#include <dropwhile.hpp>

#include "helpers.hpp"

#include <vector>
#include <string>
#include <iterator>

#include "catch.hpp"

using iter::dropwhile;

using Vec = const std::vector<int>;

TEST_CASE("dropwhile: skips initial elements", "[dropwhile]") {
    Vec ns{1,2,3,4,5,6,7,8};
    auto d = dropwhile([](int i){return i < 5; }, ns);
    Vec v(std::begin(d), std::end(d));
    Vec vc = {5,6,7,8};
    REQUIRE( v == vc );
}

TEST_CASE("dropwhile: doesn't skip anything if it shouldn't", "[dropwhile]") {
    Vec ns {3,4,5,6};
    auto d = dropwhile([](int i){return i < 3; }, ns);
    Vec v(std::begin(d), std::end(d));
    Vec vc = {3,4,5,6};
    REQUIRE( v == vc );
}

TEST_CASE("dropwhile: skips all elements when all are true under predicate",
        "[dropwhile]") {
    Vec ns {3,4,5,6};
    auto d = dropwhile([](int i){return i != 0; }, ns);
    REQUIRE( std::begin(d) == std::end(d) );
}

TEST_CASE("dropwhile: empty case is empty", "[dropwhile]") {
    Vec ns{};
    auto d = dropwhile([](int i){return i != 0; }, ns);
    REQUIRE( std::begin(d) == std::end(d) );
}

TEST_CASE("dropwhile: only drops from beginning", "[dropwhile]") {
    Vec ns {1,2,3,4,5,6,5,4,3,2,1};
    auto d = dropwhile([](int i){return i < 5; }, ns);
    Vec v(std::begin(d), std::end(d));
    Vec vc = {5,6,5,4,3,2,1};
    REQUIRE( v == vc );
}

TEST_CASE("dropwhile: operator->", "[dropwhile]") {
    std::vector<std::string> vs = {"a", "ab", "abcdef", "abcdefghi"};
    auto d = dropwhile(
            [](const std::string& str) { return str.size() < 3; }, vs);
    auto it = std::begin(d);
    REQUIRE( it->size() == 6 );
}

namespace {
    int less_than_five(int i) {
        return i < 5;
    }
}

TEST_CASE("dropwhile: works with function pointer", "[dropwhile]") {
    Vec ns{1,2,3,4,5,6,7,8};
    auto d = dropwhile(less_than_five, ns);
    Vec v(std::begin(d), std::end(d));
    Vec vc = {5,6,7,8};
    REQUIRE( v == vc );
}

TEST_CASE("dropwhile: binds to lvalues, moves rvalues", "[dropwhile]") {
    itertest::BasicIterable<int> bi{1,2,3,4};
    SECTION("binds to lvalues") {
        dropwhile(less_than_five, bi);
        REQUIRE_FALSE( bi.was_moved_from() );
    }
    SECTION("moves rvalues") {
        dropwhile(less_than_five, std::move(bi));
        REQUIRE( bi.was_moved_from() );
    }
}

TEST_CASE("dropwhile: doesn't move or copy elements of iterable",
        "[dropwhile]") {
    constexpr itertest::SolidInt arr[] = {{6}, {7}, {8}};
    for (auto&& i : dropwhile(
                [](const itertest::SolidInt&){return false;} , arr)) {
        (void)i;
    }
}

TEST_CASE("dropwhile: iterator meets requirements", "[dropwhile]") {
    std::string s{};
    auto c = dropwhile([]{return true;}, s);
    REQUIRE( itertest::IsIterator<decltype(std::begin(c))>::value );
}