package org.rendersnake.error;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import org.rendersnake.HtmlCanvas;
import org.rendersnake.Renderable;
import static org.rendersnake.HtmlAttributesFactory.*;
/**
* RenderException is a RuntimeException that is thrown in the following cases
* <li>sending close() when there is no open tag
* <li>sending close(someTag) where otherTag was expected
* <li>general exception occurred when rendering a component
*
* @author ernest
*/
public class RenderException extends RuntimeException implements Renderable {
private static final long serialVersionUID = 5155772408981115672L;
public static final String KEY_PAGECONTEXT = "renderable.error";
public boolean isNullTag = false;
public boolean isEmptyStack = false;
public String expectedTag = null;
public String closingTag = null;
public Exception exception = null;
/**
* Return a new RenderException for the situation that a different tag is being close than expected.
* This indicates that a required close tag was not sent.
* @param expected , what should have been the close tag
* @param actual , what the program is trying to close
* @return
*/
public static RenderException nullTag() {
RenderException rex = new RenderException();
rex.isNullTag = true;
return rex;
}
/**
* Return a new RenderException for the situation that a different tag is being close than expected.
* This indicates that a required close tag was not sent.
* @param expected , what should have been the close tag
* @param actual , what the program is trying to close
* @return
*/
public static RenderException unexpectedTag(String expected, String actual) {
RenderException rex = new RenderException();
rex.expectedTag = expected;
rex.closingTag = actual;
return rex;
}
/**
* Return a new RenderException for the situation that a component is trying to close an open tag when there are no open tags to close.
* @return
*/
public static RenderException emptyStack() {
RenderException rex = new RenderException();
rex.isEmptyStack = true;
return rex;
}
/**
* Return a new RenderException for the situation that an unkown problem was detected when rendering a component.
* @param ex
* @return
*/
public static RenderException caught(Exception ex) {
RenderException rex = new RenderException();
rex.exception = ex;
return rex;
}
/**
* Render the receiver on a html to provide debugging information about the exception.
*/
public void renderOn(HtmlCanvas html) throws IOException {
html.div(style("color:red"));
if (isEmptyStack) {
html.write("[Render Error] unexpected close()");
return;
}
if (expectedTag != null) {
// tag mismatch
html.write(String.format("[Render Error] expected [%s] actual [%s]", expectedTag, closingTag));
}
if (exception != null) {
// general error
html.write(String.format("[Render Error] general exception [%s]", exception.getMessage()));
}
// if debugging, the error component is available
Renderable errorComponent = (Renderable)(html.getPageContext().getObject("renderable.error"));
if (errorComponent != null) {
html.write(" in ").write(errorComponent.getClass().getName());
} else {
html.a(href("?inspect")).write(" Inspect details")._a();
this.renderStackTraceOn(html);
}
html._div();
}
/**
* Render information about the exception (if any)
* @param html
* @throws IOException
*/
public void renderStackTraceOn(HtmlCanvas html) throws IOException { // @formatter:off
if (null == exception) return;
StringWriter sw = new StringWriter();
PrintWriter buffer = new PrintWriter(sw);
exception.printStackTrace(buffer);
html.pre().write(sw.toString(), true)._pre();
html.hr();
}
@Override
public String toString() {
return super.toString()
+ "{expected=" + expectedTag
+ ",actual=" + closingTag
+ ",exception=" + exception
+ ",empty=" + isEmptyStack
+ ",null=" + isNullTag
+ "}";
}
}