// ***************************************************************************************************************************
// * 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.juneau.internal;

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

import java.io.*;
import java.nio.charset.*;

import org.apache.juneau.*;
import org.apache.juneau.utils.*;

/**
 * Various I/O related utility methods.
 */
public final class IOUtils {

   /** UTF-8 charset */
   public static final Charset UTF8 = Charset.forName("UTF-8");

   /**
    * Reads the contents of a file into a string.
    * 
    * @param path The path of the file to read using default character encoding.
    * @return The contents of the reader as a string, or <jk>null</jk> if file does not exist.
    * @throws IOException If a problem occurred trying to read from the reader.
    */
   public static String readFile(String path) throws IOException {
      return read(new File(path));
   }

   /**
    * Reads the contents of a file into a string.
    * 
    * @param in The file to read using default character encoding.
    * @return The contents of the reader as a string, or <jk>null</jk> if file does not exist.
    * @throws IOException If a problem occurred trying to read from the reader.
    */
   public static String read(File in) throws IOException {
      if (in == null || ! in.exists())
         return null;
      try (Reader r = FileReaderBuilder.create(in).build()) {
         return read(r, 0, 1024);
      }
   }

   /**
    * Reads the specified object to a <code>String</code>.
    * 
    * <p>
    * Can be any of the following object types:
    * <ul>
    *    <li>{@link CharSequence}
    *    <li>{@link File}
    *    <li>{@link Reader}
    *    <li>{@link InputStream}
    *    <li><code><jk>byte</jk>[]</code>
    * </ul>
    * 
    * @param o The object to read.
    * @return The object serialized to a string, or <jk>null</jk> if it wasn't a supported type.
    * @throws IOException
    */
   public static String read(Object o) throws IOException {
      if (o instanceof CharSequence)
         return o.toString();
      if (o instanceof File)
         return read((File)o);
      if (o instanceof Reader)
         return read((Reader)o);
      if (o instanceof InputStream)
         return read((InputStream)o);
      if (o instanceof byte[])
         return read(new ByteArrayInputStream((byte[])o));
      return null;
   }

   /**
    * Writes the contents of the specified <code>Reader</code> to the specified file.
    * 
    * @param out The file to write the output to.
    * @param in The reader to pipe from.
    * @return The number of characters written to the file.
    * @throws IOException
    */
   public static int write(File out, Reader in) throws IOException {
      assertFieldNotNull(out, "out");
      assertFieldNotNull(in, "in");
      try (Writer w = FileWriterBuilder.create(out).build()) {
         return IOPipe.create(in, w).run();
      }
   }

   /**
    * Writes the contents of the specified <code>InputStream</code> to the specified file.
    * 
    * @param out The file to write the output to.
    * @param in The input stream to pipe from.
    * @return The number of characters written to the file.
    * @throws IOException
    */
   public static int write(File out, InputStream in) throws IOException {
      assertFieldNotNull(out, "out");
      assertFieldNotNull(in, "in");
      try (OutputStream os = new FileOutputStream(out)) {
         return IOPipe.create(in, os).run();
      }
   }

   /**
    * Reads the contents of a reader into a string.
    * 
    * @param in The input reader.
    * @return The contents of the reader as a string.
    * @throws IOException If a problem occurred trying to read from the reader.
    */
   public static String read(Reader in) throws IOException {
      return read(in, 0, 1024);
   }

   /**
    * Reads the contents of an input stream into a string using the specified charset.
    * 
    * @param in The input stream.
    * @param cs The charset of the contents of the input stream.
    * @return The contents of the reader as a string.  <jk>null</jk> if input stream was null.
    * @throws IOException If a problem occurred trying to read from the input stream.
    */
   public static String read(InputStream in, Charset cs) throws IOException {
      if (in == null)
         return null;
      return read(new InputStreamReader(in, cs));
   }

   /**
    * Reads the contents of an input stream into a string using the system default charset.
    * 
    * @param in The input stream.
    * @return The contents of the reader as a string, or <jk>null</jk> if the input stream is null.
    * @throws IOException If a problem occurred trying to read from the input stream.
    */
   public static String read(InputStream in) throws IOException {
      if (in == null)
         return null;
      return read(new InputStreamReader(in, Charset.defaultCharset()));
   }

   /**
    * Read the specified input stream into a byte array and closes the stream.
    * 
    * @param in The input stream.
    * @param bufferSize The expected size of the buffer.
    * @return The contents of the stream as a byte array.
    * @throws IOException Thrown by underlying stream.
    */
   public static byte[] readBytes(InputStream in, int bufferSize) throws IOException {
      if (in == null)
         return null;
      ByteArrayOutputStream buff = new ByteArrayOutputStream(bufferSize);
      int nRead;
      byte[] b = new byte[Math.min(bufferSize, 8192)];

      try {
         while ((nRead = in.read(b, 0, b.length)) != -1)
            buff.write(b, 0, nRead);
         buff.flush();

         return buff.toByteArray();
      } finally {
         in.close();
      }
   }

   /**
    * Reads a raw stream of bytes from the specified file.
    * 
    * @param f The file to read.
    * @return A byte array containing the contents of the file.
    * @throws IOException
    */
   public static byte[] readBytes(File f) throws IOException {
      if (f == null || ! (f.exists() && f.canRead()))
         return null;

      try (FileInputStream fis = new FileInputStream(f)) {
         return readBytes(fis, (int)f.length());
      }
   }

   /**
    * Reads the specified input into a {@link String} until the end of the input is reached.
    * 
    * <p>
    * The {@code Reader} is automatically closed.
    * 
    * <p>
    * If the {@code Reader} is not an instance of a {@code BufferedReader}, then it gets wrapped in a
    * {@code BufferedReader}.
    * 
    * @param in The input reader.
    * @param length Specify a positive number if the length of the input is known.
    * @param bufferSize Specify the buffer size to use.
    * @return The contents of the reader as a string.  <jk>null</jk> if reader was null.
    * @throws IOException If a problem occurred trying to read from the reader.
    */
   public static String read(Reader in, int length, int bufferSize) throws IOException {
      if (in == null)
         return null;
      length = (length <= 0 ? bufferSize : length);
      StringBuilder sb = new StringBuilder(length); // Assume they're ASCII characters.
      try {
         char[] buf = new char[Math.min(bufferSize, length)];
         int i = 0;
         while ((i = in.read(buf)) != -1)
            sb.append(buf, 0, i);
         return sb.toString();
      } finally {
         in.close();
      }
   }

   /**
    * Pipes the contents of the specified reader into the writer.
    * 
    * <p>
    * The reader is closed, the writer is not.
    * 
    * @param in
    *    The reader to pipe from.
    * @param out
    *    The writer to pipe to.
    * @throws IOException
    */
   public static void pipe(Reader in, Writer out) throws IOException {
      assertFieldNotNull(out, "out");
      assertFieldNotNull(in, "in");
      IOPipe.create(in, out).run();
   }

   /**
    * Pipes the contents of the specified object into the writer.
    * 
    * <p>
    * The reader is closed, the writer is not.
    * 
    * @param in
    *    The input to pipe from.
    *    Can be any of the types defined by {@link #toReader(Object)}.
    * @param out
    *    The writer to pipe to.
    * @throws IOException
    */
   public static void pipe(Object in, Writer out) throws IOException {
      pipe(toReader(in), out);
   }

   /**
    * Pipes the contents of the specified streams.
    * 
    * <p>
    * The input stream is closed, the output stream is not.
    * 
    * @param in
    *    The reader to pipe from.
    * @param out
    *    The writer to pipe to.
    * @throws IOException
    */
   public static void pipe(InputStream in, OutputStream out) throws IOException {
      assertFieldNotNull(out, "out");
      assertFieldNotNull(in, "in");
      IOPipe.create(in, out).run();
   }

   /**
    * Pipes the contents of the specified object into the output stream.
    * 
    * <p>
    * The input stream is closed, the output stream is not.
    * 
    * @param in
    *    The input to pipe from.
    *    Can be any of the types defined by {@link #toInputStream(Object)}.
    * @param out
    *    The writer to pipe to.
    * @throws IOException
    */
   public static void pipe(Object in, OutputStream out) throws IOException {
      pipe(toInputStream(in), out);
   }

   /**
    * Wraps the specified reader in a buffered reader.
    * 
    * @param r The reader being wrapped.
    * @return
    *    The reader wrapped in a {@link BufferedReader}, or the original {@link Reader} if it's already a buffered
    *    reader.
    */
   public static Reader getBufferedReader(Reader r) {
      if (r == null || r instanceof BufferedReader || r instanceof StringReader)
         return r;
      return new BufferedReader(r);
   }

   /**
    * Counts the number of bytes in the input stream and then closes the stream.
    * 
    * @param is The input stream to read from.
    * @return The number of bytes read.
    * @throws IOException
    */
   public static long count(InputStream is) throws IOException {
      assertFieldNotNull(is, "is");
      long c = 0;
      long i;
      try {
         while ((i = is.skip(1024)) != 0)
            c += i;
      } finally {
         is.close();
      }
      return c;
   }

   /**
    * Counts the number of characters in the reader and then closes the reader.
    * 
    * @param r The reader to read from.
    * @return The number of characters read.
    * @throws IOException
    */
   public static long count(Reader r) throws IOException {
      assertFieldNotNull(r, "r");
      long c = 0;
      long i;
      try {
         while ((i = r.skip(1024)) != 0)
            c += i;
      } finally {
         r.close();
      }
      return c;
   }

   /**
    * Given the specified <js>"Content-Length"</js> header value, return an appropriate buffer size.
    * 
    * <p>
    * The maximum buffer size is 1MB.
    * 
    * @param contentLength The value of the <js>"Content-Length"</js> header.
    * @return The appropriate buffer size.
    */
   public static int getBufferSize(String contentLength) {
      try {
         if (! StringUtils.isEmpty(contentLength)) {
            long l = Long.decode(contentLength);
            if (l > 1048576)
               return 1048576;
            if (l <= 0)
               return 8192;
            return (int)l;
         }
      } catch (Exception e) {
         return 8192;
      }
      return 8192;
   }

   /**
    * Close input stream and ignore any exceptions.
    * 
    * <p>
    * No-op if input stream is <jk>null</jk>.
    * 
    * @param is The input stream to close.
    */
   public static void closeQuietly(InputStream is) {
      try {
         if (is != null)
            is.close();
      } catch (IOException e) {}
   }

   /**
    * Close output stream and ignore any exceptions.
    * 
    * <p>
    * No-op if output stream is <jk>null</jk>.
    * 
    * @param os The output stream to close.
    */
   public static void closeQuietly(OutputStream os) {
      try {
         if (os != null)
            os.close();
      } catch (IOException e) {}
   }

   /**
    * Close reader and ignore any exceptions.
    * 
    * <p>
    * No-op if reader is <jk>null</jk>.
    * 
    * @param r The reader to close.
    */
   public static void closeQuietly(Reader r) {
      try {
         if (r != null)
            r.close();
      } catch (IOException e) {}
   }

   /**
    * Close writer and ignore any exceptions.
    * 
    * <p>
    * No-op if writer is <jk>null</jk>.
    * 
    * @param w The writer to close.
    */
   public static void closeQuietly(Writer w) {
      try {
         if (w != null)
            w.close();
      } catch (IOException e) {}
   }

   /**
    * Quietly close all specified input streams, output streams, readers, and writers.
    * 
    * @param o The list of all objects to quietly close.
    */
   public static void closeQuietly(Object...o) {
      for (Object o2 : o) {
         if (o2 instanceof InputStream)
            closeQuietly((InputStream)o2);
         if (o2 instanceof OutputStream)
            closeQuietly((OutputStream)o2);
         if (o2 instanceof Reader)
            closeQuietly((Reader)o2);
         if (o2 instanceof Writer)
            closeQuietly((Writer)o2);
      }
   }

   /**
    * Flushes multiple output streams and writers in a single call.
    * 
    * @param o
    *    The objects to flush.
    *    <jk>null</jk> entries are ignored.
    * @throws IOException
    */
   public static void flush(Object...o) throws IOException {
      IOException ex = null;
      for (Object o2 : o) {
         try {
            if (o2 instanceof OutputStream)
               ((OutputStream)o2).flush();
            if (o2 instanceof Writer)
               ((Writer)o2).flush();
         } catch (IOException e) {
            ex = e;
         }
      }
      if (ex != null)
         throw ex;
   }

   /**
    * Close all specified input streams, output streams, readers, and writers.
    * 
    * @param o
    *    The list of all objects to close.
    *    <jk>null</jk> entries are ignored.
    * @throws IOException
    */
   public static void close(Object...o) throws IOException {
      IOException ex = null;
      for (Object o2 : o) {
         try {
            if (o2 instanceof InputStream)
               ((InputStream)o2).close();
            if (o2 instanceof OutputStream)
               ((OutputStream)o2).close();
            if (o2 instanceof Reader)
               ((Reader)o2).close();
            if (o2 instanceof Writer)
               ((Writer)o2).close();
         } catch (IOException e) {
            ex = e;
         }
      }
      if (ex != null)
         throw ex;
   }

   /**
    * Converts an object to a <code>Reader</code>.
    * 
    * @param o
    *    The object to convert to a reader.
    *    Can be any of the following:
    *    <ul>
    *       <li>{@link InputStream}
    *       <li>{@link Reader}
    *       <li>{@link File}
    *       <li>{@link CharSequence}
    *       <li><code><jk>byte</jk>[]</code>
    *       <li><code><jk>null</jk></code> - Returns <jk>null</jk>.
    *    </ul>
    * @return The object converted to a reader.
    * @throws IOException If file could not be read.
    * @throws IllegalArgumentException If invalid object passed in.
    */
   public static Reader toReader(Object o) throws IOException {
      if (o == null)
         return null;
      if (o instanceof CharSequence)
         return new StringReader(o.toString());
      if (o instanceof File)
         return new FileReader((File)o);
      if (o instanceof Reader)
         return (Reader)o;
      if (o instanceof InputStream)
         return new InputStreamReader((InputStream)o, "UTF-8");
      if (o instanceof byte[])
         return new InputStreamReader(new ByteArrayInputStream((byte[])o), "UTF-8");
      throw new FormattedIllegalArgumentException("Invalid object of type {0} passed to IOUtils.toReader(Object)", o.getClass());
   }

   /**
    * Converts an object to an <code>InputStream</code>.
    * 
    * @param o
    *    The object to convert to an input stream.
    *    Can be any of the following:
    *    <ul>
    *       <li>{@link InputStream}
    *       <li>{@link Reader}
    *       <li>{@link File}
    *       <li>{@link CharSequence} - Converted to UTF-8 stream.
    *       <li><code><jk>byte</jk>[]</code>
    *       <li><code><jk>null</jk></code> - Returns <jk>null</jk>.
    *    </ul>
    * @return The object converted to an input stream.
    * @throws IOException If file could not be read.
    * @throws IllegalArgumentException If invalid object passed in.
    */
   public static InputStream toInputStream(Object o) throws IOException {
      if (o == null)
         return null;
      if (o instanceof InputStream)
         return (InputStream)o;
      if (o instanceof File)
         return new FileInputStream((File)o);
      if (o instanceof byte[])
         return new ByteArrayInputStream((byte[])o);
      if (o instanceof CharSequence)
         return new ByteArrayInputStream(((CharSequence)o).toString().getBytes(UTF8));
      if (o instanceof Reader)
         return new ByteArrayInputStream(IOUtils.read((Reader)o).getBytes(UTF8));
      throw new FormattedIllegalArgumentException("Invalid object of type {0} passed to IOUtils.toInputStream(Object)", o.getClass());
   }
}