#include <gtest/gtest.h>
#include <stdplus/exception.hpp>
#include <stdplus/fd/gmock.hpp>
#include <stdplus/fd/line.hpp>
#include <stdplus/fd/managed.hpp>
#include <stdplus/fd/ops.hpp>
#include <stdplus/raw.hpp>
#include <stdplus/util/cexec.hpp>
#include <string_view>
#include <sys/mman.h>

namespace stdplus
{
namespace fd
{

ManagedFd makeMemfd(std::string_view contents)
{
    auto fd = ManagedFd(CHECK_ERRNO(memfd_create("test", 0), "memfd_create"));
    write(fd, contents);
    lseek(fd, 0, Whence::Set);
    return fd;
}

TEST(LineReader, Empty)
{
    auto fd = makeMemfd("");
    LineReader reader(fd);
    EXPECT_EQ("", *reader.readLine());
    EXPECT_THROW(reader.readLine(), exception::Eof);
    EXPECT_THROW(reader.readLine(), exception::Eof);
}

TEST(LineReader, SingleLine)
{
    auto fd = makeMemfd("\n");
    LineReader reader(fd);
    EXPECT_EQ("", *reader.readLine());
    EXPECT_EQ("", *reader.readLine());
    EXPECT_THROW(reader.readLine(), exception::Eof);
    EXPECT_THROW(reader.readLine(), exception::Eof);
}

TEST(LineReader, SomeData)
{
    auto fd = makeMemfd("A\nbcd\n\ne");
    LineReader reader(fd);
    EXPECT_EQ("A", *reader.readLine());
    EXPECT_EQ("bcd", *reader.readLine());
    EXPECT_EQ("", *reader.readLine());
    EXPECT_EQ("e", *reader.readLine());
    EXPECT_THROW(reader.readLine(), exception::Eof);
    EXPECT_THROW(reader.readLine(), exception::Eof);
}

TEST(LineReader, LargerThanBuf)
{
    std::string big(LineReader::buf_size + 10, 'a');
    auto fd = makeMemfd(std::string("alpha\n") + big + "\ndef");
    LineReader reader(fd);
    EXPECT_EQ("alpha", *reader.readLine());
    EXPECT_EQ(big, *reader.readLine());
    EXPECT_EQ("def", *reader.readLine());
    EXPECT_THROW(reader.readLine(), exception::Eof);
    EXPECT_THROW(reader.readLine(), exception::Eof);
}

using testing::_;

inline auto readSv(std::string_view s)
{
    return [s](std::span<std::byte> buf) {
        memcpy(buf.data(), s.data(), s.size());
        return buf.subspan(0, s.size());
    };
}

TEST(LineReader, Nonblock)
{
    FdMock fd;
    {
        testing::InSequence seq;
        EXPECT_CALL(fd, read(_)).WillOnce(readSv("alph"));
        EXPECT_CALL(fd, read(_)).WillOnce(readSv({}));
        EXPECT_CALL(fd, read(_)).WillOnce(readSv("a"));
        EXPECT_CALL(fd, read(_))
            .WillRepeatedly(testing::Throw(stdplus::exception::Eof("test")));
    }

    LineReader reader(fd);
    EXPECT_EQ(nullptr, reader.readLine());
    EXPECT_EQ("alpha", *reader.readLine());
    EXPECT_THROW(reader.readLine(), exception::Eof);
    EXPECT_THROW(reader.readLine(), exception::Eof);
}

} // namespace fd
} // namespace stdplus