/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jena.dboe.migrate;

import java.io.IOException ;
import java.io.OutputStream ;
import java.io.OutputStreamWriter ;
import java.io.Writer ;
import java.nio.ByteBuffer ;
import java.nio.charset.StandardCharsets ;
import java.util.UUID ;
import java.util.concurrent.* ;
import java.util.concurrent.locks.Lock ;
import java.util.function.Supplier ;

import org.apache.jena.atlas.io.IO ;
import org.apache.jena.atlas.lib.Bytes ;
import org.apache.jena.atlas.lib.StrUtils ;
import org.apache.jena.shared.uuid.JenaUUID ;

/** Misc class */
public class L {
    
    // Not to be confused with UUID.nameUUIDFromBytes (a helper for version 3 UUIDs)
    /**
     * Java UUID to bytes (most significant first)
     */
    public static byte[] uuidAsBytes(UUID uuid) {
        return uuidAsBytes(uuid.getMostSignificantBits(), uuid.getLeastSignificantBits()) ;
    }
    
    /**
     * Jena UUID to bytes (most significant first)
     */
    public static byte[] uuidAsBytes(JenaUUID uuid) {
        return uuidAsBytes(uuid.getMostSignificantBits(), uuid.getLeastSignificantBits()) ;
    }
    
    /** UUID, as two longs, as bytes */ 
    public static byte[] uuidAsBytes(long mostSignificantBits, long leastSignificantBits) {
        byte[] bytes = new byte[16] ;
        Bytes.setLong(mostSignificantBits, bytes, 0); 
        Bytes.setLong(leastSignificantBits, bytes, 8);
        return bytes ;
    }
    
    /** A UUID string to bytes */ 
    public static byte[] uuidAsBytes(String str) {
        return uuidAsBytes(UUID.fromString(str)) ;
    }
    
    public static String uuidToString(long mostSignificantBits, long leastSignificantBits) {
        return new UUID(mostSignificantBits, leastSignificantBits).toString() ;
        //JenaUUID.toString(mostSignificantBits, leastSignificantBits)
    }
    
    private static ExecutorService executor = Executors.newCachedThreadPool() ; 
    
    /**
     * Run asynchronously on another thread ; the thread has started
     * when this function returns.
     */
    public static void async(Runnable r) {
        Semaphore semaStart = new Semaphore(0, true) ;
        Runnable r2 = () -> {
            semaStart.release(1) ;
            r.run();
        } ;
        executor.execute(r2);
        semaStart.acquireUninterruptibly();
    }
    
    /** Run synchronously but on another thread. */
    public static void syncOtherThread(Runnable r) {
        runCallable(()->{
            r.run();
            return null ;
        }) ;
    }

    /** Run synchronously but on another thread. */
    public static <T> T syncCallThread(Supplier<T> r) {
        return runCallable(() -> {
            T t = r.get() ;
            return t ;
        }) ;
    }
    
    private static <T> T runCallable(Callable<T> action) {
        try { return executor.submit(action).get() ; }
        catch (Exception e) {
            e.printStackTrace();
            return null ;
        }
    }
    

    /** Execute. Preform the "before" action, then main action.
     *  Always call the "after" runnable if the "before" succeeded.
     *  Be careful about argument order. 
     * @param action
     * @param before
     * @param after
     */
    public static void withBeforeAfter(Runnable action, Runnable before, Runnable after) {
        before.run(); 
        try { action.run(); }
        finally { after.run();  }
    }

    /** Execute. Preform the "before" action, then main action.
     *  Always call the "after" runnable if the "before" succeeded.
     *  Be careful about argument order. 
     * @param action
     * @param before
     * @param after
     */
    public static <V> V callWithBeforeAfter(Supplier<V> action, Runnable before, Runnable after) {
        before.run(); 
        try { return action.get() ; } 
        finally { after.run();  }
    }

    /** Execute; always call the "after" runnable */
    public static void withAfter(Runnable action, Runnable after) {
        try { action.run(); } 
        finally { after.run();  }
    }

    /** Execute and return a value; always call the "after" runnable */
    public static <V> V callWithAfter(Supplier<V> action, Runnable after) {
        try { return action.get() ; }
        finally { after.run();  }
    }

    /** Run inside a Lock */
    public static  <V> V callWithLock(Lock lock, Supplier<V> r) {
        return callWithBeforeAfter(r, ()->lock.lock(), ()->lock.unlock()) ;  
    }
    
    /** Run inside a Lock */
    public static void withLock(Lock lock, Runnable r) {
        withBeforeAfter(r, ()->lock.lock(), ()->lock.unlock()) ;
    }
    
    // ==> IO.writeWholeFileAsUTF8
    
    /** Write a string to a file as UTF-8. The file is closed after the operation.
     * @param filename
     * @param content String to be written
     * @throws IOException
     */
    
    public static void writeStringAsUTF8(String filename, String content) throws IOException {
        try ( OutputStream out = IO.openOutputFileEx(filename) ) {
            writeStringAsUTF8(out, content) ;
            out.flush() ;
        }
    }

    /** Read a whole stream as UTF-8
     * 
     * @param out       OutputStream to be read
     * @param content   String to be written
     * @throws  IOException
     */
    public static void writeStringAsUTF8(OutputStream out, String content) throws IOException {
        Writer w = new OutputStreamWriter(out, StandardCharsets.UTF_8) ;
        w.write(content);
        w.flush();
        // Not close.
    }

    // ==> IO.writeWholeFileAsUTF8
    
    /** String to ByteBuffer */
    public static ByteBuffer stringToByteBuffer(String str) {
        byte[] b = StrUtils.asUTF8bytes(str) ;
        return ByteBuffer.wrap(b) ;
    }
    
    /** ByteBuffer to String */
    public static String byteBufferToString(ByteBuffer bb) {
        byte[] b = new byte[bb.remaining()] ;
        bb.get(b) ;
        return StrUtils.fromUTF8bytes(b) ;
    }


}

