server.nix

{ config, lib, pkgs, ... }:
with lib;
let

  cfg = config.hcloud.server;

  allAdmins =
    if (hasAttr "admins" config.users) then config.users.admins else { };

in {

  options.hcloud.server = mkOption {
    default = { };
    description = ''
      servers deployed to the hcloud.
    '';
    type = with types;
      attrsOf (submodule ({ name, ... }: {
        options = {
          enable = mkEnableOption ''
            really deploy server
          '';
          name = mkOption {
            default = "${name}";
            type = with types; str;
            description = ''
              name of the server
            '';
          };
          provisioners = mkOption {
            default = [ ];
            type = with types; listOf attrs;
            description = ''
              provision steps.

              `file` and `remote-exec` steps
              automatically get the connection
              part setup, if you configure
              the `provisioner.privateKeyFile`
              parameter.
            '';
            example = [
              {
                file.source = "~/.zshrc";
                file.destination = "/root/.zshrc";
              }
              { remote-exec.inline = [ "shutdown -r +1" ]; }
            ];
          };
          image = mkOption {
            default = "ubuntu-18.04";
            type = with types; str;
            description = ''
              image to spawn on the server
            '';
          };
          serverType = mkOption {
            default = "cx11";
            type = with types; str;
            description = ''
              Hardware equipment. This options influences costs!
            '';
          };
          backups = mkOption {
            default = false;
            type = with types; bool;
            description = ''
              enable backups or not
            '';
          };
        };
      }));
  };

  config = mkIf (cfg != { }) {

    hcloud.enable = true;

    resource.hcloud_server = let
      allUsers =
        mapAttrsToList (name: ignore: "\${ hcloud_ssh_key.server_${name}.id }")
        allAdmins;

      allResources = mapAttrs' (name: configuration: {
        name = "${configuration.name}";
        value = {
          # todo : check if name contains _ which is not allowed by hcloud
          name = configuration.name;
          image = configuration.image;
          server_type = configuration.serverType;
          backups = configuration.backups;
          ssh_keys = allUsers;
          provisioner = builtins.map (provisioner:
            if (builtins.hasAttr "file" provisioner) then {
              "file" = ({
                connection = {
                  type = "ssh";
                  user = "root";
                  private_key =
                    ''''${ file("${config.provisioner.privateKeyFile}") }'';
                };
              } // provisioner.file);
            } else if (builtins.hasAttr "remote-exec" provisioner) then {
              "remote-exec" = ({
                connection = {
                  type = "ssh";
                  user = "root";
                  private_key =
                    ''''${ file("${config.provisioner.privateKeyFile}") }'';
                };
              } // provisioner.remote-exec);
            } else
              provisioner) configuration.provisioners;
        };
      }) cfg;
    in allResources;

    output = let
      ipv4Address = mapAttrs' (ignore: configuration: {
        name = "${configuration.name}_ipv4_address";
        value = {
          value = "\${ hcloud_server.${configuration.name}.ipv4_address }";
        };
      }) cfg;

      ipv6Address = mapAttrs' (ignore: configuration: {
        name = "${configuration.name}_ipv6_address";
        value = {
          value = "\${ hcloud_server.${configuration.name}.ipv6_address }";
        };
      }) cfg;

    in ipv4Address // ipv6Address;

    resource.hcloud_ssh_key = let
      allResources = mapAttrs' (name: configuration: {
        name = "server_${name}";
        value = {
          name = "SSH Key ${name}";
          public_key = configuration.publicKey;
        };
      }) allAdmins;
    in allResources;

  };
}