package goodjava.bbcode;

import java.util.List;
import java.util.ArrayList;
import goodjava.parser.Parser;


public final class BBCode {

	public enum Target { HTML, TEXT }

	public interface Quoter {
		public String quote(Target target,String text,String param);
	}

	public static final Quoter defaultQuoter = new Quoter() {
		public String quote(Target target,String text,String param) {
			StringBuilder sb = new StringBuilder();
			sb.append( "<blockquote>" );
			if( param != null ) {
				sb.append( htmlEncode(param) );
				sb.append( " wrote:\n" );
			}
			sb.append( text );
			sb.append( "</blockquote>" );
			return sb.toString();
		}
	};

	public Target target = Target.HTML;
	public Quoter quoter = defaultQuoter;
	private final Parser parser;

	public BBCode(String text) {
		this.parser = new Parser(text);
	}

	public String parse() {
		StringBuilder sb = new StringBuilder();
		StringBuilder text = new StringBuilder();
		while( !parser.endOfInput() ) {
			String block = parseBlock();
			if( block != null ) {
				sb.append( textToString(text) );
				sb.append(block);
			} else {
				text.append( parser.currentChar() );
				parser.anyChar();
			}
		}
		sb.append( textToString(text) );
		return sb.toString();
	}

	private String parseWellFormed() {
		StringBuilder sb = new StringBuilder();
		StringBuilder text = new StringBuilder();
		while( !parser.endOfInput() ) {
			String block = parseBlock();
			if( block != null ) {
				sb.append( textToString(text) );
				sb.append(block);
				continue;
			}
			if( couldBeTag() )
				break;
			text.append( parser.currentChar() );
			parser.anyChar();
		}
		sb.append( textToString(text) );
		return sb.toString();
	}

	private String textToString(StringBuilder text) {
		String s = text.toString();
		text.setLength(0);
		if( target == Target.HTML )
			s = htmlEncode(s);
		return s;
	}

	private boolean couldBeTag() {
		if( parser.currentChar() != '[' )
			return false;
		return parser.testIgnoreCase("[b]")
			|| parser.testIgnoreCase("[/b]")
			|| parser.testIgnoreCase("[i]")
			|| parser.testIgnoreCase("[/i]")
			|| parser.testIgnoreCase("[u]")
			|| parser.testIgnoreCase("[/u]")
			|| parser.testIgnoreCase("[url]")
			|| parser.testIgnoreCase("[url=")
			|| parser.testIgnoreCase("[/url]")
			|| parser.testIgnoreCase("[code]")
			|| parser.testIgnoreCase("[/code]")
			|| parser.testIgnoreCase("[img]")
			|| parser.testIgnoreCase("[/img]")
			|| parser.testIgnoreCase("[color=")
			|| parser.testIgnoreCase("[/color]")
			|| parser.testIgnoreCase("[size=")
			|| parser.testIgnoreCase("[/size]")
			|| parser.testIgnoreCase("[youtube]")
			|| parser.testIgnoreCase("[/youtube]")
			|| parser.testIgnoreCase("[quote]")
			|| parser.testIgnoreCase("[quote=")
			|| parser.testIgnoreCase("[/quote]")
		;
	}

	private String parseBlock() {
		if( parser.currentChar() != '[' )
			return null;
		String s;
		s = parseB();  if(s!=null) return s;
		s = parseI();  if(s!=null) return s;
		s = parseU();  if(s!=null) return s;
		s = parseUrl1();  if(s!=null) return s;
		s = parseUrl2();  if(s!=null) return s;
		s = parseCode();  if(s!=null) return s;
		s = parseImg();  if(s!=null) return s;
		s = parseColor();  if(s!=null) return s;
		s = parseSize();  if(s!=null) return s;
		s = parseYouTube();  if(s!=null) return s;
		s = parseQuote1();  if(s!=null) return s;
		s = parseQuote2();  if(s!=null) return s;
		return null;
	}

	private String parseB() {
		parser.begin();
		if( !parser.matchIgnoreCase("[b]") )
			return parser.failure(null);
		String content = parseWellFormed();
		if( !parser.matchIgnoreCase("[/b]") )
			return parser.failure(null);
		String rtn = target==Target.HTML ? "<b>"+content+"</b>" : content;
		return parser.success(rtn);
	}

	private String parseI() {
		parser.begin();
		if( !parser.matchIgnoreCase("[i]") )
			return parser.failure(null);
		String content = parseWellFormed();
		if( !parser.matchIgnoreCase("[/i]") )
			return parser.failure(null);
		String rtn = target==Target.HTML ? "<i>"+content+"</i>" : content;
		return parser.success(rtn);
	}

	private String parseU() {
		parser.begin();
		if( !parser.matchIgnoreCase("[u]") )
			return parser.failure(null);
		String content = parseWellFormed();
		if( !parser.matchIgnoreCase("[/u]") )
			return parser.failure(null);
		String rtn = target==Target.HTML ? "<u>"+content+"</u>" : content;
		return parser.success(rtn);
	}

	private String parseUrl1() {
		parser.begin();
		if( !parser.matchIgnoreCase("[url]") )
			return parser.failure(null);
		String url = parseRealUrl();
		if( !parser.matchIgnoreCase("[/url]") )
			return parser.failure(null);
		String rtn = target==Target.HTML ? "<a href='"+url+"'>"+url+"</a>" : url;
		return parser.success(rtn);
	}

	private String parseUrl2() {
		parser.begin();
		if( !parser.matchIgnoreCase("[url=") )
			return parser.failure(null);
		String url = parseRealUrl();
		if( !parser.match(']') )
			return parser.failure(null);
		String content = parseWellFormed();
		if( !parser.matchIgnoreCase("[/url]") )
			return parser.failure(null);
		String rtn = target==Target.HTML ? "<a href='"+url+"'>"+content+"</a>" : content;
		return parser.success(rtn);
	}

	private String parseRealUrl() {
		parser.begin();
		while( parser.match(' ') );
		int start = parser.currentIndex();
		if( !parser.matchIgnoreCase("http") )
			return parser.failure(null);
		parser.matchIgnoreCase("s");
		if( !parser.matchIgnoreCase("://") )
			return parser.failure(null);
		while( parser.noneOf(" []'") );
		String url = parser.textFrom(start);
		while( parser.match(' ') );
		return parser.success(url);
	}

	private String parseCode() {
		parser.begin();
		if( !parser.matchIgnoreCase("[code]") )
			return parser.failure(null);
		int start = parser.currentIndex();
		while( !parser.testIgnoreCase("[/code]") ) {
			if( !parser.anyChar() )
				return parser.failure(null);
		}
		String content = parser.textFrom(start);
		if( !parser.matchIgnoreCase("[/code]") ) throw new RuntimeException();
		String rtn = target==Target.HTML ? "<code>"+content+"</code>" : content;
		return parser.success(rtn);
	}

	private String parseImg() {
		parser.begin();
		if( !parser.matchIgnoreCase("[img]") )
			return parser.failure(null);
		String url = parseRealUrl();
		if( !parser.matchIgnoreCase("[/img]") )
			return parser.failure(null);
		String rtn = target==Target.HTML ? "<img src='"+url+"'>" : "";
		return parser.success(rtn);
	}

	private String parseColor() {
		parser.begin();
		if( !parser.matchIgnoreCase("[color=") )
			return parser.failure(null);
		int start = parser.currentIndex();
		parser.match('#');
		while( parser.inCharRange('0','9')
			|| parser.inCharRange('a','z')
			|| parser.inCharRange('A','Z')
		);
		String color = parser.textFrom(start);
		if( !parser.match(']') )
			return parser.failure(null);
		String content = parseWellFormed();
		if( !parser.matchIgnoreCase("[/color]") )
			return parser.failure(null);
		String rtn = target==Target.HTML ? "<span style='color: "+color+"'>"+content+"</span>" : content;
		return parser.success(rtn);
	}

	private String parseSize() {
		parser.begin();
		if( !parser.matchIgnoreCase("[size=") )
			return parser.failure(null);
		int start = parser.currentIndex();
		while( parser.match('.') || parser.inCharRange('0','9') );
		String size = parser.textFrom(start);
		if( !parser.match(']') )
			return parser.failure(null);
		String content = parseWellFormed();
		if( !parser.matchIgnoreCase("[/size]") )
			return parser.failure(null);
		String rtn = target==Target.HTML ? "<span style='font-size: "+size+"em'>"+content+"</span>" : content;
		return parser.success(rtn);
	}

	private String parseYouTube() {
		parser.begin();
		if( !parser.matchIgnoreCase("[youtube]") )
			return parser.failure(null);
		int start = parser.currentIndex();
		while( parser.inCharRange('0','9')
			|| parser.inCharRange('a','z')
			|| parser.inCharRange('A','Z')
			|| parser.match('-')
			|| parser.match('_')
		);
		String id = parser.textFrom(start);
		if( id.length()==0 || !parser.matchIgnoreCase("[/youtube]") )
			return parser.failure(null);
		String rtn = target==Target.HTML ? "<iframe width='420' height='315' src='https://www.youtube.com/embed/"+id+"' frameborder='0' allowfullscreen></iframe>" : "";
		return parser.success(rtn);
	}

	private String parseQuote1() {
		parser.begin();
		if( !parser.matchIgnoreCase("[quote]") )
			return parser.failure(null);
		String content = parseWellFormed();
		if( !parser.matchIgnoreCase("[/quote]") )
			return parser.failure(null);
		String rtn = quoter.quote(target,content,null);
		return parser.success(rtn);
	}

	private String parseQuote2() {
		parser.begin();
		if( !parser.matchIgnoreCase("[quote=") )
			return parser.failure(null);
		List args = new ArrayList();
		int start = parser.currentIndex();
		while( parser.noneOf("[]") );
		String name = parser.textFrom(start).trim();
		if( !parser.match(']') )
			return parser.failure(null);
		String content = parseWellFormed();
		if( !parser.matchIgnoreCase("[/quote]") )
			return parser.failure(null);
		String rtn = quoter.quote(target,content,name);
		return parser.success(rtn);
	}

	public static String htmlEncode(String s) {
		final char[] a = s.toCharArray();
		StringBuilder buf = new StringBuilder();
		for( char c : a ) {
			switch(c) {
			case '&':
				buf.append("&amp;");
				break;
			case '<':
				buf.append("&lt;");
				break;
			case '>':
				buf.append("&gt;");
				break;
			case '"':
				buf.append("&quot;");
				break;
			default:
				buf.append(c);
			}
		}
		return buf.toString();
	}

}