#include <cstdint>

#include <unistd.h>

#include <fuzzer/FuzzedDataProvider.h>

#include "xlsxwriter.h"

const std::string mem_dir{"/dev/shm"};

const std::string file_template = "/fuzzXXXXXX";

char temp_file_dir[FILENAME_MAX] = {0};

/**

 * \brief: Performs all prep-work needed for continuous fuzzing

 * \return: Whether initialization was successful

 */

int init_for_fuzzing()

{

    // Initialize the temporary file directory, based off what is available on the system

    if (0 == access(mem_dir.c_str(), W_OK | R_OK))

    {

        // We can read and write to the in-memory directory

        memcpy(temp_file_dir, mem_dir.c_str(), strnlen(mem_dir.c_str(), FILENAME_MAX));

    }

    else

    {

        // Default to a temporary directory

        const char* tmp_prefix = getenv("TMPDIR");

        if (nullptr == tmp_prefix)

        {

            tmp_prefix = "/tmp";

        }

        memcpy((void*) temp_file_dir, tmp_prefix, strnlen(tmp_prefix, FILENAME_MAX));

    }

    return 0;

}

extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, const size_t size)

{

    static bool init_fuzzing = init_for_fuzzing();

    char fuzz_file[FILENAME_MAX + 1] = {0};

    int fuzz_fd = 0;

    int ret = -1;

    ssize_t wc = 0;

    size_t byte_len;

    lxw_workbook *workbook = nullptr;

    lxw_worksheet *worksheet = nullptr;

    FuzzedDataProvider fdp{data, size};

    std::vector<std::uint8_t> file_bytes{};

    strncpy(fuzz_file, temp_file_dir, strlen(temp_file_dir));

    strncat(fuzz_file, file_template.c_str(), file_template.length());

    if ((fuzz_fd = mkstemp(fuzz_file)) < 0)

    {

        goto fail;

    }

    byte_len = fdp.ConsumeIntegralInRange<size_t>(0, fdp.remaining_bytes());

    file_bytes = fdp.ConsumeBytes<uint8_t>(byte_len);

    write(fuzz_fd, file_bytes.data(), std::min(file_bytes.size(), byte_len));

    workbook = workbook_new(fuzz_file);

    worksheet = workbook_add_worksheet(workbook, nullptr);

    for (int row = 0; row < fdp.ConsumeIntegralInRange(0, 25); ++row)

    {

        for (int col = 0; col < fdp.ConsumeIntegralInRange(0, 25); ++col)

        {

            worksheet_write_string(worksheet, row, col, fdp.ConsumeRandomLengthString().c_str(), nullptr);

        }

    }

    ret = 0;

    fail:

    if (nullptr != workbook)

    {

        workbook_close(workbook);

    }

    close(fuzz_fd);

    unlink(fuzz_file);

    return ret;

}