import java.util.Map;
import java.util.function.Function;
import java.util.function.BiFunction;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import java.util.*;

public class Html {
	private HtmlTag tag;
	private String body;
	private Map<String, String> attrs;

	private Html(HtmlTag tag, String body) {
		this.tag = tag;
		this.body = body;
		attrs = new HashMap<>();
	}

	public static Html html(HtmlTag tag, Html... body) {
		return new Html(tag, Arrays.asList(body).stream().map(Html::toString).collect(Collectors.joining()));
	}

	public static Html str(HtmlTag tag, String body) {
		return new Html(tag, body);
	}

	public Html addAttr(String key, String value) {
		attrs.put(key, value);
		return this;
	}

	@Override
	public String toString() {
		String attr = attrs.entrySet().stream().map((e) -> e.getKey() + "=\"" + e.getValue() + "\"").collect(Collectors.joining(" "));
		return String.format("<%s %s>%s</%1$s>", tag, attr, body);
	}

	public static Function<Stream<String>, Html> mkList = (s) ->
		html(HtmlTag.UL, s.map((li) -> str(HtmlTag.LI, li)).toArray(Html[]::new));

	public static final Html index = str(HtmlTag.P, "Hello World!");
}