{ lib, pkgs, config, ... }:
let
  varDir = "/var/lib/buildbot";
  buildbot_common = pkgs.python3Packages.buildPythonPackage rec {
    name = "buildbot_common";
    src = ./common;
    format = "other";
    installPhase = ''
      mkdir -p $out/${pkgs.python3.pythonForBuild.sitePackages}
      cp -a $src $out/${pkgs.python3.pythonForBuild.sitePackages}/buildbot_common
      '';
  };
  buildbot = pkgs.python3Packages.buildbot-full;
in
{
  options = {
    myServices.buildbot.enable = lib.mkOption {
      type = lib.types.bool;
      default = false;
      description = ''
        Whether to enable buildbot.
      '';
    };
  };

  config = lib.mkIf config.myServices.buildbot.enable {
    ids.uids.buildbot = config.myEnv.buildbot.user.uid;
    ids.gids.buildbot = config.myEnv.buildbot.user.gid;

    users.groups.buildbot.gid = config.ids.gids.buildbot;
    users.users.buildbot = {
      name = "buildbot";
      uid = config.ids.uids.buildbot;
      group = "buildbot";
      description = "Buildbot user";
      home = varDir;
      extraGroups = [ "keys" ];
    };

    services.websites.env.tools.watchPaths = lib.attrsets.mapAttrsToList
      (k: project: config.secrets.fullPaths."buildbot/${project.name}/webhook-httpd-include")
      config.myEnv.buildbot.projects;

    services.websites.env.tools.vhostConfs.git.extraConfig = lib.attrsets.mapAttrsToList (k: project: ''
        RedirectMatch permanent "^/buildbot/${project.name}$" "/buildbot/${project.name}/"
        RewriteEngine On
        RewriteRule ^/buildbot/${project.name}/ws(.*)$   unix:///run/buildbot/${project.name}.sock|ws://git.immae.eu/ws$1 [P,NE,QSA,L]
        ProxyPass /buildbot/${project.name}/             unix:///run/buildbot/${project.name}.sock|http://${project.name}-git.immae.eu/
        ProxyPassReverse /buildbot/${project.name}/      unix:///run/buildbot/${project.name}.sock|http://${project.name}-git.immae.eu/
        <Location /buildbot/${project.name}/>
          Use LDAPConnect
          Require ldap-group cn=users,ou=${project.name},cn=buildbot,ou=services,dc=immae,dc=eu

          SetEnvIf X-Url-Scheme https HTTPS=1
          ProxyPreserveHost On
        </Location>
        <Location /buildbot/${project.name}/change_hook/base>
          <RequireAny>
            Require local
            Require ldap-group cn=users,ou=${project.name},cn=buildbot,ou=services,dc=immae,dc=eu
            Include ${config.secrets.fullPaths."buildbot/${project.name}/webhook-httpd-include"}
          </RequireAny>
        </Location>
        '') config.myEnv.buildbot.projects;

    system.activationScripts = lib.attrsets.mapAttrs' (k: project: lib.attrsets.nameValuePair "buildbot-${project.name}" {
      deps = [ "users" "wrappers" ];
      text = ''
        install -m 755 -o buildbot -g buildbot -d ${varDir}/${project.name}

        ${project.activationScript}
        '';
    }) config.myEnv.buildbot.projects;

    secrets.keys = lib.listToAttrs (
      lib.lists.flatten (
        lib.attrsets.mapAttrsToList (k: project:
          lib.attrsets.mapAttrsToList (k: v:
            (lib.nameValuePair "buildbot/${project.name}/${k}" {
              permissions = "0600";
              user = "buildbot";
              group = "buildbot";
              text = v;
            })
          ) project.secrets
          ++ [
            (lib.nameValuePair "buildbot/${project.name}/webhook-httpd-include" {
              permissions = "0600";
              user = "wwwrun";
              group = "wwwrun";
              text = lib.optionalString (project.webhookTokens != null) ''
                Require expr "req('Access-Key') in { ${builtins.concatStringsSep ", " (map (x: "'${x}'") project.webhookTokens)} }"
                '';
            })
            (lib.nameValuePair "buildbot/${project.name}/environment_file" {
              permissions = "0600";
              user = "buildbot";
              group = "buildbot";
              text = let
                project_env = with lib.attrsets;
                  mapAttrs' (k: v: nameValuePair "BUILDBOT_${k}" v) project.environment //
                  mapAttrs' (k: v: nameValuePair "BUILDBOT_PATH_${k}" (v pkgs)) (attrByPath ["builderPaths"] {} project) //
                  {
                    BUILDBOT_PROJECT_DIR = ./projects + "/${project.name}";
                    BUILDBOT_WORKER_PORT = builtins.toString project.workerPort;
                    BUILDBOT_HOST = config.hostEnv.fqdn;
                    BUILDBOT_VIRT_URL = "qemu+ssh://libvirt@dilion.immae.eu/system";
                  };
                in builtins.concatStringsSep "\n"
                  (lib.mapAttrsToList (envK: envV: "${envK}=${envV}") project_env);
            })
          ]
        ) config.myEnv.buildbot.projects
      )
    ) // {
      "buildbot/ldap" = {
        permissions = "0600";
        user = "buildbot";
        group = "buildbot";
        text = config.myEnv.buildbot.ldap.password;
      };
      "buildbot/worker_password" = {
        permissions = "0600";
        user = "buildbot";
        group = "buildbot";
        text = config.myEnv.buildbot.workerPassword;
      };
      "buildbot/ssh_key" = {
        permissions = "0600";
        user = "buildbot";
        group = "buildbot";
        text = config.myEnv.buildbot.ssh_key.private;
      };
    };

    services.filesWatcher = lib.attrsets.mapAttrs' (k: project: lib.attrsets.nameValuePair "buildbot-${project.name}" {
      restart = true;
      paths = [
        config.secrets.fullPaths."buildbot/ldap"
        config.secrets.fullPaths."buildbot/worker_password"
        config.secrets.fullPaths."buildbot/ssh_key"
        config.secrets.fullPaths."buildbot/${project.name}/environment_file"
      ] ++ lib.attrsets.mapAttrsToList (k: v: config.secrets.fullPaths."buildbot/${project.name}/${k}") project.secrets;
    }) config.myEnv.buildbot.projects;

    systemd.slices.buildbot = {
      description = "buildbot slice";
    };

    networking.firewall.allowedTCPPorts = lib.attrsets.mapAttrsToList (k: v: v.workerPort) config.myEnv.buildbot.projects;
    systemd.services = lib.attrsets.mapAttrs' (k: project: lib.attrsets.nameValuePair "buildbot-${project.name}" {
      description = "Buildbot Continuous Integration Server ${project.name}.";
      after = [ "network-online.target" ];
      wantedBy = [ "multi-user.target" ];
      path = project.packages pkgs ++ (project.pythonPackages buildbot.pythonModule pkgs);
      preStart = let
        master-cfg = "${buildbot_common}/${pkgs.python3.pythonForBuild.sitePackages}/buildbot_common/master.cfg";
        tac_file = pkgs.writeText "buildbot.tac" ''
            import os

            from twisted.application import service
            from buildbot.master import BuildMaster

            basedir = '${varDir}/${project.name}'
            rotateLength = 10000000
            maxRotatedFiles = 10
            configfile = '${master-cfg}'

            # Default umask for server
            umask = None

            # if this is a relocatable tac file, get the directory containing the TAC
            if basedir == '.':
                import os
                basedir = os.path.abspath(os.path.dirname(__file__))

            # note: this line is matched against to check that this is a buildmaster
            # directory; do not edit it.
            application = service.Application('buildmaster')
            from twisted.python.logfile import LogFile
            from twisted.python.log import ILogObserver, FileLogObserver
            logfile = LogFile.fromFullPath(os.path.join(basedir, "twistd.log"), rotateLength=rotateLength,
                                            maxRotatedFiles=maxRotatedFiles)
            application.setComponent(ILogObserver, FileLogObserver(logfile).emit)

            m = BuildMaster(basedir, configfile, umask)
            m.setServiceParent(application)
            m.log_rotation.rotateLength = rotateLength
            m.log_rotation.maxRotatedFiles = maxRotatedFiles
          '';
      in ''
      if [ ! -f ${varDir}/${project.name}/buildbot.tac ]; then
        ${buildbot}/bin/buildbot create-master -c "${master-cfg}" "${varDir}/${project.name}"
        rm -f ${varDir}/${project.name}/master.cfg.sample
        rm -f ${varDir}/${project.name}/buildbot.tac
      fi
      ln -sf ${tac_file} ${varDir}/${project.name}/buildbot.tac
      # different buildbots may be trying that simultaneously, add the || true to avoid complaining in case of race
      install -Dm600 -o buildbot -g buildbot -T ${config.secrets.fullPaths."buildbot/ssh_key"} ${varDir}/buildbot_key || true
      buildbot_secrets=${varDir}/${project.name}/secrets
      install -m 0700 -o buildbot -g buildbot -d $buildbot_secrets
      install -Dm600 -o buildbot -g buildbot -T ${config.secrets.fullPaths."buildbot/ldap"} $buildbot_secrets/ldap
      install -Dm600 -o buildbot -g buildbot -T ${config.secrets.fullPaths."buildbot/worker_password"} $buildbot_secrets/worker_password
      ${builtins.concatStringsSep "\n" (lib.attrsets.mapAttrsToList
        (k: v: "install -Dm600 -o buildbot -g buildbot -T ${config.secrets.fullPaths."buildbot/${project.name}/${k}"} $buildbot_secrets/${k}") project.secrets
      )}
      ${buildbot}/bin/buildbot upgrade-master ${varDir}/${project.name}
      '';
      environment = let
        buildbot_config = pkgs.python3Packages.buildPythonPackage (rec {
          name = "buildbot_config-${project.name}";
          src = ./projects + "/${project.name}";
          format = "other";
          installPhase = ''
            mkdir -p $out/${pkgs.python3.pythonForBuild.sitePackages}
            cp -a $src $out/${pkgs.python3.pythonForBuild.sitePackages}/buildbot_config
            '';
        });
        HOME = "${varDir}/${project.name}";
        PYTHONPATH = "${buildbot.pythonModule.withPackages (self: project.pythonPackages self pkgs ++ [
          pkgs.python3Packages.libvirt
          pkgs.python3Packages.wokkel
          pkgs.python3Packages.treq pkgs.python3Packages.ldap3 buildbot
          pkgs.python3Packages.buildbot-worker
          buildbot_common buildbot_config
        ])}/${buildbot.pythonModule.sitePackages}${if project.pythonPathHome then ":${varDir}/${project.name}/.local/${pkgs.python3.pythonForBuild.sitePackages}" else ""}";
      in { inherit PYTHONPATH HOME; };

      serviceConfig = {
        Slice = "buildbot.slice";
        Type = "forking";
        User = "buildbot";
        Group = "buildbot";
        RuntimeDirectory = "buildbot";
        RuntimeDirectoryPreserve = "yes";
        StateDirectory = "buildbot";
        SupplementaryGroups = "keys";
        WorkingDirectory = "${varDir}/${project.name}";
        ExecStart = "${buildbot}/bin/buildbot start";
        EnvironmentFile = config.secrets.fullPaths."buildbot/${project.name}/environment_file";
      };
    }) config.myEnv.buildbot.projects;
  };
}