's been long enough
        $pane->shown = !empty($pane->shown); // guarantee this field exists.
        // If this pane is not visible to the user, skip out and do the next one
        if (!$pane->shown || !panels_pane_access($pane, $this->display)) {
          continue;
        }
      }

      $content_type = ctools_get_content_type($pane->type);

      // If this pane wants to render last, add it to the $last array. We allow
      // this because some panes need to be rendered after other panes,
      // primarily so they can do things like the leftovers of forms.
      if (!empty($content_type['render last'])) {
        $last[$pid] = $pane;
      }
      // If it wants to render first, add it to the $first array. This is used
      // by panes that need to do some processing before other panes are
      // rendered.
      else if (!empty($content_type['render first'])) {
        $first[$pid] = $pane;
      }
      // Otherwise, render it in the normal order.
      else {
        $normal[$pid] = $pane;
      }
    }
    $this->prepared['panes'] = $first + $normal + $last;
    return $this->prepared['panes'];
  }

  /**
   * Prepare the list of regions to be rendered.
   *
   * This method is primarily about properly initializing the style plugin that
   * will be used to render the region. This is crucial as regions cannot be
   * rendered without a style plugin (in keeping with Panels' philosophy of
   * hardcoding none of its output), but for most regions no style has been
   * explicitly set. The logic here is what accommodates that situation:
   *  - If a region has had its style explicitly set, then we fetch that plugin
   *    and continue.
   *  - If the region has no explicit style, but a style was set at the display
   *    level, then inherit the style from the display.
   *  - If neither the region nor the dispay have explicitly set styles, then
   *    fall back to the hardcoded 'default' style, a very minimal style.
   *
   * The other important task accomplished by this method is ensuring that even
   * regions without any panes are still properly prepared for the rendering
   * process. This is essential because the way Panels loads display objects
   * (@see panels_load_displays) results only in a list of regions that
   * contain panes - not necessarily all the regions defined by the layout
   * plugin, which can only be determined by asking the plugin at runtime. This
   * method consults that retrieved list of regions and prepares all of those,
   * ensuring none are inadvertently skipped.
   *
   * @param array $region_pane_list
   *   An associative array of pane ids, keyed on the region to which those pids
   *   are assigned. In the default case, this is $display->panels.
   * @param array $settings
   *   All known region style settings, including both the top-level display's
   *   settings (if any) and all region-specific settings (if any).
   * @return array
   *   An array of regions prepared for rendering.
   */
  function prepare_regions($region_pane_list, $settings) {
    // Initialize defaults to be used for regions without their own explicit
    // settings. Use display settings if they exist, else hardcoded defaults.
    $default = array(
      'style' => panels_get_style(!empty($settings['style']) ? $settings['style'] : 'default'),
      'style settings' => isset($settings['style_settings']['default']) ? $settings['style_settings']['default'] : array(),
    );

    $regions = array();
    if (empty($settings)) {
      // No display/panel region settings exist, init all with the defaults.
      foreach ($this->plugins['layout']['regions'] as $region_id => $title) {
        // Ensure this region has at least an empty panes array.
        $panes = !empty($region_pane_list[$region_id]) ? $region_pane_list[$region_id] : array();

        $regions[$region_id] = $default;
        $regions[$region_id]['pids'] = $panes;
      }
    }
    else {
      // Some settings exist; iterate through each region and set individually.
      foreach ($this->plugins['layout']['regions'] as $region_id => $title) {
        // Ensure this region has at least an empty panes array.
        $panes = !empty($region_pane_list[$region_id]) ? $region_pane_list[$region_id] : array();
        if (empty($settings[$region_id]['style']) || $settings[$region_id]['style'] == -1) {
          $regions[$region_id] = $default;
        }
        else {
          $regions[$region_id]['style'] = panels_get_style($settings[$region_id]['style']);
          $regions[$region_id]['style settings'] = isset($settings['style_settings'][$region_id]) ? $settings['style_settings'][$region_id] : array();
        }
        $regions[$region_id]['pids'] = $panes;
      }
    }

    $this->prepared['regions'] = $regions;
    return $this->prepared['regions'];
  }

  /**
   * Build inner content, then hand off to layout-specified theme function for
   * final render step.
   *
   * This is the outermost method in the Panels render pipeline. It calls the
   * inner methods, which return a content array, which is in turn passed to the
   * theme function specified in the layout plugin.
   *
   * @return string
   *  Themed & rendered HTML output.
   */
  function render() {
    // Let the display refer back to the renderer.
    $this->display->renderer_handler = $this;

    // Attach out-of-band data first.
    $this->add_meta();

    if (empty($this->display->cache['method']) || !empty($this->display->skip_cache)) {
      return $this->render_layout();
    }
    else {
      $cache = panels_get_cached_content($this->display, $this->display->args, $this->display->context);
      if ($cache === FALSE) {
        $cache = new panels_cache_object();
        $cache->set_content($this->render_layout());
        panels_set_cached_content($cache, $this->display, $this->display->args, $this->display->context);
      }
      return $cache->content;
    }
  }

  /**
   * Perform display/layout-level render operations.
   *
   * This method triggers all the inner pane/region rendering processes, passes
   * that to the layout plugin's theme callback, and returns the rendered HTML.
   *
   * If display-level caching is enabled and that cache is warm, this method
   * will not be called.
   *
   * @return string
   *   The HTML string representing the entire rendered, themed panel.
   */
  function render_layout() {
    if (empty($this->prep_run)) {
      $this->prepare();
    }
    $this->render_panes();
    $this->render_regions();

    if ($this->admin && !empty($this->plugins['layout']['admin theme'])) {
      $theme = $this->plugins['layout']['admin theme'];
    }
    else {
      $theme = $this->plugins['layout']['theme'];
    }

    $this->rendered['layout'] = theme($theme, array('css_id' => check_plain($this->display->css_id), 'content' => $this->rendered['regions'], 'settings' => $this->display->layout_settings, 'display' => $this->display, 'layout' => $this->plugins['layout'], 'renderer' => $this));
    return $this->prefix . $this->rendered['layout'] . $this->suffix;
  }

  /**
   * Attach out-of-band page metadata (e.g., CSS and JS).
   *
   * This must be done before render, because panels-within-panels must have
   * their CSS added in the right order: inner content before outer content.
   */
  function add_meta() {
    if (!empty($this->plugins['layout']['css'])) {
      if (file_exists(path_to_theme() . '/' . $this->plugins['layout']['css'])) {
        $this->add_css(path_to_theme() . '/' . $this->plugins['layout']['css']);
      }
      else {
        $this->add_css($this->plugins['layout']['path'] . '/' . $this->plugins['layout']['css']);
      }
    }

    if ($this->admin && isset($this->plugins['layout']['admin css'])) {
      $this->add_css($this->plugins['layout']['path'] . '/' . $this->plugins['layout']['admin css']);
    }
  }

  /**
   * Add CSS information to the renderer.
   *
   * To facilitate previews over Views, CSS can now be added in a manner
   * that does not necessarily mean just using drupal_add_css. Therefore,
   * during the panel rendering process, this method can be used to add
   * css and make certain that ti gets to the proper location.
   *
   * The arguments should exactly match drupal_add_css().
   *
   * @see drupal_add_css
   */
  function add_css($filename) {
    switch ($this->meta_location) {
      case 'standard':
        drupal_add_css($filename);
        break;
      case 'inline':
        $url = base_path() . $filename;
        $this->prefix .= '<link type="text/css" rel="stylesheet" href="' . $url . '" />'."\n";
        break;
    }
  }

  /**
   * Render all prepared panes, first by dispatching to their plugin's render
   * callback, then handing that output off to the pane's style plugin.
   *
   * @return array
   *   The array of rendered panes, keyed on pane pid.
   */
  function render_panes() {
    ctools_include('content');

    // First, render all the panes into little boxes.
    $this->rendered['panes'] = array();
    foreach ($this->prepared['panes'] as $pid => $pane) {
      $content = $this->render_pane($pane);
      if ($content) {
        $this->rendered['panes'][$pid] = $content;
      }
    }
    return $this->rendered['panes'];
  }

  /**
   * Render a pane using its designated style.
   *
   * This method also manages 'title pane' functionality, where the title from
   * an individual pane can be bubbled up to take over the title for the entire
   * display.
   *
   * @param stdClass $pane
   *  A Panels pane object, as loaded from the database.
   */
  function render_pane(&$pane) {
    $content = $this->render_pane_content($pane);
    if ($this->display->hide_title == PANELS_TITLE_PANE && !empty($this->display->title_pane) && $this->display->title_pane == $pane->pid) {

      // If the user selected to override the title with nothing, and selected
      // this as the title pane, assume the user actually wanted the original
      // title to bubble up to the top but not actually be used on the pane.
      if (empty($content->title) && !empty($content->original_title)) {
        $this->display->stored_pane_title = $content->original_title;
      }
      else {
        $this->display->stored_pane_title = !empty($content->title) ? $content->title : '';
      }
    }

    if (!empty($content->content)) {
      if (!empty($pane->style['style'])) {
        $style = panels_get_style($pane->style['style']);

        if (isset($style) && isset($style['render pane'])) {
          $output = theme($style['render pane'], array('content' => $content, 'pane' => $pane, 'display' => $this->display, 'style' => $style, 'settings' => $pane->style['settings']));

          // This could be null if no theme function existed.
          if (isset($output)) {
            return $output;
          }
        }
      }

      // fallback
      return theme('panels_pane', array('content' => $content, 'pane' => $pane, 'display' => $this->display));
    }
  }

  /**
   * Render the interior contents of a single pane.
   *
   * This method retrieves pane content and produces a ready-to-render content
   * object. It also manages pane-specific caching.
   *
   * @param stdClass $pane
   *   A Panels pane object, as loaded from the database.
   * @return stdClass $content
   *   A renderable object, containing a subject, content, etc. Based on the
   *   renderable objects used by the block system.
   */
  function render_pane_content(&$pane) {
    ctools_include('context');
    // TODO finally safe to remove this check?
    if (!is_array($this->display->context)) {
      watchdog('panels', 'renderer::render_pane_content() hit with a non-array for the context', $this->display, WATCHDOG_DEBUG);
      $this->display->context = array();
    }

    $content = FALSE;
    $caching = !empty($pane->cache['method']) && empty($this->display->skip_cache);
    if ($caching && ($cache = panels_get_cached_content($this->display, $this->display->args, $this->display->context, $pane))) {
      $content = $cache->content;
    }
    else {
      if ($caching) {
        // This is created before rendering so that calls to drupal_add_js
        // and drupal_add_css will be captured.
        $cache = new panels_cache_object();
      }

      $content = ctools_content_render($pane->type, $pane->subtype, $pane->configuration, array(), $this->display->args, $this->display->context);

      if (empty($content)) {
        return;
      }

      foreach (module_implements('panels_pane_content_alter') as $module) {
        $function = $module . '_panels_pane_content_alter';
        $function($content, $pane, $this->display->args, $this->display->context, $this, $this->display);
      }
      if ($caching && isset($cache)) {
        $cache->set_content($content);
        panels_set_cached_content($cache, $this->display, $this->display->args, $this->display->context, $pane);
        $content = $cache->content;
      }
    }

    // Pass long the css_id that is usually available.
    if (!empty($pane->css['css_id'])) {
      $content->css_id = check_plain($pane->css['css_id']);
    }

    // Pass long the css_class that is usually available.
    if (!empty($pane->css['css_class'])) {
      $content->css_class = check_plain($pane->css['css_class']);
    }

    return $content;
  }

  /**
   * Render all prepared regions, placing already-rendered panes into their
   * appropriate positions therein.
   *
   * @return array
   *   An array of rendered panel regions, keyed on the region name.
   */
  function render_regions() {
    $this->rendered['regions'] = array();

    // Loop through all panel regions, put all panes that belong to the current
    // region in an array, then render the region. Primarily this ensures that
    // the panes are arranged in the proper order.
    $content = array();
    foreach ($this->prepared['regions'] as $region_id => $conf) {
      $region_panes = array();
      foreach ($conf['pids'] as $pid) {
        // Only include panes for region rendering if they had some output.
        if (!empty($this->rendered['panes'][$pid])) {
          $region_panes[$pid] = $this->rendered['panes'][$pid];
        }
      }
      $this->rendered['regions'][$region_id] = $this->render_region($region_id, $region_panes);
    }

    return $this->rendered['regions'];
  }

  /**
   * Render a single panel region.
   *
   * Primarily just a passthrough to the panel region rendering callback
   * specified by the style plugin that is attached to the current panel region.
   *
   * @param $region_id
   *   The ID of the panel region being rendered
   * @param $panes
   *   An array of panes that are assigned to the panel that's being rendered.
   *
   * @return string
   *   The rendered, HTML string output of the passed-in panel region.
   */
  function render_region($region_id, $panes) {
    $style = $this->prepared['regions'][$region_id]['style'];
    $style_settings = $this->prepared['regions'][$region_id]['style settings'];

    // Retrieve the pid (can be a panel page id, a mini panel id, etc.), this
    // might be used (or even necessary) for some panel display styles.
    // TODO: Got to fix this to use panel page name instead of pid, since pid is
    // no longer guaranteed. This needs an API to be able to set the final id.
    $owner_id = 0;
    if (isset($this->display->owner) && is_object($this->display->owner) && isset($this->display->owner->id)) {
      $owner_id = $this->display->owner->id;
    }

    $output = theme($style['render region'], array('display' => $this->display, 'owner_id' => $owner_id, 'panes' => $panes, 'settings' => $style_settings, 'region_id' => $region_id, 'style' => $style));
    return $output;
  }
}
