{ config, lib, pkgs, ... }:

with lib;

let

  cfg = config.services.i2pd;

  homeDir = "/var/lib/i2pd";

  extip = "EXTIP=$(${pkgs.curl}/bin/curl -sf "http://jsonip.com" | ${pkgs.gawk}/bin/awk -F'\"' '{print $4}')";

  i2pSh = pkgs.writeScriptBin "i2pd" ''
    #!/bin/sh
    ${if isNull cfg.extIp then extip else ""}
    ${pkgs.i2pd}/bin/i2p --log=1 --daemon=0 --service=0 \
      --v6=${if cfg.enableIPv6 then "1" else "0"} \
      --unreachable=${if cfg.unreachable then "1" else "0"} \
      --host=${if isNull cfg.extIp then "$EXTIP" else cfg.extIp} \
      ${if isNull cfg.port then "" else "--port=${toString cfg.port}"} \
      --httpproxyport=${toString cfg.proxy.httpPort} \
      --socksproxyport=${toString cfg.proxy.socksPort} \
      --ircport=${toString cfg.irc.port} \
      --ircdest=${cfg.irc.dest} \
      --irckeys=${cfg.irc.keyFile} \
      --eepport=${toString cfg.eep.port} \
      ${if isNull cfg.sam.port then "" else "--samport=${toString cfg.sam.port}"} \
      --eephost=${cfg.eep.host} \
      --eepkeys=${cfg.eep.keyFile}
  '';

in

{

  ###### interface

  options = {

    services.i2pd = {

      enable = mkOption {
        type = types.bool;
        default = false;
        description = ''
          Enables I2Pd as a running service upon activation.
        '';
      };

      extIp = mkOption {
        type = with types; nullOr str;
        default = null;
        description = ''
          Your external IP.
        '';
      };

      unreachable = mkOption {
        type = types.bool;
        default = false;
        description = ''
          If the router is declared to be unreachable and needs introduction nodes.
        '';
      };

      port = mkOption {
        type = with types; nullOr int;
        default = null;
        description = ''
          I2P listen port. If no one is given the router will pick between 9111 and 30777.
        '';
      };

      enableIPv6 = mkOption {
        type = types.bool;
        default = false;
        description = ''
          Enables IPv6 connectivity. Disabled by default.
        '';
      };

      http = {
        port = mkOption {
          type = types.int;
          default = 7070;
          description = ''
            HTTP listen port.
          '';
        };
      };

      proxy = {
        httpPort = mkOption {
          type = types.int;
          default = 4446;
          description = ''
            HTTP proxy listen port.
          '';
        };
        socksPort = mkOption {
          type = types.int;
          default = 4447;
          description = ''
            SOCKS proxy listen port.
          '';
        };
      };

      irc = {
        dest = mkOption {
          type = types.str;
          default = "irc.postman.i2p";
          description = ''
            Destination I2P tunnel endpoint address of IRC server. irc.postman.i2p by default.
          '';
        };
        port = mkOption {
          type = types.int;
          default = 6668;
          description = ''
            Local IRC tunnel endoint port to listen on. 6668 by default.
          '';
        };
        keyFile = mkOption {
          type = types.str;
          default = "privKeys.dat";
          description = ''
            File name containing destination keys. privKeys.dat by default.
          '';
        };
      };

      eep = {
        host = mkOption {
          type = types.str;
          default = "127.0.0.1";
          description = ''
            Address to forward incoming traffic to. 127.0.0.1 by default.
          '';
        };
        port = mkOption {
          type = types.int;
          default = 80;
          description = ''
            Port to forward incoming trafic to. 80 by default.
          '';
        };
        keyFile = mkOption {
          type = types.str;
          default = "privKeys.dat";
          description = ''
            File name containing destination keys. privKeys.dat by default.
          '';
        };
      };

      sam = {
        port = mkOption {
          type = with types; nullOr int;
          default = null;
          description = ''
            Local SAM tunnel endpoint. Usually 7656. SAM is disabled if not specified.
          '';
        };
      };
    };
  };


  ###### implementation

  config = mkIf cfg.enable {

    users.extraUsers.i2pd = {
      group = "i2pd";
      description = "I2Pd User";
      home = homeDir;
      createHome = true;
      uid = config.ids.uids.i2pd;
    };

    users.extraGroups.i2pd.gid = config.ids.gids.i2pd;

    systemd.services.i2pd = {
      description = "Minimal I2P router";
      after = [ "network.target" ];
      wantedBy = [ "multi-user.target" ];
      serviceConfig =
      {
        User = "i2pd";
        WorkingDirectory = homeDir;
        Restart = "on-abort";
        ExecStart = "${i2pSh}/bin/i2pd";
      };
    };
  };
}
#