/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Communicator client code, released
 * March 31, 1998.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */
 
/* This file is part of the Java-vendor-neutral implementation of LiveConnect
 *
 * It contains the implementation of the native methods for the 
 * netscape.javascript.JSObject Java class, which are used for calling into
 * JavaScript from Java.  It also contains the code that handles propagation
 * of exceptions both into and out of Java.
 *
 */

#include <stdlib.h>
#include <string.h>

#include "jsj_private.h"
#include "jsjava.h"

#include "jscntxt.h"        /* For js_ReportErrorAgain().
                               TODO - get rid of private header */

#include "netscape_javascript_JSObject.h"   /* javah-generated headers */


/* A captured JavaScript error, created when JS_ReportError() is called while
   running JavaScript code that is itself called from Java. */
struct CapturedJSError {
    char *              message;
    JSErrorReport       report;         /* Line # of error, etc. */
    jthrowable          java_exception; /* Java exception, error, or null */
    CapturedJSError *   next;           /* Next oldest captured JS error */
};


/*********************** Reflection of JSObjects ****************************/

#ifdef PRESERVE_JSOBJECT_IDENTITY
/*
 * This is a hash table that maps from JS objects to Java objects.
 * It is used to ensure that the same Java object results when a JS
 * object is reflected more than once, so that Java object equality
 * tests work in the expected manner.
 *
 * The entry keys are JSObject pointers and the entry values are Java objects
 * (of type jobject).  When the corresponding Java instance is finalized,
 * the entry is removed from the table, and a JavaScript GC root for the JS
 * object is removed.
 * 
 * This code is disabled because cycles in GC roots between the two systems
 * cause every reflected JS object to become uncollectable.  This can only
 * be solved by using weak links, a feature not available in JDK1.1.
 */
static JSHashTable *js_obj_reflections = NULL;

#ifdef JSJ_THREADSAFE
/*
 * Used to protect the js_obj_reflections hashtable from simultaneous
 * read/write or * write/write access.
 */
static PRMonitor *js_obj_reflections_monitor = NULL;
#endif  /* JSJ_THREADSAFE */
#endif  /* PRESERVE_JSOBJECT_IDENTITY */

JSBool
jsj_init_js_obj_reflections_table()
{
#ifdef PRESERVE_JSOBJECT_IDENTITY
    if(js_obj_reflections != NULL)
    {
      return JS_TRUE;
    }
    js_obj_reflections = JS_NewHashTable(128, NULL, JS_CompareValues,
                                         JS_CompareValues, NULL, NULL);
    if (!js_obj_reflections)
        return JS_FALSE;

#ifdef JSJ_THREADSAFE
    js_obj_reflections_monitor = PR_NewMonitor();
    if (!js_obj_reflections_monitor) {
        JS_HashTableDestroy(js_obj_reflections);
        return JS_FALSE;
    }
#endif  /* JSJ_THREADSAFE */
#endif  /* PRESERVE_JSOBJECT_IDENTITY */

    return JS_TRUE;
}

/*
 * Return a Java object that "wraps" a given JS object by storing the address
 * of the JS object in a private field of the Java object.  A hash table is
 * used to ensure that the mapping of JS objects to Java objects is done on
 * one-to-one basis.
 *
 * If an error occurs, returns NULL and reports an error.
 */

#ifdef PRESERVE_JSOBJECT_IDENTITY

jobject
jsj_WrapJSObject(JSContext *cx, JNIEnv *jEnv, JSObject *js_obj)
{
    jobject java_wrapper_obj;
    JSHashEntry *he, **hep;

    java_wrapper_obj = NULL;

#ifdef JSJ_THREADSAFE
    PR_EnterMonitor(js_obj_reflections_monitor);
#endif

    /* First, look in the hash table for an existing reflection of the same
       JavaScript object.  If one is found, return it. */
    hep = JS_HashTableRawLookup(js_obj_reflections, (JSHashNumber)js_obj, js_obj);

    /* If the same JSObject is reflected into Java more than once then we should
       return the same Java object, both for efficiency and so that the '=='
       operator works as expected in Java when comparing two JSObjects.
       However, it is not possible to hold a reference to a Java object without
       inhibiting GC of that object, at least not in a portable way, i.e.
       a weak reference. So, for now, JSObject identity is broken. */

    he = *hep;
    if (he) {
        java_wrapper_obj = (jobject)he->value;
        JS_ASSERT(java_wrapper_obj);
        if (java_wrapper_obj)
            goto done;
    }

    /* No existing reflection found, so create a new Java object that wraps
       the JavaScript object by storing its address in a private integer field. */
#ifndef OJI
    java_wrapper_obj =
        (*jEnv)->NewObject(jEnv, njJSObject, njJSObject_JSObject, (jint)js_obj);
#else
    if (JSJ_callbacks && JSJ_callbacks->get_java_wrapper != NULL) {
        java_wrapper_obj = JSJ_callbacks->get_java_wrapper(jEnv, (jint)handle);
    }
#endif /*! OJI */

    if (!java_wrapper_obj) {
        jsj_UnexpectedJavaError(cx, jEnv, "Couldn't create new instance of "
                                          "netscape.javascript.JSObject");
        goto done;
    }

    /* Add the new reflection to the hash table. */
    he = JS_HashTableRawAdd(js_obj_reflections, hep, (JSHashNumber)js_obj,
                            js_obj, java_wrapper_obj);
    if (he) {
        /* Tell the JavaScript GC about this object since the only reference
           to it may be in Java-land. */
        JS_AddNamedRoot(cx, (void*)&he->key, "&he->key");
    } else {
        JS_ReportOutOfMemory(cx);
        /* No need to delete java_wrapper_obj because Java GC will reclaim it */
        java_wrapper_obj = NULL;
    }
    
    /*
     * Release local reference to wrapper object, since some JVMs seem reticent
     * about collecting it otherwise.
     */
    /* FIXME -- beard: this seems to make calls into Java with JSObject's fail. */
    /* We should really be creating a global ref if we are putting it in a hash table. */
    /* (*jEnv)->DeleteLocalRef(jEnv, java_wrapper_obj); */

done:
#ifdef JSJ_THREADSAFE
        PR_ExitMonitor(js_obj_reflections_monitor);
#endif
        
    return java_wrapper_obj;
}

/*
 * Remove the mapping of a JS object from the hash table that maps JS objects
 * to Java objects.  This is called from the finalizer of an instance of
 * netscape.javascript.JSObject.
 */
JSBool
jsj_remove_js_obj_reflection_from_hashtable(JSContext *cx, JSObject *js_obj)
{
    JSHashEntry *he, **hep;
    JSBool success = JS_FALSE;

#ifdef JSJ_THREADSAFE
    PR_EnterMonitor(js_obj_reflections_monitor);
#endif

    /* Get the hash-table entry for this wrapper object */
    hep = JS_HashTableRawLookup(js_obj_reflections, (JSHashNumber)js_obj, js_obj);
    he = *hep;

    JS_ASSERT(he);
    if (he) {
        /* Tell the JS GC that Java no longer keeps a reference to this
           JS object. */
        success = JS_RemoveRoot(cx, (void *)&he->key);

        JS_HashTableRawRemove(js_obj_reflections, hep, he);
    }

#ifdef JSJ_THREADSAFE
    PR_ExitMonitor(js_obj_reflections_monitor);
#endif

    return success;
}

#else /* !PRESERVE_JSOBJECT_IDENTITY */


/*
 * The caller must call DeleteLocalRef() on the returned object when no more
 * references remain.
 */
jobject
jsj_WrapJSObject(JSContext *cx, JNIEnv *jEnv, JSObject *js_obj)
{
    jobject java_wrapper_obj;
    JSObjectHandle *handle;

    /* Create a tiny stub object to act as the GC root that points to the
       JSObject from its netscape.javascript.JSObject counterpart. */
    handle = (JSObjectHandle*)JS_malloc(cx, sizeof(JSObjectHandle));
    if (!handle)
        return NULL;
    handle->js_obj = js_obj;
    handle->rt = JS_GetRuntime(cx);

    /* Create a new Java object that wraps the JavaScript object by storing its
       address in a private integer field. */
#ifndef OJI
    java_wrapper_obj =
        (*jEnv)->NewObject(jEnv, njJSObject, njJSObject_JSObject, (lcjsobject)handle);
#else
    if (JSJ_callbacks && JSJ_callbacks->get_java_wrapper != NULL) {
        java_wrapper_obj = JSJ_callbacks->get_java_wrapper(jEnv, (lcjsobject)handle);
    } else  {
        java_wrapper_obj = NULL;
    }
#endif /*! OJI */
    if (!java_wrapper_obj) {
        jsj_UnexpectedJavaError(cx, jEnv, "Couldn't create new instance of "
                                          "netscape.javascript.JSObject");
        JS_free(cx, handle);
        goto done;
    }
 
    JS_AddNamedRoot(cx, &handle->js_obj, "&handle->js_obj");

done:
        
    return java_wrapper_obj;
}

JSObject *
jsj_UnwrapJSObjectWrapper(JNIEnv *jEnv, jobject java_wrapper_obj)
{
    JSObjectHandle *handle;

#ifndef OJI
#if JS_BYTES_PER_LONG == 8 || JS_BYTES_PER_WORD == 8
    handle = (JSObjectHandle*)((*jEnv)->GetLongField(jEnv, java_wrapper_obj, njJSObject_long_internal));
#else
    handle = (JSObjectHandle*)((*jEnv)->GetIntField(jEnv, java_wrapper_obj, njJSObject_internal));
#endif
#else
    /* Unwrapping this wrapper requires knowledge of the structure of the object. This is privileged
       information that only the object implementor can know. In this case the object implementor
       is the java plugin (such as the Sun plugin class sun.plugin.javascript.navig5.JSObject. 
	   Since the plugin owns this structure, we defer to it to unwrap the object. If the plugin 
	   does not implement this callback, then it should be set to null. In that case we try something 
	   that works with Sun's plugin assuming that it has not yet been implemented yet. This 'else' 
	   case should be removed as soon as the unwrap function is supported by the Sun JPI. */

    if (JSJ_callbacks && JSJ_callbacks->unwrap_java_wrapper != NULL) {
        handle = (JSObjectHandle*)JSJ_callbacks->unwrap_java_wrapper(jEnv, java_wrapper_obj);
    }
    else {
        jclass   cid = (*jEnv)->GetObjectClass(jEnv, java_wrapper_obj);
#if JS_BYTES_PER_LONG == 8 || JS_BYTES_PER_WORD == 8
        jfieldID fid = (*jEnv)->GetFieldID(jEnv, cid, "nativeJSObject", "J");
        handle = (JSObjectHandle*)((*jEnv)->GetLongField(jEnv, java_wrapper_obj, fid));
#else
        jfieldID fid = (*jEnv)->GetFieldID(jEnv, cid, "nativeJSObject", "I");
        handle = (JSObjectHandle*)((*jEnv)->GetIntField(jEnv, java_wrapper_obj, fid));
#endif
    }
#endif
    
	/* JNI returns a NULL handle for a Java 'null' */
    if (!handle)
        return NULL;

    return handle->js_obj;
	
}

#endif  /* !PRESERVE_JSOBJECT_IDENTITY */

/*************** Handling of Java exceptions in JavaScript ******************/

/*
 * Free up a JavaScript error that has been stored by the
 * capture_js_error_reports_for_java() function.
 */
static CapturedJSError *
destroy_saved_js_error(JNIEnv *jEnv, CapturedJSError *error)
{
    CapturedJSError *next_error;
    if (!error)
        return NULL;
    next_error = error->next;

    if (error->java_exception)
        (*jEnv)->DeleteGlobalRef(jEnv, error->java_exception);
    if (error->message)
        free((char*)error->message);
    if (error->report.filename)
        free((char*)error->report.filename);
    if (error->report.linebuf)
        free((char*)error->report.linebuf);
    free(error);

    return next_error;
}

/*
 * Capture a JS error that has been reported using JS_ReportError() by JS code
 * that has itself been called from Java.  A copy of the JS error data is made
 * and hung off the JSJ environment.  When JS completes and returns to its Java
 * caller, this data is used to synthesize an instance of
 * netscape.javascript.JSException.  If the resulting JSException is not caught
 * within Java, it may be propagated up the stack beyond the Java caller back
 * into JavaScript, in which case the error will be re-reported as a JavaScript
 * error.
 */
JS_STATIC_DLL_CALLBACK(void)
capture_js_error_reports_for_java(JSContext *cx, const char *message,
                                  JSErrorReport *report)
{
    CapturedJSError *new_error;
    JSJavaThreadState *jsj_env;
    jthrowable java_exception, tmp_exception;
    JNIEnv *jEnv;

    /* Warnings are not propagated as Java exceptions - they are simply
       ignored.  Ditto for exceptions that are duplicated in the form
       of error reports. */
    if (report && (report->flags & (JSREPORT_WARNING | JSREPORT_EXCEPTION)))
        return;

    /* Create an empty struct to hold the saved JS error state */
    new_error = malloc(sizeof(CapturedJSError));
    if (!new_error)
        goto out_of_memory;
    memset(new_error, 0, sizeof(CapturedJSError));

    /* Copy all the error info out of the original report into a private copy */
    if (message) {
        new_error->message = strdup(message);
        if (!new_error->message) {
            free(new_error);
            return;
        }
    }
    if (report) {
        new_error->report.lineno = report->lineno;

        if (report->filename) {
            new_error->report.filename = strdup(report->filename);
            if (!new_error->report.filename)
                goto out_of_memory;
        }

        if (report->linebuf) {
            new_error->report.linebuf = strdup(report->linebuf);
            if (!new_error->report.linebuf)
                goto out_of_memory;
            new_error->report.tokenptr =
                new_error->report.linebuf + (report->tokenptr - report->linebuf);
        }
    }

    /* Get the head of the list of pending JS errors */
    jsj_env = jsj_EnterJava(cx, &jEnv);
    if (!jsj_env)
        goto abort;

    /* If there's a Java exception associated with this error, save it too. */
    java_exception = (*jEnv)->ExceptionOccurred(jEnv);
    if (java_exception) {
        (*jEnv)->ExceptionClear(jEnv);
        tmp_exception = java_exception;     /* Make a copy */
        java_exception = (*jEnv)->NewGlobalRef(jEnv, java_exception);
        new_error->java_exception = java_exception;
        (*jEnv)->DeleteLocalRef(jEnv, tmp_exception);
    }

    /* Push this error onto the list of pending JS errors */
    new_error->next = jsj_env->pending_js_errors;
    jsj_env->pending_js_errors = new_error;
    jsj_ExitJava(jsj_env);
    return;

abort:
out_of_memory:
    /* No recovery action possible */
    JS_ASSERT(0);
    destroy_saved_js_error(jEnv, new_error);
    return;
}

void
jsj_ClearPendingJSErrors(JSJavaThreadState *jsj_env)
{
    while (jsj_env->pending_js_errors)
        jsj_env->pending_js_errors = destroy_saved_js_error(jsj_env->jEnv, jsj_env->pending_js_errors);
}

/*
 * This is called upon returning from JS back into Java.  Any JS errors
 * reported during that time will be converted into Java exceptions.  It's
 * possible that a JS error was actually triggered by Java at some point, in
 * which case the original Java exception is thrown.
 */
static void
throw_any_pending_js_error_as_a_java_exception(JSJavaThreadState *jsj_env)
{
    CapturedJSError *error;
    JNIEnv *jEnv;
    jstring message_jstr, linebuf_jstr, filename_jstr;
    jint index, lineno;
    JSErrorReport *report;
    JSContext *cx;
    jsval pending_exception; 
    jobject java_obj;
    int dummy_cost;
    JSBool is_local_refp;
    JSType primitive_type;
    jthrowable java_exception;

    message_jstr = linebuf_jstr = filename_jstr = java_exception = NULL;

    /* Get the Java JNI environment */
    jEnv = jsj_env->jEnv;

    cx = jsj_env->cx;
    /* Get the pending JS exception if it exists */
    if (cx&&JS_IsExceptionPending(cx)) {
        if (!JS_GetPendingException(cx, &pending_exception))
            goto out_of_memory;

        /* Find out the JSTYPE of this jsval. */
        primitive_type = JS_TypeOfValue(cx, pending_exception);
        
        /* Convert jsval exception to a java object and then use it to
           create an instance of JSException. */ 
        if (!jsj_ConvertJSValueToJavaObject(cx, jEnv, 
                                            pending_exception, 
                                            jsj_get_jlObject_descriptor(cx, jEnv),
                                            &dummy_cost, &java_obj, 
                                            &is_local_refp))
            goto done;
        
        java_exception = (*jEnv)->NewObject(jEnv, njJSException, 
                                            njJSException_JSException_wrap,
                                            primitive_type, java_obj);
        if (is_local_refp)
            (*jEnv)->DeleteLocalRef(jEnv, java_obj);
        if (!java_exception) 
            goto out_of_memory;
        
        /* Throw the newly-created JSException */
        if ((*jEnv)->Throw(jEnv, java_exception) < 0) {
            JS_ASSERT(0);
            jsj_LogError("Couldn't throw JSException\n");
            goto done;
        }    
        JS_ClearPendingException(cx);
        return;
    }
    if (!jsj_env->pending_js_errors) {
#ifdef DEBUG
        /* Any exception should be cleared as soon as it's detected, so there
           shouldn't be any pending. */
        if ((*jEnv)->ExceptionOccurred(jEnv)) {
            /* A Java exception occurred, but nobody in JS-land noticed. */
            JS_ASSERT(0);
            (*jEnv)->ExceptionClear(jEnv);
        }
#endif
        return;
    }

    /* Get the deepest (oldest) saved JS error */
    /* XXX - What's the right thing to do about newer errors ?
       For now we just throw them away */
    error = jsj_env->pending_js_errors;
    while (error->next)
        error = error->next;
    
    /*
     * If the JS error was originally the result of a Java exception, rethrow
     * the original exception.
     */
    if (error->java_exception) {
        (*jEnv)->Throw(jEnv, error->java_exception);
        goto done;
    }

    /* Propagate any JS errors that did not originate as Java exceptions into
       Java as an instance of netscape.javascript.JSException */

    /* First, marshall the arguments to the JSException constructor */
    message_jstr = NULL;
    if (error->message) {
        message_jstr = (*jEnv)->NewStringUTF(jEnv, error->message);
        if (!message_jstr)
            goto out_of_memory;
    }

    report = &error->report;

    filename_jstr = NULL;
    if (report->filename) {
        filename_jstr = (*jEnv)->NewStringUTF(jEnv, report->filename);
        if (!filename_jstr)
            goto out_of_memory;
    }

    linebuf_jstr = NULL;
    if (report->linebuf) {
        linebuf_jstr = (*jEnv)->NewStringUTF(jEnv, report->linebuf);
        if (!linebuf_jstr)
            goto out_of_memory;
    }

    lineno = report->lineno;
    index = report->linebuf ? report->tokenptr - report->linebuf : 0;

    /* Call the JSException constructor */
    java_exception = (*jEnv)->NewObject(jEnv, njJSException, njJSException_JSException,
                                        message_jstr, filename_jstr, lineno, linebuf_jstr, index);
    if (!java_exception)
        goto out_of_memory;

    /* Throw the newly-created JSException */
    if ((*jEnv)->Throw(jEnv, java_exception) < 0) {
        JS_ASSERT(0);
        jsj_UnexpectedJavaError(cx, jEnv, "Couldn't throw JSException\n");
    }
    goto done;

out_of_memory:
    /* No recovery possible */
    JS_ASSERT(0);
    jsj_LogError("Out of memory while attempting to throw JSException\n");

done:
    jsj_ClearPendingJSErrors(jsj_env);
    /*
     * Release local references to Java objects, since some JVMs seem reticent
     * about collecting them otherwise.
     */
    if (message_jstr)
        (*jEnv)->DeleteLocalRef(jEnv, message_jstr);
    if (filename_jstr)
        (*jEnv)->DeleteLocalRef(jEnv, filename_jstr);
    if (linebuf_jstr)
        (*jEnv)->DeleteLocalRef(jEnv, linebuf_jstr);
    if (java_exception)
        (*jEnv)->DeleteLocalRef(jEnv, java_exception);
}

/*
 * This function is called up returning from Java back into JS as a result of
 * a thrown netscape.javascript.JSException, which itself must have been caused
 * by a JS error when Java called into JS.  The original JS error is
 * reconstituted from the JSException and re-reported as a JS error.
 *
 * Returns JS_FALSE if an internal error occurs, JS_TRUE otherwise.
 */
JSBool
jsj_ReportUncaughtJSException(JSContext *cx, JNIEnv *jEnv, jthrowable java_exception)
{
    JSBool success;
    JSErrorReport report;
    const char *linebuf, *filename, *message, *tokenptr;
    jint lineno, token_index;
    jstring linebuf_jstr, filename_jstr, message_jstr;

    /* Initialize everything to NULL */
    memset(&report, 0, sizeof(JSErrorReport));
    success = JS_FALSE;
    filename_jstr = linebuf_jstr = message_jstr = NULL;
    filename = message = linebuf = tokenptr = NULL;

    lineno = (*jEnv)->GetIntField(jEnv, java_exception, njJSException_lineno);
    report.lineno = lineno;

    filename_jstr = (*jEnv)->GetObjectField(jEnv, java_exception, njJSException_filename);
    if ((*jEnv)->ExceptionOccurred(jEnv)) {
        jsj_UnexpectedJavaError(cx, jEnv, "Unable to access filename field of a JSException");
        goto done;
    }
    if (filename_jstr)
        filename = (*jEnv)->GetStringUTFChars(jEnv, filename_jstr, 0);
    report.filename = filename;

    linebuf_jstr = (*jEnv)->GetObjectField(jEnv, java_exception, njJSException_source);
    if ((*jEnv)->ExceptionOccurred(jEnv)) {
        jsj_UnexpectedJavaError(cx, jEnv, "Unable to access source field of a JSException");
        goto done;
    }
    if (linebuf_jstr)
        linebuf = (*jEnv)->GetStringUTFChars(jEnv, linebuf_jstr, 0);
    report.linebuf = linebuf;

    token_index = (*jEnv)->GetIntField(jEnv, java_exception, njJSException_lineno);
    report.tokenptr = linebuf + token_index;

    message_jstr = (*jEnv)->CallObjectMethod(jEnv, java_exception, jlThrowable_getMessage);
    if ((*jEnv)->ExceptionOccurred(jEnv)) {
        jsj_UnexpectedJavaError(cx, jEnv, "Unable to access message of a JSException");
        goto done;
    }
    if (message_jstr)
        message = (*jEnv)->GetStringUTFChars(jEnv, message_jstr, 0);

    js_ReportErrorAgain(cx, message, &report);

    success = JS_TRUE;

done:

    if (filename_jstr && filename)
        (*jEnv)->ReleaseStringUTFChars(jEnv, filename_jstr, filename);
    if (linebuf_jstr && linebuf)
        (*jEnv)->ReleaseStringUTFChars(jEnv, linebuf_jstr, linebuf);
    if (message_jstr && message)
        (*jEnv)->ReleaseStringUTFChars(jEnv, message_jstr, message);
    return success;
}



/*************** Utilities for calling JavaScript from Java *****************/

/*
 * This routine is called just prior to invoking any JS API function from
 * Java.  It performs a common set of chores, such as obtaining the LiveConnect
 * state for the invoking Java thread and determining the JSContext to be
 * used for this thread.
 *
 * Returns NULL on failure.
 */


JSJavaThreadState *
jsj_enter_js(JNIEnv *jEnv, void* applet_obj, jobject java_wrapper_obj,
             JSContext **cxp, JSObject **js_objp, JSErrorReporter *old_error_reporterp,
             void **pNSIPrincipaArray, int numPrincipals, void *pNSISecurityContext)
{
    JSContext *cx;
    char *err_msg;
    JSObject *js_obj;
    JSJavaThreadState *jsj_env;

    cx = NULL;
    err_msg = NULL;

    /* Invoke callback, presumably used to implement concurrency constraints */
    if (JSJ_callbacks && JSJ_callbacks->enter_js_from_java) {
#ifdef OJI
        if (!JSJ_callbacks->enter_js_from_java(jEnv, &err_msg, pNSIPrincipaArray, numPrincipals, pNSISecurityContext,applet_obj))
#else
        if (!JSJ_callbacks->enter_js_from_java(jEnv, &err_msg))
#endif
            goto entry_failure;
    }

    /* Check the JSObject pointer in the wrapper object. */
    if (js_objp) {

#ifdef PRESERVE_JSOBJECT_IDENTITY
#if JS_BYTES_PER_LONG == 8
        js_obj = (JSObject *)((*jEnv)->GetLongField(jEnv, java_wrapper_obj, njJSObject_long_internal));
#else
        js_obj = (JSObject *)((*jEnv)->GetIntField(jEnv, java_wrapper_obj, njJSObject_internal));
#endif
#else   /* !PRESERVE_JSOBJECT_IDENTITY */
        js_obj = jsj_UnwrapJSObjectWrapper(jEnv, java_wrapper_obj);
#endif  /* PRESERVE_JSOBJECT_IDENTITY */

        JS_ASSERT(js_obj);
        if (!js_obj)
            goto error;
        *js_objp = js_obj;
    }

    /* Get the per-thread state corresponding to the current Java thread */
    jsj_env = jsj_MapJavaThreadToJSJavaThreadState(jEnv, &err_msg);
    if (!jsj_env)
        goto error;

    /* Get the JSContext that we're supposed to use for this Java thread */
    cx = jsj_env->cx;
    if (!cx) {
        /* We called spontaneously into JS from Java, rather than from JS into
           Java and back into JS.  Invoke a callback to obtain/create a
           JSContext for us to use. */
        if (JSJ_callbacks && JSJ_callbacks->map_jsj_thread_to_js_context) {
#ifdef OJI
            cx = JSJ_callbacks->map_jsj_thread_to_js_context(jsj_env,
                                                             applet_obj,
                                                             jEnv, &err_msg);
#else
            cx = JSJ_callbacks->map_jsj_thread_to_js_context(jsj_env,
                                                             jEnv, &err_msg);
#endif
            if (!cx)
                goto error;
        } else {
            err_msg = JS_smprintf("Unable to find/create JavaScript execution "
                                  "context for JNI thread 0x%08x", jEnv);
            goto error;
        }
    }
    *cxp = cx;

    /*
     * Capture all JS error reports so that they can be thrown into the Java
     * caller as an instance of netscape.javascript.JSException.
     */
    *old_error_reporterp =
        JS_SetErrorReporter(cx, capture_js_error_reports_for_java);

#ifdef JSJ_THREADSAFE
    JS_BeginRequest(cx);
#endif

    return jsj_env;

error:
    JS_ASSERT(!cx);
    /* Invoke callback, presumably used to implement concurrency constraints */
    if (JSJ_callbacks && JSJ_callbacks->exit_js)
        JSJ_callbacks->exit_js(jEnv, cx);

entry_failure:
    JS_ASSERT(!cx);
    if (err_msg) {
        jsj_LogError(err_msg);
        JS_smprintf_free(err_msg);
    }

    return NULL;
}

/*
 * This utility function is called just prior to returning into Java from JS.
 */
JSBool
jsj_exit_js(JSContext *cx, JSJavaThreadState *jsj_env, JSErrorReporter original_reporter)
{
    JNIEnv *jEnv;

#ifdef JSJ_THREADSAFE
    JS_EndRequest(cx);
#endif

    /* Restore the JS error reporter */
    JS_SetErrorReporter(cx, original_reporter);

    jEnv = jsj_env->jEnv;

#ifdef DEBUG
    /* Any Java exceptions should have been noticed and reported already */
    if ((*jEnv)->ExceptionOccurred(jEnv)) {
        JS_ASSERT(0);
        jsj_LogError("Unhandled Java exception detected");
        return JS_FALSE;
    }
#endif

    /*
     * Convert reported JS errors to JSExceptions, unless the errors were
     * themselves the result of Java exceptions, in which case the original
     * Java exception is simply propagated.
     */
    throw_any_pending_js_error_as_a_java_exception(jsj_env);

    /* Invoke callback, presumably used to implement concurrency constraints */
    if (JSJ_callbacks && JSJ_callbacks->exit_js)
        JSJ_callbacks->exit_js(jEnv, cx);

    return JS_TRUE;
}


/* Get the JavaClassDescriptor that corresponds to java.lang.Object */
JavaClassDescriptor *
jsj_get_jlObject_descriptor(JSContext *cx, JNIEnv *jEnv)
{
    /* The JavaClassDescriptor for java.lang.Object */
    static JavaClassDescriptor *jlObject_descriptor = NULL;

    if (!jlObject_descriptor)
        jlObject_descriptor = jsj_GetJavaClassDescriptor(cx, jEnv, jlObject);
    return jlObject_descriptor;
}

/****************** Implementation of methods of JSObject *******************/

/*
 * Class:     netscape_javascript_JSObject
 * Method:    initClass
 * Signature: ()V
 */
JNIEXPORT void JNICALL
Java_netscape_javascript_JSObject_initClass(JNIEnv *jEnv, jclass java_class)
{
    jsj_init_js_obj_reflections_table();
}

/*
 * Class:     netscape_javascript_JSObject
 * Method:    getMember
 * Signature: (Ljava/lang/String;)Ljava/lang/Object;
 */
JNIEXPORT jobject JNICALL
Java_netscape_javascript_JSObject_getMember(JNIEnv *jEnv,
                                            jobject java_wrapper_obj,
                                            jstring property_name_jstr)
{
    JSContext *cx = NULL;
    JSObject *js_obj;
    jsval js_val;
    int dummy_cost;
    JSBool dummy_bool;
    const jchar *property_name_ucs2;
    jsize property_name_len;
    JSErrorReporter saved_reporter;
    jobject member;
    jboolean is_copy;
    JSJavaThreadState *jsj_env;
    
    jsj_env = jsj_enter_js(jEnv, NULL, java_wrapper_obj, &cx, &js_obj, &saved_reporter, NULL, 0, NULL);
    if (!jsj_env)
        return NULL;

    property_name_ucs2 = NULL;
    if (!property_name_jstr) {
        JS_ReportErrorNumber(cx, jsj_GetErrorMessage, NULL,
                             JSJMSG_NULL_MEMBER_NAME);
        member = NULL;
        goto done;
    }

    /* Get the Unicode string for the JS property name */
    property_name_ucs2 = (*jEnv)->GetStringChars(jEnv, property_name_jstr, &is_copy);
    if (!property_name_ucs2) {
        JS_ASSERT(0);
        goto done;
    }
    property_name_len = (*jEnv)->GetStringLength(jEnv, property_name_jstr);
    
    if (!JS_GetUCProperty(cx, js_obj, property_name_ucs2, property_name_len, &js_val))
        goto done;

    jsj_ConvertJSValueToJavaObject(cx, jEnv, js_val, 
                                   jsj_get_jlObject_descriptor(cx, jEnv),
                                   &dummy_cost, &member, &dummy_bool);

done:
    if (property_name_ucs2)
        (*jEnv)->ReleaseStringChars(jEnv, property_name_jstr, property_name_ucs2);
    if (!jsj_exit_js(cx, jsj_env, saved_reporter))
        return NULL;
    
    return member;
}

/*
 * Class:     netscape_javascript_JSObject
 * Method:    getSlot
 * Signature: (I)Ljava/lang/Object;
 */
JNIEXPORT jobject JNICALL
Java_netscape_javascript_JSObject_getSlot(JNIEnv *jEnv,
                                          jobject java_wrapper_obj,
                                          jint slot)
{
    JSContext *cx = NULL;
    JSObject *js_obj;
    jsval js_val;
    int dummy_cost;
    JSBool dummy_bool;
    JSErrorReporter saved_reporter;
    jobject member;
    JSJavaThreadState *jsj_env;
    
    jsj_env = jsj_enter_js(jEnv, NULL, java_wrapper_obj, &cx, &js_obj, &saved_reporter, NULL, 0, NULL);
    if (!jsj_env)
        return NULL;
    

    if (!JS_GetElement(cx, js_obj, slot, &js_val))
        goto done;
    if (!jsj_ConvertJSValueToJavaObject(cx, jEnv, js_val, jsj_get_jlObject_descriptor(cx, jEnv),
                                        &dummy_cost, &member, &dummy_bool))
        goto done;

done:
    if (!jsj_exit_js(cx, jsj_env, saved_reporter))
        return NULL;
    
    return member;
}

/*
 * Class:     netscape_javascript_JSObject
 * Method:    setMember
 * Signature: (Ljava/lang/String;Ljava/lang/Object;)V
 */
JNIEXPORT void JNICALL
Java_netscape_javascript_JSObject_setMember(JNIEnv *jEnv,
                                            jobject java_wrapper_obj,
                                            jstring property_name_jstr,
                                            jobject java_obj)
{
    JSContext *cx = NULL;
    JSObject *js_obj;
    jsval js_val;
    const jchar *property_name_ucs2;
    jsize property_name_len;
    JSErrorReporter saved_reporter;
    jboolean is_copy;
    JSJavaThreadState *jsj_env;
    
    jsj_env = jsj_enter_js(jEnv, NULL, java_wrapper_obj, &cx, &js_obj, &saved_reporter, NULL, 0, NULL);
    if (!jsj_env)
        return;
    
    property_name_ucs2 = NULL;
    if (!property_name_jstr) {
        JS_ReportErrorNumber(cx, jsj_GetErrorMessage, NULL,
                                            JSJMSG_NULL_MEMBER_NAME);
        goto done;
    }

    /* Get the Unicode string for the JS property name */
    property_name_ucs2 = (*jEnv)->GetStringChars(jEnv, property_name_jstr, &is_copy);
    if (!property_name_ucs2) {
        JS_ASSERT(0);
        goto done;
    }
    property_name_len = (*jEnv)->GetStringLength(jEnv, property_name_jstr);
    
    if (!jsj_ConvertJavaObjectToJSValue(cx, jEnv, java_obj, &js_val))
        goto done;

    JS_SetUCProperty(cx, js_obj, property_name_ucs2, property_name_len, &js_val);

done:
    if (property_name_ucs2)
        (*jEnv)->ReleaseStringChars(jEnv, property_name_jstr, property_name_ucs2);
    jsj_exit_js(cx, jsj_env, saved_reporter);
}

/*
 * Class:     netscape_javascript_JSObject
 * Method:    setSlot
 * Signature: (ILjava/lang/Object;)V
 */
JNIEXPORT void JNICALL
Java_netscape_javascript_JSObject_setSlot(JNIEnv *jEnv,
                                          jobject java_wrapper_obj,
                                          jint slot,
                                          jobject java_obj)
{
    JSContext *cx = NULL;
    JSObject *js_obj;
    jsval js_val;
    JSErrorReporter saved_reporter;
    JSJavaThreadState *jsj_env;
    
    jsj_env = jsj_enter_js(jEnv, NULL, java_wrapper_obj, &cx, &js_obj, &saved_reporter, NULL, 0, NULL);
    if (!jsj_env)
        return;
    
    if (!jsj_ConvertJavaObjectToJSValue(cx, jEnv, java_obj, &js_val))
        goto done;
    JS_SetElement(cx, js_obj, slot, &js_val);

done:
    jsj_exit_js(cx, jsj_env, saved_reporter);
}

/*
 * Class:     netscape_javascript_JSObject
 * Method:    removeMember
 * Signature: (Ljava/lang/String;)V
 */
JNIEXPORT void JNICALL
Java_netscape_javascript_JSObject_removeMember(JNIEnv *jEnv,
                                               jobject java_wrapper_obj,
                                               jstring property_name_jstr)
{
    JSContext *cx = NULL;
    JSObject *js_obj;
    jsval js_val;
    const jchar *property_name_ucs2;
    jsize property_name_len;
    JSErrorReporter saved_reporter;
    jboolean is_copy;
    JSJavaThreadState *jsj_env;
    
    jsj_env = jsj_enter_js(jEnv, NULL, java_wrapper_obj, &cx, &js_obj, &saved_reporter, NULL, 0, NULL);
    if (!jsj_env)
        return;
    
    if (!property_name_jstr) {
        JS_ReportErrorNumber(cx, jsj_GetErrorMessage, NULL,
                                            JSJMSG_NULL_MEMBER_NAME);
        goto done;
    }
    /* Get the Unicode string for the JS property name */
    property_name_ucs2 = (*jEnv)->GetStringChars(jEnv, property_name_jstr, &is_copy);
    if (!property_name_ucs2) {
        JS_ASSERT(0);
        goto done;
    }
    property_name_len = (*jEnv)->GetStringLength(jEnv, property_name_jstr);
    
    JS_DeleteUCProperty2(cx, js_obj, property_name_ucs2, property_name_len, &js_val);

    (*jEnv)->ReleaseStringChars(jEnv, property_name_jstr, property_name_ucs2);

done:
    jsj_exit_js(cx, jsj_env, saved_reporter);
    return;
}

/*
 * Class:     netscape_javascript_JSObject
 * Method:    call
 * Signature: (Ljava/lang/String;[Ljava/lang/Object;)Ljava/lang/Object;
 */
JNIEXPORT jobject JNICALL
Java_netscape_javascript_JSObject_call(JNIEnv *jEnv, jobject java_wrapper_obj,
                                       jstring function_name_jstr, jobjectArray java_args)
{
    int i, argc, arg_num;
    jsval *argv;
    JSContext *cx = NULL;
    JSObject *js_obj;
    jsval js_val, function_val;
    int dummy_cost;
    JSBool dummy_bool;
    const jchar *function_name_ucs2;
    jsize function_name_len;
    JSErrorReporter saved_reporter;
    jboolean is_copy;
    jobject result;
    JSJavaThreadState *jsj_env;
    
    jsj_env = jsj_enter_js(jEnv, NULL, java_wrapper_obj, &cx, &js_obj, &saved_reporter, NULL, 0, NULL);
    if (!jsj_env)
        return NULL;
    
    function_name_ucs2 = NULL;
    result = NULL;
    if (!function_name_jstr) {
        JS_ReportErrorNumber(cx, jsj_GetErrorMessage, NULL,
                                                    JSJMSG_NULL_FUNCTION_NAME);
        goto done;
    }

    /* Get the function name to eval as raw Unicode characters */
    function_name_ucs2 = (*jEnv)->GetStringChars(jEnv, function_name_jstr, &is_copy);
    if (!function_name_ucs2) {
        JS_ASSERT(0);
        goto done;
    }
    function_name_len = (*jEnv)->GetStringLength(jEnv, function_name_jstr);
    
    /* Allocate space for JS arguments */
    if (java_args) {
        argc = (*jEnv)->GetArrayLength(jEnv, java_args);
        argv = (jsval*)JS_malloc(cx, argc * sizeof(jsval));
    } else {
        argc = 0;
        argv = 0;
    }

    /* Convert arguments from Java to JS values */
    for (arg_num = 0; arg_num < argc; arg_num++) {
        jobject arg = (*jEnv)->GetObjectArrayElement(jEnv, java_args, arg_num);

        if (!jsj_ConvertJavaObjectToJSValue(cx, jEnv, arg, &argv[arg_num]))
            goto cleanup_argv;
        JS_AddNamedRoot(cx, &argv[arg_num], "&argv[arg_num]");
    }

    if (!JS_GetUCProperty(cx, js_obj, function_name_ucs2, function_name_len,
                          &function_val))
        goto cleanup_argv;

    if (!JS_CallFunctionValue(cx, js_obj, function_val, argc, argv, &js_val))
        goto cleanup_argv;

    jsj_ConvertJSValueToJavaObject(cx, jEnv, js_val, jsj_get_jlObject_descriptor(cx, jEnv),
                                   &dummy_cost, &result, &dummy_bool);

cleanup_argv:
    if (argv) {
        for (i = 0; i < arg_num; i++)
            JS_RemoveRoot(cx, &argv[i]);
        JS_free(cx, argv);
    }

done:
    if (function_name_ucs2)
        (*jEnv)->ReleaseStringChars(jEnv, function_name_jstr, function_name_ucs2);
    if (!jsj_exit_js(cx, jsj_env, saved_reporter))
        return NULL;
    
    return result;
}

/*
 * Class:     netscape_javascript_JSObject
 * Method:    eval
 * Signature: (Ljava/lang/String;)Ljava/lang/Object;
 */
JNIEXPORT jobject JNICALL
Java_netscape_javascript_JSObject_eval(JNIEnv *jEnv,
                                       jobject java_wrapper_obj,
                                       jstring eval_jstr)
{
    const char *codebase;
    JSPrincipals *principals;
    JSContext *cx = NULL;
    JSBool eval_succeeded;
    JSObject *js_obj;
    jsval js_val;
    int dummy_cost;
    JSBool dummy_bool;
    const jchar *eval_ucs2;
    jsize eval_len;
    JSErrorReporter saved_reporter;
    jboolean is_copy;
    jobject result;
    JSJavaThreadState *jsj_env;
    
    jsj_env = jsj_enter_js(jEnv, NULL, java_wrapper_obj, &cx, &js_obj, &saved_reporter, NULL, 0, NULL);
    if (!jsj_env)
        return NULL;
    
    result = NULL;
    eval_ucs2 = NULL;
    if (!eval_jstr) {
        JS_ReportErrorNumber(cx, jsj_GetErrorMessage, NULL, 
                                                JSJMSG_NULL_EVAL_ARG);
        goto done;
    }

    /* Get the string to eval as raw Unicode characters */
    eval_ucs2 = (*jEnv)->GetStringChars(jEnv, eval_jstr, &is_copy);
    if (!eval_ucs2) {
        JS_ASSERT(0);
        goto done;
    }
    eval_len = (*jEnv)->GetStringLength(jEnv, eval_jstr);
    
    /* Set up security stuff */
    principals = NULL;
    if (JSJ_callbacks && JSJ_callbacks->get_JSPrincipals_from_java_caller)
        principals = JSJ_callbacks->get_JSPrincipals_from_java_caller(jEnv, cx, NULL, 0, NULL);
    codebase = principals ? principals->codebase : NULL;

    /* Have the JS engine evaluate the unicode string */
    eval_succeeded = JS_EvaluateUCScriptForPrincipals(cx, js_obj, principals,
                                                      eval_ucs2, eval_len,
                                                      codebase, 0, &js_val);
    if (!eval_succeeded)
        goto done;

    /* Convert result to a subclass of java.lang.Object */
    jsj_ConvertJSValueToJavaObject(cx, jEnv, js_val, jsj_get_jlObject_descriptor(cx, jEnv),
                                   &dummy_cost, &result, &dummy_bool);

done:
    if (eval_ucs2)
        (*jEnv)->ReleaseStringChars(jEnv, eval_jstr, eval_ucs2);
    if (!jsj_exit_js(cx, jsj_env, saved_reporter))
        return NULL;
    
    return result;
}

/*
 * Class:     netscape_javascript_JSObject
 * Method:    toString
 * Signature: ()Ljava/lang/String;
 */
JNIEXPORT jstring JNICALL
Java_netscape_javascript_JSObject_toString(JNIEnv *jEnv,
                                           jobject java_wrapper_obj)
{
    jstring result;
    JSContext *cx = NULL;
    JSObject *js_obj;
    JSString *jsstr;
    JSErrorReporter saved_reporter;
    JSJavaThreadState *jsj_env;
    
    jsj_env = jsj_enter_js(jEnv, NULL, java_wrapper_obj, &cx, &js_obj, &saved_reporter, NULL, 0, NULL);
    if (!jsj_env)
        return NULL;
    
    result = NULL;
    jsstr = JS_ValueToString(cx, OBJECT_TO_JSVAL(js_obj));
    if (jsstr)
        result = jsj_ConvertJSStringToJavaString(cx, jEnv, jsstr);
    if (!result)
        result = (*jEnv)->NewStringUTF(jEnv, "*JavaObject*");

    if (!jsj_exit_js(cx, jsj_env, saved_reporter))
        return NULL;
    
    return result;
}

/*
 * Class:     netscape_javascript_JSObject
 * Method:    getWindow
 * Signature: (Ljava/applet/Applet;)Lnetscape/javascript/JSObject;
 */
JNIEXPORT jobject JNICALL
Java_netscape_javascript_JSObject_getWindow(JNIEnv *jEnv,
                                            jclass js_object_class,
                                            jobject java_applet_obj)
{
    char *err_msg;
    JSContext *cx = NULL;
    JSObject *js_obj = NULL;
    jsval js_val;
    int dummy_cost;
    JSBool dummy_bool;
    JSErrorReporter saved_reporter;
    jobject java_obj;
    JSJavaThreadState *jsj_env;
    
    jsj_env = jsj_enter_js(jEnv, java_applet_obj, NULL, &cx, NULL, &saved_reporter, NULL, 0, NULL);
    if (!jsj_env)
        return NULL;
    
    err_msg = NULL;
    java_obj = NULL;
    if (JSJ_callbacks && JSJ_callbacks->map_java_object_to_js_object)
        js_obj = JSJ_callbacks->map_java_object_to_js_object(jEnv, java_applet_obj, &err_msg);
    if (!js_obj) {
        if (err_msg) {
            JS_ReportError(cx, err_msg);
            free(err_msg);
        }
        goto done;
    }
    js_val = OBJECT_TO_JSVAL(js_obj);
    jsj_ConvertJSValueToJavaObject(cx, jEnv, js_val, jsj_get_jlObject_descriptor(cx, jEnv),
                                   &dummy_cost, &java_obj, &dummy_bool);
done:
    if (!jsj_exit_js(cx, jsj_env, saved_reporter))
        return NULL;
    
    return java_obj;
}

/*
 * Class:     netscape_javascript_JSObject
 * Method:    finalize
 * Signature: ()V
 */
JNIEXPORT void JNICALL
Java_netscape_javascript_JSObject_finalize(JNIEnv *jEnv, jobject java_wrapper_obj)
{
    JSBool success;
    JSObjectHandle *handle;

    success = JS_FALSE;

#if JS_BYTES_PER_LONG == 8 || JS_BYTES_PER_WORD == 8
    handle = (JSObjectHandle *)((*jEnv)->GetLongField(jEnv, java_wrapper_obj, njJSObject_long_internal));
#else    
    handle = (JSObjectHandle *)((*jEnv)->GetIntField(jEnv, java_wrapper_obj, njJSObject_internal));
#endif
    JS_ASSERT(handle);
    if (!handle)
        return;

    success = JS_RemoveRootRT(handle->rt, &handle->js_obj);
    free(handle);

    JS_ASSERT(success);
}

/*
 * Class:     netscape_javascript_JSObject
 * Method:    equals
 * Signature: (Ljava/lang/Object;)Z
 */

JNIEXPORT jboolean JNICALL
Java_netscape_javascript_JSObject_equals(JNIEnv *jEnv,
                                         jobject java_wrapper_obj,
                                         jobject comparison_obj)
{
#ifdef PRESERVE_JSOBJECT_IDENTITY
#    error "Missing code should be added here"
#else
    JSObject *js_obj1, *js_obj2;

    /* Check that we're comparing with another netscape.javascript.JSObject */
    if (!comparison_obj)
        return 0;
    if (!(*jEnv)->IsInstanceOf(jEnv, comparison_obj, njJSObject))
        return 0;

    js_obj1 = jsj_UnwrapJSObjectWrapper(jEnv, java_wrapper_obj);
    js_obj2 = jsj_UnwrapJSObjectWrapper(jEnv, comparison_obj);

    return (js_obj1 == js_obj2);
#endif  /* PRESERVE_JSOBJECT_IDENTITY */
}

