/*

 * Copyright (c) 2015, 2018, 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.tools.jjs;

import java.io.BufferedReader;

import java.io.File;

import java.io.FileReader;

import java.io.IOException;

import java.io.PrintWriter;

import java.io.UncheckedIOException;

import java.util.Collections;

import java.util.HashSet;

import java.util.Set;

import java.util.function.Consumer;

import java.util.function.Function;

import java.util.function.Supplier;

import jdk.internal.org.jline.reader.History;

import jdk.nashorn.api.scripting.AbstractJSObject;

import jdk.nashorn.api.scripting.JSObject;

import jdk.nashorn.internal.runtime.JSType;

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

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

/*

 * A script friendly object that exposes history of commands to scripts.

 */

final class HistoryObject extends AbstractJSObject {

    private static final Set<String> props;

    static {

        final HashSet<String> s = new HashSet<>();

        s.add("clear");

        s.add("forEach");

        s.add("load");

        s.add("print");

        s.add("save");

        s.add("size");

        s.add("toString");

        props = Collections.unmodifiableSet(s);

    }

    private final History hist;

    private final PrintWriter err;

    private final Consumer<String> evaluator;

    HistoryObject(final History hist, final PrintWriter err,

            final Consumer<String> evaluator) {

        this.hist = hist;

        this.err = err;

        this.evaluator = evaluator;

    }

    @Override

    public boolean isFunction() {

        return true;

    }

    @Override

    public Object call(final Object thiz, final Object... args) {

        if (args.length > 0) {

            int index = JSType.toInteger(args[0]);

            if (index < 0) {

                index += (hist.size() - 1);

            } else {

                index--;

            }

            if (index >= 0 && index < (hist.size() - 1)) {

                final CharSequence src = hist.get(index);

                var it = hist.iterator();

                while (it.hasNext()) {

                    it.next();

                }

                it.remove();

                hist.add(src.toString());

                err.println(src);

                evaluator.accept(src.toString());

            } else {

                var it = hist.iterator();

                while (it.hasNext()) {

                    it.next();

                }

                it.remove();

                err.println("no history entry @ " + (index + 1));

            }

        }

        return UNDEFINED;

    }

    @Override

    public Object getMember(final String name) {

        switch (name) {

            case "clear":

                return (Runnable) () -> {

                    try {

                    hist.purge();

                    } catch (IOException ex) {

                        throw new UncheckedIOException(ex);

                    }

                };

            case "forEach":

                return (Function<JSObject, Object>)this::iterate;

            case "load":

                return (Consumer<Object>)this::load;

            case "print":

                return (Runnable)this::print;

            case "save":

                return (Consumer<Object>)this::save;

            case "size":

                return hist.size();

            case "toString":

                return (Supplier<String>)this::toString;

        }

        return UNDEFINED;

    }

    @Override

    public Object getDefaultValue(final Class<?> hint) {

        if (hint == String.class) {

            return toString();

        }

        return UNDEFINED;

    }

    @Override

    public String toString() {

        final StringBuilder buf = new StringBuilder();

        for (History.Entry e : hist) {

            buf.append(e.line()).append('\n');

        }

        return buf.toString();

    }

    @Override

    public Set<String> keySet() {

        return props;

    }

    private void save(final Object obj) {

        final File file = getFile(obj);

        try (final PrintWriter pw = new PrintWriter(file)) {

            for (History.Entry e : hist) {

                pw.println(e.line());

            }

        } catch (final IOException exp) {

            throw new RuntimeException(exp);

        }

    }

    private void load(final Object obj) {

        final File file = getFile(obj);

        String item = null;

        try (final BufferedReader r = new BufferedReader(new FileReader(file))) {

            while ((item = r.readLine()) != null) {

                hist.add(item);

            }

        } catch (final IOException exp) {

            throw new RuntimeException(exp);

        }

    }

    private void print() {

        for (History.Entry e : hist) {

            System.out.printf("%3d %s\n", e.index() + 1, e.line());

        }

    }

    private Object iterate(final JSObject func) {

        for (History.Entry e : hist) {

            if (JSType.toBoolean(func.call(this, e.line().toString()))) {

                break; // return true from callback to skip iteration

            }

        }

        return UNDEFINED;

    }

    private static File getFile(final Object obj) {

        File file = null;

        if (obj instanceof String) {

            file = new File((String)obj);

        } else if (obj instanceof File) {

            file = (File)obj;

        } else {

            throw typeError("not.a.file", JSType.toString(obj));

        }

        return file;

    }

}