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// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
// *                                                                                                                         *
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package org.apache.juneau.utils;

import static org.apache.juneau.internal.IOUtils.*;
import static org.apache.juneau.internal.ThrowableUtils.*;

import java.io.*;
import java.util.*;

import org.apache.juneau.internal.*;

/**
 * A utility class for piping input streams and readers to output streams and writers.
 *
 * <p>
 * A typical usage is as follows...
 * <p class='bcode w800'>
 *    InputStream in = getInputStream();
 *    Writer out = getWriter();
 *    IOPipe.create(in, out).closeOut().run();
 * </p>
 *
 * <p>
 * By default, the input stream is closed and the output stream is not.
 * This can be changed by calling {@link #closeOut()} and {@link #close(boolean, boolean)}.
 */
public class IOPipe {

   private Object input, output;
   private boolean byLines;
   private boolean closeIn = true, closeOut;
   private int buffSize = 1024;
   private LineProcessor lineProcessor;

   private IOPipe(Object input, Object output) {
      assertFieldNotNull(input, "input");
      assertFieldNotNull(output, "output");

      if (input instanceof CharSequence)
         this.input = new StringReader(input.toString());
      else if (input instanceof InputStream || input instanceof Reader)
         this.input = input;
      else
         illegalArg("Invalid input class type.  Must be one of the following:  InputStream, Reader, CharSequence");

      if (output instanceof OutputStream || output instanceof Writer)
         this.output = output;
      else
         illegalArg("Invalid output class type.  Must be one of the following:  OutputStream, Writer");
   }

   /**
    * Creates a new pipe with the specified input and output.
    *
    * @param input The input.  Must be one of the following types:  Reader, InputStream, CharSequence.
    * @param output The output.  Must be one of the following types:  Writer, OutputStream.
    * @return This object (for method chaining).
    */
   public static IOPipe create(Object input, Object output) {
      return new IOPipe(input, output);
   }

   /**
    * Close output after piping.
    *
    * @return This object (for method chaining).
    */
   public IOPipe closeOut() {
      this.closeOut = true;
      return this;
   }

   /**
    * Specifies whether to close the input and output after piping.
    *
    * @param in Close input stream.  Default is <jk>true</jk>.
    * @param out Close output stream.  Default is <jk>false</jk>.
    * @return This object (for method chaining).
    */
   public IOPipe close(boolean in, boolean out) {
      this.closeIn = in;
      this.closeOut = out;
      return this;
   }

   /**
    * Specifies the temporary buffer size.
    *
    * @param buffSize The buffer size.  Default is <code>1024</code>.
    * @return This object (for method chaining).
    */
   public IOPipe buffSize(int buffSize) {
      assertFieldPositive(buffSize, "buffSize");
      this.buffSize = buffSize;
      return this;
   }

   /**
    * Specifies whether the content should be piped line-by-line.
    *
    * <p>
    * This can be useful if you're trying to pipe console-based input.
    *
    * @param byLines Pipe content line-by-line.  Default is <jk>false</jk>.
    * @return This object (for method chaining).
    */
   public IOPipe byLines(boolean byLines) {
      this.byLines = byLines;
      return this;
   }

   /**
    * Same as calling {@link #byLines()} with <jk>true</jk>.
    *
    * @return This object (for method chaining).
    */
   public IOPipe byLines() {
      this.byLines = true;
      return this;
   }

   /**
    * Specifies a line processor that can be used to process lines before they're piped to the output.
    *
    * @param lineProcessor The line processor.
    * @return This object (for method chaining).
    */
   public IOPipe lineProcessor(LineProcessor lineProcessor) {
      this.lineProcessor = lineProcessor;
      return this;
   }

   /**
    * Interface to implement for the {@link #lineProcessor(LineProcessor)} method.
    */
   public interface LineProcessor {
      /**
       * Process the specified line.
       *
       * @param line The line to process.
       * @return The processed line.
       */
      public String process(String line);
   }

   /**
    * Performs the piping of the input to the output.
    *
    * @return The number of bytes (if streams) or characters (if readers/writers) piped.
    * @throws IOException
    */
   public int run() throws IOException {

      int c = 0;

      try {
         if (input instanceof InputStream && output instanceof OutputStream && lineProcessor == null) {
            InputStream in = (InputStream)input;
            OutputStream out = (OutputStream)output;
            byte[] b = new byte[buffSize];
            int i;
            while ((i = in.read(b)) > 0) {
               c += i;
               out.write(b, 0, i);
            }
            out.flush();
         } else {
            Reader in = (input instanceof Reader ? (Reader)input : new InputStreamReader((InputStream)input, UTF8));
            Writer out = (output instanceof Writer ? (Writer)output : new OutputStreamWriter((OutputStream)output, UTF8));
            output = out;
            input = in;
            if (byLines || lineProcessor != null) {
               try (Scanner s = new Scanner(in)) {
                  while (s.hasNextLine()) {
                     String l = s.nextLine();
                     if (lineProcessor != null)
                        l = lineProcessor.process(l);
                     if (l != null) {
                        out.write(l);
                        out.write("\n");
                        out.flush();
                        c += l.length() + 1;
                     }
                  }
               }
            } else {
               int i;
               char[] b = new char[buffSize];
               while ((i = in.read(b)) > 0) {
                  c += i;
                  out.write(b, 0, i);
               }
            }
            out.flush();
         }
      } finally {
         closeQuietly(input, output);
      }
      return c;
   }

   private void closeQuietly(Object input, Object output) {
      if (closeIn)
         IOUtils.closeQuietly(input);
      if (closeOut)
         IOUtils.closeQuietly(output);
   }
}