#include <boost/iostreams/detail/adapter/non_blocking_adapter.hpp>
#include <boost/iterator/counting_iterator.hpp>
#include <boost/test/unit_test.hpp>
#include <boost/iostreams/categories.hpp>

#include <algorithm>

// a toy source implementation that reads only one byte every time read is called
class read_one_source_t
{
public:
    typedef char char_type;

    typedef boost::iostreams::source_tag category;

    read_one_source_t() : pos_m(0)
    {
        // generate data that we can inspect later
        std::copy(boost::counting_iterator<char>(0), boost::counting_iterator<char>(100), data_m);
    }

    std::streamsize read(char* s, std::streamsize n)
    {
        // bounds checking
        if (pos_m >= 100 || n <= 0)
            return -1;

        // write a single char
        *s = data_m[pos_m++];
        
        // always return 1
        return 1;
    }

private:
    std::size_t pos_m;
    char        data_m[100];
};

void nonblocking_read_test()
{
    read_one_source_t src;
    boost::iostreams::non_blocking_adapter<read_one_source_t> nb(src);

    char read_data[100];

    std::streamsize amt = boost::iostreams::read(nb, read_data, 100);

    BOOST_CHECK_EQUAL(amt, 100);

    for (int i = 0; i < 100; ++i)
    {
        BOOST_CHECK_EQUAL(std::char_traits<char>::to_int_type(read_data[i]), i);
    }
}

boost::unit_test::test_suite* init_unit_test_suite(int, char* [])
{
    boost::unit_test::test_suite* test = BOOST_TEST_SUITE("non-blocking read test");
    test->add(BOOST_TEST_CASE(&nonblocking_read_test));
    return test;
}