#include "net.hpp"
#include "net_if.hpp"
#include <stdexcept>
#include <llarp/constants/platform.hpp>

#include <arpa/inet.h>

#include "ip.hpp"
#include "ip_range.hpp"
#include <llarp/util/logging.hpp>
#include <llarp/util/str.hpp>

#ifdef ANDROID
#include <llarp/android/ifaddrs.h>
#else
#include <ifaddrs.h>
#endif

#include <cstdio>
#include <list>
#include <type_traits>

namespace llarp::net
{
  class Platform_Impl : public Platform
  {
    template <typename Visit_t>
    void
    iter_all(Visit_t&& visit) const
    {
      ifaddrs* addrs{nullptr};
      if (getifaddrs(&addrs))
        throw std::runtime_error{fmt::format("getifaddrs(): {}", strerror(errno))};

      for (auto next = addrs; next; next = next->ifa_next)
        visit(next);

      freeifaddrs(addrs);
    }

   public:
    std::string
    LoopbackInterfaceName() const override
    {
      std::string ifname;
      iter_all([this, &ifname](auto i) {
        if (i and i->ifa_addr and i->ifa_addr->sa_family == AF_INET)
        {
          const SockAddr addr{*i->ifa_addr};
          if (IsLoopbackAddress(addr.getIP()))
          {
            ifname = i->ifa_name;
          }
        }
      });
      if (ifname.empty())
        throw std::runtime_error{"we have no ipv4 loopback interface for some ungodly reason"};
      return ifname;
    }

    std::optional<std::string>
    GetBestNetIF(int af) const override
    {
      std::optional<std::string> found;
      iter_all([this, &found, af](auto i) {
        if (found)
          return;
        if (i and i->ifa_addr and i->ifa_addr->sa_family == af)
        {
          if (not IsBogon(*i->ifa_addr))
          {
            found = i->ifa_name;
          }
        }
      });

      return found;
    }

    std::optional<IPRange>
    FindFreeRange() const override
    {
      std::list<IPRange> currentRanges;
      iter_all([&currentRanges](auto i) {
        if (i and i->ifa_addr and i->ifa_addr->sa_family == AF_INET)
        {
          ipv4addr_t addr{reinterpret_cast<sockaddr_in*>(i->ifa_addr)->sin_addr.s_addr};
          ipv4addr_t mask{reinterpret_cast<sockaddr_in*>(i->ifa_netmask)->sin_addr.s_addr};
          currentRanges.emplace_back(IPRange::FromIPv4(addr, mask));
        }
      });

      return IPRange::FindPrivateRange(currentRanges);
    }

    std::optional<int>
    GetInterfaceIndex(ipaddr_t) const override
    {
      // todo: implement me
      return std::nullopt;
    }

    std::optional<std::string>
    FindFreeTun() const override
    {
      int num = 0;
      while (num < 255)
      {
        std::string ifname = fmt::format("lokitun{}", num);
        if (GetInterfaceAddr(ifname, AF_INET) == std::nullopt)
          return ifname;
        num++;
      }
      return std::nullopt;
    }

    std::optional<SockAddr>
    GetInterfaceAddr(std::string_view ifname, int af) const override
    {
      std::optional<SockAddr> addr;
      iter_all([&addr, af, ifname = std::string{ifname}](auto i) {
        if (addr)
          return;
        if (i and i->ifa_addr and i->ifa_addr->sa_family == af and i->ifa_name == ifname)
          addr = llarp::SockAddr{*i->ifa_addr};
      });
      return addr;
    }

    std::optional<SockAddr>
    AllInterfaces(SockAddr fallback) const override
    {
      std::optional<SockAddr> found;
      iter_all([fallback, &found](auto i) {
        if (found)
          return;
        if (i == nullptr or i->ifa_addr == nullptr)
          return;
        if (i->ifa_addr->sa_family != fallback.Family())
          return;
        SockAddr addr{*i->ifa_addr};
        if (addr == fallback)
          found = addr;
      });

      // 0.0.0.0 is used in our compat shim as our public ip so we check for that special case
      const auto zero = IPRange::FromIPv4(0, 0, 0, 0, 8);
      // when we cannot find an address but we are looking for 0.0.0.0 just default to the old
      // style
      if (not found and (fallback.isIPv4() and zero.Contains(fallback.asIPv4())))
        found = Wildcard(fallback.Family());
      return found;
    }

    bool
    HasInterfaceAddress(ipaddr_t ip) const override
    {
      bool found{false};
      iter_all([&found, ip](auto i) {
        if (found)
          return;

        if (not(i and i->ifa_addr))
          return;
        const SockAddr addr{*i->ifa_addr};
        found = addr.getIP() == ip;
      });
      return found;
    }
    std::vector<InterfaceInfo>
    AllNetworkInterfaces() const override
    {
      std::unordered_map<std::string, InterfaceInfo> ifmap;
      iter_all([&ifmap](auto* i) {
        if (i == nullptr or i->ifa_addr == nullptr)
          return;

        const auto fam = i->ifa_addr->sa_family;
        if (fam != AF_INET and fam != AF_INET6)
          return;

        auto& ent = ifmap[i->ifa_name];
        if (ent.name.empty())
        {
          ent.name = i->ifa_name;
          ent.index = if_nametoindex(i->ifa_name);
        }
        SockAddr addr{*i->ifa_addr};
        SockAddr mask{*i->ifa_netmask};
        ent.addrs.emplace_back(addr.asIPv6(), mask.asIPv6());
      });
      std::vector<InterfaceInfo> all;
      for (auto& [name, ent] : ifmap)
        all.emplace_back(std::move(ent));
      return all;
    }
  };

  const Platform_Impl g_plat{};

  const Platform*
  Platform::Default_ptr()
  {
    return &g_plat;
  }
}  // namespace llarp::net