package ash.parser;

import java.io.Serializable;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import bruce.common.utils.CommonUtils;

public final class Parser {
	private static final Pattern getFirstPlainTextPattern = Pattern.compile("(\\S+)\\s*");
	private static final char ESCAPE_CHAR = '\\';
	private static final char STRING_WRAPPING_CHAR = '\"';
	private static final char QUOTE_CHAR = '\'';

	private Parser() {}
	
	protected static Serializable createAst(String readIn) {
		if (readIn.charAt(0) == '(') {
			String unWrapped = unWrapped(readIn);
			return CommonUtils.isStringNullOrWriteSpace(unWrapped) ? Node.NIL : split(unWrapped);
		} else
			return readIn;
	}

	private static String unWrapped(String exp) {
		if (exp.charAt(0) == '(' && exp.charAt(exp.length() - 1) == ')')
			return exp.substring(1, exp.length() - 1);
		throw new UnsupportedOperationException("Can not Unwrap:" + exp);
	}

	public static Node split(String str) {
		String trim = str.trim();
		boolean quoteSugar = trim.charAt(0) == QUOTE_CHAR;
		String first = quoteSugar ? getFirst(trim.substring(1)) : getFirst(trim);
		String rest = getRest(trim, quoteSugar ? first.length() + 1 : first.length());
		
		Serializable ast = quoteSugar ? new Node("quote", new Node(createAst(first))) : createAst(first);
		if (CommonUtils.isStringNullOrWriteSpace(rest))
			return new Node(ast);
		else
			return new Node(ast, split(rest));
	}

	private static String getRest(String str, int firstStrLen) {
		return str.substring(firstStrLen);
	}

	private static String getFirst(String str) {
		char headCh = str.charAt(0);
		return headCh == '(' || headCh == STRING_WRAPPING_CHAR
				? str.substring(0, getFirstElemLen(str, 0, 0, '\0'))
				: getHeadPlainText(str);
	}

	protected static String getHeadPlainText(String str) {
		Matcher m = getFirstPlainTextPattern.matcher(str);
		m.find();
		return m.group(1);
	}

	private static int getFirstElemLen(String src, int balance, int elemLen, char spanChar) {
		if (elemLen != 0 && balance == 0 && spanChar == '\0') return elemLen;
		
		final char c = src.charAt(elemLen);
		return getFirstElemLen(src,
				spanChar == STRING_WRAPPING_CHAR
					? balance
					: balance + (c == '(' ? 1 : (c == ')' ? -1 : 0)),
				elemLen + (c == ESCAPE_CHAR ? 2 : 1),
				STRING_WRAPPING_CHAR == c ? (spanChar == c ? '\0' : c) : spanChar);
	}
}

@@ -1258,25 +1258,12 @@
 e%22, 
-new Node(createAs
+spli
 t(fi
@@ -1267,17 +1267,16 @@
 (first))
-)
  : creat

make (car ''asd) work