/*

 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.nashorn.internal.runtime;

import static jdk.nashorn.internal.codegen.CompilerConstants.STRICT_MODE;

import static jdk.nashorn.internal.runtime.ECMAErrors.typeError;

import static jdk.nashorn.internal.runtime.ScriptRuntime.UNDEFINED;

import java.io.File;

import java.io.IOException;

import java.io.PrintWriter;

import java.lang.reflect.Modifier;

import java.net.MalformedURLException;

import java.net.URL;

import java.security.AccessControlContext;

import java.security.AccessController;

import java.security.CodeSigner;

import java.security.CodeSource;

import java.security.Permissions;

import java.security.PrivilegedAction;

import java.security.ProtectionDomain;

import java.util.Map;

import java.util.concurrent.atomic.AtomicLong;

import jdk.internal.org.objectweb.asm.ClassReader;

import jdk.internal.org.objectweb.asm.util.CheckClassAdapter;

import jdk.nashorn.api.scripting.ScriptObjectMirror;

import jdk.nashorn.internal.codegen.Compiler;

import jdk.nashorn.internal.codegen.ObjectClassGenerator;

import jdk.nashorn.internal.ir.FunctionNode;

import jdk.nashorn.internal.ir.debug.ASTWriter;

import jdk.nashorn.internal.ir.debug.PrintVisitor;

import jdk.nashorn.internal.objects.Global;

import jdk.nashorn.internal.parser.Parser;

import jdk.nashorn.internal.runtime.options.Options;

/**

 * This class manages the global state of execution. Context is immutable.

 */

public final class Context {

    // nashorn specific security runtime access permission names

    /**

     * Permission needed to pass arbitrary nashorn command line options when creating Context.

     */

    public static final String NASHORN_SET_CONFIG      = "nashorn.setConfig";

    /**

     * Permission needed to create Nashorn Context instance.

     */

    public static final String NASHORN_CREATE_CONTEXT  = "nashorn.createContext";

    /**

     * Permission needed to create Nashorn Global instance.

     */

    public static final String NASHORN_CREATE_GLOBAL   = "nashorn.createGlobal";

    /**

     * Permission to get current Nashorn Context from thread local storage.

     */

    public static final String NASHORN_GET_CONTEXT     = "nashorn.getContext";

    /**

     * Permission to use Java reflection/jsr292 from script code.

     */

    public static final String NASHORN_JAVA_REFLECTION = "nashorn.JavaReflection";

    /**

     * Permission to enable nashorn debug mode.

     */

    public static final String NASHORN_DEBUG_MODE = "nashorn.debugMode";

    // nashorn load psuedo URL prefixes

    private static final String LOAD_CLASSPATH = "classpath:";

    private static final String LOAD_FX = "fx:";

    private static final String LOAD_NASHORN = "nashorn:";

    /* Force DebuggerSupport to be loaded. */

    static {

        DebuggerSupport.FORCELOAD = true;

    }

    /**

     * ContextCodeInstaller that has the privilege of installing classes in the Context.

     * Can only be instantiated from inside the context and is opaque to other classes

     */

    public static class ContextCodeInstaller implements CodeInstaller<ScriptEnvironment> {

        private final Context      context;

        private final ScriptLoader loader;

        private final CodeSource   codeSource;

        private ContextCodeInstaller(final Context context, final ScriptLoader loader, final CodeSource codeSource) {

            this.context    = context;

            this.loader     = loader;

            this.codeSource = codeSource;

        }

        /**

         * Return the context for this installer

         * @return ScriptEnvironment

         */

        @Override

        public ScriptEnvironment getOwner() {

            return context.env;

        }

        @Override

        public Class<?> install(final String className, final byte[] bytecode) {

            return loader.installClass(className, bytecode, codeSource);

        }

        @Override

        public void verify(final byte[] code) {

            context.verify(code);

        }

        @Override

        public long getUniqueScriptId() {

            return context.getUniqueScriptId();

        }

        @Override

        public long getUniqueEvalId() {

            return context.getUniqueEvalId();

        }

    }

    /** Is Context global debug mode enabled ? */

    public static final boolean DEBUG = Options.getBooleanProperty("nashorn.debug");

    private static final ThreadLocal<ScriptObject> currentGlobal = new ThreadLocal<>();

    /**

     * Get the current global scope

     * @return the current global scope

     */

    public static ScriptObject getGlobal() {

        // This class in a package.access protected package.

        // Trusted code only can call this method.

        return getGlobalTrusted();

    }

    /**

     * Set the current global scope

     * @param global the global scope

     */

    public static void setGlobal(final ScriptObject global) {

        if (global != null && !(global instanceof Global)) {

            throw new IllegalArgumentException("global is not an instance of Global!");

        }

        setGlobalTrusted(global);

    }

    /**

     * Get context of the current global

     * @return current global scope's context.

     */

    public static Context getContext() {

        final SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

            sm.checkPermission(new RuntimePermission(NASHORN_GET_CONTEXT));

        }

        return getContextTrusted();

    }

    /**

     * Get current context's error writer

     *

     * @return error writer of the current context

     */

    public static PrintWriter getCurrentErr() {

        final ScriptObject global = getGlobalTrusted();

        return (global != null)? global.getContext().getErr() : new PrintWriter(System.err);

    }

    /**

     * Output text to this Context's error stream

     * @param str text to write

     */

    public static void err(final String str) {

        err(str, true);

    }

    /**

     * Output text to this Context's error stream, optionally with

     * a newline afterwards

     *

     * @param str  text to write

     * @param crlf write a carriage return/new line after text

     */

    @SuppressWarnings("resource")

    public static void err(final String str, final boolean crlf) {

        final PrintWriter err = Context.getCurrentErr();

        if (err != null) {

            if (crlf) {

                err.println(str);

            } else {

                err.print(str);

            }

        }

    }

    /** Current environment. */

    private final ScriptEnvironment env;

    /** is this context in strict mode? Cached from env. as this is used heavily. */

    final boolean _strict;

    /** class loader to resolve classes from script. */

    private final ClassLoader  appLoader;

    /** Class loader to load classes from -classpath option, if set. */

    private final ClassLoader  classPathLoader;

    /** Class loader to load classes compiled from scripts. */

    private final ScriptLoader scriptLoader;

    /** Current error manager. */

    private final ErrorManager errors;

    /** Unique id for script. Used only when --loader-per-compile=false */

    private final AtomicLong uniqueScriptId;

    /** Unique id for 'eval' */

    private final AtomicLong uniqueEvalId;

    private static final ClassLoader myLoader = Context.class.getClassLoader();

    private static final StructureLoader sharedLoader;

    /*package-private*/ @SuppressWarnings("static-method")

    ClassLoader getSharedLoader() {

        return sharedLoader;

    }

    private static AccessControlContext createNoPermAccCtxt() {

        return new AccessControlContext(new ProtectionDomain[] { new ProtectionDomain(null, new Permissions()) });

    }

    private static AccessControlContext createPermAccCtxt(final String permName) {

        final Permissions perms = new Permissions();

        perms.add(new RuntimePermission(permName));

        return new AccessControlContext(new ProtectionDomain[] { new ProtectionDomain(null, perms) });

    }

    private static final AccessControlContext NO_PERMISSIONS_ACC_CTXT = createNoPermAccCtxt();

    private static final AccessControlContext CREATE_LOADER_ACC_CTXT  = createPermAccCtxt("createClassLoader");

    private static final AccessControlContext CREATE_GLOBAL_ACC_CTXT  = createPermAccCtxt(NASHORN_CREATE_GLOBAL);

    static {

        sharedLoader = AccessController.doPrivileged(new PrivilegedAction<StructureLoader>() {

            @Override

            public StructureLoader run() {

                return new StructureLoader(myLoader);

            }

        }, CREATE_LOADER_ACC_CTXT);

    }

    /**

     * ThrowErrorManager that throws ParserException upon error conditions.

     */

    public static class ThrowErrorManager extends ErrorManager {

        @Override

        public void error(final String message) {

            throw new ParserException(message);

        }

        @Override

        public void error(final ParserException e) {

            throw e;

        }

    }

    /**

     * Constructor

     *

     * @param options options from command line or Context creator

     * @param errors  error manger

     * @param appLoader application class loader

     */

    public Context(final Options options, final ErrorManager errors, final ClassLoader appLoader) {

        this(options, errors, new PrintWriter(System.out, true), new PrintWriter(System.err, true), appLoader);

    }

    /**

     * Constructor

     *

     * @param options options from command line or Context creator

     * @param errors  error manger

     * @param out     output writer for this Context

     * @param err     error writer for this Context

     * @param appLoader application class loader

     */

    public Context(final Options options, final ErrorManager errors, final PrintWriter out, final PrintWriter err, final ClassLoader appLoader) {

        final SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

            sm.checkPermission(new RuntimePermission(NASHORN_CREATE_CONTEXT));

        }

        this.env       = new ScriptEnvironment(options, out, err);

        this._strict   = env._strict;

        this.appLoader = appLoader;

        if (env._loader_per_compile) {

            this.scriptLoader = null;

            this.uniqueScriptId = null;

        } else {

            this.scriptLoader = createNewLoader();

            this.uniqueScriptId = new AtomicLong();

        }

        this.errors    = errors;

        this.uniqueEvalId = new AtomicLong();

        // if user passed -classpath option, make a class loader with that and set it as

        // thread context class loader so that script can access classes from that path.

        final String classPath = options.getString("classpath");

            // make sure that caller can create a class loader.

            if (sm != null) {

                sm.checkPermission(new RuntimePermission("createClassLoader"));

            }

            this.classPathLoader = NashornLoader.createClassLoader(classPath);

        } else {

            this.classPathLoader = null;

        }

        // print version info if asked.

        if (env._version) {

            getErr().println("nashorn " + Version.version());

        }

        if (env._fullversion) {

            getErr().println("nashorn full version " + Version.fullVersion());

        }

    }

    /**

     * Get the error manager for this context

     * @return error manger

     */

    public ErrorManager getErrorManager() {

        return errors;

    }

    /**

     * Get the script environment for this context

     * @return script environment

     */

    public ScriptEnvironment getEnv() {

        return env;

    }

    /**

     * Get the output stream for this context

     * @return output print writer

     */

    public PrintWriter getOut() {

        return env.getOut();

    }

    /**

     * Get the error stream for this context

     * @return error print writer

     */

    public PrintWriter getErr() {

        return env.getErr();

    }

    /**

     * Get the PropertyMap of the current global scope

     * @return the property map of the current global scope

     */

    public static PropertyMap getGlobalMap() {

        return Context.getGlobalTrusted().getMap();

    }

    /**

     * Compile a top level script.

     *

     * @param source the source

     * @param scope  the scope

     *

     * @return top level function for script

     */

    public ScriptFunction compileScript(final Source source, final ScriptObject scope) {

        return compileScript(source, scope, this.errors);

    }

    /**

     * Entry point for {@code eval}

     *

     * @param initialScope The scope of this eval call

     * @param string       Evaluated code as a String

     * @param callThis     "this" to be passed to the evaluated code

     * @param location     location of the eval call

     * @param strict       is this {@code eval} call from a strict mode code?

     *

     * @return the return value of the {@code eval}

     */

    public Object eval(final ScriptObject initialScope, final String string, final Object callThis, final Object location, final boolean strict) {

        final String  file       = (location == UNDEFINED || location == null) ? "<eval>" : location.toString();

        final Source  source     = new Source(file, string);

        final boolean directEval = location != UNDEFINED; // is this direct 'eval' call or indirectly invoked eval?

        final ScriptObject global = Context.getGlobalTrusted();

        ScriptObject scope = initialScope;

        // ECMA section 10.1.1 point 2 says eval code is strict if it begins

        // with "use strict" directive or eval direct call itself is made

        // from from strict mode code. We are passed with caller's strict mode.

        boolean strictFlag = directEval && strict;

        Class<?> clazz = null;

        try {

            clazz = compile(source, new ThrowErrorManager(), strictFlag);

        } catch (final ParserException e) {

            e.throwAsEcmaException(global);

            return null;

        }

        if (!strictFlag) {

            // We need to get strict mode flag from compiled class. This is

            // because eval code may start with "use strict" directive.

            try {

                strictFlag = clazz.getField(STRICT_MODE.symbolName()).getBoolean(null);

            } catch (final NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException e) {

                //ignored

                strictFlag = false;

            }

        }

        // In strict mode, eval does not instantiate variables and functions

        // in the caller's environment. A new environment is created!

        if (strictFlag) {

            // Create a new scope object

            final ScriptObject strictEvalScope = ((GlobalObject)global).newObject();

            // bless it as a "scope"

            strictEvalScope.setIsScope();

            // set given scope to be it's proto so that eval can still

            // access caller environment vars in the new environment.

            strictEvalScope.setProto(scope);

            scope = strictEvalScope;

        }

        Object evalThis;

        if (directEval) {

            evalThis = (callThis instanceof ScriptObject || strictFlag) ? callThis : global;

        } else {

            evalThis = global;

        }

        return ScriptRuntime.apply(func, evalThis);

    }

    private static Source loadInternal(final String srcStr, final String prefix, final String resourcePath) {

        if (srcStr.startsWith(prefix)) {

            final String resource = resourcePath + srcStr.substring(prefix.length());

            // NOTE: even sandbox scripts should be able to load scripts in nashorn: scheme

            // These scripts are always available and are loaded from nashorn.jar's resources.

            return AccessController.doPrivileged(

                    new PrivilegedAction<Source>() {

                        @Override

                        public Source run() {

                            try {

                                final URL resURL = Context.class.getResource(resource);

                                return (resURL != null)? new Source(srcStr, resURL) : null;

                            } catch (final IOException exp) {

                                return null;

                            }

                        }

                    });

        }

        return null;

    }

    /**