sp-mastodon-module/module.nix

{
  config,
  lib,
  pkgs,
  ...
}:
let
  sp = config.selfprivacy;
  cfg = sp.modules.mastodon;
  oauthClientID = "mastodon";
  auth-passthru = config.selfprivacy.passthru.auth;
  oauthDiscoveryURL = config.services.kanidm.serverSettings.origin;
  issuer = lib.strings.removeSuffix "/.well-known/openid-configuration" oauthDiscoveryURL;

  # SelfPrivacy uses SP Module ID to identify the group!
  usersGroup = "sp.mastodon.users";

  oauthClientSecretFP = auth-passthru.mkOAuth2ClientSecretFP oauthClientID;
  oauthRedirectURL = "https://${cfg.subdomain}.${sp.domain}/auth/auth/openid_connect/callback";
in
{
  options.selfprivacy.modules.mastodon = {
    enable =
      (lib.mkOption {
        default = false;
        type = lib.types.bool;
        description = "Enable Mastodon";
      })
      // {
        meta = {
          type = "enable";
        };
      };
    location =
      (lib.mkOption {
        type = lib.types.str;
        description = "Mastodon location";
      })
      // {
        meta = {
          type = "location";
        };
      };
    subdomain =
      (lib.mkOption {
        default = "mastodon";
        type = lib.types.strMatching "[A-Za-z0-9][A-Za-z0-9\-]{0,61}[A-Za-z0-9]";
        description = "Subdomain";
      })
      // {
        meta = {
          widget = "subdomain";
          type = "string";
          regex = "[A-Za-z0-9][A-Za-z0-9\-]{0,61}[A-Za-z0-9]";
          weight = 0;
        };
      };
  };

  config = lib.mkIf cfg.enable {
    assertions = [
      {
        assertion = sp.sso.enable;
        message = "Mastodon cannot be enabled when SSO is disabled.";
      }
    ];

    fileSystems = lib.mkIf sp.useBinds {
      "/var/lib/mastodon" = {
        device = "/volumes/${cfg.location}/mastodon";
        options = [ "bind" ];
      };
    };

    # services.postgresql = {
    #   ensureDatabases = [ "mastodon" ];
    #   ensureUsers = [
    #     {
    #       name = "mastodon";
    #       ensureDBOwnership = true;
    #     }
    #   ];
    # };

    services.mastodon = {
      enable = true;
      localDomain = "${cfg.subdomain}.${sp.domain}";
      enableUnixSocket = false;
      configureNginx = true;
      database.createLocally = true;
    };


    systemd = {
      services.mastodon = {
        unitConfig.RequiresMountsFor = lib.mkIf sp.useBinds "/volumes/${cfg.location}/mastodon";
        serviceConfig = {
          loadCredentials = ["client-secret:${oauthClientSecretFP}"];
          ExecStart = ''
            export CLIENT_SECRET=$(cat $CREDENTIALS_DIRECTORY/client-secret)
            ${config.services.mastodon.package}/bin/puma -C config/puma.rb`
          '';
        };
        environment = {
          OIDC_ENABLED = true;
          OIDC_DISPLAY_NAME= "Kanidm";
          OIDC_ISSUER = issuer;
          OIDC_DISCOVERY = true;
          OIDC_SCOPE = "openid,profile";
          OIDC_UID_FIELD = "sub";
          OIDC_CLIENT_ID = oauthClientID;
          OIDC_REDIRECT_URI = oauthRedirectURL;
        };        
      };
      slices.mastodon = {
        description = "Mastodon service slice";
      };
    };

    selfprivacy.auth.clients.${oauthClientID} = {
      inherit usersGroup;
      subdomain = cfg.subdomain;
      originLanding = "https://${cfg.subdomain}.${sp.domain}/";
      originUrl = oauthRedirectURL;
      clientSystemdUnits = [ "mastodon.service" ];
      enablePkce = true;
      linuxUserOfClient = "mastodon";
      linuxGroupOfClient = "mastodon";
    };
  };
}