8 - progressbar

#pragma once
#ifndef __PROGRESSBAR_HPP
#define __PROGRESSBAR_HPP

#include <iostream>
#include <ostream>
#include <string>
#include <stdexcept>

class progressbar {

public:
    // default destructor
    ~progressbar() = default;

    // delete everything else
    progressbar(progressbar const&) = delete;
    progressbar& operator=(progressbar const&) = delete;
    progressbar(progressbar&&) = delete;
    progressbar& operator=(progressbar&&) = delete;

    // default constructor, must call set_niter later
    inline progressbar();
    inline progressbar(int n, bool showbar = true, std::ostream& out = std::cerr);

    // reset bar to use it again
    inline void reset();
    // set number of loop iterations
    inline void set_niter(int iter);
    // chose your style
    inline void set_done_char(const std::string& sym) { done_char = sym; }
    inline void set_todo_char(const std::string& sym) { todo_char = sym; }
    inline void set_opening_bracket_char(const std::string& sym) { opening_bracket_char = sym; }
    inline void set_closing_bracket_char(const std::string& sym) { closing_bracket_char = sym; }
    // to show only the percentage
    inline void show_bar(bool flag = true) { do_show_bar = flag; }
    // set the output stream
    inline void set_output_stream(const std::ostream& stream) { output.rdbuf(stream.rdbuf()); }
    // main function
    inline void update();

private:
    int progress;
    int n_cycles;
    int last_perc;
    bool do_show_bar;
    bool update_is_called;

    std::string done_char;
    std::string todo_char;
    std::string opening_bracket_char;
    std::string closing_bracket_char;

    std::ostream& output;
};

inline progressbar::progressbar() :
    progress(0),
    n_cycles(0),
    last_perc(0),
    do_show_bar(true),
    update_is_called(false),
    done_char("#"),
    todo_char(" "),
    opening_bracket_char("["),
    closing_bracket_char("]"),
    output(std::cerr) {}

inline progressbar::progressbar(int n, bool showbar, std::ostream& out) :
    progress(0),
    n_cycles(n),
    last_perc(0),
    do_show_bar(showbar),
    update_is_called(false),
    done_char("#"),
    todo_char(" "),
    opening_bracket_char("["),
    closing_bracket_char("]"),
    output(out) {}

inline void progressbar::reset() {
    progress = 0,
        update_is_called = false;
    last_perc = 0;
    return;
}

inline void progressbar::set_niter(int niter) {
    if (niter <= 0) throw std::invalid_argument(
        "progressbar::set_niter: number of iterations null or negative");
    n_cycles = niter;
    return;
}

inline void progressbar::update() {

    if (n_cycles == 0) throw std::runtime_error(
        "progressbar::update: number of cycles not set");

    if (!update_is_called) {
        if (do_show_bar == true) {
            output << opening_bracket_char;
            for (int _ = 0; _ < 50; _++) output << todo_char;
            output << closing_bracket_char << " 0%";
        }
        else output << "0%";
    }
    update_is_called = true;

    int perc = 0;

    // compute percentage, if did not change, do nothing and return
    perc = progress * 100. / (n_cycles - 1);
    if (perc < last_perc) return;

    // update percentage each unit
    if (perc == last_perc + 1) {
        // erase the correct  number of characters
        if (perc <= 10)                output << "\b\b" << perc << '%';
        else if (perc > 10 and perc < 100) output << "\b\b\b" << perc << '%';
        else if (perc == 100)               output << "\b\b\b" << perc << '%';
    }
    if (do_show_bar == true) {
        // update bar every ten units
        if (perc % 2 == 0) {
            // erase closing bracket
            output << std::string(closing_bracket_char.size(), '\b');
            // erase trailing percentage characters
            if (perc < 10)               output << "\b\b\b";
            else if (perc >= 10 && perc < 100) output << "\b\b\b\b";
            else if (perc == 100)              output << "\b\b\b\b\b";

            // erase 'todo_char'
            for (int j = 0; j < 50 - (perc - 1) / 2; ++j) {
                output << std::string(todo_char.size(), '\b');
            }

            // add one additional 'done_char'
            if (perc == 0) output << todo_char;
            else           output << done_char;

            // refill with 'todo_char'
            for (int j = 0; j < 50 - (perc - 1) / 2 - 1; ++j) output << todo_char;

            // readd trailing percentage characters
            output << closing_bracket_char << ' ' << perc << '%';
        }
    }
    last_perc = perc;
    ++progress;
    output << std::flush;

    return;
}

#endif