/*
 * Copyright (c) 2002-2012, the original author or authors.
 *
 * This software is distributable under the BSD license. See the terms of the
 * BSD license in the documentation provided with this software.
 *
 * http://www.opensource.org/licenses/bsd-license.php
 */
package jdk.internal.jline.console.internal;

import jdk.internal.jline.console.ConsoleReader;

import java.io.IOException;
import java.io.InputStream;
import java.io.SequenceInputStream;
import java.util.Enumeration;

// FIXME: Clean up API and move to jline.console.runner package

/**
 * An {@link InputStream} implementation that wraps a {@link ConsoleReader}.
 * It is useful for setting up the {@link System#in} for a generic console.
 *
 * @author <a href="mailto:mwp1@cornell.edu">Marc Prud'hommeaux</a>
 * @since 2.7
 */
class ConsoleReaderInputStream
    extends SequenceInputStream
{
    private static InputStream systemIn = System.in;

    public static void setIn() throws IOException {
        setIn(new ConsoleReader());
    }

    public static void setIn(final ConsoleReader reader) {
        System.setIn(new ConsoleReaderInputStream(reader));
    }

    /**
     * Restore the original {@link System#in} input stream.
     */
    public static void restoreIn() {
        System.setIn(systemIn);
    }

    public ConsoleReaderInputStream(final ConsoleReader reader) {
        super(new ConsoleEnumeration(reader));
    }

    private static class ConsoleEnumeration
        implements Enumeration<InputStream>
    {
        private final ConsoleReader reader;
        private ConsoleLineInputStream next = null;
        private ConsoleLineInputStream prev = null;

        public ConsoleEnumeration(final ConsoleReader reader) {
            this.reader = reader;
        }

        public InputStream nextElement() {
            if (next != null) {
                InputStream n = next;
                prev = next;
                next = null;

                return n;
            }

            return new ConsoleLineInputStream(reader);
        }

        public boolean hasMoreElements() {
            // the last line was null
            if ((prev != null) && (prev.wasNull == true)) {
                return false;
            }

            if (next == null) {
                next = (ConsoleLineInputStream) nextElement();
            }

            return next != null;
        }
    }

    private static class ConsoleLineInputStream
        extends InputStream
    {
        private final ConsoleReader reader;
        private String line = null;
        private int index = 0;
        private boolean eol = false;
        protected boolean wasNull = false;

        public ConsoleLineInputStream(final ConsoleReader reader) {
            this.reader = reader;
        }

        public int read() throws IOException {
            if (eol) {
                return -1;
            }

            if (line == null) {
                line = reader.readLine();
            }

            if (line == null) {
                wasNull = true;
                return -1;
            }

            if (index >= line.length()) {
                eol = true;
                return '\n'; // lines are ended with a newline
            }

            return line.charAt(index++);
        }
    }
}