package commons.web.mvc;

import jakarta.servlet.jsp.JspException;
import jakarta.servlet.jsp.PageContext;
import jakarta.servlet.jsp.tagext.Tag;

public class ExpEval {
	public static Object evalObject(String attrName, String attrValue, Tag tagObject, PageContext pageContext) throws JspException {
		return evalExpression(attrName, attrValue, Object.class, tagObject, pageContext);
	}

	public static String evalString(String attrName, String attrValue, Tag tagObject, PageContext pageContext) throws JspException {
		return (String) evalExpression(attrName, attrValue, String.class, tagObject, pageContext);
	}

	public static Integer evalInteger(String attrName, String attrValue, Tag tagObject, PageContext pageContext) throws JspException {
		return (Integer) evalExpression(attrName, attrValue, Integer.class, tagObject, pageContext);
	}

	public static Boolean evalBoolean(String attrName, String attrValue, Tag tagObject, PageContext pageContext) throws JspException {
		return (Boolean) evalExpression(attrName, attrValue, Boolean.class, tagObject, pageContext);
	}

	private static Object evalExpression(String attrName, String attrValue, Class<?> expectedType, Tag tagObject, PageContext pageContext) throws JspException {
		if (attrValue == null) return null;
		if (attrValue.indexOf("${") == -1) {
			return attrValue;
		}
		try {
			jakarta.el.ELProcessor elProcessor = new jakarta.el.ELProcessor();
			elProcessor.defineBean("pageContext", pageContext);
			elProcessor.defineBean("param", pageContext.getRequest().getParameterMap());
			return elProcessor.eval(attrValue);
		} catch (Exception e) {
			throw new JspException("Error evaluating expression: " + attrValue, e);
		}
	}
}