Show child documents on Phriction pages

Summary: Pull the next couple levels of hierarchy and render them at the bottom
of the page. This might need some tweaking but it seems OK at first glance.
Test Plan:
https://secure.phabricator.com/file/info/PHID-FILE-ef0af5d4dc6dceaeb2e3/

Also reduced limit to 1 and verified the "more" behavior worked properly.

Reviewed By: hsb
Reviewers: hsb, codeblock, jungejason, tuomaspelkonen, aran
CC: aran, hsb
Differential Revision: 676

src/applications/phriction/controller/document/PhrictionDocumentController.php

@@ -137,6 +137,8 @@ class PhrictionDocumentController
       $version_note = $version_note->render();
     }
 
+    $children = $this->renderChildren($slug);
+
     $page =
       '<div class="phriction-header">'.
         $button.
@@ -144,7 +146,8 @@ class PhrictionDocumentController
         $breadcrumbs.
       '</div>'.
       $version_note.
-      $page_content;
+      $page_content.
+      $children;
 
     return $this->buildStandardPageResponse(
       $page,
@@ -208,4 +211,124 @@ class PhrictionDocumentController
       '</div>';
   }
 
+  private function renderChildren($slug) {
+    $document_dao = new PhrictionDocument();
+    $content_dao = new PhrictionContent();
+    $conn = $document_dao->establishConnection('r');
+
+    $limit = 50;
+    $d_child = PhrictionDocument::getSlugDepth($slug) + 1;
+    $d_grandchild = PhrictionDocument::getSlugDepth($slug) + 2;
+
+    // Select children and grandchildren.
+    $children = queryfx_all(
+      $conn,
+      'SELECT d.slug, d.depth, c.title FROM %T d JOIN %T c
+        ON d.contentID = c.id
+        WHERE d.slug LIKE %> AND d.depth IN (%d, %d)
+        ORDER BY d.depth, c.title LIMIT %d',
+      $document_dao->getTableName(),
+      $content_dao->getTableName(),
+      ($slug == '/' ? '' : $slug),
+      $d_child,
+      $d_grandchild,
+      $limit);
+
+    if (!$children) {
+      return;
+    }
+
+    // We're going to render in one of three modes to try to accommodate
+    // different information scales:
+    //
+    //  - If we found fewer than $limit rows, we know we have all the children
+    //    and grandchildren and there aren't all that many. We can just render
+    //    everything.
+    //  - If we found $limit rows but the results included some grandchildren,
+    //    we just throw them out and render only the children, as we know we
+    //    have them all.
+    //  - If we found $limit rows and the results have no grandchildren, we
+    //    have a ton of children. Render them and then let the user know that
+    //    this is not an exhaustive list.
+
+    if (count($children) == $limit) {
+      $more_children = true;
+      foreach ($children as $child) {
+        if ($child['depth'] == $d_grandchild) {
+          $more_children = false;
+        }
+      }
+      $show_grandchildren = false;
+    } else {
+      $show_grandchildren = true;
+      $more_children = false;
+    }
+
+    $grandchildren = array();
+    foreach ($children as $key => $child) {
+      if ($child['depth'] == $d_child) {
+        continue;
+      } else {
+        unset($children[$key]);
+        if ($show_grandchildren) {
+          $ancestors = PhrictionDocument::getSlugAncestry($child['slug']);
+          $grandchildren[end($ancestors)][] = $child;
+        }
+      }
+    }
+
+    // Fill in any missing children.
+    $known_slugs = ipull($children, null, 'slug');
+    foreach ($grandchildren as $slug => $ignored) {
+      if (empty($known_slugs[$slug])) {
+        $children[] = array(
+          'slug'    => $slug,
+          'depth'   => $d_child,
+          'title'   => PhrictionDocument::getDefaultSlugTitle($slug),
+          'empty'   => true,
+        );
+      }
+    }
+
+    $list = array();
+    $list[] = '<ul>';
+    foreach ($children as $child) {
+      $list[] = $this->renderChildDocumentLink($child);
+      $grand = idx($grandchildren, $child['slug'], array());
+      if ($grand) {
+        $list[] = '<ul>';
+        foreach ($grand as $grandchild) {
+          $list[] = $this->renderChildDocumentLink($grandchild);
+        }
+        $list[] = '</ul>';
+      }
+    }
+    if ($more_children) {
+      $list[] = '<li>More...</li>';
+    }
+    $list[] = '</ul>';
+    $list = implode("\n", $list);
+
+    return
+      '<div class="phriction-children">'.
+        '<div class="phriction-children-header">Document Hierarchy</div>'.
+        $list.
+      '</div>';
+  }
+
+  private function renderChildDocumentLink(array $info) {
+    $item = phutil_render_tag(
+      'a',
+      array(
+        'href' => PhrictionDocument::getSlugURI($info['slug']),
+      ),
+      phutil_escape_html($info['title']));
+
+    if (isset($info['empty'])) {
+      $item = '<em>'.$item.'</em>';
+    }
+
+    return '<li>'.$item.'</li>';
+  }
+
 }

src/applications/phriction/controller/document/__init__.php

@@ -15,6 +15,7 @@ phutil_require_module('phabricator', 'applications/phriction/controller/base');
 phutil_require_module('phabricator', 'applications/phriction/storage/content');
 phutil_require_module('phabricator', 'applications/phriction/storage/document');
 phutil_require_module('phabricator', 'infrastructure/celerity/api');
+phutil_require_module('phabricator', 'storage/queryfx');
 phutil_require_module('phabricator', 'view/form/error');
 phutil_require_module('phabricator', 'view/utils');
 

webroot/rsrc/css/application/phriction/phriction-document-css.css

@@ -38,3 +38,21 @@
 .phriction-document-crumbs a {
   font-weight: bold;
 }
+
+.phriction-children {
+  padding: 1em 2em;
+  background: #eeeeee;
+  border-top: 1px solid #dddddd;
+}
+
+.phriction-children ul {
+  margin-left: 2.5em;
+  list-style: circle;
+  color: #999999;
+}
+
+.phriction-children-header {
+  padding: 0 0 .5em 0;
+  margin: 0;
+  font-weight: bold;
+}