package jj.document;

import static java.nio.charset.StandardCharsets.UTF_8;
import java.io.IOException;
import java.nio.charset.Charset;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.List;

import javax.inject.Inject;
import jj.event.Publisher;
import jj.resource.AbstractFileResource;
import org.jsoup.nodes.Comment;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Node;
import org.jsoup.parser.ParseError;
import org.jsoup.parser.Parser;
import org.jsoup.select.NodeTraversor;
import org.jsoup.select.NodeVisitor;

/**
 * An immutable collection of information about an
 * HTML resource.
 * @author jason
 *
 */
public class HtmlResource extends AbstractFileResource<Void> {

	private final Document document;
	
	private static final class CommentKiller implements NodeVisitor {
		
		List<Node> comments = new ArrayList<>();

		@Override
		public void head(Node node, int depth) {
		}

		@Override
		public void tail(Node node, int depth) {
			if (node instanceof Comment) {
				comments.add(node);
			}
		}
		
		void kill() {
			for (Node node: comments) {
				node.remove();
			}
		}
		
	}
	
	/**
	 * @param absoluteUri The server absolute URI to this resource
	 * @param path The filesystem Path to this resource
	 * @throws IOException
	 */
	@Inject
	HtmlResource(
		final DocumentConfiguration configuration,
		final Publisher publisher,
		final Dependencies dependencies,
		final Path path
	) throws IOException {
		super(dependencies, path);
		
		String html = byteBuffer.toString(UTF_8);
		
		Parser parser = Parser.htmlParser().setTrackErrors(configuration.showParsingErrors() ? Integer.MAX_VALUE : 0);
		
		this.document = parser.parseInput(html, name());
		
		List<ParseError> errors = parser.getErrors();
		if (!errors.isEmpty()) {
			publisher.publish(new HtmlParseError(path, errors));
		}
		
		if (configuration.removeComments()) {
			CommentKiller commentKiller = new CommentKiller();
			new NodeTraversor(commentKiller).traverse(document);
			commentKiller.kill();
		}
	}
	
	public Document document() {
		return document;
	}
	
	@Override
	public Charset charset() {
		return UTF_8;
	}
}