A text run array contains any number of paragraphs objects which are referred to by PARAGRAPH_KEY below.

[PARAGRAPH_KEY]->metadata->style: empty or 'code'.
[PARAGRAPH_KEY]->style->align: empty, 'left, 'right', 'center'. Always empty right now.
[PARAGRAPH_KEY]->style->list_style: = empty, 'disc' or 'decimal'.
[PARAGRAPH_KEY]->style->list_depth: = Integer specifying the indentation for the list.
[PARAGRAPH_KEY]->style->list_index: = Integer specifying the starting number for the list.
[PARAGRAPH_KEY]->style->left_indent: = A positive value if the text is indented.
[PARAGRAPH_KEY]->runs: An array of run objects. Referred to as [RUN_KEY] below.

[RUN_KEY]->style->font_family: The font to use for the run of text.
[RUN_KEY]->style->font_size: The size of the font.
[RUN_KEY]->style->font_styles: empty or any combination of 'italic', 'bold', and 'underline' (e.g. 'bold,italic');
[RUN_KEY]->style->color: The color of the text in RGB format.
[RUN_KEY]->style->text_shift: empty or an integer <> 0. If the integer is positive then the text is subscript. If the integer is negative then the text is superscript.
[RUN_KEY]->style->link: The hyperlink assigned to the text.
[RUN_KEY]->metadata->style: empty or 'code'
[RUN_KEY]->text: The text.

Here is some sample code that iterates over a text run array and generates markup appropriate for MediaWiki.

function printTextRunAsMediaWiki($textrun, $type='instructions') {
  $output = '';
  $listDepth = 0;

  // If there is no text then just return an empty string.
  if (!is_array($textrun)) return '';

  // Iterate through paragraphs.
  foreach($textrun as $para)
  {
    $closingPara = '';

    /* Unused    
    $para->style->align  
    */  

    // Is this paragraph formatted as code?
    // If not is it a list item?
    if ($para->metadata->style == 'code')
    {
      $output .= '<code>';
      $closingPara = '</code>';
    } else {
      switch ($para->style->list_style)
      {
        case 'decimal':
          $output .= str_repeat('#', $para->style->list_depth) . ' ';
          break;
        default:
          $output .= str_repeat('*', $para->style->list_depth) . ' ';
          break;
      }
    }

    // Iterate through each text run in the paragraph.
    if (isset($para->runs))
    {
      foreach ($para->runs as $run)
      {
        $closingRun = '';
        $prefix = '';
        $suffix = '';
        $styles = explode(',', $run->style->font_styles);

        $hasBold = array_search('bold', $styles) != FALSE;
        $hasItalic = array_search('italic', $styles) != FALSE;
        $hasUnderline = array_search('underline', $styles) != FALSE;

        if (!empty($run->style->color))
        {
          $output .= '<span style="color: rgb(' . $run->style->color . ');">';
          $closingRun = '</span>';
        }

        if ($hasItalic) { $prefix .= "''"; $suffix = "''" . $suffix; }
        if ($hasBold) { $prefix .= "'''"; $suffix = "'''" . $suffix; }
        if ($hasUnderline) { $prefix .= '<ul>'; $suffix = '</ul>' . $suffix; }

        /* Unused
        $run->style->font_family
        $run->style->font_size
        $run->style->text_shift
        */

        $output .= $prefix;
        $output .= $run->text;
        $output .= $suffix;
        $output .= $closingRun;
      }
    }

    $output .= $closingPara;

    if ($type != 'title') $output .= PHP_EOL;
  }

  return $output;
}