Summarize WordPress post content using PHP

summarize-content.php

<?php
// A function that takes a content string and returns an array of up to 3 sentences with the highest scores
function gtcontent_summarize($content) {

$content = str_replace("’","'", $content);
$content = str_replace("; ",".", $content);	
$content = remove_h2_to_h6_and_no_period($content);
$content = wp_strip_all_tags($content,true);
$content = wp_trim_words($content,700);

// Assume $sentences is a string variable that contains the sentences to be split
// Define an array of punctuation marks to use as delimiters
$punctuation = array(".", "!", "?", ":");
// Use preg_split function to split the string by the punctuation marks
// The PREG_SPLIT_NO_EMPTY flag will remove any empty elements from the resulting array
$sentences = preg_split("/[" . implode("", $punctuation) . "]/", $content, -1, PREG_SPLIT_NO_EMPTY);
  
  // Initialize an array to store the scores of each sentence
  $scores = array();
  
  // Loop through each sentence
  foreach ($sentences as $index => $sentence) {
    // Split the sentence by white space and get the words
    $words = preg_split('/\s+/', $sentence);
    
    // Initialize the score of the current sentence to zero
    $scores[$index] = 0;
    
    // Loop through each word in the current sentence
    foreach ($words as $word) {
      // Loop through each other sentence
      foreach ($sentences as $other_index => $other_sentence) {
        // If the other sentence is not the same as the current sentence
        if ($other_index != $index) {
          // If the word exists in the other sentence, increase the score of the current sentence by one
          if (stripos($other_sentence, $word) !== false) {
            $scores[$index]++;
          }
        }
      }
    }
  }
  
  // Sort the sentences by their scores in descending order and preserve the keys
  arsort($scores);
  
  // Get the keys of the top three sentences with the highest scores
  $keys = array_slice(array_keys($scores), 0, 5);
  
  // Initialize an array to store the top sentences
  $top_sentences = array();
  
  // Loop through each key and get the corresponding sentence
  foreach ($keys as $key) {
    $top_sentences[] = $sentences[$key];
  }

	$top_sentences = array_values(array_intersect($sentences, $top_sentences));
  
  // Return the array of top sentences
  return $top_sentences;
}

function remove_h2_to_h6_and_no_period($string) {

  // Split the string by line break
  $lines = explode("\n", $string);
  // Loop through each line
  foreach ($lines as &$line) {
    // Trim the whitespace from the line
    $line = trim($line);
    // Check if the line is empty
    if ($line == "") {
      // Skip this line
      continue;
    }
    // Check if the line ends with a punctuation mark
    if (!preg_match("/[.?!:]$/", $line)) {
      // Append a period to the line
      $line .= ".";
    }
  }
  // Join the lines back into a string, also remove newline
  $new_string = implode(" ", $lines);
  // Return the new string


  return $new_string;

}

function gtcontent_display_after_headline() {
    global $post;
    if ($post && get_post_type($post) == 'post') {
        $content = get_the_content(null, false, $post);
        $summary = gtcontent_summarize($content);
        $output = '<aside class="hide-on-print"><details style="border: 1px solid #ddd; border-radius: 4px; padding: 10px; background-color: #FFFEF1; margin-bottom: 20px"><summary style="color: #333; font-weight: bold; cursor: pointer; padding: 5px;">Quick Summary</summary><div style="padding: 10px; color: #555; line-height: 1.6;"><ul class="list styled">';
        foreach ($summary as $sentence) {
            $output .= "<li>" . $sentence . ".</li>";
        }
        $output .= "</ul></div></details></aside>";
        echo $output;
    }
}

add_action('md_hook_content_item_text_top', 'gtcontent_display_after_headline'); // Replace md_hook_content_item_text_top with your hook
?>