{ config, lib, ... }:

with lib;
let
  netOpts = { name, ... }: {
    options = {
      vlan = mkOption {
        description = "VLAN tag number";
        type = types.int;
      };
      subnet4 = mkOption {
        description = "v.w.x.y/z";
        type = with types; nullOr str;
        default = null;
      };
      subnets6 = mkOption {
        description = "IPv6 subnets w/o prefixlen (always 64)";
        type = with types; attrsOf str;
        default = {};
      };
    };
  };
  hostOpts = { name, ... }: {
    options = {
      role = mkOption {
        type = types.enum [ "ap" "switch" "server" "gateway" "client" ];
        default = "client";
      };
      model = mkOption {
        type = types.str;
        default = "pc";
      };
      password = mkOption {
        type = with types; nullOr str;
        default = null;
      };
      location = mkOption {
        type = with types; nullOr str;
        default = null;
      };
    };
  };
in
{
  options.warnings = mkOption {
    type = types.listOf types.str;
    default = [];
    internal = true;
  };

  options.site = {
    net = mkOption {
      default = {};
      type = with types; attrsOf (submodule netOpts);
    };
    hosts = mkOption {
      default = {};
      type = with types; attrsOf (submodule hostOpts);
    };
  };

  config.warnings =
    let
      findCollisions = getter: xs:
        (builtins.foldl' ({ known, dup }: k:
          let
            ks = builtins.toString k;
          in
            if known ? ${ks}
            then { inherit known; dup = dup ++ [ks]; }
            else { known = known // { ${ks} = true; }; inherit dup; }
        ) {
          known = {}; dup = [];
        } (
          concatMap getter (builtins.attrValues xs)
        )).dup;
      reportCollisions = name: getter: xs:
        map (k: "Duplicate ${name}: ${k}") (findCollisions getter xs);
    in
      (reportCollisions "VLAN tag" (x: [x.vlan]) config.site.net) ++
      (reportCollisions "IPv4 subnet" (x: if x.subnet4 == null then [] else [x.subnet4]) config.site.net) ++
      (reportCollisions "IPv6 subnet" (x: builtins.attrValues x.subnets6) config.site.net);
}