{ nixpkgs, ... }:
{ config
, pkgs
, lib
, ...
}:
let
  cfg = config.services.buildbot-nix.master;
  inherit (lib) mkRemovedOptionModule mkRenamedOptionModule;
in
{
  _file = ./master.nix;
  imports = [
    (mkRenamedOptionModule
      [
        "services"
        "buildbot-nix"
        "master"
        "github"
        "admins"
      ]
      [
        "services"
        "buildbot-nix"
        "master"
        "admins"
      ]
    )
    (mkRenamedOptionModule
      [
        "services"
        "buildbot-nix"
        "master"
        "github"
        "tokenFile"
      ]
      [
        "services"
        "buildbot-nix"
        "master"
        "github"
        "authType"
        "legacy"
        "tokenFile"
      ]
    )
    (mkRemovedOptionModule
      [
        "services"
        "buildbot-nix"
        "master"
        "github"
        "user"
      ]
      ''
        Setting a user is not required.
      ''
    )
  ];

  options = {
    services.buildbot-nix.vendorBuildbot = lib.mkOption {
      type = lib.types.bool;
      default = true;
      description = ''
        Whether to vendow `buildbot-master` from the `nixpkgs` input of the `buildbot-nix` flake.
        `buildbot-nix` requires `buildbot-master` to be at least of version `4`.
      '';
    };
    services.buildbot-nix.master = {
      enable = lib.mkEnableOption "buildbot-master";
      package = lib.mkPackageOption pkgs "buildbot" { };
      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.
        '';
      };
      buildRetries = lib.mkOption {
        type = lib.types.int;
        default = 1;
        description = "Number of times a build is retried";
      };
      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";
        };

        authType = lib.mkOption {
          type = lib.types.attrTag {
            legacy = lib.mkOption {
              description = "GitHub legacy auth backend";
              type = lib.types.submodule {
                options.tokenFile = lib.mkOption {
                  type = lib.types.path;
                  description = "Github token file";
                };
              };
            };

            app = lib.mkOption {
              description = "GitHub legacy auth backend";
              type = lib.types.submodule {
                options.id = lib.mkOption {
                  type = lib.types.int;
                  description = ''
                    GitHub app ID.
                  '';
                };

                options.secretKeyFile = lib.mkOption {
                  type = lib.types.nullOr lib.types.path;
                  description = ''
                    GitHub app secret key file location.
                  '';
                };
              };
            };
          };
        };

        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";
        };
        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";
      };

      webhookBaseUrl = lib.mkOption {
        type = lib.types.str;
        description = "URL base for the webhook endpoint that will be registered for github or gitea repos.";
        example = "https://buildbot-webhooks.numtide.com/";
        default = config.services.buildbot-master.buildbotUrl;
      };
      useHTTPS = lib.mkOption {
        type = lib.types.nullOr lib.types.bool;
        default = false;
        description = ''
          If buildbot is setup behind a reverse proxy other than the configured nginx set this to true
          to force the endpoint to use https:// instead of http://.
        '';
      };

      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.mkMerge [
    (lib.mkIf config.services.buildbot-nix.vendorBuildbot {
      nixpkgs.overlays = [
        (final: prev:
          {
            buildbotPackages = prev.python3.pkgs.callPackage "${nixpkgs}/pkgs/development/tools/continuous-integration/buildbot" { };
          })
      ];
    })
    (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 =
            lib.versionAtLeast cfg.package.version "4.0.0";
          message = "`buildbot-nix` requires `buildbot` 4.0.0 or greater to function";
        }
        {
          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,
          )
          from buildbot_nix.github.auth._type import (
            AuthTypeLegacy,
            AuthTypeApp,
          )
        '';
        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=${builtins.toJSON cfg.github.oauthId},
                    topic=${builtins.toJSON cfg.github.topic},
                    auth_type=${
                            if cfg.github.authType ? "legacy" then
                              ''AuthTypeLegacy()''
                            else if cfg.github.authType ? "app" then
                              ''
                                AuthTypeApp(
                                  app_id=${toString cfg.github.authType.app.id},
                                )
                              ''
                            else
                              throw "One of AuthTypeApp or AuthTypeLegacy must be enabled"
                          }
                )"
                },
                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},
                )"
                },
                build_retries=${builtins.toJSON cfg.buildRetries},
                cachix=${
                  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=${builtins.toJSON config.services.buildbot-nix.master.webhookBaseUrl},
                nix_eval_max_memory_size=${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 || cfg.useHTTPS;
          in
          "${if hasSSL then "https" else "http"}://${cfg.domain}/";
        dbUrl = config.services.buildbot-nix.master.dbUrl;
        package = cfg.package;
        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 = cfg.package; })
        ];
      };

      systemd.services.buildbot-master = {
        after = [ "postgresql.service" ];
        path = [
          pkgs.openssl
        ];
        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-webhook-secret:${cfg.github.webhookSecretFile}"
            ]
            ++ lib.optionals (cfg.github.authType ? "legacy") [
              "github-token:${cfg.github.authType.legacy.tokenFile}"
            ]
            ++ lib.optionals (cfg.github.authType ? "app") [
              "github-app-secret-key:${cfg.github.authType.app.secretKeyFile}"
            ])
            ++ lib.optionals cfg.gitea.enable [
              "gitea-token:${cfg.gitea.tokenFile}"
              "gitea-webhook-secret:${cfg.gitea.webhookSecretFile}"
            ];
        };
      };

      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 - -";
    })
  ];
}