/*
 * RserveConnection.java
 *
 * Created on 10. Juli 2005, 19:59
 *
 */

package org.rosuda.JClaR;
import org.rosuda.JRclient.RFileInputStream;
import org.rosuda.JRclient.REXP;
import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import org.rosuda.JRclient.RSrvException;
import org.rosuda.JRclient.Rconnection;

/**
 * Manages the connection to Rserve.
 * @author tobias
 */
public final class RserveConnection {
   
    private static final int RERROR_SYNTAX = 3;
    static final int RERROR_OTHER = 127;
    
    private static Rconnection rcon;
    private static RserveConnection instance;
    private static boolean windows;
    
    private static String lastRcall="";
    
    /** Creates a new instance of RserveConnection */
    private RserveConnection() {
    }
    
    /**
     * Opens a connection to Rserve if not done so already.
     * @return the Rconnection
     */
    static RserveConnection getRconnection() {
        if(instance==null) {
            instance = new RserveConnection();
            if(System.getProperty("os.name").toLowerCase().indexOf("windows")!=-1)  {
                windows=true;
            }
            
            else  {
                windows=false;
            }
        }
        if(rcon==null) {
            if (checkLocalRserve())  {
                try{
                    rcon = new Rconnection();
                } catch (RSrvException rse){
                    ErrorDialog.show(null, rse, "RserveConnection.getRconnection()");
                }
            } else {
                ErrorDialog.show(null, "Could not start Rserve. Please start it manually and restart JClaR.");
                System.exit(-1);
            }
        }
        return instance;
    }
    
    /**
     * From org.rosuda.Mondrian.
     * @author Matrin Theus
     */
    private static final class StreamHog extends Thread {
        InputStream is;
        
        StreamHog(final InputStream is) { this.is=is; start(); }
        public void run() {
            try {
                final BufferedReader br = new BufferedReader(new InputStreamReader(is));
                String line=null;
                while ( (line = br.readLine()) != null) {
                    System.out.println("Rserve>" + line);
                }
            } catch (IOException e) { e.printStackTrace(); }
        }
    }
    
    /**
     * From org.rosuda.Mondrian.
     * @author Martin Theus
     */
    private static boolean launchRserve(final String cmd) {
        try {
            final Process p = Runtime.getRuntime().exec(cmd);
            System.out.println("waiting for Rserve to start ... ("+p+")");
            // we need to fetch the output - some platforms will die if you don't ...
            final StreamHog errorHog = new StreamHog(p.getErrorStream());
            final StreamHog outputHog = new StreamHog(p.getInputStream());
            p.waitFor();
            System.out.println("call terminated, let us try to connect ...");
        } catch (Exception x) {
            System.out.println("failed to start Rserve process with "+x.getMessage());
            return false;
        }
        try {
            final Rconnection c = new Rconnection();
            System.out.println("Rserve is running.");
            c.close();
            return true;
        } catch (Exception e2) {
            System.out.println("Try failed with: "+e2.getMessage());
        }
        return false;
    }
    
    /**
     * From org.rosuda.Mondrian.
     * @author Martin Theus
     */
    private static boolean checkLocalRserve() {
        try {
            final Rconnection c = new Rconnection();
            System.out.println("Rserve is running.");
            c.close();
            return true;
        } catch (Exception e) {
            System.out.println("First connect try failed with: "+e.getMessage());
        }
        final String opt=" CMD Rserve --no-save";
        return (launchRserve("R"+opt) ||
                ((new File("/usr/local/lib/R/bin/R")).exists() &&
                launchRserve("/usr/local/lib/R/bin/R"+opt)) ||
                ((new File("/usr/lib/R/bin/R")).exists() && launchRserve("/usr/lib/R/bin/R"+opt)) ||
                ((new File("/usr/local/bin/R")).exists() && launchRserve("/usr/local/bin/R"+opt)) ||
                ((new File("/sw/bin/R")).exists() && launchRserve("/sw/bin/R"+opt)) ||
                ((new File("/Library/Frameworks/R.framework/Resources/bin/R")).exists() &&
                launchRserve("/Library/Frameworks/R.framework/Resources/bin/R"+opt)));
    }
    
    /**
     * Delegate method for org.rosuda.JRclient.Rconnection.Rserve.eval(String str).
     * Adds try(...) on Windows systems.
     * @param str The R command to be executed.
     * Has to be exactly one command, i.e. not multiple commands separated by
     * semicolons or line breaks.
     * @throws org.rosuda.JRclient.RSrvException The RSrvException thrown by the delegated method.
     * @return The object returned by R.
     */
    REXP eval(final String str) throws RSrvException {
        lastRcall=str;
        if("".equals(str) || str==null)  {
            return null;
        }
        
        try{
            if(windows) {
                return rcon.eval("try(" + str + ")");
            } else {
                return rcon.eval(str);
            }
        } catch (RSrvException rse){
            switch(rse.getRequestReturnCode()){
                case RERROR_SYNTAX:
                    syntaxError(str);
                    return null;
                default:
                    throw(rse);
            }
        }
    }
    
    /**
     * Delegate method for org.rosuda.JRclient.Rconnection.voidEval(String str).
     * Adds try(...) on Windows systems.
     * @param str The R command to be executed.
     * Has to be exactly one command, i.e. not multiple commands separated by
     * semicolons or line breaks.
     * @throws org.rosuda.JRclient.RSrvException The RSrvException thrown by the delegated method.
     */
    void voidEval(final String str) throws RSrvException {
        lastRcall=str;
        if("".equals(str) || str==null)  {
            return;
        }
        
        try{
            if(windows) {
                rcon.voidEval("try(" + str + ")");
            } else{
                rcon.voidEval(str);
            }
        } catch (RSrvException rse){
            switch(rse.getRequestReturnCode()){
                case RERROR_SYNTAX:
                    syntaxError(str);
                    break;
                default:
                    throw(rse);
            }
        }
    }
    
    /**
     * Delegate method for org.rosuda.JRclient.Rconnection.Rserve.openFile(String str).
     */
    RFileInputStream openFile(final String str) throws IOException {
        return rcon.openFile(str);
    }
    
    private void syntaxError(String rcall){
        ErrorDialog.show(null,"Syntax error in R command. Please report this to the developer.\n" +
                "Error occured on evaluating\n\n" + 
                rcall);
    }

    static String getLastRcall() {
        return lastRcall;
    }
}