{ config
, pkgs
, lib
, ...
}:
let
  cfg = config.services.buildbot-nix.master;
  inherit (lib) mkRenamedOptionModule;
in
{
  imports = [
    (mkRenamedOptionModule
      [
        "services"
        "buildbot-nix"
        "master"
        "github"
        "admins"
      ]
      [
        "services"
        "buildbot-nix"
        "master"
        "admins"
      ]
    )
  ];

  options = {
    services.buildbot-nix.master = {
      enable = lib.mkEnableOption "buildbot-master";
      dbUrl = lib.mkOption {
        type = lib.types.str;
        default = "postgresql://@/buildbot";
        description = "Postgresql database url";
      };
      authBackend = lib.mkOption {
        type = lib.types.enum [
          "github"
          "gitea"
          "none"
        ];
        default = "github";
        description = ''
          Which OAuth2 backend to use.
        '';
      };
      cachix = {
        name = lib.mkOption {
          type = lib.types.nullOr lib.types.str;
          default = null;
          description = "Cachix name";
        };

        signingKeyFile = lib.mkOption {
          type = lib.types.nullOr lib.types.path;
          default = null;
          description = "Cachix signing key";
        };

        authTokenFile = lib.mkOption {
          type = lib.types.nullOr lib.types.str;
          default = null;
          description = "Cachix auth token";
        };
      };
      gitea = {
        enable = lib.mkEnableOption "Enable Gitea integration" // {
          default = cfg.authBackend == "gitea";
        };

        tokenFile = lib.mkOption {
          type = lib.types.path;
          description = "Gitea token file";
        };
        webhookSecretFile = lib.mkOption {
          type = lib.types.path;
          description = "Gitea webhook secret file";
        };
        oauthSecretFile = lib.mkOption {
          type = lib.types.nullOr lib.types.path;
          default = null;
          description = "Gitea oauth secret file";
        };

        instanceUrl = lib.mkOption {
          type = lib.types.str;
          description = "Gitea instance URL";
        };
        oauthId = lib.mkOption {
          type = lib.types.nullOr lib.types.str;
          default = null;
          description = "Gitea oauth id. Used for the login button";
        };
        topic = lib.mkOption {
          type = lib.types.nullOr lib.types.str;
          default = "build-with-buildbot";
          description = ''
            Projects that have this topic will be built by buildbot.
            If null, all projects that the buildbot Gitea user has access to, are built.
          '';
        };
      };
      github = {
        enable = lib.mkEnableOption "Enable GitHub integration" // {
          default = cfg.authBackend == "github";
        };

        tokenFile = lib.mkOption {
          type = lib.types.path;
          description = "Github token file";
        };
        webhookSecretFile = lib.mkOption {
          type = lib.types.path;
          description = "Github webhook secret file";
        };
        oauthSecretFile = lib.mkOption {
          type = lib.types.nullOr lib.types.path;
          default = null;
          description = "Github oauth secret file";
        };
        # TODO: make this an option
        # https://github.com/organizations/numtide/settings/applications
        # Application name: BuildBot
        # Homepage URL: https://buildbot.numtide.com
        # Authorization callback URL: https://buildbot.numtide.com/auth/login
        # oauth_token:  2516248ec6289e4d9818122cce0cbde39e4b788d
        oauthId = lib.mkOption {
          type = lib.types.nullOr lib.types.str;
          default = null;
          description = "Github oauth id. Used for the login button";
        };
        # Most likely you want to use the same user as for the buildbot
        user = lib.mkOption {
          type = lib.types.str;
          description = "Github user that is used for the buildbot";
        };
        topic = lib.mkOption {
          type = lib.types.nullOr lib.types.str;
          default = "build-with-buildbot";
          description = ''
            Projects that have this topic will be built by buildbot.
            If null, all projects that the buildbot github user has access to, are built.
          '';
        };
      };
      admins = lib.mkOption {
        type = lib.types.listOf lib.types.str;
        default = [ ];
        description = "Users that are allowed to login to buildbot, trigger builds and change settings";
      };
      workersFile = lib.mkOption {
        type = lib.types.path;
        description = "File containing a list of nix workers";
      };
      buildSystems = lib.mkOption {
        type = lib.types.listOf lib.types.str;
        default = [ pkgs.hostPlatform.system ];
        description = "Systems that we will be build";
      };
      evalMaxMemorySize = lib.mkOption {
        type = lib.types.str;
        default = "2048";
        description = ''
          Maximum memory size for nix-eval-jobs (in MiB) per
          worker. After the limit is reached, the worker is
          restarted.
        '';
      };
      evalWorkerCount = lib.mkOption {
        type = lib.types.nullOr lib.types.int;
        default = null;
        description = ''
          Number of nix-eval-jobs worker processes. If null, the number of cores is used.
          If you experience memory issues (buildbot-workers going out-of-memory), you can reduce this number.
        '';
      };
      domain = lib.mkOption {
        type = lib.types.str;
        description = "Buildbot domain";
        example = "buildbot.numtide.com";
      };

      outputsPath = lib.mkOption {
        type = lib.types.nullOr lib.types.path;
        description = "Path where we store the latest build store paths names for nix attributes as text files. This path will be exposed via nginx at \${domain}/nix-outputs";
        default = null;
        example = "/var/www/buildbot/nix-outputs";
      };
    };
  };
  config = lib.mkIf cfg.enable {
    # By default buildbot uses a normal user, which is not a good default, because
    # we grant normal users potentially access to other resources. Also
    # we don't to be able to ssh into buildbot.

    users.users.buildbot = {
      isNormalUser = lib.mkForce false;
      isSystemUser = true;
    };

    assertions = [
      {
        assertion =
          cfg.cachix.name != null -> cfg.cachix.signingKeyFile != null || cfg.cachix.authTokenFile != null;
        message = "if cachix.name is provided, then cachix.signingKeyFile and cachix.authTokenFile must be set";
      }
      {
        assertion =
          cfg.authBackend != "github" || (cfg.github.oauthId != null && cfg.github.oauthSecretFile != null);
        message = ''If config.services.buildbot-nix.master.authBackend is set to "github", then config.services.buildbot-nix.master.github.oauthId and config.services.buildbot-nix.master.github.oauthSecretFile have to be set.'';
      }
      {
        assertion =
          cfg.authBackend != "gitea" || (cfg.gitea.oauthId != null && cfg.gitea.oauthSecretFile != null);
        message = ''config.services.buildbot-nix.master.authBackend is set to "gitea", then config.services.buildbot-nix.master.gitea.oauthId and config.services.buildbot-nix.master.gitea.oauthSecretFile have to be set.'';
      }
    ];

    services.buildbot-master = {
      enable = true;

      # disable example workers from nixpkgs
      builders = [ ];
      schedulers = [ ];
      workers = [ ];

      home = "/var/lib/buildbot";
      extraImports = ''
        from datetime import timedelta
        from buildbot_nix import GithubConfig, NixConfigurator, CachixConfig, GiteaConfig
      '';
      configurators = [
        ''
          util.JanitorConfigurator(logHorizon=timedelta(weeks=4), hour=12, dayOfWeek=6)
        ''
        ''
          NixConfigurator(
              auth_backend=${builtins.toJSON cfg.authBackend},
              github=${
                if (!cfg.github.enable) then
                  "None"
                else
                  "GithubConfig(
                  oauth_id=${builtins.toJSON cfg.github.oauthId},
                  buildbot_user=${builtins.toJSON cfg.github.user},
                  topic=${builtins.toJSON cfg.github.topic},
              )"
              },
              gitea=${
                if !cfg.gitea.enable then
                  "None"
                else
                  "GiteaConfig(
                  instance_url=${builtins.toJSON cfg.gitea.instanceUrl},
                  oauth_id=${builtins.toJSON cfg.gitea.oauthId},
                  topic=${builtins.toJSON cfg.gitea.topic},
              )"
              },
              cachix=${
                if cfg.cachix.name == null then
                  "None"
                else
                  "CachixConfig(
                  name=${builtins.toJSON cfg.cachix.name},
                  signing_key_secret_name=${
                                      if cfg.cachix.signingKeyFile != null then builtins.toJSON "cachix-signing-key" else "None"
                                    },
                  auth_token_secret_name=${
                                      if cfg.cachix.authTokenFile != null then builtins.toJSON "cachix-auth-token" else "None"
                                    },
              )"
              },
              admins=${builtins.toJSON cfg.admins},
              url=${builtins.toJSON config.services.buildbot-master.buildbotUrl},
              nix_eval_max_memory_size=${builtins.toJSON cfg.evalMaxMemorySize},
              nix_eval_worker_count=${
                if cfg.evalWorkerCount == null then "None" else builtins.toString cfg.evalWorkerCount
              },
              nix_supported_systems=${builtins.toJSON cfg.buildSystems},
              outputs_path=${if cfg.outputsPath == null then "None" else builtins.toJSON cfg.outputsPath},
          )
        ''
      ];
      buildbotUrl =
        let
          host = config.services.nginx.virtualHosts.${cfg.domain};
          hasSSL = host.forceSSL || host.addSSL;
        in
        "${if hasSSL then "https" else "http"}://${cfg.domain}/";
      dbUrl = config.services.buildbot-nix.master.dbUrl;
      # Can be dropped after we have 24.05 everywhere
      package = lib.mkIf (lib.versionOlder pkgs.buildbot.version "3.10.0") (
        pkgs.buildbot.overrideAttrs (old: {
          patches = old.patches ++ [ ./0001-allow-secrets-to-be-group-readable.patch ];
        })
      );
      pythonPackages = ps: [
        ps.requests
        ps.treq
        ps.psycopg2
        (ps.toPythonModule pkgs.buildbot-worker)
        pkgs.buildbot-plugins.www-react
        (pkgs.python3.pkgs.callPackage ../default.nix { })
        (pkgs.python3.pkgs.callPackage ./buildbot-gitea.nix { buildbot = pkgs.buildbot; })
      ];
    };

    systemd.services.buildbot-master = {
      after = [ "postgresql.service" ];
      serviceConfig = {
        # in master.py we read secrets from $CREDENTIALS_DIRECTORY
        LoadCredential =
          [ "buildbot-nix-workers:${cfg.workersFile}" ]
          ++ lib.optional (cfg.authBackend == "gitea") "gitea-oauth-secret:${cfg.gitea.oauthSecretFile}"
          ++ lib.optional (cfg.authBackend == "github") "github-oauth-secret:${cfg.github.oauthSecretFile}"
          ++ lib.optional
            (
              cfg.cachix.signingKeyFile != null
            ) "cachix-signing-key:${builtins.toString cfg.cachix.signingKeyFile}"
          ++ lib.optional
            (
              cfg.cachix.authTokenFile != null
            ) "cachix-auth-token:${builtins.toString cfg.cachix.authTokenFile}"
          ++ lib.optionals (cfg.github.enable) [
            "github-token:${cfg.github.tokenFile}"
            "github-webhook-secret:${cfg.github.webhookSecretFile}"
          ]
          ++ lib.optionals cfg.gitea.enable [
            "gitea-token:${cfg.gitea.tokenFile}"
            "gitea-webhook-secret:${cfg.gitea.webhookSecretFile}"
          ];

        # Needed because it tries to reach out to github on boot.
        # FIXME: if github is not available, we shouldn't fail buildbot, instead it should just try later again in the background
        Restart = "on-failure";
        RestartSec = "30s";
      };
    };

    services.postgresql = {
      enable = true;
      ensureDatabases = [ "buildbot" ];
      ensureUsers = [
        {
          name = "buildbot";
          ensureDBOwnership = true;
        }
      ];
    };

    services.nginx.enable = true;
    services.nginx.virtualHosts.${cfg.domain} = {
      locations = {
        "/".proxyPass = "http://127.0.0.1:${builtins.toString config.services.buildbot-master.port}/";
        "/sse" = {
          proxyPass = "http://127.0.0.1:${builtins.toString config.services.buildbot-master.port}/sse";
          # proxy buffering will prevent sse to work
          extraConfig = "proxy_buffering off;";
        };
        "/ws" = {
          proxyPass = "http://127.0.0.1:${builtins.toString config.services.buildbot-master.port}/ws";
          proxyWebsockets = true;
          # raise the proxy timeout for the websocket
          extraConfig = "proxy_read_timeout 6000s;";
        };
      } // lib.optionalAttrs (cfg.outputsPath != null) { "/nix-outputs".root = cfg.outputsPath; };
    };

    systemd.tmpfiles.rules =
      [
        # delete legacy gcroot location, can be dropped after 2024-06-01
        "R /var/lib/buildbot-worker/gcroot - - - - -"
      ]
      ++ lib.optional (cfg.outputsPath != null)
        # Allow buildbot-master to write to this directory
        "d ${cfg.outputsPath} 0755 buildbot buildbot - -";
  };
}