/*
 * Iris is a World Generator for Minecraft Bukkit Servers
 * Copyright (c) 2021 Arcane Arts (Volmit Software)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

package com.volmit.iris.util;

import com.volmit.iris.Iris;

import java.io.*;
import java.nio.charset.StandardCharsets;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.*;
import java.util.function.Consumer;
import java.util.zip.GZIPInputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;

@SuppressWarnings("ALL")
public class IO {
    /**
     * The Unix directory separator character.
     */
    public static final char DIR_SEPARATOR_UNIX = '/';
    /**
     * The Windows directory separator character.
     */
    public static final char DIR_SEPARATOR_WINDOWS = '\\';
    /**
     * The system directory separator character.
     */
    public static final char DIR_SEPARATOR = File.separatorChar;
    /**
     * The Unix line separator string.
     */
    public static final String LINE_SEPARATOR_UNIX = "\n";
    /**
     * The Windows line separator string.
     */
    public static final String LINE_SEPARATOR_WINDOWS = "\r\n";
    /**
     * The system line separator string.
     */
    public static final String LINE_SEPARATOR;

    /**
     * The default buffer size to use.
     */
    private static final int DEFAULT_BUFFER_SIZE = 1024 * 4;
    private final static char[] hexArray = "0123456789ABCDEF".toCharArray();

    public static String decompress(String gz) throws IOException {
        ByteArrayInputStream bin = new ByteArrayInputStream(Base64.getUrlDecoder().decode(gz));
        GZIPInputStream gzi = new GZIPInputStream(bin);
        ByteArrayOutputStream boas = new ByteArrayOutputStream();
        IO.fullTransfer(gzi, boas, 256);
        gzi.close();

        return boas.toString();
    }

    public static byte[] sdecompress(String compressed) throws IOException {
        ByteArrayInputStream bin = new ByteArrayInputStream(Base64.getUrlDecoder().decode(compressed));
        GZIPInputStream gzi = new GZIPInputStream(bin);
        ByteArrayOutputStream boas = new ByteArrayOutputStream();
        IO.fullTransfer(gzi, boas, 256);
        gzi.close();

        return boas.toByteArray();
    }

    public static String encode(byte[] data) {
        return Base64.getUrlEncoder().encodeToString(data);
    }

    public static byte[] decode(String u) {
        return Base64.getUrlDecoder().decode(u);
    }

    public static String hash(String b) {
        try {
            MessageDigest d = MessageDigest.getInstance("SHA-256");
            return bytesToHex(d.digest(b.getBytes(StandardCharsets.UTF_8)));
        } catch (NoSuchAlgorithmException e) {
            Iris.reportError(e);
            e.printStackTrace();
        }

        return "¯\\_(ツ)_/¯";
    }

    public static String hash(File b) {
        try {
            MessageDigest d = MessageDigest.getInstance("SHA-256");
            DigestInputStream din = new DigestInputStream(new FileInputStream(b), d);
            fullTransfer(din, new VoidOutputStream(), 8192);
            din.close();
            return bytesToHex(din.getMessageDigest().digest());
        } catch (Throwable e) {Iris.reportError(e);
            e.printStackTrace();
        }

        return "¯\\_(ツ)_/¯";
    }

    public static String bytesToHex(byte[] bytes) {
        char[] hexChars = new char[bytes.length * 2];
        for (int j = 0; j < bytes.length; j++) {
            int v = bytes[j] & 0xFF;
            hexChars[j * 2] = hexArray[v >>> 4];
            hexChars[j * 2 + 1] = hexArray[v & 0x0F];
        }

        return new String(hexChars).toUpperCase();
    }

    /**
     * Transfers the length of the buffer amount of data from the input stream to
     * the output stream
     *
     * @param in     the input
     * @param out    the output
     * @return the actual transfered amount
     * @throws IOException shit happens
     */
    public static int transfer(InputStream in, OutputStream out, byte[] buffer) throws IOException {
        int r = in.read(buffer);

        if (r != -1) {
            out.write(buffer, 0, r);
        }

        return r;
    }

    /**
     * Transfers the length of the buffer amount of data from the input stream to
     * the output stream
     *
     * @param in           the input
     * @param out          the output
     * @param targetBuffer the buffer and size to use
     * @param totalSize    the total amount to transfer
     * @return the actual transfered amount
     * @throws IOException shit happens
     */
    public static long transfer(InputStream in, OutputStream out, int targetBuffer, long totalSize) throws IOException {
        long total = totalSize;
        long wrote = 0;
        byte[] buf = new byte[targetBuffer];
        int r = 0;

        while ((r = in.read(buf, 0, (int) (total < targetBuffer ? total : targetBuffer))) != -1) {
            total -= r;
            out.write(buf, 0, r);
            wrote += r;

            if (total <= 0) {
                break;
            }
        }

        return wrote;
    }

    /**
     * Fully move data from a finite inputstream to an output stream using a buffer
     * size of 8192. This does NOT close streams.
     *
     * @param in
     * @param out
     * @return total size transfered
     * @throws IOException
     */
    public static long fillTransfer(InputStream in, OutputStream out) throws IOException {
        return fullTransfer(in, out, 8192);
    }

    public static void deleteUp(File f) {
        if (f.exists()) {
            f.delete();

            if (f.getParentFile().list().length == 0) {
                deleteUp(f.getParentFile());
            }
        }
    }

    /**
     * Fully move data from a finite inputstream to an output stream using a given
     * buffer size. This does NOT close streams.
     *
     * @param in         the input stream to read from
     * @param out        the output stream to write to
     * @param bufferSize the target buffer size
     * @return total size transfered
     * @throws IOException shit happens
     */
    public static long fullTransfer(InputStream in, OutputStream out, int bufferSize) throws IOException {
        long wrote = 0;
        byte[] buf = new byte[bufferSize];
        int r = 0;

        while ((r = in.read(buf)) != -1) {
            out.write(buf, 0, r);
            wrote += r;
        }

        return wrote;
    }

    /**
     * Recursive delete (deleting folders)
     *
     * @param f the file to delete (and subfiles if folder)
     */
    public static void delete(File f) {
        if (f == null || !f.exists()) {
            return;
        }

        if (f.isDirectory()) {
            for (File i : f.listFiles()) {
                delete(i);
            }
        }

        f.delete();
    }

    public static long size(File file) {
        long s = 0;

        if (file.exists()) {
            if (file.isDirectory()) {
                for (File i : file.listFiles()) {
                    s += size(i);
                }
            } else {
                s += file.length();
            }
        }

        return s;
    }

    public static long count(File file) {
        long s = 0;

        if (file.exists()) {
            if (file.isDirectory()) {
                for (File i : file.listFiles()) {
                    s += count(i);
                }
            } else {
                s++;
            }
        }

        return s;
    }

    public static long transfer(InputStream in, OutputStream out, byte[] buf, int totalSize) throws IOException {
        long total = totalSize;
        long wrote = 0;
        int r = 0;

        while ((r = in.read(buf, 0, (int) (total < buf.length ? total : buf.length))) != -1) {
            total -= r;
            out.write(buf, 0, r);
            wrote += r;

            if (total <= 0) {
                break;
            }
        }

        return wrote;
    }

    public static void readEntry(File zipfile, String entryname, Consumer<InputStream> v) throws IOException {
        ZipFile file = new ZipFile(zipfile);
        Throwable x = null;

        try {
            Enumeration<? extends ZipEntry> entries = file.entries();
            while (entries.hasMoreElements()) {
                ZipEntry entry = entries.nextElement();

                if (entryname.equals(entry.getName())) {
                    InputStream in = file.getInputStream(entry);
                    v.accept(in);
                }
            }
        } catch (Exception ex) {Iris.reportError(ex);
            x = ex.getCause();
        } finally {
            file.close();
        }

        if (x != null) {
            throw new IOException("Failed to read zip entry, however it has been closed safely.", x);
        }
    }

    public static void writeAll(File f, Object c) throws IOException {
        f.getParentFile().mkdirs();
        PrintWriter pw = new PrintWriter(new FileWriter(f));
        pw.println(c.toString());
        pw.close();
    }

    public static String readAll(File f) throws IOException {
        FileReader fr;
        try {
            fr = new FileReader(f);
        } catch (IOException e) {Iris.reportError(e);
            throw e;
        }
        BufferedReader bu = new BufferedReader(fr);
        StringBuilder c = new StringBuilder();
        String l = "";

        while ((l = bu.readLine()) != null) {
            c.append(l).append("\n");
        }

        bu.close();

        return c.toString();
    }

    public static String readAll(InputStream in) throws IOException {
        BufferedReader bu = new BufferedReader(new InputStreamReader(in));
        StringBuilder c = new StringBuilder();
        String l = "";

        while ((l = bu.readLine()) != null) {
            c.append(l).append("\n");
        }

        bu.close();

        return c.toString();
    }

    /**
     * Implements the same behaviour as the "touch" utility on Unix. It creates a
     * new file with size 0 or, if the file exists already, it is opened and closed
     * without modifying it, but updating the file date and time.
     *
     * @param file the File to touch
     * @throws IOException If an I/O problem occurs
     */
    public static void touch(File file) throws IOException {
        if (!file.exists()) {
            OutputStream out = new FileOutputStream(file);
            out.close();
        }
        file.setLastModified(System.currentTimeMillis());
    }

    /**
     * Copies a file to a new location preserving the file date.
     * <p>
     * This method copies the contents of the specified source file to the specified
     * destination file. The directory holding the destination file is created if it
     * does not exist. If the destination file exists, then this method will
     * overwrite it.
     *
     * @param srcFile  an existing file to copy, must not be null
     * @param destFile the new file, must not be null
     * @throws NullPointerException if source or destination is null
     * @throws IOException          if source or destination is invalid
     * @throws IOException          if an IO error occurs during copying
     */
    public static void copyFile(File srcFile, File destFile) throws IOException {
        copyFile(srcFile, destFile, true);
    }

    /**
     * Copies a file to a new location.
     * <p>
     * This method copies the contents of the specified source file to the specified
     * destination file. The directory holding the destination file is created if it
     * does not exist. If the destination file exists, then this method will
     * overwrite it.
     *
     * @param srcFile          an existing file to copy, must not be null
     * @param destFile         the new file, must not be null
     * @param preserveFileDate true if the file date of the copy should be the same as the
     *                         original
     * @throws NullPointerException if source or destination is null
     * @throws IOException          if source or destination is invalid
     * @throws IOException          if an IO error occurs during copying
     */
    public static void copyFile(File srcFile, File destFile, boolean preserveFileDate) throws IOException {
        if (srcFile == null) {
            throw new NullPointerException("Source must not be null");
        }
        if (destFile == null) {
            throw new NullPointerException("Destination must not be null");
        }
        if (!srcFile.exists()) {
            throw new FileNotFoundException("Source '" + srcFile + "' does not exist");
        }
        if (srcFile.isDirectory()) {
            throw new IOException("Source '" + srcFile + "' exists but is a directory");
        }
        if (srcFile.getCanonicalPath().equals(destFile.getCanonicalPath())) {
            throw new IOException("Source '" + srcFile + "' and destination '" + destFile + "' are the same");
        }
        if (destFile.getParentFile() != null && !destFile.getParentFile().exists()) {
            if (!destFile.getParentFile().mkdirs()) {
                throw new IOException("Destination '" + destFile + "' directory cannot be created");
            }
        }
        if (destFile.exists() && !destFile.canWrite()) {
            throw new IOException("Destination '" + destFile + "' exists but is read-only");
        }
        doCopyFile(srcFile, destFile, preserveFileDate);
    }

    /**
     * Internal copy file method.
     *
     * @param srcFile          the validated source file, not null
     * @param destFile         the validated destination file, not null
     * @param preserveFileDate whether to preserve the file date
     * @throws IOException if an error occurs
     */
    private static void doCopyFile(File srcFile, File destFile, boolean preserveFileDate) throws IOException {
        if (destFile.exists() && destFile.isDirectory()) {
            throw new IOException("Destination '" + destFile + "' exists but is a directory");
        }

        FileInputStream input = new FileInputStream(srcFile);
        try {
            FileOutputStream output = new FileOutputStream(destFile);
            try {
                IO.copy(input, output);
            } finally {
                output.close();
            }
        } finally {
            input.close();
        }

        if (srcFile.length() != destFile.length()) {
            throw new IOException("Failed to copy full contents from '" + srcFile + "' to '" + destFile + "'");
        }
        if (preserveFileDate) {
            destFile.setLastModified(srcFile.lastModified());
        }
    }

    // -----------------------------------------------------------------------

    /**
     * Unconditionally close an <code>Reader</code>.
     * <p>
     * Equivalent to {@link Reader#close()}, except any exceptions will be ignored.
     * This is typically used in finally blocks.
     *
     * @param input the Reader to close, may be null or already closed
     */
    public static void closeQuietly(Reader input) {
        try {
            if (input != null) {
                input.close();
            }
        } catch (IOException e) {Iris.reportError(e);
            // ignore
        }
    }

    /**
     * Unconditionally close a <code>Writer</code>.
     * <p>
     * Equivalent to {@link Writer#close()}, except any exceptions will be ignored.
     * This is typically used in finally blocks.
     *
     * @param output the Writer to close, may be null or already closed
     */
    public static void closeQuietly(Writer output) {
        try {
            if (output != null) {
                output.close();
            }
        } catch (IOException e) {Iris.reportError(e);
            // ignore
        }
    }

    /**
     * Unconditionally close an <code>InputStream</code>.
     * <p>
     * Equivalent to {@link InputStream#close()}, except any exceptions will be
     * ignored. This is typically used in finally blocks.
     *
     * @param input the InputStream to close, may be null or already closed
     */
    public static void closeQuietly(InputStream input) {
        try {
            if (input != null) {
                input.close();
            }
        } catch (IOException e) {Iris.reportError(e);
            // ignore
        }
    }

    /**
     * Unconditionally close an <code>OutputStream</code>.
     * <p>
     * Equivalent to {@link OutputStream#close()}, except any exceptions will be
     * ignored. This is typically used in finally blocks.
     *
     * @param output the OutputStream to close, may be null or already closed
     */
    public static void closeQuietly(OutputStream output) {
        try {
            if (output != null) {
                output.close();
            }
        } catch (IOException e) {Iris.reportError(e);
            // ignore
        }
    }

    // read toByteArray
    // -----------------------------------------------------------------------

    /**
     * Get the contents of an <code>InputStream</code> as a <code>byte[]</code>.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedInputStream</code>.
     *
     * @param input the <code>InputStream</code> to read from
     * @return the requested byte array
     * @throws NullPointerException if the input is null
     * @throws IOException          if an I/O error occurs
     */
    public static byte[] toByteArray(InputStream input) throws IOException {
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        copy(input, output);
        return output.toByteArray();
    }

    /**
     * Get the contents of a <code>Reader</code> as a <code>byte[]</code> using the
     * default character encoding of the platform.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedReader</code>.
     *
     * @param input the <code>Reader</code> to read from
     * @return the requested byte array
     * @throws NullPointerException if the input is null
     * @throws IOException          if an I/O error occurs
     */
    public static byte[] toByteArray(Reader input) throws IOException {
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        copy(input, output);
        return output.toByteArray();
    }

    /**
     * Get the contents of a <code>Reader</code> as a <code>byte[]</code> using the
     * specified character encoding.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedReader</code>.
     *
     * @param input    the <code>Reader</code> to read from
     * @param encoding the encoding to use, null means platform default
     * @return the requested byte array
     * @throws NullPointerException if the input is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static byte[] toByteArray(Reader input, String encoding) throws IOException {
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        copy(input, output, encoding);
        return output.toByteArray();
    }

    /**
     * Get the contents of a <code>String</code> as a <code>byte[]</code> using the
     * default character encoding of the platform.
     * <p>
     * This is the same as {@link String#getBytes()}.
     *
     * @param input the <code>String</code> to convert
     * @return the requested byte array
     * @deprecated Use {@link String#getBytes()}
     */
    public static byte[] toByteArray(String input) {
        return input.getBytes();
    }

    // read char[]
    // -----------------------------------------------------------------------

    /**
     * Get the contents of an <code>InputStream</code> as a character array using
     * the default character encoding of the platform.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedInputStream</code>.
     *
     * @param is the <code>InputStream</code> to read from
     * @return the requested character array
     * @throws NullPointerException if the input is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static char[] toCharArray(InputStream is) throws IOException {
        CharArrayWriter output = new CharArrayWriter();
        copy(is, output);
        return output.toCharArray();
    }

    /**
     * Get the contents of an <code>InputStream</code> as a character array using
     * the specified character encoding.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedInputStream</code>.
     *
     * @param is       the <code>InputStream</code> to read from
     * @param encoding the encoding to use, null means platform default
     * @return the requested character array
     * @throws NullPointerException if the input is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static char[] toCharArray(InputStream is, String encoding) throws IOException {
        CharArrayWriter output = new CharArrayWriter();
        copy(is, output, encoding);
        return output.toCharArray();
    }

    /**
     * Get the contents of a <code>Reader</code> as a character array.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedReader</code>.
     *
     * @param input the <code>Reader</code> to read from
     * @return the requested character array
     * @throws NullPointerException if the input is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static char[] toCharArray(Reader input) throws IOException {
        CharArrayWriter sw = new CharArrayWriter();
        copy(input, sw);
        return sw.toCharArray();
    }

    // read toString
    // -----------------------------------------------------------------------

    /**
     * Get the contents of an <code>InputStream</code> as a String using the default
     * character encoding of the platform.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedInputStream</code>.
     *
     * @param input the <code>InputStream</code> to read from
     * @return the requested String
     * @throws NullPointerException if the input is null
     * @throws IOException          if an I/O error occurs
     */
    public static String toString(InputStream input) throws IOException {
        StringWriter sw = new StringWriter();
        copy(input, sw);
        return sw.toString();
    }

    /**
     * Get the contents of an <code>InputStream</code> as a String using the
     * specified character encoding.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedInputStream</code>.
     *
     * @param input    the <code>InputStream</code> to read from
     * @param encoding the encoding to use, null means platform default
     * @return the requested String
     * @throws NullPointerException if the input is null
     * @throws IOException          if an I/O error occurs
     */
    public static String toString(InputStream input, String encoding) throws IOException {
        StringWriter sw = new StringWriter();
        copy(input, sw, encoding);
        return sw.toString();
    }

    /**
     * Get the contents of a <code>Reader</code> as a String.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedReader</code>.
     *
     * @param input the <code>Reader</code> to read from
     * @return the requested String
     * @throws NullPointerException if the input is null
     * @throws IOException          if an I/O error occurs
     */
    public static String toString(Reader input) throws IOException {
        StringWriter sw = new StringWriter();
        copy(input, sw);
        return sw.toString();
    }

    /**
     * Get the contents of a <code>byte[]</code> as a String using the default
     * character encoding of the platform.
     *
     * @param input the byte array to read from
     * @return the requested String
     * @deprecated Use {@link String#String(byte[])}
     */
    public static String toString(byte[] input) {
        return new String(input);
    }

    /**
     * Get the contents of a <code>byte[]</code> as a String using the specified
     * character encoding.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     *
     * @param input    the byte array to read from
     * @param encoding the encoding to use, null means platform default
     * @return the requested String
     * @throws NullPointerException if the input is null
     * @throws IOException          if an I/O error occurs (never occurs)
     * @deprecated Use {@link String#String(byte[], String)}
     */
    public static String toString(byte[] input, String encoding) throws IOException {
        if (encoding == null) {
            return new String(input);
        } else {
            return new String(input, encoding);
        }
    }

    // readLines
    // -----------------------------------------------------------------------

    /**
     * Get the contents of an <code>InputStream</code> as a list of Strings, one
     * entry per line, using the default character encoding of the platform.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedInputStream</code>.
     *
     * @param input the <code>InputStream</code> to read from, not null
     * @return the list of Strings, never null
     * @throws NullPointerException if the input is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static List<String> readLines(InputStream input) throws IOException {
        InputStreamReader reader = new InputStreamReader(input);
        return readLines(reader);
    }

    /**
     * Get the contents of an <code>InputStream</code> as a list of Strings, one
     * entry per line, using the specified character encoding.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedInputStream</code>.
     *
     * @param input    the <code>InputStream</code> to read from, not null
     * @param encoding the encoding to use, null means platform default
     * @return the list of Strings, never null
     * @throws NullPointerException if the input is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static List<String> readLines(InputStream input, String encoding) throws IOException {
        if (encoding == null) {
            return readLines(input);
        } else {
            InputStreamReader reader = new InputStreamReader(input, encoding);
            return readLines(reader);
        }
    }

    /**
     * Get the contents of a <code>Reader</code> as a list of Strings, one entry per
     * line.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedReader</code>.
     *
     * @param input the <code>Reader</code> to read from, not null
     * @return the list of Strings, never null
     * @throws NullPointerException if the input is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static List<String> readLines(Reader input) throws IOException {
        BufferedReader reader = new BufferedReader(input);
        List<String> list = new ArrayList<String>();
        String line = reader.readLine();
        while (line != null) {
            list.add(line);
            line = reader.readLine();
        }
        return list;
    }

    // -----------------------------------------------------------------------

    /**
     * Convert the specified string to an input stream, encoded as bytes using the
     * default character encoding of the platform.
     *
     * @param input the string to convert
     * @return an input stream
     * @since Commons IO 1.1
     */
    public static InputStream toInputStream(String input) {
        byte[] bytes = input.getBytes();
        return new ByteArrayInputStream(bytes);
    }

    /**
     * Convert the specified string to an input stream, encoded as bytes using the
     * specified character encoding.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     *
     * @param input    the string to convert
     * @param encoding the encoding to use, null means platform default
     * @return an input stream
     * @throws IOException if the encoding is invalid
     * @since Commons IO 1.1
     */
    public static InputStream toInputStream(String input, String encoding) throws IOException {
        byte[] bytes = encoding != null ? input.getBytes(encoding) : input.getBytes();
        return new ByteArrayInputStream(bytes);
    }

    // write byte[]
    // -----------------------------------------------------------------------

    /**
     * Writes bytes from a <code>byte[]</code> to an <code>OutputStream</code>.
     *
     * @param data   the byte array to write, do not modify during output, null ignored
     * @param output the <code>OutputStream</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void write(byte[] data, OutputStream output) throws IOException {
        if (data != null) {
            output.write(data);
        }
    }

    /**
     * Writes bytes from a <code>byte[]</code> to chars on a <code>Writer</code>
     * using the default character encoding of the platform.
     * <p>
     * This method uses {@link String#String(byte[])}.
     *
     * @param data   the byte array to write, do not modify during output, null ignored
     * @param output the <code>Writer</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void write(byte[] data, Writer output) throws IOException {
        if (data != null) {
            output.write(new String(data));
        }
    }

    /**
     * Writes bytes from a <code>byte[]</code> to chars on a <code>Writer</code>
     * using the specified character encoding.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     * <p>
     * This method uses {@link String#String(byte[], String)}.
     *
     * @param data     the byte array to write, do not modify during output, null ignored
     * @param output   the <code>Writer</code> to write to
     * @param encoding the encoding to use, null means platform default
     * @throws NullPointerException if output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void write(byte[] data, Writer output, String encoding) throws IOException {
        if (data != null) {
            if (encoding == null) {
                write(data, output);
            } else {
                output.write(new String(data, encoding));
            }
        }
    }

    // write char[]
    // -----------------------------------------------------------------------

    /**
     * Writes chars from a <code>char[]</code> to a <code>Writer</code> using the
     * default character encoding of the platform.
     *
     * @param data   the char array to write, do not modify during output, null ignored
     * @param output the <code>Writer</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void write(char[] data, Writer output) throws IOException {
        if (data != null) {
            output.write(data);
        }
    }

    /**
     * Writes chars from a <code>char[]</code> to bytes on an
     * <code>OutputStream</code>.
     * <p>
     * This method uses {@link String#String(char[])} and {@link String#getBytes()}.
     *
     * @param data   the char array to write, do not modify during output, null ignored
     * @param output the <code>OutputStream</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void write(char[] data, OutputStream output) throws IOException {
        if (data != null) {
            output.write(new String(data).getBytes());
        }
    }

    /**
     * Writes chars from a <code>char[]</code> to bytes on an
     * <code>OutputStream</code> using the specified character encoding.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     * <p>
     * This method uses {@link String#String(char[])} and
     * {@link String#getBytes(String)}.
     *
     * @param data     the char array to write, do not modify during output, null ignored
     * @param output   the <code>OutputStream</code> to write to
     * @param encoding the encoding to use, null means platform default
     * @throws NullPointerException if output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void write(char[] data, OutputStream output, String encoding) throws IOException {
        if (data != null) {
            if (encoding == null) {
                write(data, output);
            } else {
                output.write(new String(data).getBytes(encoding));
            }
        }
    }

    // write String
    // -----------------------------------------------------------------------

    /**
     * Writes chars from a <code>String</code> to a <code>Writer</code>.
     *
     * @param data   the <code>String</code> to write, null ignored
     * @param output the <code>Writer</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void write(String data, Writer output) throws IOException {
        if (data != null) {
            output.write(data);
        }
    }

    /**
     * Writes chars from a <code>String</code> to bytes on an
     * <code>OutputStream</code> using the default character encoding of the
     * platform.
     * <p>
     * This method uses {@link String#getBytes()}.
     *
     * @param data   the <code>String</code> to write, null ignored
     * @param output the <code>OutputStream</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void write(String data, OutputStream output) throws IOException {
        if (data != null) {
            output.write(data.getBytes());
        }
    }

    /**
     * Writes chars from a <code>String</code> to bytes on an
     * <code>OutputStream</code> using the specified character encoding.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     * <p>
     * This method uses {@link String#getBytes(String)}.
     *
     * @param data     the <code>String</code> to write, null ignored
     * @param output   the <code>OutputStream</code> to write to
     * @param encoding the encoding to use, null means platform default
     * @throws NullPointerException if output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void write(String data, OutputStream output, String encoding) throws IOException {
        if (data != null) {
            if (encoding == null) {
                write(data, output);
            } else {
                output.write(data.getBytes(encoding));
            }
        }
    }

    // write StringBuffer
    // -----------------------------------------------------------------------

    /**
     * Writes chars from a <code>StringBuffer</code> to a <code>Writer</code>.
     *
     * @param data   the <code>StringBuffer</code> to write, null ignored
     * @param output the <code>Writer</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void write(StringBuffer data, Writer output) throws IOException {
        if (data != null) {
            output.write(data.toString());
        }
    }

    /**
     * Writes chars from a <code>StringBuffer</code> to bytes on an
     * <code>OutputStream</code> using the default character encoding of the
     * platform.
     * <p>
     * This method uses {@link String#getBytes()}.
     *
     * @param data   the <code>StringBuffer</code> to write, null ignored
     * @param output the <code>OutputStream</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void write(StringBuffer data, OutputStream output) throws IOException {
        if (data != null) {
            output.write(data.toString().getBytes());
        }
    }

    /**
     * Writes chars from a <code>StringBuffer</code> to bytes on an
     * <code>OutputStream</code> using the specified character encoding.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     * <p>
     * This method uses {@link String#getBytes(String)}.
     *
     * @param data     the <code>StringBuffer</code> to write, null ignored
     * @param output   the <code>OutputStream</code> to write to
     * @param encoding the encoding to use, null means platform default
     * @throws NullPointerException if output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void write(StringBuffer data, OutputStream output, String encoding) throws IOException {
        if (data != null) {
            if (encoding == null) {
                write(data, output);
            } else {
                output.write(data.toString().getBytes(encoding));
            }
        }
    }

    // writeLines
    // -----------------------------------------------------------------------

    /**
     * Writes the <code>toString()</code> value of each item in a collection to an
     * <code>OutputStream</code> line by line, using the default character encoding
     * of the platform and the specified line ending.
     *
     * @param lines      the lines to write, null entries produce blank lines
     * @param lineEnding the line separator to use, null is system default
     * @param output     the <code>OutputStream</code> to write to, not null, not closed
     * @throws NullPointerException if the output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void writeLines(Collection<String> lines, String lineEnding, OutputStream output) throws IOException {
        if (lines == null) {
            return;
        }
        if (lineEnding == null) {
            lineEnding = LINE_SEPARATOR;
        }
        for (Iterator<String> it = lines.iterator(); it.hasNext(); ) {
            Object line = it.next();
            if (line != null) {
                output.write(line.toString().getBytes());
            }
            output.write(lineEnding.getBytes());
        }
    }

    /**
     * Writes the <code>toString()</code> value of each item in a collection to an
     * <code>OutputStream</code> line by line, using the specified character
     * encoding and the specified line ending.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     *
     * @param lines      the lines to write, null entries produce blank lines
     * @param lineEnding the line separator to use, null is system default
     * @param output     the <code>OutputStream</code> to write to, not null, not closed
     * @param encoding   the encoding to use, null means platform default
     * @throws NullPointerException if the output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void writeLines(Collection<String> lines, String lineEnding, OutputStream output, String encoding) throws IOException {
        if (encoding == null) {
            writeLines(lines, lineEnding, output);
        } else {
            if (lines == null) {
                return;
            }
            if (lineEnding == null) {
                lineEnding = LINE_SEPARATOR;
            }
            for (Iterator<String> it = lines.iterator(); it.hasNext(); ) {
                Object line = it.next();
                if (line != null) {
                    output.write(line.toString().getBytes(encoding));
                }
                output.write(lineEnding.getBytes(encoding));
            }
        }
    }

    /**
     * Writes the <code>toString()</code> value of each item in a collection to a
     * <code>Writer</code> line by line, using the specified line ending.
     *
     * @param lines      the lines to write, null entries produce blank lines
     * @param lineEnding the line separator to use, null is system default
     * @param writer     the <code>Writer</code> to write to, not null, not closed
     * @throws NullPointerException if the input is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void writeLines(Collection<String> lines, String lineEnding, Writer writer) throws IOException {
        if (lines == null) {
            return;
        }
        if (lineEnding == null) {
            lineEnding = LINE_SEPARATOR;
        }
        for (Iterator<String> it = lines.iterator(); it.hasNext(); ) {
            Object line = it.next();
            if (line != null) {
                writer.write(line.toString());
            }
            writer.write(lineEnding);
        }
    }

    // copy from InputStream
    // -----------------------------------------------------------------------

    /**
     * Copy bytes from an <code>InputStream</code> to an <code>OutputStream</code>.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedInputStream</code>.
     * <p>
     * Large streams (over 2GB) will return a bytes copied value of <code>-1</code>
     * after the copy has completed since the correct number of bytes cannot be
     * returned as an int. For large streams use the
     * <code>copyLarge(InputStream, OutputStream)</code> method.
     *
     * @param input  the <code>InputStream</code> to read from
     * @param output the <code>OutputStream</code> to write to
     * @return the number of bytes copied
     * @throws NullPointerException if the input or output is null
     * @throws IOException          if an I/O error occurs
     * @throws ArithmeticException  if the byte count is too large
     * @since Commons IO 1.1
     */
    public static int copy(InputStream input, OutputStream output) throws IOException {
        long count = copyLarge(input, output);
        if (count > Integer.MAX_VALUE) {
            return -1;
        }
        return (int) count;
    }

    /**
     * Copy bytes from a large (over 2GB) <code>InputStream</code> to an
     * <code>OutputStream</code>.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedInputStream</code>.
     *
     * @param input  the <code>InputStream</code> to read from
     * @param output the <code>OutputStream</code> to write to
     * @return the number of bytes copied
     * @throws NullPointerException if the input or output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.3
     */
    public static long copyLarge(InputStream input, OutputStream output) throws IOException {
        byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
        long count = 0;
        int n = 0;
        while (-1 != (n = input.read(buffer))) {
            output.write(buffer, 0, n);
            count += n;
        }
        return count;
    }

    /**
     * Copy bytes from an <code>InputStream</code> to chars on a <code>Writer</code>
     * using the default character encoding of the platform.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedInputStream</code>.
     * <p>
     * This method uses {@link InputStreamReader}.
     *
     * @param input  the <code>InputStream</code> to read from
     * @param output the <code>Writer</code> to write to
     * @throws NullPointerException if the input or output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void copy(InputStream input, Writer output) throws IOException {
        InputStreamReader in = new InputStreamReader(input);
        copy(in, output);
    }

    /**
     * Copy bytes from an <code>InputStream</code> to chars on a <code>Writer</code>
     * using the specified character encoding.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedInputStream</code>.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     * <p>
     * This method uses {@link InputStreamReader}.
     *
     * @param input    the <code>InputStream</code> to read from
     * @param output   the <code>Writer</code> to write to
     * @param encoding the encoding to use, null means platform default
     * @throws NullPointerException if the input or output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void copy(InputStream input, Writer output, String encoding) throws IOException {
        if (encoding == null) {
            copy(input, output);
        } else {
            InputStreamReader in = new InputStreamReader(input, encoding);
            copy(in, output);
        }
    }

    // copy from Reader
    // -----------------------------------------------------------------------

    /**
     * Copy chars from a <code>Reader</code> to a <code>Writer</code>.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedReader</code>.
     * <p>
     * Large streams (over 2GB) will return a chars copied value of <code>-1</code>
     * after the copy has completed since the correct number of chars cannot be
     * returned as an int. For large streams use the
     * <code>copyLarge(Reader, Writer)</code> method.
     *
     * @param input  the <code>Reader</code> to read from
     * @param output the <code>Writer</code> to write to
     * @return the number of characters copied
     * @throws NullPointerException if the input or output is null
     * @throws IOException          if an I/O error occurs
     * @throws ArithmeticException  if the character count is too large
     * @since Commons IO 1.1
     */
    public static int copy(Reader input, Writer output) throws IOException {
        long count = copyLarge(input, output);
        if (count > Integer.MAX_VALUE) {
            return -1;
        }
        return (int) count;
    }

    /**
     * Copy chars from a large (over 2GB) <code>Reader</code> to a
     * <code>Writer</code>.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedReader</code>.
     *
     * @param input  the <code>Reader</code> to read from
     * @param output the <code>Writer</code> to write to
     * @return the number of characters copied
     * @throws NullPointerException if the input or output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.3
     */
    public static long copyLarge(Reader input, Writer output) throws IOException {
        char[] buffer = new char[DEFAULT_BUFFER_SIZE];
        long count = 0;
        int n = 0;
        while (-1 != (n = input.read(buffer))) {
            output.write(buffer, 0, n);
            count += n;
        }
        return count;
    }

    /**
     * Copy chars from a <code>Reader</code> to bytes on an
     * <code>OutputStream</code> using the default character encoding of the
     * platform, and calling flush.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedReader</code>.
     * <p>
     * Due to the implementation of OutputStreamWriter, this method performs a
     * flush.
     * <p>
     * This method uses {@link OutputStreamWriter}.
     *
     * @param input  the <code>Reader</code> to read from
     * @param output the <code>OutputStream</code> to write to
     * @throws NullPointerException if the input or output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void copy(Reader input, OutputStream output) throws IOException {
        OutputStreamWriter out = new OutputStreamWriter(output);
        copy(input, out);
        // have to flush here.
        out.flush();
    }

    /**
     * Copy chars from a <code>Reader</code> to bytes on an
     * <code>OutputStream</code> using the specified character encoding, and calling
     * flush.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedReader</code>.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     * <p>
     * Due to the implementation of OutputStreamWriter, this method performs a
     * flush.
     * <p>
     * This method uses {@link OutputStreamWriter}.
     *
     * @param input    the <code>Reader</code> to read from
     * @param output   the <code>OutputStream</code> to write to
     * @param encoding the encoding to use, null means platform default
     * @throws NullPointerException if the input or output is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static void copy(Reader input, OutputStream output, String encoding) throws IOException {
        if (encoding == null) {
            copy(input, output);
        } else {
            OutputStreamWriter out = new OutputStreamWriter(output, encoding);
            copy(input, out);
            // we have to flush here.
            out.flush();
        }
    }

    // content equals
    // -----------------------------------------------------------------------

    /**
     * Compare the contents of two Streams to determine if they are equal or not.
     * <p>
     * This method buffers the input internally using
     * <code>BufferedInputStream</code> if they are not already buffered.
     *
     * @param input1 the first stream
     * @param input2 the second stream
     * @return true if the content of the streams are equal or they both don't
     * exist, false otherwise
     * @throws NullPointerException if either input is null
     * @throws IOException          if an I/O error occurs
     */
    public static boolean contentEquals(InputStream input1, InputStream input2) throws IOException {
        if (!(input1 instanceof BufferedInputStream)) {
            input1 = new BufferedInputStream(input1);
        }
        if (!(input2 instanceof BufferedInputStream)) {
            input2 = new BufferedInputStream(input2);
        }

        int ch = input1.read();
        while (-1 != ch) {
            int ch2 = input2.read();
            if (ch != ch2) {
                return false;
            }
            ch = input1.read();
        }

        int ch2 = input2.read();
        return (ch2 == -1);
    }

    /**
     * Compare the contents of two Readers to determine if they are equal or not.
     * <p>
     * This method buffers the input internally using <code>BufferedReader</code> if
     * they are not already buffered.
     *
     * @param input1 the first reader
     * @param input2 the second reader
     * @return true if the content of the readers are equal or they both don't
     * exist, false otherwise
     * @throws NullPointerException if either input is null
     * @throws IOException          if an I/O error occurs
     * @since Commons IO 1.1
     */
    public static boolean contentEquals(Reader input1, Reader input2) throws IOException {
        if (!(input1 instanceof BufferedReader)) {
            input1 = new BufferedReader(input1);
        }
        if (!(input2 instanceof BufferedReader)) {
            input2 = new BufferedReader(input2);
        }

        int ch = input1.read();
        while (-1 != ch) {
            int ch2 = input2.read();
            if (ch != ch2) {
                return false;
            }
            ch = input1.read();
        }

        int ch2 = input2.read();
        return (ch2 == -1);
    }

    static {
        // avoid security issues
        StringWriter buf = new StringWriter(4);
        PrintWriter out = new PrintWriter(buf);
        out.println();
        LINE_SEPARATOR = buf.toString();
    }
}