/*
 * Copyright (C) 2012 Intel Corporation.
 * Copyright (C) 2013 Cable Television Laboratories, Inc.
 *
 * Author: Jens Georg <jensg@openismus.com>
 *         Craig Pratt <craig@ecaspia.com>
 *
 * This file is part of Rygel.
 *
 * Rygel is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * Rygel 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

using Soup;

/**
 * Class that converts the push DataSource into the pull required by libsoup.
 */
internal class Rygel.DataSink : Object {
    private DataSource source;
    private Server server;
    private Message message;

    private const uint MAX_BUFFERED_CHUNKS = 32;
    private const uint MIN_BUFFERED_CHUNKS = 4;

    private int64 chunks_buffered;
    private int64 bytes_sent;
    private int64 max_bytes;

    public DataSink (DataSource source,
                     Server     server,
                     Message    message,
                     HTTPSeekRequest?  offsets) {
        this.source = source;
        this.server = server;
        this.message = message;

        this.chunks_buffered = 0;
        this.bytes_sent = 0;
        this.max_bytes = this.get_max_bytes (offsets);
        debug ("Setting max_bytes to %s", (this.max_bytes == int64.MAX)
                                          ? "MAX" : this.max_bytes.to_string());
        this.source.data_available.connect (this.on_data_available);
        this.message.wrote_chunk.connect (this.on_wrote_chunk);
    }

    private void on_wrote_chunk (Soup.Message msg) {
        this.chunks_buffered--;
        if (this.chunks_buffered < MIN_BUFFERED_CHUNKS) {
            this.source.thaw ();
        }
    }

    private void on_data_available (uint8[] buffer) {
        var left = this.max_bytes - this.bytes_sent;

        if (left <= 0) {
            return;
        }

        var to_send = int64.min (buffer.length, left);

        this.message.response_body.append (Soup.MemoryUse.COPY,
                                           buffer[0:to_send]);
        this.chunks_buffered++;
        this.bytes_sent += to_send;

        this.server.unpause_message (this.message);

        if (this.chunks_buffered > MAX_BUFFERED_CHUNKS) {
            this.source.freeze ();
        }
    }

    private int64 get_max_bytes (HTTPSeekRequest? offsets) {
        if (offsets == null || !(offsets is HTTPByteSeekRequest)) {
            debug ("Setting max_bytes to MAX");

            return int64.MAX;
        }

        var request = offsets as HTTPByteSeekRequest;
        debug ("Setting max_bytes to %lld", request.range_length);

        return request.range_length;
    }
}
