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

let
  inherit (lib) mapAttrsToList match;

  metis = import sources.metis { inherit pkgs; };
in
{
  services.nginx.virtualHosts."calendrier.dgnum.eu" = {
    enableACME = true;
    forceSSL = true;
    root = metis.package;

    locations = lib.mapAttrs' (
      name: domain:
      lib.nameValuePair "/cal/${name}/" {
        extraConfig = ''
          proxy_set_header X-Forwarded-Host $host;
          proxy_set_header X-Forwarded-Server $host;
          proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
          proxy_pass https://${domain}/remote.php/dav/public-calendars/;
        '';
      }
    ) metis.providers;

    extraConfig = ''
      rewrite ^/calendrier(.*)$ $1 permanent;
    '';
  };

  assertions = mapAttrsToList (name: domain: {
    assertion = (match "[a-z-]+" name == [ ]) && (match "[a-z.-]+" domain == [ ]);
    message = "The provider `${name}` associated to the domain `${domain}` seems to have an incorrect definition.";
  }) metis.providers;
}