package noodle.sky.xgrid;

import java.io.File;
import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang.StringUtils;

/**
 * Run a job with the xgrid command-line client. Here is an example:
 * <p>
 *   <pre>
 *     XGridJob job = new XGridJob("host.domain", "script.sh");
 *     job.addFile(new File("script.sh"));
 *     job.submit();
 *     while (!job.resultsAvailable()) {
 *       Thread.sleep(500);
 *     }
 *     String results = job.getResults();
 *     job.dispose();
 *   </pre>
 * </p>
 * 
 * @author tom riley
 */
public class XGridJob
{
    private String command;
    private String host;
    private File tmpDir;
    private Pattern idPattern = Pattern.compile("^\\D+(\\d+)\\D+\n$");
    private String id;
    
    /**
     * Construct a new instance of XGridJob.
     * 
     * @param host controller host
     * @param command command to run on the grid
     * @throws IOException if something goes wrong
     */
    public XGridJob(String host, String command) throws IOException {
        this.command = command;
        this.host = host;
        if (command == null)
            throw new NullPointerException("command");
        if (host == null)
            throw new NullPointerException("host");
        tmpDir = createTempDir();
    }
    
    /**
     * Add a file to be passed with the job.
     * 
     * @param fname file name
     * @param contents files contents
     * @throws IOException if an IO error occurs
     */
    public void addFile(String fname, String contents) throws IOException {
        FileUtils.writeStringToFile(new File(tmpDir, fname), contents, null);
    }
    

    /**
     * Add a file to be passed with the job.
     * 
     * @param file file to send
     * @throws IOException if an IO error occurs
     */
    public void addFile(File file) throws IOException {
        FileUtils.copyFile(file, new File(tmpDir, file.getName()));
    }
    
    /**
     * Submit the job. Returns immediately.
     * 
     * @throws IOException if an IO error occurs
     */
    public void submit() throws IOException {
        String out = process(tmpDir, new String[]{"xgrid", "-h", host, "-job", "submit", "-in", tmpDir.getAbsolutePath(), command});
        Matcher m = idPattern.matcher(out);
        if (m.matches()) {
            id = m.group(1);
        }
    }

    /**
     * Find out whether results are available. Poll this function to
     * know when to call {@link #getResults()}.
     * 
     * @return true if results available, false if not
     * @throws IOException if an IO error occurs
     */
    public boolean resultsAvailable() throws IOException {
        String attributes = process(tmpDir, new String[]{"xgrid", "-h", host, "-job", "attributes", "-id", id});
        return (attributes.indexOf("jobStatus = Finished") >= 0);
    }
    
    /**
     * Get the job output.
     * 
     * @return Text written to STDOUT by job.
     * @throws IOException if an IO error occurs
     */
    public String getResults() throws IOException {
        String results = process(tmpDir, new String[]{"xgrid", "-h", host, "-job", "results", "-id", id});
        return results;
    }
    
    /**
     * Delete the job from the controller. Call after getting results.
     * 
     * @throws IOException if an IO error occurs
     */
    public void dispose() throws IOException {
        try {
            process(tmpDir, new String[]{"xgrid", "-h", host, "-job", "delete", "-id", id});
        } finally {
            if (tmpDir != null) {
                FileUtils.deleteDirectory(tmpDir);
            }
        }
    }

    private File createTempDir() throws IOException {
        File tempDir = File.createTempFile("xgridclient", "");
        tempDir.delete();
        if (!tempDir.mkdir()) {
            throw new RuntimeException("Failed to create temporary directory " + tempDir.getAbsolutePath());
        }
        return tempDir;
    }
    
    private String process(File workingDir, String args[]) throws IOException {
        ProcessBuilder pb = new ProcessBuilder(args);
        if (workingDir != null)
            pb.directory(workingDir);
        
        Process p = pb.start();
        String out = IOUtils.toString(p.getInputStream());
        String err = IOUtils.toString(p.getErrorStream());
        
        try {
            int exitCode = p.waitFor();
            if (exitCode != 0) {
                throw new RuntimeException(StringUtils.join(args, ' ') + " returned " + exitCode);
            }
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
        
        return out;
    }
}