/*

 * Copyright (c) 2015, 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.jshell;

import java.io.ByteArrayInputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.PrintStream;

import java.text.MessageFormat;

import java.util.Collections;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import java.util.MissingResourceException;

import java.util.Objects;

import java.util.ResourceBundle;

import java.util.function.BiFunction;

import java.util.function.Consumer;

import java.util.function.Supplier;

import jdk.internal.jshell.debug.InternalDebugControl;

import static java.util.stream.Collectors.collectingAndThen;

import static java.util.stream.Collectors.toList;

import static jdk.jshell.Util.expunge;

import jdk.jshell.Snippet.Status;

/**

 * The JShell evaluation state engine.  This is the central class in the JShell

 * API.  A <code>JShell</code> instance holds the evolving compilation and

 * execution state.  The state is changed with the instance methods

 * {@link jdk.jshell.JShell#eval(java.lang.String) eval(String)},

 * {@link jdk.jshell.JShell#drop(jdk.jshell.PersistentSnippet) drop(PersistentSnippet)} and

 * {@link jdk.jshell.JShell#addToClasspath(java.lang.String) addToClasspath(String)}.

 * The majority of methods query the state.

 * A <code>JShell</code> instance also allows registering for events with

 * {@link jdk.jshell.JShell#onSnippetEvent(java.util.function.Consumer) onSnippetEvent(Consumer)}

 * and {@link jdk.jshell.JShell#onShutdown(java.util.function.Consumer) onShutdown(Consumer)}, which

 * are unregistered with

 * {@link jdk.jshell.JShell#unsubscribe(jdk.jshell.JShell.Subscription) unsubscribe(Subscription)}.

 * Access to the source analysis utilities is via

 * {@link jdk.jshell.JShell#sourceCodeAnalysis()}.

 * When complete the instance should be closed to free resources --

 * {@link jdk.jshell.JShell#close()}.

 * <p>

 * An instance of <code>JShell</code> is created with

 * <code>JShell.create()</code>.

 * <p>

 * This class is not thread safe, except as noted, all access should be through

 * a single thread.

 * @see jdk.jshell

 * @author Robert Field

 */

public class JShell implements AutoCloseable {

    final SnippetMaps maps;

    final KeyMap keyMap;

    final TaskFactory taskFactory;

    final InputStream in;

    final PrintStream out;

    final PrintStream err;

    final Supplier<String> tempVariableNameGenerator;

    final BiFunction<Snippet, Integer, String> idGenerator;

    private int nextKeyIndex = 1;

    final Eval eval;

    final ClassTracker classTracker;

    private final Map<Subscription, Consumer<JShell>> shutdownListeners = new HashMap<>();

    private final Map<Subscription, Consumer<SnippetEvent>> keyStatusListeners = new HashMap<>();

    private boolean closed = false;

    private ExecutionControl executionControl = null;

    private SourceCodeAnalysisImpl sourceCodeAnalysis = null;

    private static final String L10N_RB_NAME    = "jdk.jshell.resources.l10n";

    private static ResourceBundle outputRB  = null;

    JShell(Builder b) {

        this.in = b.in;

        this.out = b.out;

        this.err = b.err;

        this.tempVariableNameGenerator = b.tempVariableNameGenerator;

        this.idGenerator = b.idGenerator;

        this.maps = new SnippetMaps(this);

        maps.setPackageName("REPL");

        this.keyMap = new KeyMap(this);

        this.taskFactory = new TaskFactory(this);

        this.eval = new Eval(this);

        this.classTracker = new ClassTracker(this);

    }

    /**

     * Builder for <code>JShell</code> instances.

     * Create custom instances of <code>JShell</code> by using the setter

     * methods on this class.  After zero or more of these, use the

     * {@link #build()} method to create a <code>JShell</code> instance.

     * These can all be chained. For example, setting the remote output and

     * error streams:

     * <pre>

     * <code>

     *     JShell myShell =

     *       JShell.builder()

     *         .out(myOutStream)

     *         .err(myErrStream)

     *         .build(); </code> </pre>

     * If no special set-up is needed, just use

     * <code>JShell.builder().build()</code> or the short-cut equivalent

     * <code>JShell.create()</code>.

     */

    public static class Builder {

        InputStream in = new ByteArrayInputStream(new byte[0]);

        PrintStream out = System.out;

        PrintStream err = System.err;

        Supplier<String> tempVariableNameGenerator = null;

        BiFunction<Snippet, Integer, String> idGenerator = null;

        Builder() { }

        /**

         * Input for the running evaluation (it's <code>System.in</code>). Note:

         * applications that use <code>System.in</code> for snippet or other

         * user input cannot use <code>System.in</code> as the input stream for

         * the remote process.

         * <p>

         * The default, if this is not set, is to provide an empty input stream

         * -- <code>new ByteArrayInputStream(new byte[0])</code>.

         *

         * @param in the <code>InputStream</code> to be channelled to

         * <code>System.in</code> in the remote execution process.

         * @return the <code>Builder</code> instance (for use in chained

         * initialization).

         */

        public Builder in(InputStream in) {

            this.in = in;

            return this;

        }

        /**

         * Output for the running evaluation (it's <code>System.out</code>).

         * The controlling process and

         * the remote process can share <code>System.out</code>.

         * <p>

         * The default, if this is not set, is <code>System.out</code>.

         *

         * @param out the <code>PrintStream</code> to be channelled to

         * <code>System.out</code> in the remote execution process.

         * @return the <code>Builder</code> instance (for use in chained

         * initialization).

         */

        public Builder out(PrintStream out) {

            this.out = out;

            return this;

        }

        /**

         * Error output for the running evaluation (it's

         * <code>System.err</code>). The controlling process and the remote

         * process can share <code>System.err</code>.

         * <p>

         * The default, if this is not set, is <code>System.err</code>.

         *

         * @param err the <code>PrintStream</code> to be channelled to

         * <code>System.err</code> in the remote execution process.

         * @return the <code>Builder</code> instance (for use in chained

         * initialization).

         */

        public Builder err(PrintStream err) {

            this.err = err;

            return this;

        }

        /**

         * Set a generator of temp variable names for

         * {@link jdk.jshell.VarSnippet} of

         * {@link jdk.jshell.Snippet.SubKind#TEMP_VAR_EXPRESSION_SUBKIND}.

         * <p>

         * Do not use this method unless you have explicit need for it.

         * <p>

         * The generator will be used for newly created VarSnippet

         * instances. The name of a variable is queried with

         * {@link jdk.jshell.VarSnippet#name()}.

         * <p>

         * The callback is sent during the processing of the snippet, the

         * JShell state is not stable. No calls whatsoever on the

         * <code>JShell</code> instance may be made from the callback.

         * <p>

         * The generated name must be unique within active snippets.

         * <p>

         * The default behavior (if this is not set or <code>generator</code>

         * is null) is to generate the name as a sequential number with a

         * prefixing dollar sign ("$").

         *

         * @param generator the <code>Supplier</code> to generate the temporary

         * variable name string or <code>null</code>.

         * @return the <code>Builder</code> instance (for use in chained

         * initialization).

         */

        public Builder tempVariableNameGenerator(Supplier<String> generator) {

            this.tempVariableNameGenerator = generator;

            return this;

        }

        /**

         * Set the generator of identifying names for Snippets.

         * <p>

         * Do not use this method unless you have explicit need for it.

         * <p>

         * The generator will be used for newly created Snippet instances. The

         * identifying name (id) is accessed with

         * {@link jdk.jshell.Snippet#id()} and can be seen in the

         * <code>StackTraceElement.getFileName()</code> for a

         * {@link jdk.jshell.EvalException} and

         * {@link jdk.jshell.UnresolvedReferenceException}.

         * <p>

         * The inputs to the generator are the {@link jdk.jshell.Snippet} and an

         * integer. The integer will be the same for two Snippets which would

         * overwrite one-another, but otherwise is unique.

         * <p>

         * The callback is sent during the processing of the snippet and the

         * Snippet and the state as a whole are not stable. No calls to change

         * system state (including Snippet state) should be made. Queries of

         * Snippet may be made except to {@link jdk.jshell.Snippet#id()}. No

         * calls on the <code>JShell</code> instance may be made from the

         * callback, except to

         * {@link #status(jdk.jshell.Snippet) status(Snippet)}.

         * <p>

         * The default behavior (if this is not set or <code>generator</code>

         * is null) is to generate the id as the integer converted to a string.

         *

         * @param generator the <code>BiFunction</code> to generate the id

         * string or <code>null</code>.

         * @return the <code>Builder</code> instance (for use in chained

         * initialization).

         */

        public Builder idGenerator(BiFunction<Snippet, Integer, String> generator) {

            this.idGenerator = generator;

            return this;

        }

        /**

         * Build a JShell state engine. This is the entry-point to all JShell

         * functionality. This creates a remote process for execution. It is

         * thus important to close the returned instance.

         *

         * @return the state engine.

         */

        public JShell build() {

            return new JShell(this);

        }

    }

    // --- public API ---

    /**

     * Create a new JShell state engine.

     * That is, create an instance of <code>JShell</code>.

     * <p>

     * Equivalent to {@link JShell#builder() JShell.builder()}{@link JShell.Builder#build() .build()}.

     * @return an instance of <code>JShell</code>.

     */

    public static JShell create() {

        return builder().build();

    }

    /**

     * Factory method for <code>JShell.Builder</code> which, in-turn, is used

     * for creating instances of <code>JShell</code>.

     * Create a default instance of <code>JShell</code> with

     * <code>JShell.builder().build()</code>. For more construction options

     * see {@link jdk.jshell.JShell.Builder}.

     * @return an instance of <code>Builder</code>.

     * @see jdk.jshell.JShell.Builder

     */

    public static Builder builder() {

        return new Builder();

    }

    /**

     * Access to source code analysis functionality.

     * An instance of <code>JShell</code> will always return the same

     * <code>SourceCodeAnalysis</code> instance from

     * <code>sourceCodeAnalysis()</code>.

     * @return an instance of {@link SourceCodeAnalysis SourceCodeAnalysis}

     * which can be used for source analysis such as completion detection and

     * completion suggestions.

     */

    public SourceCodeAnalysis sourceCodeAnalysis() {

        if (sourceCodeAnalysis == null) {

            sourceCodeAnalysis = new SourceCodeAnalysisImpl(this);

        }

        return sourceCodeAnalysis;

    }

    /**

     * Evaluate the input String, including definition and/or execution, if

     * applicable. The input is checked for errors, unless the errors can be

     * deferred (as is the case with some unresolvedDependencies references),

     * errors will abort evaluation. The input should be

     * exactly one complete snippet of source code, that is, one expression,

     * statement, variable declaration, method declaration, class declaration,

     * or import.

     * To break arbitrary input into individual complete snippets, use

     * {@link SourceCodeAnalysis#analyzeCompletion(String)}.

     * <p>

     * For imports, the import is added.  Classes, interfaces. methods,

     * and variables are defined.  The initializer of variables, statements,

     * and expressions are executed.

     * The modifiers public, protected, private, static, and final are not

     * allowed on op-level declarations and are ignored with a warning.

     * Synchronized, native, abstract, and default top-level methods are not

     * allowed and are errors.

     * If a previous definition of a declaration is overwritten then there will

     * be an event showing its status changed to OVERWRITTEN, this will not

     * occur for dropped, rejected, or already overwritten declarations.

     * <p>

     * The execution environment is out of process.  If the evaluated code

     * causes the execution environment to terminate, this <code>JShell</code>

     * instance will be closed but the calling process and VM remain valid.

     * @param input The input String to evaluate

     * @return the list of events directly or indirectly caused by this evaluation.

     * @throws IllegalStateException if this <code>JShell</code> instance is closed.

     * @see SourceCodeAnalysis#analyzeCompletion(String)

     * @see JShell#onShutdown(java.util.function.Consumer)

     */

    public List<SnippetEvent> eval(String input) throws IllegalStateException {

        SourceCodeAnalysisImpl a = sourceCodeAnalysis;

        if (a != null) {

            a.suspendIndexing();

        }

        try {

            checkIfAlive();

            List<SnippetEvent> events = eval.eval(input);

            events.forEach(this::notifyKeyStatusEvent);

            return Collections.unmodifiableList(events);

        } finally {

            if (a != null) {

                a.resumeIndexing();

            }

        }

    }

    /**

     * Remove a declaration from the state.

     * @param snippet The snippet to remove

     * @return The list of events from updating declarations dependent on the

     * dropped snippet.

     * @throws IllegalStateException if this <code>JShell</code> instance is closed.

     * @throws IllegalArgumentException if the snippet is not associated with

     * this <code>JShell</code> instance.

     */

    public List<SnippetEvent> drop(PersistentSnippet snippet) throws IllegalStateException {

        checkIfAlive();

        checkValidSnippet(snippet);

        List<SnippetEvent> events = eval.drop(snippet);

        events.forEach(this::notifyKeyStatusEvent);

        return Collections.unmodifiableList(events);

    }

    /**

     * The specified path is added to the end of the classpath used in eval().

     * Note that the unnamed package is not accessible from the package in which

     * @param path the path to add to the classpath.

     */

    public void addToClasspath(String path) {

        taskFactory.addToClasspath(path);  // Compiler

        executionControl().commandAddToClasspath(path);       // Runtime

        if (sourceCodeAnalysis != null) {

            sourceCodeAnalysis.classpathChanged();

        }

    }

    /**

     * Attempt to stop currently running evaluation. When called while

     * the {@link #eval(java.lang.String) } method is running and the

     * user's code being executed, an attempt will be made to stop user's code.

     * Note that typically this method needs to be called from a different thread

     * than the one running the {@code eval} method.

     * <p>

     * If the {@link #eval(java.lang.String) } method is not running, does nothing.

     * <p>

     * The attempt to stop the user's code may fail in some case, which may include

     * when the execution is blocked on an I/O operation, or when the user's code is

     * catching the {@link ThreadDeath} exception.

     */

    public void stop() {

        if (executionControl != null)

            executionControl.commandStop();

    }

    /**

     * Close this state engine. Frees resources. Should be called when this

     * state engine is no longer needed.

     */

    @Override

    public void close() {

        if (!closed) {

            closeDown();

            executionControl().commandExit();

        }

    }

    /**

     * Return all snippets.

     * @return the snippets for all current snippets in id order.

     * @throws IllegalStateException if this JShell instance is closed.

     */

    public List<Snippet> snippets() throws IllegalStateException {

        checkIfAlive();

        return Collections.unmodifiableList(maps.snippetList());

    }

    /**

     * Returns the active variable snippets.

     * This convenience method is equivalent to <code>snippets()</code> filtered for

     * {@link jdk.jshell.Snippet.Status#isActive status(snippet).isActive}

     * <code>&amp;&amp; snippet.kind() == Kind.VARIABLE</code>

     * and cast to <code>VarSnippet</code>.

     * @return the active declared variables.

     * @throws IllegalStateException if this JShell instance is closed.

     */

    public List<VarSnippet> variables() throws IllegalStateException {

        return snippets().stream()

                     .filter(sn -> status(sn).isActive && sn.kind() == Snippet.Kind.VAR)

                     .map(sn -> (VarSnippet) sn)

                     .collect(collectingAndThen(toList(), Collections::unmodifiableList));

    }

    /**

     * Returns the active method snippets.

     * This convenience method is equivalent to <code>snippets()</code> filtered for

     * {@link jdk.jshell.Snippet.Status#isActive status(snippet).isActive}

     * <code>&amp;&amp; snippet.kind() == Kind.METHOD</code>

     * and cast to MethodSnippet.

     * @return the active declared methods.

     * @throws IllegalStateException if this JShell instance is closed.

     */

    public List<MethodSnippet> methods() throws IllegalStateException {

        return snippets().stream()

                     .filter(sn -> status(sn).isActive && sn.kind() == Snippet.Kind.METHOD)

                     .map(sn -> (MethodSnippet)sn)

                     .collect(collectingAndThen(toList(), Collections::unmodifiableList));

    }

    /**

     * Returns the active type declaration (class, interface, annotation type, and enum) snippets.

     * This convenience method is equivalent to <code>snippets()</code> filtered for

     * {@link jdk.jshell.Snippet.Status#isActive status(snippet).isActive}

     * <code>&amp;&amp; snippet.kind() == Kind.TYPE_DECL</code>

     * and cast to TypeDeclSnippet.

     * @return the active declared type declarations.

     * @throws IllegalStateException if this JShell instance is closed.

     */

    public List<TypeDeclSnippet> types() throws IllegalStateException {

        return snippets().stream()

                .filter(sn -> status(sn).isActive && sn.kind() == Snippet.Kind.TYPE_DECL)

                .map(sn -> (TypeDeclSnippet) sn)

                .collect(collectingAndThen(toList(), Collections::unmodifiableList));

    }

    /**

     * Returns the active import snippets.

     * This convenience method is equivalent to <code>snippets()</code> filtered for

     * {@link jdk.jshell.Snippet.Status#isActive status(snippet).isActive}

     * <code>&amp;&amp; snippet.kind() == Kind.IMPORT</code>

     * and cast to ImportSnippet.

     * @return the active declared import declarations.

     * @throws IllegalStateException if this JShell instance is closed.

     */

    public List<ImportSnippet> imports() throws IllegalStateException {

        return snippets().stream()

                .filter(sn -> status(sn).isActive && sn.kind() == Snippet.Kind.IMPORT)

                .map(sn -> (ImportSnippet) sn)

                .collect(collectingAndThen(toList(), Collections::unmodifiableList));

    }

    /**

     * Return the status of the snippet.

     * This is updated either because of an explicit <code>eval()</code> call or

     * an automatic update triggered by a dependency.

     * @param snippet the <code>Snippet</code> to look up

     * @return the status corresponding to this snippet

     * @throws IllegalStateException if this <code>JShell</code> instance is closed.

     * @throws IllegalArgumentException if the snippet is not associated with

     * this <code>JShell</code> instance.

     */

    public Status status(Snippet snippet) {

        return checkValidSnippet(snippet).status();

    }

    /**

     * Return the diagnostics of the most recent evaluation of the snippet.

     * The evaluation can either because of an explicit <code>eval()</code> call or

     * an automatic update triggered by a dependency.

     * @param snippet the <code>Snippet</code> to look up

     * @return the diagnostics corresponding to this snippet.  This does not

     * include unresolvedDependencies references reported in <code>unresolvedDependencies()</code>.

     * @throws IllegalStateException if this <code>JShell</code> instance is closed.

     * @throws IllegalArgumentException if the snippet is not associated with

     * this <code>JShell</code> instance.