/////////////////////////// Interest Calculator ///////////////////////////////
//  Copyright (c) 2012 Adrian Serio
//
//  SPDX-License-Identifier: BSL-1.0
//  Distributed under the Boost Software License, Version 1.0. (See accompanying
//  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// Purpose: Calculates compound interest while using dataflow objects.
//
// In this example, you supply the program with the principal [$], the interest
// rate [%], the length of the compound period [months], and the length of time
// the money is invested [months]. The program will calculate the new total
// amount of money you have and the amount of interest made. For example if
// you have $100, an interest rate of 5%, a compound period of 6 months and
// you leave your money in that account for 36 months you will end up with
// $134.01 and will have made $34.01 in interest.
///////////////////////////////////////////////////////////////////////////////

#include <hpx/hpx.hpp>
#include <hpx/hpx_init.hpp>
#include <hpx/runtime/actions/plain_action.hpp>
#include <hpx/dataflow.hpp>

#include <iostream>

using hpx::program_options::variables_map;
using hpx::program_options::options_description;
using hpx::program_options::value;

///////////////////////////////////////////////////////////////////////////////
//[interest_calc_add_action
// Calculate interest for one period
double calc(double principal, double rate)
{
    return principal * rate;
}

///////////////////////////////////////////////////////////////////////////////
// Add the amount made to the principal
double add(double principal, double interest)
{
    return principal + interest;
}
//]

///////////////////////////////////////////////////////////////////////////////
//[interest_hpx_main
int hpx_main(variables_map & vm)
{
    {
        using hpx::shared_future;
        using hpx::make_ready_future;
        using hpx::dataflow;
        using hpx::util::unwrapping;
        hpx::naming::id_type here = hpx::find_here();

        double init_principal=vm["principal"].as<double>(); //Initial principal
        double init_rate=vm["rate"].as<double>(); //Interest rate
        int cp=vm["cp"].as<int>(); //Length of a compound period
        int t=vm["time"].as<int>(); //Length of time money is invested

        init_rate/=100; //Rate is a % and must be converted
        t/=cp; //Determine how many times to iterate interest calculation:
               //How many full compound periods can fit in the time invested

        // In non-dataflow terms the implemented algorithm would look like:
        //
        // int t = 5;    // number of time periods to use
        // double principal = init_principal;
        // double rate = init_rate;
        //
        // for (int i = 0; i < t; ++i)
        // {
        //     double interest = calc(principal, rate);
        //     principal = add(principal, interest);
        // }
        //
        // Please note the similarity with the code below!

        shared_future<double> principal = make_ready_future(init_principal);
        shared_future<double> rate = make_ready_future(init_rate);

        for (int i = 0; i < t; ++i)
        {
            shared_future<double> interest = dataflow(unwrapping(calc), principal, rate);
            principal = dataflow(unwrapping(add), principal, interest);
        }

        // wait for the dataflow execution graph to be finished calculating our
        // overall interest
        double result = principal.get();

        std::cout << "Final amount: " << result << std::endl;
        std::cout << "Amount made: " << result-init_principal << std::endl;
    }

    return hpx::finalize();
}
//]

///////////////////////////////////////////////////////////////////////////////
//[interest_main
int main(int argc, char ** argv)
{
    options_description cmdline("Usage: " HPX_APPLICATION_STRING " [options]");

    cmdline.add_options()
        ("principal", value<double>()->default_value(1000), "The principal [$]")
        ("rate", value<double>()->default_value(7), "The interest rate [%]")
        ("cp", value<int>()->default_value(12), "The compound period [months]")
        ("time", value<int>()->default_value(12*30),
            "The time money is invested [months]")
    ;

    return hpx::init(cmdline, argc, argv);
}
//]