/*

 * Copyright (c) 2015, 2016, 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.

 *

 * 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.

 */

import javax.tools.*;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.OutputStream;

import java.net.URI;

import java.util.Arrays;

import java.util.List;

import java.util.Map;

import java.util.stream.Collectors;

class Compiler {

    final private Map<String,String> input;

    private List<String> options;

    Compiler(Map<String,String> input) {

        this.input = input;

    }

    Compiler setRelease(int release) {

        // Setting the -release option does not work for some reason

        // so do it the old fashioned way

        // options = Arrays.asList("-release", String.valueOf(release));

        String target = String.valueOf(release);

        options = Arrays.asList("-source", target, "-target", target, "-classpath", "");

        return this;

    }

    Map<String,byte[]> compile() {

        List<SourceFileObject> cunits = createCompilationUnits();

        Map<String,ClassFileObject> cfos = createClassFileObjects();

        JavaCompiler jc = ToolProvider.getSystemJavaCompiler();

        JavaFileManager jfm = new CustomFileManager(jc.getStandardFileManager(null, null, null), cfos);

        if(!jc.getTask(null, jfm, null, options, null, cunits).call()) {

            throw new RuntimeException("Compilation failed");

        }

        return createOutput(cfos);

    }

    private List<SourceFileObject> createCompilationUnits() {

        return input.entrySet().stream()

                .map(e -> new SourceFileObject(e.getKey(), e.getValue())).collect(Collectors.toList());

    }

    private Map<String,ClassFileObject> createClassFileObjects() {

        return input.keySet().stream()

                .collect(Collectors.toMap(k -> k, k -> new ClassFileObject(k)));

    }

    private Map<String,byte[]> createOutput(Map<String,ClassFileObject> cfos) {

        return cfos.keySet().stream().collect(Collectors.toMap(k -> k, k -> cfos.get(k).getBytes()));

    }

    private static class SourceFileObject extends SimpleJavaFileObject {

        private final String source;

        SourceFileObject(String name, String source) {

            super(URI.create("string:///" + name.replace('.', '/') + Kind.SOURCE.extension), Kind.SOURCE);

            this.source = source;

        }

        @Override

        public CharSequence getCharContent(boolean ignoreEncodingErrors) {

            return source;

        }

    }

    private static class ClassFileObject extends SimpleJavaFileObject {

        private final ByteArrayOutputStream baos = new ByteArrayOutputStream();

        ClassFileObject(String className) {

            super(URI.create(className), Kind.CLASS);

        }

        @Override

        public OutputStream openOutputStream() throws IOException {

            return baos;

        }

        public byte[] getBytes() {

            return baos.toByteArray();

        }

    }

    private static class CustomFileManager extends ForwardingJavaFileManager<JavaFileManager> {

        private final Map<String,ClassFileObject> cfos;

        CustomFileManager(JavaFileManager jfm, Map<String,ClassFileObject> cfos) {

            super(jfm);

            this.cfos = cfos;

        }

        @Override

        public JavaFileObject getJavaFileForOutput(JavaFileManager.Location loc, String name,

                                                   JavaFileObject.Kind kind, FileObject sibling) throws IOException {

            ClassFileObject cfo = cfos.get(name);

            return cfo;

        }

    }

}