Feature: highlight fulltext search results

How it works:

  1. when a fulltext search is made, Shaarli looks for the first
occurence position of every term matching the search. No change here,
but we store these positions in an array, in Bookmark's additionalContent.
  2. when formatting bookmarks (through BookmarkFormatter
implementation):
    1. first we insert specific tokens at every search result positions
    2. we format the content (escape HTML, apply markdown, etc.)
    3. as a last step, we replace our token with displayable span
elements

Cons: this tightens coupling between search filters and formatters
Pros: it was absolutely necessary not to perform the
search twice. this solution has close to no impact on performances.

Fixes #205

1 files changed, 127 insertions, 5 deletions

diff --git a/application/formatter/BookmarkDefaultFormatter.php b/application/formatter/BookmarkDefaultFormatter.php
index 9d4a0fa0..d58a5e39 100644
--- a/application/formatter/BookmarkDefaultFormatter.php
+++ b/application/formatter/BookmarkDefaultFormatter.php
@@ -12,10 +12,13 @@ namespace Shaarli\Formatter;
  */
 class BookmarkDefaultFormatter extends BookmarkFormatter
 {
+    const SEARCH_HIGHLIGHT_OPEN = '|@@HIGHLIGHT';
+    const SEARCH_HIGHLIGHT_CLOSE = 'HIGHLIGHT@@|';
+
     /**
      * @inheritdoc
      */
-    public function formatTitle($bookmark)
+    protected function formatTitle($bookmark)
     {
         return escape($bookmark->getTitle());
     }
@@ -23,10 +26,28 @@ class BookmarkDefaultFormatter extends BookmarkFormatter
     /**
      * @inheritdoc
      */
-    public function formatDescription($bookmark)
+    protected function formatTitleHtml($bookmark)
+    {
+        $title = $this->tokenizeSearchHighlightField(
+            $bookmark->getTitle() ?? '',
+            $bookmark->getAdditionalContentEntry('search_highlight')['title'] ?? []
+        );
+
+        return $this->replaceTokens(escape($title));
+    }
+
+    /**
+     * @inheritdoc
+     */
+    protected function formatDescription($bookmark)
     {
         $indexUrl = ! empty($this->contextData['index_url']) ? $this->contextData['index_url'] : '';
-        return format_description(escape($bookmark->getDescription()), $indexUrl);
+        $description = $this->tokenizeSearchHighlightField(
+            $bookmark->getDescription() ?? '',
+            $bookmark->getAdditionalContentEntry('search_highlight')['description'] ?? []
+        );
+
+        return $this->replaceTokens(format_description(escape($description), $indexUrl));
     }
 
     /**
@@ -40,7 +61,27 @@ class BookmarkDefaultFormatter extends BookmarkFormatter
     /**
      * @inheritdoc
      */
-    public function formatTagString($bookmark)
+    protected function formatTagListHtml($bookmark)
+    {
+        if (empty($bookmark->getAdditionalContentEntry('search_highlight')['tags'])) {
+            return $this->formatTagList($bookmark);
+        }
+
+        $tags = $this->tokenizeSearchHighlightField(
+            $bookmark->getTagsString(),
+            $bookmark->getAdditionalContentEntry('search_highlight')['tags']
+        );
+        $tags = $this->filterTagList(explode(' ', $tags));
+        $tags = escape($tags);
+        $tags = $this->replaceTokensArray($tags);
+
+        return $tags;
+    }
+
+    /**
+     * @inheritdoc
+     */
+    protected function formatTagString($bookmark)
     {
         return implode(' ', $this->formatTagList($bookmark));
     }
@@ -48,7 +89,7 @@ class BookmarkDefaultFormatter extends BookmarkFormatter
     /**
      * @inheritdoc
      */
-    public function formatUrl($bookmark)
+    protected function formatUrl($bookmark)
     {
         if ($bookmark->isNote() && isset($this->contextData['index_url'])) {
             return rtrim($this->contextData['index_url'], '/') . '/' . escape(ltrim($bookmark->getUrl(), '/'));
@@ -80,8 +121,89 @@ class BookmarkDefaultFormatter extends BookmarkFormatter
     /**
      * @inheritdoc
      */
+    protected function formatUrlHtml($bookmark)
+    {
+        $url = $this->tokenizeSearchHighlightField(
+            $bookmark->getUrl() ?? '',
+            $bookmark->getAdditionalContentEntry('search_highlight')['url'] ?? []
+        );
+
+        return $this->replaceTokens(escape($url));
+    }
+
+    /**
+     * @inheritdoc
+     */
     protected function formatThumbnail($bookmark)
     {
         return escape($bookmark->getThumbnail());
     }
+
+    /**
+     * Insert search highlight token in provided field content based on a list of search result positions
+     *
+     * @param string     $fieldContent
+     * @param array|null $positions    List of of search results with 'start' and 'end' positions.
+     *
+     * @return string Updated $fieldContent.
+     */
+    protected function tokenizeSearchHighlightField(string $fieldContent, ?array $positions): string
+    {
+        if (empty($positions)) {
+            return $fieldContent;
+        }
+
+        $insertedTokens = 0;
+        $tokenLength = strlen(static::SEARCH_HIGHLIGHT_OPEN);
+        foreach ($positions as $position) {
+            $position = [
+                'start' => $position['start'] + ($insertedTokens * $tokenLength),
+                'end' => $position['end'] + ($insertedTokens * $tokenLength),
+            ];
+
+            $content = mb_substr($fieldContent, 0, $position['start']);
+            $content .= static::SEARCH_HIGHLIGHT_OPEN;
+            $content .= mb_substr($fieldContent, $position['start'], $position['end'] - $position['start']);
+            $content .= static::SEARCH_HIGHLIGHT_CLOSE;
+            $content .= mb_substr($fieldContent, $position['end']);
+
+            $fieldContent = $content;
+
+            $insertedTokens += 2;
+        }
+
+        return $fieldContent;
+    }
+
+    /**
+     * Replace search highlight tokens with HTML highlighted span.
+     *
+     * @param string $fieldContent
+     *
+     * @return string updated content.
+     */
+    protected function replaceTokens(string $fieldContent): string
+    {
+        return str_replace(
+            [static::SEARCH_HIGHLIGHT_OPEN, static::SEARCH_HIGHLIGHT_CLOSE],
+            ['<span class="search-highlight">', '</span>'],
+            $fieldContent
+        );
+    }
+
+    /**
+     * Apply replaceTokens to an array of content strings.
+     *
+     * @param string[] $fieldContents
+     *
+     * @return array
+     */
+    protected function replaceTokensArray(array $fieldContents): array
+    {
+        foreach ($fieldContents as &$entry) {
+            $entry = $this->replaceTokens($entry);
+        }
+
+        return $fieldContents;
+    }
 }