/**
 * @file src/network.cpp
 * @brief todo
 */
#include "network.h"
#include "config.h"
#include "logging.h"
#include "utility.h"
#include <algorithm>

using namespace std::literals;

namespace ip = boost::asio::ip;

namespace net {
  std::vector<ip::network_v4> pc_ips_v4 {
    ip::make_network_v4("127.0.0.0/8"sv),
  };
  std::vector<ip::network_v4> lan_ips_v4 {
    ip::make_network_v4("192.168.0.0/16"sv),
    ip::make_network_v4("172.16.0.0/12"sv),
    ip::make_network_v4("10.0.0.0/8"sv),
    ip::make_network_v4("100.64.0.0/10"sv),
    ip::make_network_v4("169.254.0.0/16"sv),
  };

  std::vector<ip::network_v6> pc_ips_v6 {
    ip::make_network_v6("::1/128"sv),
  };
  std::vector<ip::network_v6> lan_ips_v6 {
    ip::make_network_v6("fc00::/7"sv),
    ip::make_network_v6("fe80::/64"sv),
  };

  net_e
  from_enum_string(const std::string_view &view) {
    if (view == "wan") {
      return WAN;
    }
    if (view == "lan") {
      return LAN;
    }

    return PC;
  }

  net_e
  from_address(const std::string_view &view) {
    auto addr = normalize_address(ip::make_address(view));

    if (addr.is_v6()) {
      for (auto &range : pc_ips_v6) {
        if (range.hosts().find(addr.to_v6()) != range.hosts().end()) {
          return PC;
        }
      }

      for (auto &range : lan_ips_v6) {
        if (range.hosts().find(addr.to_v6()) != range.hosts().end()) {
          return LAN;
        }
      }
    }
    else {
      for (auto &range : pc_ips_v4) {
        if (range.hosts().find(addr.to_v4()) != range.hosts().end()) {
          return PC;
        }
      }

      for (auto &range : lan_ips_v4) {
        if (range.hosts().find(addr.to_v4()) != range.hosts().end()) {
          return LAN;
        }
      }
    }

    return WAN;
  }

  std::string_view
  to_enum_string(net_e net) {
    switch (net) {
      case PC:
        return "pc"sv;
      case LAN:
        return "lan"sv;
      case WAN:
        return "wan"sv;
    }

    // avoid warning
    return "wan"sv;
  }

  /**
   * @brief Returns the `af_e` enum value for the `address_family` config option value.
   * @param view The config option value.
   * @return The `af_e` enum value.
   */
  af_e
  af_from_enum_string(const std::string_view &view) {
    if (view == "ipv4") {
      return IPV4;
    }
    if (view == "both") {
      return BOTH;
    }

    // avoid warning
    return BOTH;
  }

  /**
   * @brief Returns the wildcard binding address for a given address family.
   * @param af Address family.
   * @return Normalized address.
   */
  std::string_view
  af_to_any_address_string(af_e af) {
    switch (af) {
      case IPV4:
        return "0.0.0.0"sv;
      case BOTH:
        return "::"sv;
    }

    // avoid warning
    return "::"sv;
  }

  /**
   * @brief Converts an address to a normalized form.
   * @details Normalization converts IPv4-mapped IPv6 addresses into IPv4 addresses.
   * @param address The address to normalize.
   * @return Normalized address.
   */
  boost::asio::ip::address
  normalize_address(boost::asio::ip::address address) {
    // Convert IPv6-mapped IPv4 addresses into regular IPv4 addresses
    if (address.is_v6()) {
      auto v6 = address.to_v6();
      if (v6.is_v4_mapped()) {
        return boost::asio::ip::make_address_v4(boost::asio::ip::v4_mapped, v6);
      }
    }

    return address;
  }

  /**
   * @brief Returns the given address in normalized string form.
   * @details Normalization converts IPv4-mapped IPv6 addresses into IPv4 addresses.
   * @param address The address to normalize.
   * @return Normalized address in string form.
   */
  std::string
  addr_to_normalized_string(boost::asio::ip::address address) {
    return normalize_address(address).to_string();
  }

  /**
   * @brief Returns the given address in a normalized form for in the host portion of a URL.
   * @details Normalization converts IPv4-mapped IPv6 addresses into IPv4 addresses.
   * @param address The address to normalize and escape.
   * @return Normalized address in URL-escaped string.
   */
  std::string
  addr_to_url_escaped_string(boost::asio::ip::address address) {
    address = normalize_address(address);
    if (address.is_v6()) {
      return "["s + address.to_string() + ']';
    }
    else {
      return address.to_string();
    }
  }

  /**
   * @brief Returns the encryption mode for the given remote endpoint address.
   * @param address The address used to look up the desired encryption mode.
   * @return The WAN or LAN encryption mode, based on the provided address.
   */
  int
  encryption_mode_for_address(boost::asio::ip::address address) {
    auto nettype = net::from_address(address.to_string());
    if (nettype == net::net_e::PC || nettype == net::net_e::LAN) {
      return config::stream.lan_encryption_mode;
    }
    else {
      return config::stream.wan_encryption_mode;
    }
  }

  host_t
  host_create(af_e af, ENetAddress &addr, std::size_t peers, std::uint16_t port) {
    static std::once_flag enet_init_flag;
    std::call_once(enet_init_flag, []() {
      enet_initialize();
    });

    auto any_addr = net::af_to_any_address_string(af);
    enet_address_set_host(&addr, any_addr.data());
    enet_address_set_port(&addr, port);

    auto host = host_t { enet_host_create(af == IPV4 ? AF_INET : AF_INET6, &addr, peers, 0, 0, 0) };

    // Enable opportunistic QoS tagging (automatically disables if the network appears to drop tagged packets)
    enet_socket_set_option(host->socket, ENET_SOCKOPT_QOS, 1);

    return host;
  }

  void
  free_host(ENetHost *host) {
    std::for_each(host->peers, host->peers + host->peerCount, [](ENetPeer &peer_ref) {
      ENetPeer *peer = &peer_ref;

      if (peer) {
        enet_peer_disconnect_now(peer, 0);
      }
    });

    enet_host_destroy(host);
  }

  /**
   * @brief Map a specified port based on the base port.
   * @param port The port to map as a difference from the base port.
   * @return `std:uint16_t` : The mapped port number.
   *
   * EXAMPLES:
   * ```cpp
   * std::uint16_t mapped_port = net::map_port(1);
   * ```
   */
  std::uint16_t
  map_port(int port) {
    // calculate the port from the config port
    auto mapped_port = (std::uint16_t)((int) config::sunshine.port + port);

    // Ensure port is in the range of 1024-65535
    if (mapped_port < 1024 || mapped_port > 65535) {
      BOOST_LOG(warning) << "Port out of range: "sv << mapped_port;
    }

    // TODO: Ensure port is not already in use by another application

    return mapped_port;
  }
}  // namespace net