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

let
  inherit (lib) mapAttrs' mkEnableOption mkIf mkOption nameValuePair types;

  package = import sources.linkal { inherit pkgs; };

  cfg = config.dgn-linkal;

  jsonFormat = pkgs.formats.json { };
in {
  options.dgn-linkal = {
    enable = mkEnableOption "the linkal server.";

    package = mkOption {
      type = types.package;
      default = package.overrideAttrs (_: { buildInputs = [ ]; });
    };

    domain = mkOption { type = types.str; };

    calendarGroups = mkOption {
      type = let inherit (types) attrsOf port submodule;
      in attrsOf (submodule {
        options = {
          port = mkOption { type = port; };
          calendars = mkOption { inherit (jsonFormat) type; };
        };
      });
      default = { };
    };
  };

  config = mkIf cfg.enable {
    systemd.services = mapAttrs' (name:
      { port, calendars }:
      nameValuePair "linkal-${name}" {
        description = "Linkal - ${name}";
        wantedBy = [ "multi-user.target" ];
        serviceConfig = {
          Type = "simple";
          ExecStart = "${cfg.package}/bin/linkal --port ${
              builtins.toString port
            } --calendar-file ${
              jsonFormat.generate "linkal-${name}.json" { inherit calendars; }
            }";
        };
      }) cfg.calendarGroups;

    services.nginx = {
      enable = true;

      virtualHosts.${cfg.domain} = {
        enableACME = true;
        forceSSL = true;

        locations = mapAttrs' (name:
          { port, ... }:
          nameValuePair "^~ /${name}" {
            proxyPass = "http://127.0.0.1:${builtins.toString port}/";
            # extraConfig = ''
            #   proxy_set_header    X-Real-IP  $remote_addr;
            #   proxy_set_header    X-Forwarded-For $proxy_add_x_forwarded_for;
            #   proxy_set_header    Host $host;
            #   proxy_redirect      off;
            # '';
          }) cfg.calendarGroups;
      };
    };
  };
}