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Copyright 2010, Google Inc.
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    * Redistributions of source code must retain the above copyright
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    * Redistributions in binary form must reproduce the above
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contributors may be used to endorse or promote products derived from
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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*/

package com.google.refine.jython;

import java.io.File;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Properties;

import org.python.core.Py;
import org.python.core.PyException;
import org.python.core.PyFloat;
import org.python.core.PyFunction;
import org.python.core.PyInteger;
import org.python.core.PyLong;
import org.python.core.PyNone;
import org.python.core.PyObject;
import org.python.core.PyString;
import org.python.util.PythonInterpreter;

import com.google.refine.expr.EvalError;
import com.google.refine.expr.Evaluable;
import com.google.refine.expr.HasFields;
import com.google.refine.expr.LanguageSpecificParser;
import com.google.refine.expr.ParsingException;

public class JythonEvaluable implements Evaluable {
    
    static public LanguageSpecificParser createParser() {
        return new LanguageSpecificParser() {
            
            @Override
            public Evaluable parse(String s) throws ParsingException {
                return new JythonEvaluable(s);
            }
        };
    }
    
    private final String s_functionName;
    
    private static PythonInterpreter _engine; 
    
    // FIXME(SM): this initialization logic depends on the fact that the JVM's 
    // current working directory is the root of the OpenRefine distributions
    // or the development checkouts. While this works in practice, it would
    // be preferable to have a more reliable address space, but since we
    // don't have access to the servlet context from this class this is
    // the best we can do for now.
    static {
        File libPath = new File("webapp/WEB-INF/lib/jython");
        if (!libPath.exists() && !libPath.canRead()) {
            libPath = new File("main/webapp/WEB-INF/lib/jython");
            if (!libPath.exists() && !libPath.canRead()) {
                libPath = null;
            }
        }
        
        if (libPath != null) {
            Properties props = new Properties();
            props.setProperty("python.path", libPath.getAbsolutePath());
            PythonInterpreter.initialize(System.getProperties(), props, new String[] { "" });
        }
        
        _engine = new PythonInterpreter();
    }

    public JythonEvaluable(String s) {
        this.s_functionName = String.format("__temp_%d__", Math.abs(s.hashCode()));

        // indent and create a function out of the code
        String[] lines = s.split("\r\n|\r|\n");
        
        StringBuffer sb = new StringBuffer(1024);
        sb.append("def ");
        sb.append(s_functionName);
        sb.append("(value, cell, cells, row, rowIndex):");
        for (String line : lines) {
            sb.append("\n  ");
            sb.append(line);
        }

        _engine.exec(sb.toString());
    }
    
    @Override
    public Object evaluate(Properties bindings) {
        try {
            // call the temporary PyFunction directly
            Object result = ((PyFunction)_engine.get(s_functionName)).__call__(
                new PyObject[] {
                    Py.java2py( bindings.get("value") ),
                    new JythonHasFieldsWrapper((HasFields) bindings.get("cell"), bindings),
                    new JythonHasFieldsWrapper((HasFields) bindings.get("cells"), bindings),
                    new JythonHasFieldsWrapper((HasFields) bindings.get("row"), bindings),
                    Py.java2py( bindings.get("rowIndex") )
                }
            );

            return unwrap(result);
        } catch (PyException e) {
            return new EvalError(e.toString());
        }
    }
    
    protected Object unwrap(Object result) {
        if (result != null) {
            if (result instanceof JythonObjectWrapper) {
                return ((JythonObjectWrapper) result)._obj;
            } else if (result instanceof JythonHasFieldsWrapper) {
                return ((JythonHasFieldsWrapper) result)._obj;
            } else if (result instanceof PyString) {
                return ((PyString) result).asString();
            } else if (result instanceof PyInteger) {
                return (long) ((PyInteger) result).asInt();
            } else if (result instanceof PyLong) {
                return ((PyLong) result).getLong(Long.MIN_VALUE, Long.MAX_VALUE);
            } else if (result instanceof PyFloat) {
                return ((PyFloat) result).asDouble();
            } else if (result instanceof PyObject) {
                return unwrap((PyObject) result);
            }
        }
        
        return result;      
    }
    
    protected Object unwrap(PyObject po) {
        if (po instanceof PyNone) {
            return null;
        } else if (po.isNumberType()) {
            return po.asDouble();
        } else if (po.isSequenceType()) {
            Iterator<PyObject> i = po.asIterable().iterator();
            
            List<Object> list = new ArrayList<Object>();
            while (i.hasNext()) {
                list.add(unwrap((Object) i.next()));
            }
            
            return list.toArray();
        } else {
            return po;
        }
    }
}
