// The contents of this file are subject to the BOINC Public License
// Version 1.0 (the "License"); you may not use this file except in
// compliance with the License. You may obtain a copy of the License at
// http://boinc.berkeley.edu/license_1.0.txt
// 
// 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. 
// 
// The Original Code is the Berkeley Open Infrastructure for Network Computing. 
// 
// The Initial Developer of the Original Code is the SETI@home project.
// Portions created by the SETI@home project are Copyright (C) 2002
// University of California at Berkeley. All Rights Reserved. 
// 
// Contributor(s):
//

// NET_STATS estimates average network throughput,
// i.e. the average total throughput in both the up and down directions.
// Here's how it works: NET_STATS::poll() is called every second or so.
// If there are any file transfers active,
// it increments elapsed time and byte counts,
// and maintains an exponential average of throughput.

#include <string.h>

#include "windows_cpp.h"

#include "math.h"
#include "parse.h"
#include "time.h"

#include "util.h"
#include "error_numbers.h"
#include "net_stats.h"

#define EXP_DECAY_RATE (1./SECONDS_PER_DAY)

NET_STATS::NET_STATS() {
    last_time = 0;
    memset(&up, 0, sizeof(up));
    memset(&down, 0, sizeof(down));
}

void NET_INFO::update(double dt, double nb, bool active) {
    if (active) {
        delta_t += dt;
        delta_nbytes += nb-last_bytes;
    }
    last_bytes = nb;
}

double NET_INFO::throughput() {
    double x, tp;
    if (starting_throughput > 0) {
        if (delta_t > 0) {
            x = exp(delta_t*EXP_DECAY_RATE);
            tp = delta_nbytes/delta_t;
            return x*starting_throughput + (1-x)*tp;
        } else {
            return starting_throughput;
        }
    } else if (delta_t > 0) {
        return delta_nbytes/delta_t;
    }
    return 0;
}

void NET_STATS::poll(NET_XFER_SET& nxs) {
    double t, dt;
    bool upload_active, download_active;

    t = dtime();
    if (last_time == 0) {
        dt = 0;
    } else {
        dt = t - last_time;
    }
    last_time = t;

    nxs.check_active(upload_active, download_active);
    up.update(dt, nxs.bytes_up, upload_active);
    down.update(dt, nxs.bytes_down, download_active);
}

// Write XML based network statistics
//
int NET_STATS::write(FILE* out, bool to_server) {
    fprintf(out,
        "<net_stats>\n"
        "    <bwup>%f</bwup>\n"
        "    <bwdown>%f</bwdown>\n"
        "</net_stats>\n",
        up.throughput(),
        down.throughput()
    );
    return 0;
}

// Read XML based network statistics
//
int NET_STATS::parse(FILE* in) {
    char buf[256];
    double bwup, bwdown;

    memset(this, 0, sizeof(NET_STATS));
    while (fgets(buf, 256, in)) {
        if (match_tag(buf, "</net_stats>")) return 0;
        else if (parse_double(buf, "<bwup>", bwup)) {
            up.starting_throughput = bwup;
            continue;
        }
        else if (parse_double(buf, "<bwdown>", bwdown)) {
            down.starting_throughput = bwdown;
            continue;
        }
        else fprintf(stderr, "NET_STATS::parse(): unrecognized: %s\n", buf);
    }
    return 1;
}