//Dstl (c) Crown Copyright 2017
package uk.gov.dstl.baleen.contentmanipulators;

import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;

import uk.gov.dstl.baleen.contentmanipulators.helpers.ContentManipulator;

/**
 * Convert JSP101 style paragraph text to headings.
 * 
 * Supports only subject headings (mapped to h1) and group/main headings (both mapped to h2)
 * 
 * See notes in source code (or JSP101 itself) to definitions of each heading type.
 *
 */

public class Jsp101Headings implements ContentManipulator {

	@Override
	public void manipulate(Document document) {

		// Descriptions taken from the JSP101 Chapter 6, Paragraph 23

		// Documents start with a subject heading, which helps the
		// reader know at a glance the general subject of the document. However, you may
		// omit a subject heading from a letter to a member of the public. The subject heading
		// is written in bold capitals (not underlined and not followed by a full stop).

		// => H1 if bold and in CAPS, no full stop.

		addHeading(document, true, "h1");


		// A main heading introduces 2 or more groups of paragraphs
		// relating to the same general topic. Use main headings only when the document is
		// lengthy or complicated. A main heading shows the general content as far as the
		// next main heading. Centre a main heading above the text and use bold letters (not
		// numbered, not underlined and not followed by a full stop)

		// => H2 if bold, no full stop
		addHeading(document, false, "h2");


		// A group heading introduces one or more paragraphs relating
		// to the same general topic. It shows the content as far as the next group or main
		// heading. Starting at the left margin, write a group heading in bold letters (not
		// numbered, not underlined and not followed by a full stop).

		// => h3 if bold, no full stop and centred
		// BUT can't do centred, so the same as the main heading covered above


		// A paragraph heading indicates the content only of its
		// own paragraph (including any sub-paragraphs and further subdivisions), but not of
		// any following text. Once you use a paragraph heading, give all following paragraphs
		// a heading until the next main or group heading. Put a paragraph heading on the
		// same line as the opening words of the paragraph, preceded by a paragraph number
		// if appropriate. Write a paragraph heading in bold (but not underlined), with a full
		// stop to show where the heading ends.
		// Ditto sub paragraph heading.

		// => h4 if p starts (after a para number eg 1. / a.) with a bold sentence, ending in full stop.
		// BUT seems little reason to treat this differently to the a real sentence.
		// Plus there's the complexity of list item vs paragraph number.


	}

	/**
	 * Adds the heading for all bold paragraphs which don't end in full stop (which are captials
	 * depending on the boolean)
	 *
	 * @param document the document
	 * @param capitals does the heading need to be in capitals
	 * @param headingTag the HTML heading tag to use
	 */
	private void addHeading(Document document, boolean capitals, String headingTag) {
		document.select("p").forEach(p -> {
			String text = p.text().trim();

			if (!isBold(p, text))
				return;

			// No full stop (or similar) at the end of a title
			if(text.isEmpty() || text.substring(text.length() - 1).matches("[\\.:!\\?,;]"))
				return;

			if(!capitals  || isAllUpperCase(text))
				p.tagName(headingTag);
		});

	}

	private boolean isAllUpperCase(String text) {
		return text.toUpperCase().equals(text);
	}

	private boolean isBold(Element e, String text) {
		// Bold if one of the parents is bold
		if (!e.getElementsByTag("b").select("b").isEmpty()) {
			return true;
		}

		// Or if Bold child which has the same text.
		Elements boldChildren = e.select("b");
		if (boldChildren.isEmpty()) {
			return false;
		}

		return boldChildren.first().text().equals(text);
	}

}