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/*-*- mode: Java; tab-width:8 -*-*/

package io.soluble.pjb.script;

/*
 * Copyright (C) 2003-2007 Jost Boekemeier
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.StringReader;
import java.io.Writer;
import java.lang.reflect.Proxy;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import javax.script.Bindings;
import javax.script.Invocable;
import javax.script.ScriptContext;
import javax.script.ScriptException;

import io.soluble.pjb.bridge.PhpProcedure;
import io.soluble.pjb.bridge.Request;
import io.soluble.pjb.bridge.Util;
import io.soluble.pjb.bridge.http.IContext;

/**
 * This class implements the ScriptEngine and the Invocable interface.
 * Example:
 * 

 * 
 * ScriptEngine e = (new ScriptEngineManager()).getEngineByName("php-invocable");

 * e.eval(<? function f() {return java_server_name();}?>

 * System.out.println(((Invocable)e).invokeFunction("f", new Object[]{}));

 * ((Closeable)e).close();

 * 
 * 


 * Another example which invokes a remote PHP "method" bound in the closed-over PHP environment. The PHP script "hello.php":
 * 
 * 
 * <?php require_once("java/Java.inc");

 * function f() {return java_server_name();};

 * java_call_with_continuation(java_closure());

 * ?>

 * 
 * 


 * The Java code:
 * 
 * 
 * ScriptEngine e = (new ScriptEngineManager()).getEngineByName("php-invocable");

 * e.eval(new io.soluble.pjb.script.URLReader(new URL("http://localhost/hello.php")));

 * System.out.println(((Invocable)e).invokeMethod(e.get("io.soluble.pjb.PhpProcedure"), "f", new Object[]{}));

 * ((Closeable)e).close();

 * 
 * 
 */
public class InvocablePhpScriptEngine extends AbstractPhpScriptEngine implements Invocable {
    private static final String X_JAVABRIDGE_INCLUDE = Util.X_JAVABRIDGE_INCLUDE;
    private static final String PHP_JAVA_CONTEXT_CALL_JAVA_CLOSURE = "call(java_closure()); ?>";
    protected static final Object EMPTY_INCLUDE = "@";
    private static boolean registeredHook = false;
    private static final List engines = new LinkedList();
    private static final String PHP_EMPTY_SCRIPT = "";

    /**
     * Create a new ScriptEngine with a default context.
     */
    public InvocablePhpScriptEngine() {
        this(new PhpScriptEngineFactory());
    }

    /**
     * Create a new ScriptEngine from a factory.
     *
     * @param factory The factory
     * @see #getFactory()
     */
    public InvocablePhpScriptEngine(PhpScriptEngineFactory factory) {
        super(factory);
    }

    /**
     * Create a new ScriptEngine with bindings.
     *
     * @param n the bindings
     */
    public InvocablePhpScriptEngine(Bindings n) {
        this();
        setBindings(n, ScriptContext.ENGINE_SCOPE);
    }

    /* (non-Javadoc)
     * @see javax.script.Invocable#call(java.lang.String, java.lang.Object[])
     */
    protected Object invoke(String methodName, Object[] args)
            throws ScriptException, NoSuchMethodException {
        if (methodName == null) {
            release();
            return null;
        }

        if (scriptClosure == null) {
            if (Util.logLevel > 4)
                Util.warn("Evaluating an empty script either because eval() has not been called or release() has been called.");
            eval(PHP_EMPTY_SCRIPT);
        }
        try {
            return invoke(scriptClosure, methodName, args);
        } catch (Request.AbortException e) {
            release();
            throw new ScriptException(e);
        } catch (NoSuchMethodError e) { // conform to jsr223
            throw new NoSuchMethodException(String.valueOf(e.getMessage()));
        }
    }

    /**
     * {@inheritDoc}
     */
    public Object invokeFunction(String methodName, Object[] args)
            throws ScriptException, NoSuchMethodException {
        return invoke(methodName, args);
    }

    private void checkPhpClosure(Object thiz) {
        if (thiz == null)
            throw new IllegalStateException("PHP script did not pass its continuation to us!. Please check if the previous call to eval() reported any errors. Or else check if it called OUR continuation.");
    }

    /* (non-Javadoc)
     * @see javax.script.Invocable#call(java.lang.String, java.lang.Object, java.lang.Object[])
     */
    protected Object invoke(Object thiz, String methodName, Object[] args)
            throws ScriptException, NoSuchMethodException {
        checkPhpClosure(thiz);
        PhpProcedure proc = (PhpProcedure) (Proxy.getInvocationHandler(thiz));
        try {
            return proc.invoke(script, methodName, args);
        } catch (ScriptException e) {
            throw e;
        } catch (NoSuchMethodException e) {
            throw e;
        } catch (RuntimeException e) {
            throw e; // don't wrap RuntimeException
        } catch (NoSuchMethodError e) { // conform to jsr223
            throw new NoSuchMethodException(String.valueOf(e.getMessage()));
        } catch (Error er) {
            throw er;
        } catch (Throwable e) {
            throw new PhpScriptException("Invocation threw exception ", e);
        }
    }

    /**
     * {@inheritDoc}
     */
    public Object invokeMethod(Object thiz, String methodName, Object[] args)
            throws ScriptException, NoSuchMethodException {
        return invoke(thiz, methodName, args);
    }

    /**
     * {@inheritDoc}
     */
    public Object getInterface(Class clasz) {
        checkPhpClosure(script);
        return getInterface(script, clasz);
    }

    /**
     * {@inheritDoc}
     */
    public Object getInterface(Object thiz, Class clasz) {
        checkPhpClosure(thiz);
        Class[] interfaces = clasz == null ? Util.ZERO_PARAM : new Class[]{clasz};
        return PhpProcedure.createProxy(interfaces, (PhpProcedure) Proxy.getInvocationHandler(thiz));
    }

    protected Reader getLocalReader(Reader reader, boolean embedJavaInc) throws IOException {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        Writer w = new OutputStreamWriter(out);

        String stdHeader = embedJavaInc ? null : ((IContext) getContext()).getRedirectURL("/JavaBridge");
        Reader localReader = new StringReader(getStandardHeader(stdHeader));

        char[] buf = new char[Util.BUF_SIZE];
        int c;
        try {
            /* header: /JavaBridge/java/Java.inc"); ?> */
            while ((c = localReader.read(buf)) > 0) w.write(buf, 0, c);
            localReader.close();
            localReader = null;
    
            /* the script: */
            while ((c = reader.read(buf)) > 0) w.write(buf, 0, c);
    
            /* get the default, top-level, closure and call it, to stop the script from terminating */
            localReader = new StringReader(PHP_JAVA_CONTEXT_CALL_JAVA_CLOSURE);
            while ((c = localReader.read(buf)) > 0) w.write(buf, 0, c);
            localReader.close();
            localReader = null;
            w.close();
            w = null;
    
            /* now evaluate our script */
            localReader = new InputStreamReader(new ByteArrayInputStream(out.toByteArray()));
            return localReader;
        } finally {
            if (w != null) try {
                w.close();
            } catch (IOException e) {/*ignore*/}
        }
    }

    protected Object doEvalPhp(Reader reader, ScriptContext context) throws ScriptException {
        if (reader instanceof URLReader) return eval((URLReader) reader, context);

        if ((continuation != null) || (reader == null)) release();
        if (reader == null) return null;

        setNewContextFactory();
        env.put(X_JAVABRIDGE_INCLUDE, EMPTY_INCLUDE);
        Reader localReader = null;
        try {
            localReader = getLocalReader(reader, false);
            this.script = doEval(localReader, context);
            if (this.script != null) {
            /* get the proxy, either the one from the user script or our default proxy */
                this.scriptClosure = script;
            }
        } catch (Exception e) {
            Util.printStackTrace(e);
            if (e instanceof RuntimeException) throw (RuntimeException) e;
            if (e instanceof ScriptException) throw (ScriptException) e;
            throw new ScriptException(e);
        } finally {
            if (localReader != null) try {
                localReader.close();
            } catch (IOException e) {/*ignore*/}
            handleRelease();
        }
        return resultProxy;
    }

    protected Object doEvalCompiledPhp(Reader reader, ScriptContext context) throws ScriptException {
        if ((continuation != null) || (reader == null)) release();
        if (reader == null) return null;

        setNewContextFactory();
        env.put(X_JAVABRIDGE_INCLUDE, EMPTY_INCLUDE);
        try {
            this.script = doEval(reader, context);
            if (this.script != null) {
            /* get the proxy, either the one from the user script or our default proxy */
                this.scriptClosure = script;
            }
        } catch (Exception e) {
            Util.printStackTrace(e);
            if (e instanceof RuntimeException) throw (RuntimeException) e;
            if (e instanceof ScriptException) throw (ScriptException) e;
            throw new ScriptException(e);
        } finally {
            handleRelease();
        }
        return resultProxy;
    }

    protected Object eval(URLReader reader, ScriptContext context) throws ScriptException {
        if ((continuation != null) || (reader == null)) release();
        if (reader == null) return null;

        setNewContextFactory();
        env.put(X_JAVABRIDGE_INCLUDE, EMPTY_INCLUDE);

        ByteArrayOutputStream out = new ByteArrayOutputStream();
        Writer w = new OutputStreamWriter(out);
        try {
            this.script = doEval(reader, context);
            if (this.script != null) {
        	/* get the proxy, either the one from the user script or our default proxy */
                this.scriptClosure = script;
            }
        } catch (Exception e) {
            Util.printStackTrace(e);
            if (e instanceof RuntimeException) throw (RuntimeException) e;
            if (e instanceof ScriptException) throw (ScriptException) e;
            throw new ScriptException(e);
        } finally {
            if (w != null) try {
                w.close();
            } catch (IOException e) {/*ignore*/}
            handleRelease();
        }
        return resultProxy;
    }

    protected void handleRelease() {
        // make sure to properly release them upon System.exit().
        synchronized (engines) {
            if (!registeredHook) {
                registeredHook = true;
                try {
                    Runtime.getRuntime().addShutdownHook(new Util.Thread() {
                        public void run() {
                            if (engines == null) return;
                            synchronized (engines) {
                                for (Iterator ii = engines.iterator(); ii.hasNext(); ii.remove()) {
                                    InvocablePhpScriptEngine e = (InvocablePhpScriptEngine) ii.next();
                                    e.releaseInternal();
                                }
                            }
                        }
                    });
                } catch (SecurityException e) {/*ignore*/}
            }
            engines.add(this);
        }
    }

    private void releaseInternal() {
        super.release();
    }

    /**
     * {@inheritDoc}
     */
    public void release() {
        synchronized (engines) {
            releaseInternal();
            engines.remove(this);
        }
    }
}