#include <stdexcept>
#include <cstddef>
#include <cstring>
#include <string>
#include <sys/inotify.h>
#include <unistd.h>
#include <experimental/filesystem>
#include <phosphor-logging/log.hpp>
#include "config.h"
#include "watch.hpp"
#include "image_manager.hpp"

namespace phosphor
{
namespace software
{
namespace manager
{

using namespace phosphor::logging;
using namespace std::string_literals;
namespace fs = std::experimental::filesystem;

Watch::Watch(sd_event* loop,
             std::function<int(std::string&)> imageCallback) : imageCallback(
                     imageCallback)
{
    // Check if IMAGE DIR exists.
    fs::path imgDirPath(IMG_UPLOAD_DIR);
    if (!fs::is_directory(imgDirPath))
    {
        log<level::ERR>("ERROR No Image Dir",
                        entry("IMAGEDIR=%s", IMG_UPLOAD_DIR));
        throw std::runtime_error(
            "No Image Dir, IMAGEDIR=" + std::string{IMG_UPLOAD_DIR});
    }

    fd = inotify_init1(IN_NONBLOCK);
    if (-1 == fd)
    {
        // Store a copy of errno, because the string creation below will
        // invalidate errno due to one more system calls.
        auto error = errno;
        throw std::runtime_error(
            "inotify_init1 failed, errno="s + std::strerror(error));
    }

    wd = inotify_add_watch(fd, IMG_UPLOAD_DIR, IN_CLOSE_WRITE);
    if (-1 == wd)
    {
        auto error = errno;
        close(fd);
        throw std::runtime_error(
            "inotify_add_watch failed, errno="s + std::strerror(error));
    }

    auto rc = sd_event_add_io(loop,
                              nullptr,
                              fd,
                              EPOLLIN,
                              callback,
                              this);
    if (0 > rc)
    {
        throw std::runtime_error(
            "failed to add to event loop, rc="s + std::strerror(-rc));
    }
}

Watch::~Watch()
{
    if ((-1 != fd) && (-1 != wd))
    {
        inotify_rm_watch(fd, wd);
        close(fd);
    }
}

int Watch::callback(sd_event_source* s,
                    int fd,
                    uint32_t revents,
                    void* userdata)
{
    if (!(revents & EPOLLIN))
    {
        return 0;
    }

    constexpr auto maxBytes = 1024;
    uint8_t buffer[maxBytes];
    auto bytes = read(fd, buffer, maxBytes);
    if (0 > bytes)
    {
        auto error = errno;
        throw std::runtime_error(
            "failed to read inotify event, errno="s + std::strerror(error));
    }

    auto offset = 0;
    while (offset < bytes)
    {
        auto event = reinterpret_cast<inotify_event*>(&buffer[offset]);
        if ((event->mask & IN_CLOSE_WRITE) && !(event->mask & IN_ISDIR))
        {
            auto tarballPath = std::string{IMG_UPLOAD_DIR} + '/' + event->name;
            auto rc = static_cast<Watch*>(userdata)->imageCallback(tarballPath);
            if (rc < 0)
            {
                log<level::ERR>("Error processing image",
                                entry("IMAGE=%s", tarballPath));
            }

        }

        offset += offsetof(inotify_event, name) + event->len;
    }

    return 0;
}

} // namespace manager
} // namespace software
} // namespace phosphor