/**
 * @file src/misc.cpp
 * @brief todo
 */
// standard includes
#include <fstream>

// lib includes
#include <arpa/inet.h>
#include <boost/asio/ip/address.hpp>
#include <boost/process.hpp>
#include <dlfcn.h>
#include <fcntl.h>
#include <ifaddrs.h>
#include <netinet/udp.h>
#include <pwd.h>
#include <unistd.h>

// local includes
#include "graphics.h"
#include "misc.h"
#include "src/config.h"
#include "src/main.h"
#include "src/platform/common.h"
#include "vaapi.h"

#ifdef __GNUC__
  #define SUNSHINE_GNUC_EXTENSION __extension__
#else
  #define SUNSHINE_GNUC_EXTENSION
#endif

using namespace std::literals;
namespace fs = std::filesystem;
namespace bp = boost::process;

window_system_e window_system;

namespace dyn {
  void *
  handle(const std::vector<const char *> &libs) {
    void *handle;

    for (auto lib : libs) {
      handle = dlopen(lib, RTLD_LAZY | RTLD_LOCAL);
      if (handle) {
        return handle;
      }
    }

    std::stringstream ss;
    ss << "Couldn't find any of the following libraries: ["sv << libs.front();
    std::for_each(std::begin(libs) + 1, std::end(libs), [&](auto lib) {
      ss << ", "sv << lib;
    });

    ss << ']';

    BOOST_LOG(error) << ss.str();

    return nullptr;
  }

  int
  load(void *handle, const std::vector<std::tuple<apiproc *, const char *>> &funcs, bool strict) {
    int err = 0;
    for (auto &func : funcs) {
      TUPLE_2D_REF(fn, name, func);

      *fn = SUNSHINE_GNUC_EXTENSION(apiproc) dlsym(handle, name);

      if (!*fn && strict) {
        BOOST_LOG(error) << "Couldn't find function: "sv << name;

        err = -1;
      }
    }

    return err;
  }
}  // namespace dyn
namespace platf {
  using ifaddr_t = util::safe_ptr<ifaddrs, freeifaddrs>;

  ifaddr_t
  get_ifaddrs() {
    ifaddrs *p { nullptr };

    getifaddrs(&p);

    return ifaddr_t { p };
  }

  fs::path
  appdata() {
    const char *homedir;
    if ((homedir = getenv("HOME")) == nullptr) {
      homedir = getpwuid(geteuid())->pw_dir;
    }

    return fs::path { homedir } / ".config/sunshine"sv;
  }

  std::string
  from_sockaddr(const sockaddr *const ip_addr) {
    char data[INET6_ADDRSTRLEN] = {};

    auto family = ip_addr->sa_family;
    if (family == AF_INET6) {
      inet_ntop(AF_INET6, &((sockaddr_in6 *) ip_addr)->sin6_addr, data,
        INET6_ADDRSTRLEN);
    }
    else if (family == AF_INET) {
      inet_ntop(AF_INET, &((sockaddr_in *) ip_addr)->sin_addr, data,
        INET_ADDRSTRLEN);
    }

    return std::string { data };
  }

  std::pair<std::uint16_t, std::string>
  from_sockaddr_ex(const sockaddr *const ip_addr) {
    char data[INET6_ADDRSTRLEN] = {};

    auto family = ip_addr->sa_family;
    std::uint16_t port = 0;
    if (family == AF_INET6) {
      inet_ntop(AF_INET6, &((sockaddr_in6 *) ip_addr)->sin6_addr, data,
        INET6_ADDRSTRLEN);
      port = ((sockaddr_in6 *) ip_addr)->sin6_port;
    }
    else if (family == AF_INET) {
      inet_ntop(AF_INET, &((sockaddr_in *) ip_addr)->sin_addr, data,
        INET_ADDRSTRLEN);
      port = ((sockaddr_in *) ip_addr)->sin_port;
    }

    return { port, std::string { data } };
  }

  std::string
  get_mac_address(const std::string_view &address) {
    auto ifaddrs = get_ifaddrs();
    for (auto pos = ifaddrs.get(); pos != nullptr; pos = pos->ifa_next) {
      if (pos->ifa_addr && address == from_sockaddr(pos->ifa_addr)) {
        std::ifstream mac_file("/sys/class/net/"s + pos->ifa_name + "/address");
        if (mac_file.good()) {
          std::string mac_address;
          std::getline(mac_file, mac_address);
          return mac_address;
        }
      }
    }

    BOOST_LOG(warning) << "Unable to find MAC address for "sv << address;
    return "00:00:00:00:00:00"s;
  }

  bp::child
  run_command(bool elevated, bool interactive, const std::string &cmd, boost::filesystem::path &working_dir, const bp::environment &env, FILE *file, std::error_code &ec, bp::group *group) {
    if (!group) {
      if (!file) {
        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_out > bp::null, bp::std_err > bp::null, ec);
      }
      else {
        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_out > file, bp::std_err > file, ec);
      }
    }
    else {
      if (!file) {
        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_out > bp::null, bp::std_err > bp::null, ec, *group);
      }
      else {
        return bp::child(cmd, env, bp::start_dir(working_dir), bp::std_out > file, bp::std_err > file, ec, *group);
      }
    }
  }

  /**
   * @brief Open a url in the default web browser.
   * @param url The url to open.
   */
  void
  open_url(const std::string &url) {
    // set working dir to user home directory
    auto working_dir = boost::filesystem::path(std::getenv("HOME"));
    std::string cmd = R"(xdg-open ")" + url + R"(")";

    boost::process::environment _env = boost::this_process::environment();
    std::error_code ec;
    auto child = run_command(false, false, cmd, working_dir, _env, nullptr, ec, nullptr);
    if (ec) {
      BOOST_LOG(warning) << "Couldn't open url ["sv << url << "]: System: "sv << ec.message();
    }
    else {
      BOOST_LOG(info) << "Opened url ["sv << url << "]"sv;
      child.detach();
    }
  }

  void
  adjust_thread_priority(thread_priority_e priority) {
    // Unimplemented
  }

  void
  streaming_will_start() {
    // Nothing to do
  }

  void
  streaming_will_stop() {
    // Nothing to do
  }

  void
  restart_on_exit() {
    char executable[PATH_MAX];
    ssize_t len = readlink("/proc/self/exe", executable, PATH_MAX - 1);
    if (len == -1) {
      BOOST_LOG(fatal) << "readlink() failed: "sv << errno;
      return;
    }
    executable[len] = '\0';

    // ASIO doesn't use O_CLOEXEC, so we have to close all fds ourselves
    int openmax = (int) sysconf(_SC_OPEN_MAX);
    for (int fd = STDERR_FILENO + 1; fd < openmax; fd++) {
      close(fd);
    }

    // Re-exec ourselves with the same arguments
    if (execv(executable, lifetime::get_argv()) < 0) {
      BOOST_LOG(fatal) << "execv() failed: "sv << errno;
      return;
    }
  }

  void
  restart() {
    // Gracefully clean up and restart ourselves instead of exiting
    atexit(restart_on_exit);
    lifetime::exit_sunshine(0, true);
  }

  bool
  send_batch(batched_send_info_t &send_info) {
    auto sockfd = (int) send_info.native_socket;

    // Convert the target address into a sockaddr
    struct sockaddr_in saddr_v4 = {};
    struct sockaddr_in6 saddr_v6 = {};
    struct sockaddr *addr;
    socklen_t addr_len;
    if (send_info.target_address.is_v6()) {
      auto address_v6 = send_info.target_address.to_v6();

      saddr_v6.sin6_family = AF_INET6;
      saddr_v6.sin6_port = htons(send_info.target_port);
      saddr_v6.sin6_scope_id = address_v6.scope_id();

      auto addr_bytes = address_v6.to_bytes();
      memcpy(&saddr_v6.sin6_addr, addr_bytes.data(), sizeof(saddr_v6.sin6_addr));

      addr = (struct sockaddr *) &saddr_v6;
      addr_len = sizeof(saddr_v6);
    }
    else {
      auto address_v4 = send_info.target_address.to_v4();

      saddr_v4.sin_family = AF_INET;
      saddr_v4.sin_port = htons(send_info.target_port);

      auto addr_bytes = address_v4.to_bytes();
      memcpy(&saddr_v4.sin_addr, addr_bytes.data(), sizeof(saddr_v4.sin_addr));

      addr = (struct sockaddr *) &saddr_v4;
      addr_len = sizeof(saddr_v4);
    }

#ifdef UDP_SEGMENT
    {
      struct msghdr msg = {};
      struct iovec iov = {};
      union {
        char buf[CMSG_SPACE(sizeof(uint16_t))];
        struct cmsghdr alignment;
      } cmbuf;

      // UDP GSO on Linux currently only supports sending 64K or 64 segments at a time
      size_t seg_index = 0;
      const size_t seg_max = 65536 / 1500;
      while (seg_index < send_info.block_count) {
        iov.iov_base = (void *) &send_info.buffer[seg_index * send_info.block_size];
        iov.iov_len = send_info.block_size * std::min(send_info.block_count - seg_index, seg_max);

        msg.msg_name = addr;
        msg.msg_namelen = addr_len;
        msg.msg_iov = &iov;
        msg.msg_iovlen = 1;

        // We should not use GSO if the data is <= one full block size
        if (iov.iov_len > send_info.block_size) {
          msg.msg_control = cmbuf.buf;
          msg.msg_controllen = CMSG_SPACE(sizeof(uint16_t));

          // Enable GSO to perform segmentation of our buffer for us
          auto cm = CMSG_FIRSTHDR(&msg);
          cm->cmsg_level = SOL_UDP;
          cm->cmsg_type = UDP_SEGMENT;
          cm->cmsg_len = CMSG_LEN(sizeof(uint16_t));
          *((uint16_t *) CMSG_DATA(cm)) = send_info.block_size;
        }
        else {
          msg.msg_control = nullptr;
          msg.msg_controllen = 0;
        }

        // This will fail if GSO is not available, so we will fall back to non-GSO if
        // it's the first sendmsg() call. On subsequent calls, we will treat errors as
        // actual failures and return to the caller.
        auto bytes_sent = sendmsg(sockfd, &msg, 0);
        if (bytes_sent < 0) {
          // If there's no send buffer space, wait for some to be available
          if (errno == EAGAIN) {
            struct pollfd pfd;

            pfd.fd = sockfd;
            pfd.events = POLLOUT;

            if (poll(&pfd, 1, -1) != 1) {
              BOOST_LOG(warning) << "poll() failed: "sv << errno;
              break;
            }

            // Try to send again
            continue;
          }

          break;
        }

        seg_index += bytes_sent / send_info.block_size;
      }

      // If we sent something, return the status and don't fall back to the non-GSO path.
      if (seg_index != 0) {
        return seg_index >= send_info.block_count;
      }
    }
#endif

    {
      // If GSO is not supported, use sendmmsg() instead.
      struct mmsghdr msgs[send_info.block_count];
      struct iovec iovs[send_info.block_count];
      for (size_t i = 0; i < send_info.block_count; i++) {
        iovs[i] = {};
        iovs[i].iov_base = (void *) &send_info.buffer[i * send_info.block_size];
        iovs[i].iov_len = send_info.block_size;

        msgs[i] = {};
        msgs[i].msg_hdr.msg_name = addr;
        msgs[i].msg_hdr.msg_namelen = addr_len;
        msgs[i].msg_hdr.msg_iov = &iovs[i];
        msgs[i].msg_hdr.msg_iovlen = 1;
      }

      // Call sendmmsg() until all messages are sent
      size_t blocks_sent = 0;
      while (blocks_sent < send_info.block_count) {
        int msgs_sent = sendmmsg(sockfd, &msgs[blocks_sent], send_info.block_count - blocks_sent, 0);
        if (msgs_sent < 0) {
          // If there's no send buffer space, wait for some to be available
          if (errno == EAGAIN) {
            struct pollfd pfd;

            pfd.fd = sockfd;
            pfd.events = POLLOUT;

            if (poll(&pfd, 1, -1) != 1) {
              BOOST_LOG(warning) << "poll() failed: "sv << errno;
              break;
            }

            // Try to send again
            continue;
          }

          BOOST_LOG(warning) << "sendmmsg() failed: "sv << errno;
          return false;
        }

        blocks_sent += msgs_sent;
      }

      return true;
    }
  }

  class qos_t: public deinit_t {
  public:
    qos_t(int sockfd, int level, int option):
        sockfd(sockfd), level(level), option(option) {}

    virtual ~qos_t() {
      int reset_val = -1;
      if (setsockopt(sockfd, level, option, &reset_val, sizeof(reset_val)) < 0) {
        BOOST_LOG(warning) << "Failed to reset IP TOS: "sv << errno;
      }
    }

  private:
    int sockfd;
    int level;
    int option;
  };

  std::unique_ptr<deinit_t>
  enable_socket_qos(uintptr_t native_socket, boost::asio::ip::address &address, uint16_t port, qos_data_type_e data_type) {
    int sockfd = (int) native_socket;

    int level;
    int option;
    if (address.is_v6()) {
      level = SOL_IPV6;
      option = IPV6_TCLASS;
    }
    else {
      level = SOL_IP;
      option = IP_TOS;
    }

    // The specific DSCP values here are chosen to be consistent with Windows
    int dscp;
    switch (data_type) {
      case qos_data_type_e::video:
        dscp = 40;
        break;
      case qos_data_type_e::audio:
        dscp = 56;
        break;
      default:
        BOOST_LOG(error) << "Unknown traffic type: "sv << (int) data_type;
        return nullptr;
    }

    // Shift to put the DSCP value in the correct position in the TOS field
    dscp <<= 2;

    if (setsockopt(sockfd, level, option, &dscp, sizeof(dscp)) < 0) {
      return nullptr;
    }

    return std::make_unique<qos_t>(sockfd, level, option);
  }

  namespace source {
    enum source_e : std::size_t {
#ifdef SUNSHINE_BUILD_CUDA
      NVFBC,
#endif
#ifdef SUNSHINE_BUILD_WAYLAND
      WAYLAND,
#endif
#ifdef SUNSHINE_BUILD_DRM
      KMS,
#endif
#ifdef SUNSHINE_BUILD_X11
      X11,
#endif
      MAX_FLAGS
    };
  }  // namespace source

  static std::bitset<source::MAX_FLAGS> sources;

#ifdef SUNSHINE_BUILD_CUDA
  std::vector<std::string>
  nvfbc_display_names();
  std::shared_ptr<display_t>
  nvfbc_display(mem_type_e hwdevice_type, const std::string &display_name, const video::config_t &config);

  bool
  verify_nvfbc() {
    return !nvfbc_display_names().empty();
  }
#endif

#ifdef SUNSHINE_BUILD_WAYLAND
  std::vector<std::string>
  wl_display_names();
  std::shared_ptr<display_t>
  wl_display(mem_type_e hwdevice_type, const std::string &display_name, const video::config_t &config);

  bool
  verify_wl() {
    return window_system == window_system_e::WAYLAND && !wl_display_names().empty();
  }
#endif

#ifdef SUNSHINE_BUILD_DRM
  std::vector<std::string>
  kms_display_names();
  std::shared_ptr<display_t>
  kms_display(mem_type_e hwdevice_type, const std::string &display_name, const video::config_t &config);

  bool
  verify_kms() {
    return !kms_display_names().empty();
  }
#endif

#ifdef SUNSHINE_BUILD_X11
  std::vector<std::string>
  x11_display_names();
  std::shared_ptr<display_t>
  x11_display(mem_type_e hwdevice_type, const std::string &display_name, const video::config_t &config);

  bool
  verify_x11() {
    return window_system == window_system_e::X11 && !x11_display_names().empty();
  }
#endif

  std::vector<std::string>
  display_names(mem_type_e hwdevice_type) {
#ifdef SUNSHINE_BUILD_CUDA
    // display using NvFBC only supports mem_type_e::cuda
    if (sources[source::NVFBC] && hwdevice_type == mem_type_e::cuda) return nvfbc_display_names();
#endif
#ifdef SUNSHINE_BUILD_WAYLAND
    if (sources[source::WAYLAND]) return wl_display_names();
#endif
#ifdef SUNSHINE_BUILD_DRM
    if (sources[source::KMS]) return kms_display_names();
#endif
#ifdef SUNSHINE_BUILD_X11
    if (sources[source::X11]) return x11_display_names();
#endif
    return {};
  }

  std::shared_ptr<display_t>
  display(mem_type_e hwdevice_type, const std::string &display_name, const video::config_t &config) {
#ifdef SUNSHINE_BUILD_CUDA
    if (sources[source::NVFBC] && hwdevice_type == mem_type_e::cuda) {
      BOOST_LOG(info) << "Screencasting with NvFBC"sv;
      return nvfbc_display(hwdevice_type, display_name, config);
    }
#endif
#ifdef SUNSHINE_BUILD_WAYLAND
    if (sources[source::WAYLAND]) {
      BOOST_LOG(info) << "Screencasting with Wayland's protocol"sv;
      return wl_display(hwdevice_type, display_name, config);
    }
#endif
#ifdef SUNSHINE_BUILD_DRM
    if (sources[source::KMS]) {
      BOOST_LOG(info) << "Screencasting with KMS"sv;
      return kms_display(hwdevice_type, display_name, config);
    }
#endif
#ifdef SUNSHINE_BUILD_X11
    if (sources[source::X11]) {
      BOOST_LOG(info) << "Screencasting with X11"sv;
      return x11_display(hwdevice_type, display_name, config);
    }
#endif

    return nullptr;
  }

  std::unique_ptr<deinit_t>
  init() {
    // These are allowed to fail.
    gbm::init();
    va::init();

    window_system = window_system_e::NONE;
#ifdef SUNSHINE_BUILD_WAYLAND
    if (std::getenv("WAYLAND_DISPLAY")) {
      window_system = window_system_e::WAYLAND;
    }
#endif
#if defined(SUNSHINE_BUILD_X11) || defined(SUNSHINE_BUILD_CUDA)
    if (std::getenv("DISPLAY") && window_system != window_system_e::WAYLAND) {
      if (std::getenv("WAYLAND_DISPLAY")) {
        BOOST_LOG(warning) << "Wayland detected, yet sunshine will use X11 for screencasting, screencasting will only work on XWayland applications"sv;
      }

      window_system = window_system_e::X11;
    }
#endif

#ifdef SUNSHINE_BUILD_CUDA
    if (config::video.capture.empty() || config::video.capture == "nvfbc") {
      if (verify_nvfbc()) {
        sources[source::NVFBC] = true;
      }
    }
#endif
#ifdef SUNSHINE_BUILD_WAYLAND
    if (config::video.capture.empty() || config::video.capture == "wlr") {
      if (verify_wl()) {
        sources[source::WAYLAND] = true;
      }
    }
#endif
#ifdef SUNSHINE_BUILD_DRM
    if (config::video.capture.empty() || config::video.capture == "kms") {
      if (verify_kms()) {
        if (window_system == window_system_e::WAYLAND) {
          // On Wayland, using KMS, the cursor is unreliable.
          // Hide it by default
          display_cursor = false;
        }
        sources[source::KMS] = true;
      }
    }
#endif
#ifdef SUNSHINE_BUILD_X11
    if (config::video.capture.empty() || config::video.capture == "x11") {
      if (verify_x11()) {
        sources[source::X11] = true;
      }
    }
#endif

    if (sources.none()) {
      BOOST_LOG(error) << "Unable to initialize capture method"sv;
      return nullptr;
    }

    if (!gladLoaderLoadEGL(EGL_NO_DISPLAY) || !eglGetPlatformDisplay) {
      BOOST_LOG(warning) << "Couldn't load EGL library"sv;
    }

    return std::make_unique<deinit_t>();
  }
}  // namespace platf
