{ config, options, pkgs, lib, ... }:

let
  cfg = config.services.keycloak;
  opt = options.services.keycloak;

  inherit (lib) types mkOption concatStringsSep mapAttrsToList
    escapeShellArg recursiveUpdate optionalAttrs boolToString mkOrder
    sort filterAttrs concatMapStringsSep concatStrings mkIf
    optionalString optionals mkDefault literalExpression hasSuffix
    foldl' isAttrs filter attrNames elem literalDocBook
    maintainers;

  inherit (builtins) match typeOf;
in
{
  options.services.keycloak =
    let
      inherit (types) bool str nullOr attrsOf path enum anything
        package port;
    in
    {
      enable = mkOption {
        type = bool;
        default = false;
        example = true;
        description = ''
          Whether to enable the Keycloak identity and access management
          server.
        '';
      };

      bindAddress = mkOption {
        type = str;
        default = "\${jboss.bind.address:0.0.0.0}";
        example = "127.0.0.1";
        description = ''
          On which address Keycloak should accept new connections.

          A special syntax can be used to allow command line Java system
          properties to override the value: ''${property.name:value}
        '';
      };

      httpPort = mkOption {
        type = str;
        default = "\${jboss.http.port:80}";
        example = "8080";
        description = ''
          On which port Keycloak should listen for new HTTP connections.

          A special syntax can be used to allow command line Java system
          properties to override the value: ''${property.name:value}
        '';
      };

      httpsPort = mkOption {
        type = str;
        default = "\${jboss.https.port:443}";
        example = "8443";
        description = ''
          On which port Keycloak should listen for new HTTPS connections.

          A special syntax can be used to allow command line Java system
          properties to override the value: ''${property.name:value}
        '';
      };

      frontendUrl = mkOption {
        type = str;
        apply = x:
          if x == "" || hasSuffix "/" x then
            x
          else
            x + "/";
        example = "keycloak.example.com/auth";
        description = ''
          The public URL used as base for all frontend requests. Should
          normally include a trailing <literal>/auth</literal>.

          See <link xlink:href="https://www.keycloak.org/docs/latest/server_installation/#_hostname">the
          Hostname section of the Keycloak server installation
          manual</link> for more information.
        '';
      };

      forceBackendUrlToFrontendUrl = mkOption {
        type = bool;
        default = false;
        example = true;
        description = ''
          Whether Keycloak should force all requests to go through the
          frontend URL configured in <xref
          linkend="opt-services.keycloak.frontendUrl" />. By default,
          Keycloak allows backend requests to instead use its local
          hostname or IP address and may also advertise it to clients
          through its OpenID Connect Discovery endpoint.

          See <link
          xlink:href="https://www.keycloak.org/docs/latest/server_installation/#_hostname">the
          Hostname section of the Keycloak server installation
          manual</link> for more information.
        '';
      };

      sslCertificate = mkOption {
        type = nullOr path;
        default = null;
        example = "/run/keys/ssl_cert";
        description = ''
          The path to a PEM formatted certificate to use for TLS/SSL
          connections.

          This should be a string, not a Nix path, since Nix paths are
          copied into the world-readable Nix store.
        '';
      };

      sslCertificateKey = mkOption {
        type = nullOr path;
        default = null;
        example = "/run/keys/ssl_key";
        description = ''
          The path to a PEM formatted private key to use for TLS/SSL
          connections.

          This should be a string, not a Nix path, since Nix paths are
          copied into the world-readable Nix store.
        '';
      };

      database = {
        type = mkOption {
          type = enum [ "mysql" "postgresql" ];
          default = "postgresql";
          example = "mysql";
          description = ''
            The type of database Keycloak should connect to.
          '';
        };

        host = mkOption {
          type = str;
          default = "localhost";
          description = ''
            Hostname of the database to connect to.
          '';
        };

        port =
          let
            dbPorts = {
              postgresql = 5432;
              mysql = 3306;
            };
          in
          mkOption {
            type = port;
            default = dbPorts.${cfg.database.type};
            defaultText = literalDocBook "default port of selected database";
            description = ''
              Port of the database to connect to.
            '';
          };

        useSSL = mkOption {
          type = bool;
          default = cfg.database.host != "localhost";
          defaultText = literalExpression ''config.${opt.database.host} != "localhost"'';
          description = ''
            Whether the database connection should be secured by SSL /
            TLS.
          '';
        };

        caCert = mkOption {
          type = nullOr path;
          default = null;
          description = ''
            The SSL / TLS CA certificate that verifies the identity of the
            database server.

            Required when PostgreSQL is used and SSL is turned on.

            For MySQL, if left at <literal>null</literal>, the default
            Java keystore is used, which should suffice if the server
            certificate is issued by an official CA.
          '';
        };

        createLocally = mkOption {
          type = bool;
          default = true;
          description = ''
            Whether a database should be automatically created on the
            local host. Set this to false if you plan on provisioning a
            local database yourself. This has no effect if
            services.keycloak.database.host is customized.
          '';
        };

        username = mkOption {
          type = str;
          default = "keycloak";
          description = ''
            Username to use when connecting to an external or manually
            provisioned database; has no effect when a local database is
            automatically provisioned.

            To use this with a local database, set <xref
            linkend="opt-services.keycloak.database.createLocally" /> to
            <literal>false</literal> and create the database and user
            manually. The database should be called
            <literal>keycloak</literal>.
          '';
        };

        passwordFile = mkOption {
          type = path;
          example = "/run/keys/db_password";
          description = ''
            File containing the database password.

            This should be a string, not a Nix path, since Nix paths are
            copied into the world-readable Nix store.
          '';
        };
      };

      package = mkOption {
        type = package;
        default = pkgs.keycloak;
        defaultText = literalExpression "pkgs.keycloak";
        description = ''
          Keycloak package to use.
        '';
      };

      initialAdminPassword = mkOption {
        type = str;
        default = "changeme";
        description = ''
          Initial password set for the <literal>admin</literal>
          user. The password is not stored safely and should be changed
          immediately in the admin panel.
        '';
      };

      themes = mkOption {
        type = attrsOf package;
        default = { };
        description = ''
          Additional theme packages for Keycloak. Each theme is linked into
          subdirectory with a corresponding attribute name.

          Theme packages consist of several subdirectories which provide
          different theme types: for example, <literal>account</literal>,
          <literal>login</literal> etc. After adding a theme to this option you
          can select it by its name in Keycloak administration console.
        '';
      };

      extraConfig = mkOption {
        type = attrsOf anything;
        default = { };
        example = literalExpression ''
          {
            "subsystem=keycloak-server" = {
              "spi=hostname" = {
                "provider=default" = null;
                "provider=fixed" = {
                  enabled = true;
                  properties.hostname = "keycloak.example.com";
                };
                default-provider = "fixed";
              };
            };
          }
        '';
        description = ''
          Additional Keycloak configuration options to set in
          <literal>standalone.xml</literal>.

          Options are expressed as a Nix attribute set which matches the
          structure of the jboss-cli configuration. The configuration is
          effectively overlayed on top of the default configuration
          shipped with Keycloak. To remove existing nodes and undefine
          attributes from the default configuration, set them to
          <literal>null</literal>.

          The example configuration does the equivalent of the following
          script, which removes the hostname provider
          <literal>default</literal>, adds the deprecated hostname
          provider <literal>fixed</literal> and defines it the default:

          <programlisting>
          /subsystem=keycloak-server/spi=hostname/provider=default:remove()
          /subsystem=keycloak-server/spi=hostname/provider=fixed:add(enabled = true, properties = { hostname = "keycloak.example.com" })
          /subsystem=keycloak-server/spi=hostname:write-attribute(name=default-provider, value="fixed")
          </programlisting>

          You can discover available options by using the <link
          xlink:href="http://docs.wildfly.org/21/Admin_Guide.html#Command_Line_Interface">jboss-cli.sh</link>
          program and by referring to the <link
          xlink:href="https://www.keycloak.org/docs/latest/server_installation/index.html">Keycloak
          Server Installation and Configuration Guide</link>.
        '';
      };

    };

  config =
    let
      # We only want to create a database if we're actually going to connect to it.
      databaseActuallyCreateLocally = cfg.database.createLocally && cfg.database.host == "localhost";
      createLocalPostgreSQL = databaseActuallyCreateLocally && cfg.database.type == "postgresql";
      createLocalMySQL = databaseActuallyCreateLocally && cfg.database.type == "mysql";

      mySqlCaKeystore = pkgs.runCommand "mysql-ca-keystore" { } ''
        ${pkgs.jre}/bin/keytool -importcert -trustcacerts -alias MySQLCACert -file ${cfg.database.caCert} -keystore $out -storepass notsosecretpassword -noprompt
      '';

      # Both theme and theme type directories need to be actual directories in one hierarchy to pass Keycloak checks.
      themesBundle = pkgs.runCommand "keycloak-themes" { } ''
        linkTheme() {
          theme="$1"
          name="$2"

          mkdir "$out/$name"
          for typeDir in "$theme"/*; do
            if [ -d "$typeDir" ]; then
              type="$(basename "$typeDir")"
              mkdir "$out/$name/$type"
              for file in "$typeDir"/*; do
                ln -sn "$file" "$out/$name/$type/$(basename "$file")"
              done
            fi
          done
        }

        mkdir -p "$out"
        for theme in ${cfg.package}/themes/*; do
          if [ -d "$theme" ]; then
            linkTheme "$theme" "$(basename "$theme")"
          fi
        done

        ${concatStringsSep "\n" (mapAttrsToList (name: theme: "linkTheme ${theme} ${escapeShellArg name}") cfg.themes)}
      '';

      keycloakConfig' = foldl' recursiveUpdate
        {
          "interface=public".inet-address = cfg.bindAddress;
          "socket-binding-group=standard-sockets"."socket-binding=http".port = cfg.httpPort;
          "subsystem=keycloak-server" = {
            "spi=hostname"."provider=default" = {
              enabled = true;
              properties = {
                inherit (cfg) frontendUrl forceBackendUrlToFrontendUrl;
              };
            };
            "theme=defaults".dir = toString themesBundle;
          };
          "subsystem=datasources"."data-source=KeycloakDS" = {
            max-pool-size = "20";
            user-name = if databaseActuallyCreateLocally then "keycloak" else cfg.database.username;
            password = "@db-password@";
          };
        } [
        (optionalAttrs (cfg.database.type == "postgresql") {
          "subsystem=datasources" = {
            "jdbc-driver=postgresql" = {
              driver-module-name = "org.postgresql";
              driver-name = "postgresql";
              driver-xa-datasource-class-name = "org.postgresql.xa.PGXADataSource";
            };
            "data-source=KeycloakDS" = {
              connection-url = "jdbc:postgresql://${cfg.database.host}:${toString cfg.database.port}/keycloak";
              driver-name = "postgresql";
              "connection-properties=ssl".value = boolToString cfg.database.useSSL;
            } // (optionalAttrs (cfg.database.caCert != null) {
              "connection-properties=sslrootcert".value = cfg.database.caCert;
              "connection-properties=sslmode".value = "verify-ca";
            });
          };
        })
        (optionalAttrs (cfg.database.type == "mysql") {
          "subsystem=datasources" = {
            "jdbc-driver=mysql" = {
              driver-module-name = "com.mysql";
              driver-name = "mysql";
              driver-class-name = "com.mysql.jdbc.Driver";
            };
            "data-source=KeycloakDS" = {
              connection-url = "jdbc:mysql://${cfg.database.host}:${toString cfg.database.port}/keycloak";
              driver-name = "mysql";
              "connection-properties=useSSL".value = boolToString cfg.database.useSSL;
              "connection-properties=requireSSL".value = boolToString cfg.database.useSSL;
              "connection-properties=verifyServerCertificate".value = boolToString cfg.database.useSSL;
              "connection-properties=characterEncoding".value = "UTF-8";
              valid-connection-checker-class-name = "org.jboss.jca.adapters.jdbc.extensions.mysql.MySQLValidConnectionChecker";
              validate-on-match = true;
              exception-sorter-class-name = "org.jboss.jca.adapters.jdbc.extensions.mysql.MySQLExceptionSorter";
            } // (optionalAttrs (cfg.database.caCert != null) {
              "connection-properties=trustCertificateKeyStoreUrl".value = "file:${mySqlCaKeystore}";
              "connection-properties=trustCertificateKeyStorePassword".value = "notsosecretpassword";
            });
          };
        })
        (optionalAttrs (cfg.sslCertificate != null && cfg.sslCertificateKey != null) {
          "socket-binding-group=standard-sockets"."socket-binding=https".port = cfg.httpsPort;
          "subsystem=elytron" = mkOrder 900 {
            "key-store=httpsKS" = mkOrder 900 {
              path = "/run/keycloak/ssl/certificate_private_key_bundle.p12";
              credential-reference.clear-text = "notsosecretpassword";
              type = "JKS";
            };
            "key-manager=httpsKM" = mkOrder 901 {
              key-store = "httpsKS";
              credential-reference.clear-text = "notsosecretpassword";
            };
            "server-ssl-context=httpsSSC" = mkOrder 902 {
              key-manager = "httpsKM";
            };
          };
          "subsystem=undertow" = mkOrder 901 {
            "server=default-server"."https-listener=https".ssl-context = "httpsSSC";
          };
        })
        cfg.extraConfig
      ];


      /* Produces a JBoss CLI script that creates paths and sets
         attributes matching those described by `attrs`. When the
         script is run, the existing settings are effectively overlayed
         by those from `attrs`. Existing attributes can be unset by
         defining them `null`.

         JBoss paths and attributes / maps are distinguished by their
         name, where paths follow a `key=value` scheme.

         Example:
           mkJbossScript {
             "subsystem=keycloak-server"."spi=hostname" = {
               "provider=fixed" = null;
               "provider=default" = {
                 enabled = true;
                 properties = {
                   inherit frontendUrl;
                   forceBackendUrlToFrontendUrl = false;
                 };
               };
             };
           }
           => ''
             if (outcome != success) of /:read-resource()
                 /:add()
             end-if
             if (outcome != success) of /subsystem=keycloak-server:read-resource()
                 /subsystem=keycloak-server:add()
             end-if
             if (outcome != success) of /subsystem=keycloak-server/spi=hostname:read-resource()
                 /subsystem=keycloak-server/spi=hostname:add()
             end-if
             if (outcome != success) of /subsystem=keycloak-server/spi=hostname/provider=default:read-resource()
                 /subsystem=keycloak-server/spi=hostname/provider=default:add(enabled = true, properties = { forceBackendUrlToFrontendUrl = false, frontendUrl = "https://keycloak.example.com/auth" })
             end-if
             if (result != true) of /subsystem=keycloak-server/spi=hostname/provider=default:read-attribute(name="enabled")
               /subsystem=keycloak-server/spi=hostname/provider=default:write-attribute(name=enabled, value=true)
             end-if
             if (result != false) of /subsystem=keycloak-server/spi=hostname/provider=default:read-attribute(name="properties.forceBackendUrlToFrontendUrl")
               /subsystem=keycloak-server/spi=hostname/provider=default:write-attribute(name=properties.forceBackendUrlToFrontendUrl, value=false)
             end-if
             if (result != "https://keycloak.example.com/auth") of /subsystem=keycloak-server/spi=hostname/provider=default:read-attribute(name="properties.frontendUrl")
               /subsystem=keycloak-server/spi=hostname/provider=default:write-attribute(name=properties.frontendUrl, value="https://keycloak.example.com/auth")
             end-if
             if (outcome != success) of /subsystem=keycloak-server/spi=hostname/provider=fixed:read-resource()
                 /subsystem=keycloak-server/spi=hostname/provider=fixed:remove()
             end-if
           ''
      */
      mkJbossScript = attrs:
        let
          /* From a JBoss path and an attrset, produces a JBoss CLI
             snippet that writes the corresponding attributes starting
             at `path`. Recurses down into subattrsets as necessary,
             producing the variable name from its full path in the
             attrset.

             Example:
               writeAttributes "/subsystem=keycloak-server/spi=hostname/provider=default" {
                 enabled = true;
                 properties = {
                   forceBackendUrlToFrontendUrl = false;
                   frontendUrl = "https://keycloak.example.com/auth";
                 };
               }
               => ''
                 if (result != true) of /subsystem=keycloak-server/spi=hostname/provider=default:read-attribute(name="enabled")
                   /subsystem=keycloak-server/spi=hostname/provider=default:write-attribute(name=enabled, value=true)
                 end-if
                 if (result != false) of /subsystem=keycloak-server/spi=hostname/provider=default:read-attribute(name="properties.forceBackendUrlToFrontendUrl")
                   /subsystem=keycloak-server/spi=hostname/provider=default:write-attribute(name=properties.forceBackendUrlToFrontendUrl, value=false)
                 end-if
                 if (result != "https://keycloak.example.com/auth") of /subsystem=keycloak-server/spi=hostname/provider=default:read-attribute(name="properties.frontendUrl")
                   /subsystem=keycloak-server/spi=hostname/provider=default:write-attribute(name=properties.frontendUrl, value="https://keycloak.example.com/auth")
                 end-if
               ''
          */
          writeAttributes = path: set:
            let
              # JBoss expressions like `${var}` need to be prefixed
              # with `expression` to evaluate.
              prefixExpression = string:
                let
                  matchResult = match ''"\$\{.*}"'' string;
                in
                if matchResult != null then
                  "expression " + string
                else
                  string;

              writeAttribute = attribute: value:
                let
                  type = typeOf value;
                in
                if type == "set" then
                  let
                    names = attrNames value;
                  in
                  foldl' (text: name: text + (writeAttribute "${attribute}.${name}" value.${name})) "" names
                else if value == null then ''
                  if (outcome == success) of ${path}:read-attribute(name="${attribute}")
                      ${path}:undefine-attribute(name="${attribute}")
                  end-if
                ''
                else if elem type [ "string" "path" "bool" ] then
                  let
                    value' = if type == "bool" then boolToString value else ''"${value}"'';
                  in
                  ''
                    if (result != ${prefixExpression value'}) of ${path}:read-attribute(name="${attribute}")
                      ${path}:write-attribute(name=${attribute}, value=${value'})
                    end-if
                  ''
                else throw "Unsupported type '${type}' for path '${path}'!";
            in
            concatStrings
              (mapAttrsToList
                (attribute: value: (writeAttribute attribute value))
                set);


          /* Produces an argument list for the JBoss `add()` function,
             which adds a JBoss path and takes as its arguments the
             required subpaths and attributes.

             Example:
               makeArgList {
                 enabled = true;
                 properties = {
                   forceBackendUrlToFrontendUrl = false;
                   frontendUrl = "https://keycloak.example.com/auth";
                 };
               }
               => ''
                 enabled = true, properties = { forceBackendUrlToFrontendUrl = false, frontendUrl = "https://keycloak.example.com/auth" }
               ''
          */
          makeArgList = set:
            let
              makeArg = attribute: value:
                let
                  type = typeOf value;
                in
                if type == "set" then
                  "${attribute} = { " + (makeArgList value) + " }"
                else if elem type [ "string" "path" "bool" ] then
                  "${attribute} = ${if type == "bool" then boolToString value else ''"${value}"''}"
                else if value == null then
                  ""
                else
                  throw "Unsupported type '${type}' for attribute '${attribute}'!";

            in
            concatStringsSep ", " (mapAttrsToList makeArg set);


          /* Recurses into the `nodeValue` attrset. Only subattrsets that
             are JBoss paths, i.e. follows the `key=value` format, are recursed
             into - the rest are considered JBoss attributes / maps.
          */
          recurse = nodePath: nodeValue:
            let
              nodeContent =
                if isAttrs nodeValue && nodeValue._type or "" == "order" then
                  nodeValue.content
                else
                  nodeValue;
              isPath = name:
                let
                  value = nodeContent.${name};
                in
                if (match ".*([=]).*" name) == [ "=" ] then
                  if isAttrs value || value == null then
                    true
                  else
                    throw "Parsing path '${concatStringsSep "." (nodePath ++ [ name ])}' failed: JBoss attributes cannot contain '='!"
                else
                  false;
              jbossPath = "/" + concatStringsSep "/" nodePath;
              children = if !isAttrs nodeContent then { } else nodeContent;
              subPaths = filter isPath (attrNames children);
              getPriority = name:
                let
                  value = children.${name};
                in
                if value._type or "" == "order" then value.priority else 1000;
              orderedSubPaths = sort (a: b: getPriority a < getPriority b) subPaths;
              jbossAttrs = filterAttrs (name: _: !(isPath name)) children;
              text =
                if nodeContent != null then
                  ''
                    if (outcome != success) of ${jbossPath}:read-resource()
                        ${jbossPath}:add(${makeArgList jbossAttrs})
                    end-if
                  '' + writeAttributes jbossPath jbossAttrs
                else
                  ''
                    if (outcome == success) of ${jbossPath}:read-resource()
                        ${jbossPath}:remove()
                    end-if
                  '';
            in
            text + concatMapStringsSep "\n" (name: recurse (nodePath ++ [ name ]) children.${name}) orderedSubPaths;
        in
        recurse [ ] attrs;

      jbossCliScript = pkgs.writeText "jboss-cli-script" (mkJbossScript keycloakConfig');

      keycloakConfig = pkgs.runCommand "keycloak-config"
        {
          nativeBuildInputs = [ cfg.package ];
        }
        ''
          export JBOSS_BASE_DIR="$(pwd -P)";
          export JBOSS_MODULEPATH="${cfg.package}/modules";
          export JBOSS_LOG_DIR="$JBOSS_BASE_DIR/log";

          cp -r ${cfg.package}/standalone/configuration .
          chmod -R u+rwX ./configuration

          mkdir -p {deployments,ssl}

          standalone.sh&

          attempt=1
          max_attempts=30
          while ! jboss-cli.sh --connect ':read-attribute(name=server-state)'; do
              if [[ "$attempt" == "$max_attempts" ]]; then
                  echo "ERROR: Could not connect to Keycloak after $attempt attempts! Failing.." >&2
                  exit 1
              fi
              echo "Keycloak not fully started yet, retrying.. ($attempt/$max_attempts)"
              sleep 1
              (( attempt++ ))
          done

          jboss-cli.sh --connect --file=${jbossCliScript} --echo-command

          cp configuration/standalone.xml $out
        '';
    in
    mkIf cfg.enable
      {
        assertions = [
          {
            assertion = (cfg.database.useSSL && cfg.database.type == "postgresql") -> (cfg.database.caCert != null);
            message = "A CA certificate must be specified (in 'services.keycloak.database.caCert') when PostgreSQL is used with SSL";
          }
        ];

        environment.systemPackages = [ cfg.package ];

        systemd.services.keycloakPostgreSQLInit = mkIf createLocalPostgreSQL {
          after = [ "postgresql.service" ];
          before = [ "keycloak.service" ];
          bindsTo = [ "postgresql.service" ];
          path = [ config.services.postgresql.package ];
          serviceConfig = {
            Type = "oneshot";
            RemainAfterExit = true;
            User = "postgres";
            Group = "postgres";
            LoadCredential = [ "db_password:${cfg.database.passwordFile}" ];
          };
          script = ''
            set -o errexit -o pipefail -o nounset -o errtrace
            shopt -s inherit_errexit

            create_role="$(mktemp)"
            trap 'rm -f "$create_role"' ERR EXIT

            db_password="$(<"$CREDENTIALS_DIRECTORY/db_password")"
            echo "CREATE ROLE keycloak WITH LOGIN PASSWORD '$db_password' CREATEDB" > "$create_role"
            psql -tAc "SELECT 1 FROM pg_roles WHERE rolname='keycloak'" | grep -q 1 || psql -tA --file="$create_role"
            psql -tAc "SELECT 1 FROM pg_database WHERE datname = 'keycloak'" | grep -q 1 || psql -tAc 'CREATE DATABASE "keycloak" OWNER "keycloak"'
          '';
        };

        systemd.services.keycloakMySQLInit = mkIf createLocalMySQL {
          after = [ "mysql.service" ];
          before = [ "keycloak.service" ];
          bindsTo = [ "mysql.service" ];
          path = [ config.services.mysql.package ];
          serviceConfig = {
            Type = "oneshot";
            RemainAfterExit = true;
            User = config.services.mysql.user;
            Group = config.services.mysql.group;
            LoadCredential = [ "db_password:${cfg.database.passwordFile}" ];
          };
          script = ''
            set -o errexit -o pipefail -o nounset -o errtrace
            shopt -s inherit_errexit
            db_password="$(<"$CREDENTIALS_DIRECTORY/db_password")"
            ( echo "CREATE USER IF NOT EXISTS 'keycloak'@'localhost' IDENTIFIED BY '$db_password';"
              echo "CREATE DATABASE IF NOT EXISTS keycloak CHARACTER SET utf8 COLLATE utf8_unicode_ci;"
              echo "GRANT ALL PRIVILEGES ON keycloak.* TO 'keycloak'@'localhost';"
            ) | mysql -N
          '';
        };

        systemd.services.keycloak =
          let
            databaseServices =
              if createLocalPostgreSQL then [
                "keycloakPostgreSQLInit.service"
                "postgresql.service"
              ]
              else if createLocalMySQL then [
                "keycloakMySQLInit.service"
                "mysql.service"
              ]
              else [ ];
          in
          {
            after = databaseServices;
            bindsTo = databaseServices;
            wantedBy = [ "multi-user.target" ];
            path = with pkgs; [
              cfg.package
              openssl
              replace-secret
            ];
            environment = {
              JBOSS_LOG_DIR = "/var/log/keycloak";
              JBOSS_BASE_DIR = "/run/keycloak";
              JBOSS_MODULEPATH = "${cfg.package}/modules";
            };
            serviceConfig = {
              LoadCredential = [
                "db_password:${cfg.database.passwordFile}"
              ] ++ optionals (cfg.sslCertificate != null && cfg.sslCertificateKey != null) [
                "ssl_cert:${cfg.sslCertificate}"
                "ssl_key:${cfg.sslCertificateKey}"
              ];
              User = "keycloak";
              Group = "keycloak";
              DynamicUser = true;
              RuntimeDirectory = map (p: "keycloak/" + p) [
                "configuration"
                "deployments"
                "data"
                "ssl"
                "log"
                "tmp"
              ];
              RuntimeDirectoryMode = 0700;
              LogsDirectory = "keycloak";
              AmbientCapabilities = "CAP_NET_BIND_SERVICE";
            };
            script = ''
              set -o errexit -o pipefail -o nounset -o errtrace
              shopt -s inherit_errexit

              umask u=rwx,g=,o=

              install -m 0600 ${cfg.package}/standalone/configuration/*.properties /run/keycloak/configuration
              install -T -m 0600 ${keycloakConfig} /run/keycloak/configuration/standalone.xml

              replace-secret '@db-password@' "$CREDENTIALS_DIRECTORY/db_password" /run/keycloak/configuration/standalone.xml

              export JAVA_OPTS=-Djboss.server.config.user.dir=/run/keycloak/configuration
              add-user-keycloak.sh -u admin -p '${cfg.initialAdminPassword}'
            '' + optionalString (cfg.sslCertificate != null && cfg.sslCertificateKey != null) ''
              pushd /run/keycloak/ssl/
              cat "$CREDENTIALS_DIRECTORY/ssl_cert" <(echo) \
                  "$CREDENTIALS_DIRECTORY/ssl_key" <(echo) \
                  /etc/ssl/certs/ca-certificates.crt \
                  > allcerts.pem
              openssl pkcs12 -export -in "$CREDENTIALS_DIRECTORY/ssl_cert" -inkey "$CREDENTIALS_DIRECTORY/ssl_key" -chain \
                             -name "${cfg.frontendUrl}" -out certificate_private_key_bundle.p12 \
                             -CAfile allcerts.pem -passout pass:notsosecretpassword
              popd
            '' + ''
              ${cfg.package}/bin/standalone.sh
            '';
          };

        services.postgresql.enable = mkDefault createLocalPostgreSQL;
        services.mysql.enable = mkDefault createLocalMySQL;
        services.mysql.package = mkIf createLocalMySQL pkgs.mariadb;
      };

  meta.doc = ./keycloak.xml;
  meta.maintainers = [ maintainers.talyz ];
}