package pt.ist.renderers.servlets.functionalities;

import java.io.FileWriter;
import java.io.IOException;
import java.util.HashSet;
import java.util.Set;

import javax.annotation.processing.AbstractProcessor;
import javax.annotation.processing.RoundEnvironment;
import javax.annotation.processing.SupportedAnnotationTypes;
import javax.annotation.processing.SupportedSourceVersion;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.Element;
import javax.lang.model.element.TypeElement;

import pt.ist.struts.dispatch.annotation.Mapping;

@SupportedSourceVersion(SourceVersion.RELEASE_6)
@SupportedAnnotationTypes(value = { "pt.ist.fenixWebFramework.servlets.functionalities.Functionality" })
public class FunctionalityAnnotationProcessor extends AbstractProcessor {

    public static final String FUNCTIONALITIES_FILE = ".functionalitiesMappingLog";
    private static final String EMPTY_LINK = "-";
    private static final String SEPERATOR = ",";
    private static final Set<String> existingLinks = new HashSet<String>();

    @Override
    public boolean process(Set<? extends TypeElement> elements, RoundEnvironment env) {
	for (Element elem : env.getElementsAnnotatedWith(Functionality.class)) {
	    Functionality functionality = elem.getAnnotation(Functionality.class);
	    if (functionality == null) {
		continue;
	    }

	    String relativeLink = functionality.relativeLink();
	    String mappingPath = elem.getEnclosingElement().getAnnotation(Mapping.class).path();
	    String methodName = elem.getSimpleName().toString();

	    String link = mappingPath + relativeLink;

	    if (existingLinks.contains(link)) {
		throw new RuntimeException("Functionality in action: " + elem.getEnclosingElement().getSimpleName()
			+ " in method " + methodName + " has a semantic link that already exists");
	    }
	    existingLinks.add(link);

	    try {
		appendToFile(mappingPath, methodName, relativeLink);
	    } catch (IOException e) {
		e.printStackTrace();
	    }
	}

	return true;
    }

    private void appendToFile(String... strings) throws IOException {
	FileWriter writer = new FileWriter(FUNCTIONALITIES_FILE, true);

	int i = strings.length;
	for (String str : strings) {
	    if (isEmpty(str)) {
		writer.append(EMPTY_LINK);
	    } else {
		writer.append(str);
	    }
	    i--;
	    if (i > 0) {
		writer.append(SEPERATOR);
	    } else {
		writer.append("\n");
	    }
	}

	writer.close();
    }

    private boolean isEmpty(String str) {
	if (str == null) {
	    return true;
	}
	return str.isEmpty();
    }

}