package pt.ist.bennu.plugin;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

import org.apache.commons.io.FileUtils;
import org.apache.maven.artifact.Artifact;
import org.apache.maven.model.Resource;
import org.apache.maven.plugin.AbstractMojo;
import org.apache.maven.plugin.MojoExecutionException;
import org.apache.maven.project.MavenProject;
import org.codehaus.plexus.util.DirectoryScanner;
import org.codehaus.plexus.util.StringUtils;

/**
 * Generate base classes from the DML files
 * 
 * @goal update-web-fragment
 * 
 * @phase generate-sources
 * 
 * @requiresDependencyResolution runtime
 */
public class BennuMojo extends AbstractMojo {

    private static final String OPEN_NAME_TAG = "<name>";
    private static final String CLOSE_NAME_TAG = "</name>";
    private static final String NEW_LINE_CHAR = "\n";

    private static final String TEMPLATE_START = "<!-- [START OF BENNU GENERATED FRAGMENT] -->";

    private static final String TEMPLATE_END = "<!-- [END OF BENNU GENERATED FRAGMENT] -->";

    /**
     * Maven Project
     * 
     * @parameter default-value="${project}"
     */
    private MavenProject mavenProject;

    /**
     * web-fragment.xml file
     * 
     * @parameter expression="${webFragment}"
     *            default-value="${basedir}/src/main/resources/META-INF/web-fragment.xml"
     */
    private File webFragment;

    @Override
    public void execute() throws MojoExecutionException {
	if (mavenProject.getArtifact().getType().equals("pom"))
	    return;
	try {
	    if (webFragment.exists()) {
		String template = FileUtils.readFileToString(webFragment);
		int start = template.indexOf(TEMPLATE_START);
		int numSpaces = getIndentation(template, start);
		if (start != -1) {
		    int end = template.indexOf(TEMPLATE_END, start);
		    if (end != -1) {
			try (PrintWriter printWriter = new PrintWriter(webFragment)) {
			    printWriter.append(template.substring(0, start + TEMPLATE_START.length()));
			    printWriter.append(NEW_LINE_CHAR);
			    printWriter.append(getModuleDependenciesAsStrings(numSpaces));
			    printWriter.append(template.substring(end));
			}
		    } else {
			throw new MojoExecutionException("Missing template end comment: " + TEMPLATE_END);
		    }
		} else {
		    throw new MojoExecutionException("Missing template start comment: " + TEMPLATE_START);
		}
	    } else {
		getLog().info("File: " + webFragment.getAbsolutePath() + " not found. No depency injection could be made");
	    }
	} catch (IOException e) {
	    throw new MojoExecutionException(null, e);
	}

	List<Resource> resources = mavenProject.getResources();
	StringBuilder messages = new StringBuilder();
	for (Resource resource : resources) {
	    DirectoryScanner scanner = new DirectoryScanner();
	    scanner.setBasedir(resource.getDirectory());
	    scanner.setIncludes(new String[] { "resources/*.properties" });
	    scanner.scan();

	    for (String resourceFile : scanner.getIncludedFiles()) {
		if (!resourceFile.contains("_")) {
		    messages.append(resourceFile.substring("resources/".length(), resourceFile.length() - ".properties".length()));
		    messages.append("\n");
		}
	    }
	}
	String output = mavenProject.getBuild().getOutputDirectory() + File.separatorChar + mavenProject.getArtifactId()
		+ File.separatorChar + ".messageResources";
	try {
	    FileUtils.writeStringToFile(new File(output), messages.toString(), "UTF-8");
	} catch (IOException e) {
	    throw new MojoExecutionException(null, e);
	}
    }

    public String getModuleDependenciesAsStrings(int indentation) throws MojoExecutionException {
	StringBuilder stringBuilder = new StringBuilder();
	String indentSpace = StringUtils.repeat(" ", indentation - 1);
	for (Artifact artifact : mavenProject.getArtifacts()) {
	    if (isWebModule(artifact)) {
		stringBuilder.append(indentSpace);
		stringBuilder.append(OPEN_NAME_TAG);
		stringBuilder.append(artifact.getArtifactId());
		stringBuilder.append(CLOSE_NAME_TAG);
		stringBuilder.append(NEW_LINE_CHAR);
	    }
	}
	stringBuilder.append(indentSpace);
	return stringBuilder.toString();
    }

    public boolean isWebModule(Artifact artifact) throws MojoExecutionException {
	if (artifact.getType().equals("pom")) {
	    return false;
	}
	try (JarFile artifactJar = new JarFile(artifact.getFile())) {
	    JarEntry webFragmentFile = artifactJar.getJarEntry("META-INF/web-fragment.xml");
	    return webFragmentFile != null;
	} catch (IOException ex) {
	    throw new MojoExecutionException("Could not load jar file from artifact");
	}
    }

    private int getIndentation(String template, int i) {
	return i - template.lastIndexOf(NEW_LINE_CHAR, i);
    }
}