// Copyright (C) 2012 Internet Systems Consortium, Inc. ("ISC")
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>

#include <boost/date_time/posix_time/posix_time.hpp>

#include <dhcp/libdhcp++.h>
#include <dhcp/dhcp4.h>
#include <exceptions/exceptions.h>
#include "test_control.h"
#include "command_options.h"

using namespace std;
using namespace boost;
using namespace boost::posix_time;
using namespace isc;
using namespace isc::dhcp;

namespace isc {
namespace perfdhcp {

TestControl&
TestControl::instance() {
    static TestControl test_control;
    return (test_control);
}

TestControl::TestControl() :
    send_due_(microsec_clock::universal_time()),
    last_sent_(send_due_) {
}

bool
TestControl::checkExitConditions() const {
    CommandOptions& options = CommandOptions::instance();
    if ((options.getNumRequests().size() > 0) &&
        (sent_packets_0_ >= options.getNumRequests()[0])) {
        return(true);
    } else if ((options.getNumRequests().size() == 2) &&
               (sent_packets_1_ >= options.getNumRequests()[1])) {
        return(true);
    }
    return(false);
}

Pkt4*
TestControl::createDiscoverPkt4() {
    const uint32_t transid = static_cast<uint32_t>(random());
    Pkt4* pkt4 = new Pkt4(DHCPDISCOVER, transid);

    OptionBuffer opt_request_list_buf();
    // createRequestListBuffer4(opt_request_list_buf);
    return NULL;
}

OptionPtr
TestControl::factoryRequestList4(Option::Universe u,
                                 uint16_t type,
                                 const OptionBuffer& buf)
{
    const uint8_t buf_array[] = {
        DHO_SUBNET_MASK,
        DHO_BROADCAST_ADDRESS,
        DHO_TIME_OFFSET,
        DHO_ROUTERS,
        DHO_DOMAIN_NAME,
        DHO_DOMAIN_NAME_SERVERS,
        DHO_HOST_NAME
    };

    OptionBuffer buf_with_options(buf_array, buf_array + sizeof(buf_array));
    Option* opt = new Option(u, type, buf);
    opt->setData(buf_with_options.begin(),
                 buf_with_options.end());
    return OptionPtr(opt);
}

uint64_t
TestControl::getNextExchangesNum() const {
    CommandOptions& options = CommandOptions::instance();
    // Reset number of exchanges.
    uint64_t due_exchanges = 0;
    // Get current time.
    ptime now(microsec_clock::universal_time());
    // The due time indicates when we should start sening next chunk
    // of packets. If it is already due time, we should calculate
    // how many packets to send.
    if (now >= send_due_) {
        // If rate is specified from the command line we have to
        // synchornize with it.
        if (options.getRate() != 0) {
            time_period period(send_due_, now);
            // Null condition should not occur because we
            // have checked it in the first if statement but
            // let's keep this check just in case.
            if (period.is_null()) {
                return (0);
            }
            time_duration duration = period.length();
            // due_factor indicates the number of seconds that
            // sending next chunk of packets will take.
            double due_factor = duration.fractional_seconds() /
                time_duration::ticks_per_second();
            due_factor += duration.total_seconds();
            // Multiplying due_factor by expected rate gives the number
            // of exchanges to be initiated.
            due_exchanges = static_cast<uint64_t>(due_factor * options.getRate());
            // We want to make sure that at least one packet goes out.
            due_exchanges += 1;
            // We should not exceed aggressivity as it could have been
            // restricted from command line.
            if (due_exchanges > options.getAggressivity()) {
                due_exchanges = options.getAggressivity();
            }
        } else {
            // Rate is not specified so we rely on aggressivity
            // which is the number of packets to be sent in
            // one chunk.
            due_exchanges = options.getAggressivity();
        }
        return (due_exchanges);
    }
    return (0);
}

void
TestControl::registerOptionFactories4() const {
    static bool factories_registered = false;
    if (!factories_registered) {
        LibDHCP::OptionFactoryRegister(Option::V4,
                                       DHO_DHCP_PARAMETER_REQUEST_LIST,
                                       &TestControl::factoryRequestList4);
    }
    factories_registered = true;
}

void
TestControl::registerOptionFactories6() const {
    static bool factories_registered = false;
    if (!factories_registered) {
    }
    factories_registered = true;
}

void
TestControl::registerOptionFactories() const {
    CommandOptions& options = CommandOptions::instance();
    switch(options.getIpVersion()) {
    case 4:
        registerOptionFactories4();
        break;
    case 6:
        registerOptionFactories6();
        break;
    default:
        isc_throw(InvalidOperation, "command line options have to be parsed "
                  "before DHCP option factories can be registered");
    }
}

void
TestControl::run() {
    sent_packets_0_ = 0;
    sent_packets_1_ = 0;
    CommandOptions& options = CommandOptions::instance();
    // Ip version is not set ONLY in case the command options
    // where not parsed. This surely means that parse() function
    // was not called prior to starting the test. This is fatal
    // error.
    if (options.getIpVersion() == 0) {
        isc_throw(InvalidOperation, "command options must be parsed before running " 
                  "a test");
    }
    registerOptionFactories();
    uint64_t packets_sent = 0;
    for (;;) {
        updateSendDue();
        if (checkExitConditions()) {
            break;
        }
        uint64_t packets_due = getNextExchangesNum();
        for (uint64_t i = packets_due; i > 0; --i) {
            startExchange();
            ++packets_sent;
            cout << "Packets sent " << packets_sent << endl;
        }
    }

}

void
TestControl::startExchange() {
    ++sent_packets_0_;
    last_sent_ = microsec_clock::universal_time();
}

void
TestControl::updateSendDue() {
    // If default constructor was called, this should not happen but
    // if somebody has changed default constructor it is better to
    // keep this check.
    if (last_sent_.is_not_a_date_time()) {
        isc_throw(Unexpected, "time of last sent packet not initialized");
    }
    // Get the expected exchange rate.
    CommandOptions& options = CommandOptions::instance();
    int rate = options.getRate();
    // If rate was not specified we will wait just one clock tick to
    // send next packet. This simulates best effort conditions.
    long duration = 1;
    if (rate != 0) {
        // We use number of ticks instead of nanoseconds because
        // nanosecond resolution may not be available on some
        // machines. Number of ticks guarantees the highest possible
        // timer resolution.
        duration = time_duration::ticks_per_second() / rate;
    }
    // Calculate due time to initate next chunk of exchanges.
    send_due_ = last_sent_ + time_duration(0, 0, 0, duration);
}


} // namespace perfdhcp
} // namespace isc