#include <ranges>
#include <map>
#include <string>
#include <vector>

// waiting for C++23 support: P2286 Formatting Ranges ...
#if defined(__cpp_lib_format_ranges) && defined(__cpp_lib_print)
#include <print>

template <typename Range, typename Msg>
void show(Range&& r, Msg message)
{
    std::print("{:<40}: {}", message, r);
}

template <typename Range, typename Msg>
void show_range_of_ranges(Range&& r, Msg message)
{
    show(r, message);    
}

template <typename Range, typename Msg>
void show_range_of_pairs(Range&& r, Msg message)
{
    show(r, message);    
}

template <typename Range, typename Msg>
void show_map(Range&& r, Msg message)
{
    show(r, message);    
}

#else
#include <iostream>

auto decorate(auto e) 
{
    return e;
}

auto decorate(char e) 
{
    return std::string("\'") + e + "\'";
}

auto decorate(std::string e) 
{
    return std::string("\"") + e + "\"";
}

template <typename Range, typename Msg>
void show(Range&& r, Msg message)
{
    std::cout.width(40);
    std::cout << std::left << message <<  " : [";
    int cnt = 0;    
    for (auto&& e : r) 
    {
        std::cout << (cnt++ ? ", ":"") << decorate(e);
    }    
    std::cout << "]\n";
}

template <typename Range, typename Msg>
void show_range_of_ranges(Range&& r, Msg message)
{
    std::cout.width(40);
    std::cout << std::left << message << " : [";
    int cnt = 0;    
    for (auto&& inner_range : r) 
    {
        std::cout << (cnt++ ? ", ":"") << "[";
        int inner_cnt = 0;    
        for (auto&& e : inner_range) 
        {
            std::cout << (inner_cnt++ ? ", ":"") 
                      << decorate(e);
        }
        std::cout << "]";        
    }    
    std::cout << "]\n";
}

template <typename Range, typename Msg>
void show_range_of_pairs(Range&& r, Msg message)
{
    std::cout.width(40);
    std::cout << std::left << message <<  " : [";
    int cnt = 0;    
    for (auto&& [a,b] : r) 
    {
        std::cout << (cnt++ ? ", ":"") 
                  << "(" << decorate(a) << ", " << decorate(b) << ")";    
    }    
    std::cout << "]\n";
}

template <typename Range, typename Msg>
void show_map(Range&& r, Msg message)
{
    std::cout.width(40);
    std::cout << std::left << message <<  " : {";
    int cnt = 0;    
    for (auto&& [k,v] : r) 
    {
        std::cout << (cnt++ ? ", ":"")
                  << decorate(k) << ": " << decorate(v);    
    }    
    std::cout << "}\n";
}

#endif // defined(__cpp_lib_format_ranges) && defined(__cpp_lib_print)

int main()
{
    using namespace std::views;
    using namespace std::string_literals;
    
    auto v = std::vector{ 1, 3, 5, 4, 2 };
    auto s = "AB CDE"s;
    auto m = std::map<std::string,int>{{"wrong", 6*9}, {"answer", 42}};
    auto below_5 = [](int x){ return x < 5; };
    auto double_digit = [](int a, int b) { return 10*a + b; };
    
    show( empty<int>, "empty<T>");
    show( single(42), "single(42)");
    show( iota(0,6), "iota(0,6)");
    show( iota(0) | take(3), "iota(0) | take(3)");
    show( repeat(6) | take(3), "repeat(6) | take(3)");
    std::cout << '\n';

    show( counted(begin(v), size(v)), "counted(begin(v),size(v))");
    show( v | all, "v | all");
    show( v | drop_while(below_5), "v | drop_while(below_5)");
    show_range_of_pairs(v | enumerate, "v | enumerate");
    show( v | filter(below_5), "v | filter(below_5)");
    show( v | reverse, "v | reverse");
    show( v | take_while(below_5), "v | take_while(below_5)");
    show( v | transform([](int x){ return x*x; }), "v | transform(square)");
    std::cout << '\n';

    show_range_of_ranges( v | chunk(3), "v | chunk(3)" );
    show_range_of_ranges( v | chunk_by(std::ranges::less{}), "v | chunk_by(std::ranges::less{})" );
    show( v | pairwise_transform(double_digit), "v | pairwise_transform(double_digit)" );
    show_range_of_pairs( v | pairwise, "v | pairwise" );
    show_range_of_ranges( v | slide(2), "v | slide(2)" );
    show( v | stride(2), "v | stride(2)" );
    std::cout << '\n';

    show( s , "s");
    show_range_of_ranges( s | split(' '), "s | split(\' \')");
    show( s | split(' ') | join, "s | split(\' \') | join");
    show( s | split(' ') | join_with("<>"s), "s | split(\' \') | join_with(\"<>\"s)");
    std::cout << '\n';

    show_range_of_pairs( zip(v, s), "zip(v, s)" );
    show( zip_transform(double_digit, v, v), "zip_transform(double_digit, v, v)" );
    show_range_of_pairs( cartesian_product(v|take(2), s|take(2)), "cartesian_product(v|take(2), s|take(2))" );
    std::cout << '\n';

    show_map( m , "m");
    show( m | keys , "m | keys");
    show( m | values , "m | values");
}