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/***** BEGIN LICENSE BLOCK *****
 * Version: EPL 2.0/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Eclipse Public
 * 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.eclipse.org/legal/epl-v20.html
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * Copyright (C) 2006 Nick Sieger 
 * 
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
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package org.jruby.ext.io.wait;

import org.jruby.Ruby;
import org.jruby.RubyClass;
import org.jruby.RubyIO;
import org.jruby.RubyNumeric;
import org.jruby.RubySymbol;
import org.jruby.RubyTime;
import org.jruby.anno.JRubyMethod;
import org.jruby.runtime.Helpers;
import org.jruby.runtime.ThreadContext;
import org.jruby.runtime.builtin.IRubyObject;
import org.jruby.runtime.load.Library;
import org.jruby.util.io.OpenFile;

import java.nio.channels.SelectionKey;

/**
 * @author Nick Sieger
 */
public class IOWaitLibrary implements Library {

    public void load(Ruby runtime, boolean wrap) {
        RubyClass ioClass = runtime.getIO();
        ioClass.defineAnnotatedMethods(IOWaitLibrary.class);
    }

    @JRubyMethod
    public static IRubyObject nread(ThreadContext context, IRubyObject _io) {
        Ruby runtime = context.runtime;
        OpenFile fptr;
        int len;
//        ioctl_arg n;
        RubyIO io = (RubyIO)_io;

        fptr = io.getOpenFileChecked();
        fptr.checkReadable(context);
        len = fptr.readPending();
        if (len > 0) return runtime.newFixnum(len);
        // TODO: better effort to get available bytes from our channel
//        if (!FIONREAD_POSSIBLE_P(fptr->fd)) return INT2FIX(0);
//        if (ioctl(fptr->fd, FIONREAD, &n)) return INT2FIX(0);
//        if (n > 0) return ioctl_arg2num(n);
        // Because we can't get an actual system-level buffer available count, we fake it by returning 1 if ready
        return RubyNumeric.int2fix(runtime, fptr.readyNow(context) ? 1 : 0);
    }

    /**
     * returns non-nil if input available without blocking, false if EOF or not open/readable, otherwise nil.
     */
    @JRubyMethod(name = "ready?")
    public static IRubyObject ready(ThreadContext context, IRubyObject _io) {
        RubyIO io = (RubyIO)_io;
        Ruby runtime = context.runtime;
        OpenFile fptr;
//        ioctl_arg n;

        fptr = io.getOpenFileChecked();
        fptr.checkReadable(context);
        if (fptr.readPending() != 0) return runtime.getTrue();
        // TODO: better effort to get available bytes from our channel
//        if (!FIONREAD_POSSIBLE_P(fptr->fd)) return Qnil;
//        if (ioctl(fptr->fd, FIONREAD, &n)) return Qnil;
//        if (n > 0) return Qtrue;
        return runtime.newBoolean(fptr.readyNow(context));
    }

    @JRubyMethod(optional = 1)
    public static IRubyObject wait_readable(ThreadContext context, IRubyObject _io, IRubyObject[] argv) {
        RubyIO io = (RubyIO)_io;
        OpenFile fptr = io.getOpenFileChecked();

        fptr.checkReadable(context);

        long tv = prepareTimeout(context, argv);

        if (fptr.readPending() != 0) return context.tru;

        return doWait(context, io, fptr, tv, SelectionKey.OP_READ | SelectionKey.OP_ACCEPT);
    }

    /**
     * waits until input available or timed out and returns self, or nil when EOF reached.
     */
    @JRubyMethod(optional = 1)
    public static IRubyObject wait_writable(ThreadContext context, IRubyObject _io, IRubyObject[] argv) {
        RubyIO io = (RubyIO)_io;

        OpenFile fptr = io.getOpenFileChecked();

        fptr.checkWritable(context);

        long tv = prepareTimeout(context, argv);

        return doWait(context, io, fptr, tv, SelectionKey.OP_CONNECT | SelectionKey.OP_WRITE);
    }

    @JRubyMethod(optional = 2)
    public static IRubyObject wait(ThreadContext context, IRubyObject _io, IRubyObject[] argv) {
        RubyIO io = (RubyIO)_io;

        OpenFile fptr = io.getOpenFileChecked();

        int ops = 0;

        if (argv.length == 2) {
            if (argv[1] instanceof RubySymbol) {
                RubySymbol sym = (RubySymbol) argv[1];
                switch (sym.asJavaString()) { // 7 bit comparison
                    case "r":
                    case "read":
                    case "readable":
                        ops |= SelectionKey.OP_ACCEPT | SelectionKey.OP_READ;
                        break;
                    case "w":
                    case "write":
                    case "writable":
                        ops |= SelectionKey.OP_CONNECT | SelectionKey.OP_WRITE;
                        break;
                    case "rw":
                    case "read_write":
                    case "readable_writable":
                        ops |= SelectionKey.OP_ACCEPT | SelectionKey.OP_READ | SelectionKey.OP_CONNECT | SelectionKey.OP_WRITE;
                        break;
                    default:
                        throw context.runtime.newArgumentError("unsupported mode: " + sym);
                }
            } else {
                throw context.runtime.newArgumentError("unsupported mode: " + argv[1].getType());
            }
        } else {
            ops |= SelectionKey.OP_ACCEPT | SelectionKey.OP_READ;
        }

        if ((ops & SelectionKey.OP_READ) == SelectionKey.OP_READ && fptr.readPending() != 0) return context.tru;

        long tv = prepareTimeout(context, argv);

        return doWait(context, io, fptr, tv, ops);
    }

    private static IRubyObject doWait(ThreadContext context, RubyIO io, OpenFile fptr, long tv, int ops) {
        boolean ready = fptr.ready(context.runtime, context.getThread(), ops, tv);
        fptr.checkClosed();
        if (ready) return io;
        return context.nil;
    }

    private static long prepareTimeout(ThreadContext context, IRubyObject[] argv) {
        IRubyObject timeout;
        long tv;
        switch (argv.length) {
            case 2:
            case 1:
                timeout = argv[0];
                break;
            default:
                timeout = context.nil;
        }

        if (timeout.isNil()) {
            tv = -1;
        }
        else {
            tv = (long)(RubyTime.convertTimeInterval(context, timeout) * 1000);
            if (tv < 0) throw context.runtime.newArgumentError("time interval must be positive");
        }
        return tv;
    }
}