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

# TODO: support non-postgresql

with lib;

let
  cfg = config.services.gitlab;

  ruby = cfg.packages.gitlab.ruby;
  bundler = pkgs.bundler;

  gemHome = "${cfg.packages.gitlab.ruby-env}/${ruby.gemPath}";

  gitlabSocket = "${cfg.statePath}/tmp/sockets/gitlab.socket";
  gitalySocket = "${cfg.statePath}/tmp/sockets/gitaly.socket";
  pathUrlQuote = url: replaceStrings ["/"] ["%2F"] url;

  databaseYml = ''
    production:
      adapter: postgresql
      database: ${cfg.databaseName}
      host: ${cfg.databaseHost}
      password: ${cfg.databasePassword}
      username: ${cfg.databaseUsername}
      encoding: utf8
  '';

  gitalyToml = pkgs.writeText "gitaly.toml" ''
    socket_path = "${lib.escape ["\""] gitalySocket}"
    # prometheus metrics

    ${concatStringsSep "\n" (attrValues (mapAttrs (k: v: ''
    [[storage]]
    name = "${lib.escape ["\""] k}"
    path = "${lib.escape ["\""] v.path}"
    '') gitlabConfig.production.repositories.storages))}
  '';

  gitlabShellYml = ''
    user: ${cfg.user}
    gitlab_url: "http+unix://${pathUrlQuote gitlabSocket}"
    http_settings:
      self_signed_cert: false
    repos_path: "${cfg.statePath}/repositories"
    secret_file: "${cfg.statePath}/config/gitlab_shell_secret"
    log_file: "${cfg.statePath}/log/gitlab-shell.log"
    redis:
      bin: ${pkgs.redis}/bin/redis-cli
      host: 127.0.0.1
      port: 6379
      database: 0
      namespace: resque:gitlab
  '';

  secretsYml = ''
    production:
      secret_key_base: ${cfg.secrets.secret}
      otp_key_base: ${cfg.secrets.otp}
      db_key_base: ${cfg.secrets.db}
      jws_private_key: ${builtins.toJSON cfg.secrets.jws}
  '';

  gitlabConfig = {
    # These are the default settings from config/gitlab.example.yml
    production = flip recursiveUpdate cfg.extraConfig {
      gitlab = {
        host = cfg.host;
        port = cfg.port;
        https = cfg.https;
        user = cfg.user;
        email_enabled = true;
        email_display_name = "GitLab";
        email_reply_to = "noreply@localhost";
        default_theme = 2;
        default_projects_features = {
          issues = true;
          merge_requests = true;
          wiki = true;
          snippets = true;
          builds = true;
          container_registry = true;
        };
      };
      repositories.storages.default.path = "${cfg.statePath}/repositories";
      repositories.storages.default.gitaly_address = "unix:${gitalySocket}";
      artifacts.enabled = true;
      lfs.enabled = true;
      gravatar.enabled = true;
      cron_jobs = { };
      gitlab_ci.builds_path = "${cfg.statePath}/builds";
      ldap.enabled = false;
      omniauth.enabled = false;
      shared.path = "${cfg.statePath}/shared";
      backup.path = "${cfg.backupPath}";
      gitlab_shell = {
        path = "${cfg.packages.gitlab-shell}";
        hooks_path = "${cfg.statePath}/shell/hooks";
        secret_file = "${cfg.statePath}/config/gitlab_shell_secret";
        upload_pack = true;
        receive_pack = true;
      };
      git = {
        bin_path = "git";
        max_size = 20971520; # 20MB
        timeout = 10;
      };
      extra = {};
    };
  };

  gitlabEnv = {
    HOME = "${cfg.statePath}/home";
    GEM_HOME = gemHome;
    BUNDLE_GEMFILE = "${cfg.packages.gitlab}/share/gitlab/Gemfile";
    UNICORN_PATH = "${cfg.statePath}/";
    GITLAB_PATH = "${cfg.packages.gitlab}/share/gitlab/";
    GITLAB_STATE_PATH = "${cfg.statePath}";
    GITLAB_UPLOADS_PATH = "${cfg.statePath}/uploads";
    GITLAB_LOG_PATH = "${cfg.statePath}/log";
    GITLAB_SHELL_PATH = "${cfg.packages.gitlab-shell}";
    GITLAB_SHELL_CONFIG_PATH = "${cfg.statePath}/home/config.yml";
    GITLAB_SHELL_SECRET_PATH = "${cfg.statePath}/config/gitlab_shell_secret";
    GITLAB_SHELL_HOOKS_PATH = "${cfg.statePath}/home/hooks";
    RAILS_ENV = "production";
  };

  unicornConfig = builtins.readFile ./defaultUnicornConfig.rb;

  gitlab-rake = pkgs.stdenv.mkDerivation rec {
    name = "gitlab-rake";
    buildInputs = [ cfg.packages.gitlab cfg.packages.gitlab.ruby-env pkgs.makeWrapper ];
    phases = "installPhase fixupPhase";
    buildPhase = "";
    installPhase = ''
      mkdir -p $out/bin
      makeWrapper ${cfg.packages.gitlab.ruby-env}/bin/bundle $out/bin/gitlab-bundle \
          ${concatStrings (mapAttrsToList (name: value: "--set ${name} '${value}' ") gitlabEnv)} \
          --set GITLAB_CONFIG_PATH '${cfg.statePath}/config' \
          --set PATH '${lib.makeBinPath [ pkgs.nodejs pkgs.gzip config.services.postgresql.package ]}:$PATH' \
          --set RAKEOPT '-f ${cfg.packages.gitlab}/share/gitlab/Rakefile' \
          --run 'cd ${cfg.packages.gitlab}/share/gitlab'
      makeWrapper $out/bin/gitlab-bundle $out/bin/gitlab-rake \
          --add-flags "exec rake"
     '';
  };

  smtpSettings = pkgs.writeText "gitlab-smtp-settings.rb" ''
    if Rails.env.production?
      Rails.application.config.action_mailer.delivery_method = :smtp

      ActionMailer::Base.delivery_method = :smtp
      ActionMailer::Base.smtp_settings = {
        address: "${cfg.smtp.address}",
        port: ${toString cfg.smtp.port},
        ${optionalString (cfg.smtp.username != null) ''user_name: "${cfg.smtp.username}",''}
        ${optionalString (cfg.smtp.password != null) ''password: "${cfg.smtp.password}",''}
        domain: "${cfg.smtp.domain}",
        ${optionalString (cfg.smtp.authentication != null) "authentication: :${cfg.smtp.authentication},"}
        enable_starttls_auto: ${toString cfg.smtp.enableStartTLSAuto},
        openssl_verify_mode: '${cfg.smtp.opensslVerifyMode}'
      }
    end
  '';

in {

  options = {
    services.gitlab = {
      enable = mkOption {
        type = types.bool;
        default = false;
        description = ''
          Enable the gitlab service.
        '';
      };

      packages.gitlab = mkOption {
        type = types.package;
        default = pkgs.gitlab;
        defaultText = "pkgs.gitlab";
        description = "Reference to the gitlab package";
      };

      packages.gitlab-shell = mkOption {
        type = types.package;
        default = pkgs.gitlab-shell;
        defaultText = "pkgs.gitlab-shell";
        description = "Reference to the gitlab-shell package";
      };

      packages.gitlab-workhorse = mkOption {
        type = types.package;
        default = pkgs.gitlab-workhorse;
        defaultText = "pkgs.gitlab-workhorse";
        description = "Reference to the gitlab-workhorse package";
      };

      packages.gitaly = mkOption {
        type = types.package;
        default = pkgs.gitaly;
        defaultText = "pkgs.gitaly";
        description = "Reference to the gitaly package";
      };

      statePath = mkOption {
        type = types.str;
        default = "/var/gitlab/state";
        description = "Gitlab state directory, logs are stored here.";
      };

      backupPath = mkOption {
        type = types.str;
        default = cfg.statePath + "/backup";
        description = "Gitlab path for backups.";
      };

      databaseHost = mkOption {
        type = types.str;
        default = "127.0.0.1";
        description = "Gitlab database hostname.";
      };

      databasePassword = mkOption {
        type = types.str;
        default = "";
        description = "Gitlab database user password.";
      };

      databaseName = mkOption {
        type = types.str;
        default = "gitlab";
        description = "Gitlab database name.";
      };

      databaseUsername = mkOption {
        type = types.str;
        default = "gitlab";
        description = "Gitlab database user.";
      };

      host = mkOption {
        type = types.str;
        default = config.networking.hostName;
        description = "Gitlab host name. Used e.g. for copy-paste URLs.";
      };

      port = mkOption {
        type = types.int;
        default = 8080;
        description = ''
          Gitlab server port for copy-paste URLs, e.g. 80 or 443 if you're
          service over https.
        '';
      };

      https = mkOption {
        type = types.bool;
        default = false;
        description = "Whether gitlab prints URLs with https as scheme.";
      };

      user = mkOption {
        type = types.str;
        default = "gitlab";
        description = "User to run gitlab and all related services.";
      };

      group = mkOption {
        type = types.str;
        default = "gitlab";
        description = "Group to run gitlab and all related services.";
      };

      initialRootEmail = mkOption {
        type = types.str;
        default = "admin@local.host";
        description = ''
          Initial email address of the root account if this is a new install.
        '';
      };

      initialRootPassword = mkOption {
        type = types.str;
        default = "UseNixOS!";
        description = ''
          Initial password of the root account if this is a new install.
        '';
      };

      smtp = {
        enable = mkOption {
          type = types.bool;
          default = false;
          description = "Enable gitlab mail delivery over SMTP.";
        };

        address = mkOption {
          type = types.str;
          default = "localhost";
          description = "Address of the SMTP server for Gitlab.";
        };

        port = mkOption {
          type = types.int;
          default = 465;
          description = "Port of the SMTP server for Gitlab.";
        };

        username = mkOption {
          type = types.nullOr types.str;
          default = null;
          description = "Username of the SMTP server for Gitlab.";
        };

        password = mkOption {
          type = types.nullOr types.str;
          default = null;
          description = "Password of the SMTP server for Gitlab.";
        };

        domain = mkOption {
          type = types.str;
          default = "localhost";
          description = "HELO domain to use for outgoing mail.";
        };

        authentication = mkOption {
          type = types.nullOr types.str;
          default = null;
          description = "Authentitcation type to use, see http://api.rubyonrails.org/classes/ActionMailer/Base.html";
        };

        enableStartTLSAuto = mkOption {
          type = types.bool;
          default = true;
          description = "Whether to try to use StartTLS.";
        };

        opensslVerifyMode = mkOption {
          type = types.str;
          default = "peer";
          description = "How OpenSSL checks the certificate, see http://api.rubyonrails.org/classes/ActionMailer/Base.html";
        };
      };

      secrets.secret = mkOption {
        type = types.str;
        description = ''
          The secret is used to encrypt variables in the DB. If
          you change or lose this key you will be unable to access variables
          stored in database.

          Make sure the secret is at least 30 characters and all random,
          no regular words or you'll be exposed to dictionary attacks.
        '';
      };

      secrets.db = mkOption {
        type = types.str;
        description = ''
          The secret is used to encrypt variables in the DB. If
          you change or lose this key you will be unable to access variables
          stored in database.

          Make sure the secret is at least 30 characters and all random,
          no regular words or you'll be exposed to dictionary attacks.
        '';
      };

      secrets.otp = mkOption {
        type = types.str;
        description = ''
          The secret is used to encrypt secrets for OTP tokens. If
          you change or lose this key, users which have 2FA enabled for login
          won't be able to login anymore.

          Make sure the secret is at least 30 characters and all random,
          no regular words or you'll be exposed to dictionary attacks.
        '';
      };

      secrets.jws = mkOption {
        type = types.str;
        description = ''
          The secret is used to encrypt session keys. If you change or lose
          this key, users will be disconnected.

          Make sure the secret is an RSA private key in PEM format. You can
          generate one with

          openssl genrsa 2048openssl genpkey -algorithm RSA -out - -pkeyopt rsa_keygen_bits:2048
        '';
      };

      extraConfig = mkOption {
        type = types.attrs;
        default = {};
        example = {
          gitlab = {
            default_projects_features = {
              builds = false;
            };
          };
        };
        description = ''
          Extra options to be merged into config/gitlab.yml as nix
          attribute set.
        '';
      };
    };
  };

  config = mkIf cfg.enable {

    environment.systemPackages = [ pkgs.git gitlab-rake cfg.packages.gitlab-shell ];

    assertions = [
      { assertion = cfg.databasePassword != "";
        message = "databasePassword must be set";
      }
    ];

    # Redis is required for the sidekiq queue runner.
    services.redis.enable = mkDefault true;
    # We use postgres as the main data store.
    services.postgresql.enable = mkDefault true;
    # Use postfix to send out mails.
    services.postfix.enable = mkDefault true;

    users.extraUsers = [
      { name = cfg.user;
        group = cfg.group;
        home = "${cfg.statePath}/home";
        shell = "${pkgs.bash}/bin/bash";
        uid = config.ids.uids.gitlab;
      }
    ];

    users.extraGroups = [
      { name = cfg.group;
        gid = config.ids.gids.gitlab;
      }
    ];

    systemd.services.gitlab-sidekiq = {
      after = [ "network.target" "redis.service" ];
      wantedBy = [ "multi-user.target" ];
      partOf = [ "gitlab.service" ];
      environment = gitlabEnv;
      path = with pkgs; [
        config.services.postgresql.package
        gitAndTools.git
        ruby
        openssh
        nodejs
      ];
      serviceConfig = {
        Type = "simple";
        User = cfg.user;
        Group = cfg.group;
        TimeoutSec = "300";
        Restart = "on-failure";
        WorkingDirectory = "${cfg.packages.gitlab}/share/gitlab";
        ExecStart="${cfg.packages.gitlab.ruby-env}/bin/bundle exec \"sidekiq -C \"${cfg.packages.gitlab}/share/gitlab/config/sidekiq_queues.yml\" -e production -P ${cfg.statePath}/tmp/sidekiq.pid\"";
      };
    };

    systemd.services.gitaly = {
      after = [ "network.target" "gitlab.service" ];
      wantedBy = [ "multi-user.target" ];
      environment.HOME = gitlabEnv.HOME;
      path = with pkgs; [ gitAndTools.git ];
      serviceConfig = {
        #PermissionsStartOnly = true; # preStart must be run as root
        Type = "simple";
        User = cfg.user;
        Group = cfg.group;
        TimeoutSec = "300";
        Restart = "on-failure";
        WorkingDirectory = gitlabEnv.HOME;
        ExecStart = "${cfg.packages.gitaly}/bin/gitaly ${gitalyToml}";
      };
    };

    systemd.services.gitlab-workhorse = {
      after = [ "network.target" "gitlab.service" ];
      wantedBy = [ "multi-user.target" ];
      environment.HOME = gitlabEnv.HOME;
      environment.GITLAB_SHELL_CONFIG_PATH = gitlabEnv.GITLAB_SHELL_CONFIG_PATH;
      path = with pkgs; [
        gitAndTools.git
        gnutar
        gzip
        openssh
        gitlab-workhorse
      ];
      preStart = ''
        mkdir -p /run/gitlab
        chown ${cfg.user}:${cfg.group} /run/gitlab
      '';
      serviceConfig = {
        PermissionsStartOnly = true; # preStart must be run as root
        Type = "simple";
        User = cfg.user;
        Group = cfg.group;
        TimeoutSec = "300";
        Restart = "on-failure";
        WorkingDirectory = gitlabEnv.HOME;
        ExecStart =
          "${cfg.packages.gitlab-workhorse}/bin/gitlab-workhorse "
          + "-listenUmask 0 "
          + "-listenNetwork unix "
          + "-listenAddr /run/gitlab/gitlab-workhorse.socket "
          + "-authSocket ${gitlabSocket} "
          + "-documentRoot ${cfg.packages.gitlab}/share/gitlab/public "
          + "-secretPath ${cfg.packages.gitlab}/share/gitlab/.gitlab_workhorse_secret";
      };
    };

    systemd.services.gitlab = {
      after = [ "network.target" "postgresql.service" "redis.service" ];
      requires = [ "gitlab-sidekiq.service" ];
      wantedBy = [ "multi-user.target" ];
      environment = gitlabEnv;
      path = with pkgs; [
        config.services.postgresql.package
        gitAndTools.git
        openssh
        nodejs
        procps
      ];
      preStart = ''
        mkdir -p ${cfg.backupPath}
        mkdir -p ${cfg.statePath}/builds
        mkdir -p ${cfg.statePath}/repositories
        mkdir -p ${gitlabConfig.production.shared.path}/artifacts
        mkdir -p ${gitlabConfig.production.shared.path}/lfs-objects
        mkdir -p ${gitlabConfig.production.shared.path}/pages
        mkdir -p ${cfg.statePath}/log
        mkdir -p ${cfg.statePath}/tmp/pids
        mkdir -p ${cfg.statePath}/tmp/sockets

        rm -rf ${cfg.statePath}/config ${cfg.statePath}/home/hooks
        mkdir -p ${cfg.statePath}/config

        tr -dc A-Za-z0-9 < /dev/urandom | head -c 32 > ${cfg.statePath}/config/gitlab_shell_secret

        # The uploads directory is hardcoded somewhere deep in rails. It is
        # symlinked in the gitlab package to /run/gitlab/uploads to make it
        # configurable
        mkdir -p /run/gitlab
        mkdir -p ${cfg.statePath}/uploads
        ln -sf ${cfg.statePath}/uploads /run/gitlab/uploads
        chown -R ${cfg.user}:${cfg.group} /run/gitlab

        # Prepare home directory
        mkdir -p ${gitlabEnv.HOME}/.ssh
        touch ${gitlabEnv.HOME}/.ssh/authorized_keys
        chown -R ${cfg.user}:${cfg.group} ${gitlabEnv.HOME}/
        chmod -R u+rwX,go-rwx+X ${gitlabEnv.HOME}/

        cp -rf ${cfg.packages.gitlab}/share/gitlab/config.dist/* ${cfg.statePath}/config
        ${optionalString cfg.smtp.enable ''
          ln -sf ${smtpSettings} ${cfg.statePath}/config/initializers/smtp_settings.rb
        ''}
        ln -sf ${cfg.statePath}/config /run/gitlab/config
        cp ${cfg.packages.gitlab}/share/gitlab/VERSION ${cfg.statePath}/VERSION

        # JSON is a subset of YAML
        ln -fs ${pkgs.writeText "gitlab.yml" (builtins.toJSON gitlabConfig)} ${cfg.statePath}/config/gitlab.yml
        ln -fs ${pkgs.writeText "database.yml" databaseYml} ${cfg.statePath}/config/database.yml
        ln -fs ${pkgs.writeText "secrets.yml" secretsYml} ${cfg.statePath}/config/secrets.yml
        ln -fs ${pkgs.writeText "unicorn.rb" unicornConfig} ${cfg.statePath}/config/unicorn.rb

        chown -R ${cfg.user}:${cfg.group} ${cfg.statePath}/
        chmod -R ug+rwX,o-rwx+X ${cfg.statePath}/

        # Install the shell required to push repositories
        ln -fs ${pkgs.writeText "config.yml" gitlabShellYml} "$GITLAB_SHELL_CONFIG_PATH"
        ln -fs ${cfg.packages.gitlab-shell}/hooks "$GITLAB_SHELL_HOOKS_PATH"
        ${cfg.packages.gitlab-shell}/bin/install

        if [ "${cfg.databaseHost}" = "127.0.0.1" ]; then
          if ! test -e "${cfg.statePath}/db-created"; then
            ${pkgs.sudo}/bin/sudo -u postgres psql postgres -c "CREATE ROLE ${cfg.databaseUsername} WITH LOGIN NOCREATEDB NOCREATEROLE ENCRYPTED PASSWORD '${cfg.databasePassword}'"
            ${pkgs.sudo}/bin/sudo -u postgres ${config.services.postgresql.package}/bin/createdb --owner ${cfg.databaseUsername} ${cfg.databaseName}
            touch "${cfg.statePath}/db-created"
          fi
        fi

        # enable required pg_trgm extension for gitlab
        ${pkgs.sudo}/bin/sudo -u postgres psql gitlab -c "CREATE EXTENSION IF NOT EXISTS pg_trgm"
        # Always do the db migrations just to be sure the database is up-to-date
        ${gitlab-rake}/bin/gitlab-rake db:migrate RAILS_ENV=production

        # The gitlab:setup task is horribly broken somehow, the db:migrate
        # task above and the db:seed_fu below will do the same for setting
        # up the initial database
        if ! test -e "${cfg.statePath}/db-seeded"; then
          ${gitlab-rake}/bin/gitlab-rake db:seed_fu RAILS_ENV=production \
            GITLAB_ROOT_PASSWORD="${cfg.initialRootPassword}" GITLAB_ROOT_EMAIL="${cfg.initialRootEmail}"
          touch "${cfg.statePath}/db-seeded"
        fi

        # Change permissions in the last step because some of the
        # intermediary scripts like to create directories as root.
        chown -R ${cfg.user}:${cfg.group} ${cfg.statePath}
        chmod -R u+rwX,go-rwx+X ${cfg.statePath}
      '';

      serviceConfig = {
        PermissionsStartOnly = true; # preStart must be run as root
        Type = "simple";
        User = cfg.user;
        Group = cfg.group;
        TimeoutSec = "300";
        Restart = "on-failure";
        WorkingDirectory = "${cfg.packages.gitlab}/share/gitlab";
        ExecStart = "${cfg.packages.gitlab.ruby-env}/bin/bundle exec \"unicorn -c ${cfg.statePath}/config/unicorn.rb -E production\"";
      };

    };

  };

  meta.doc = ./gitlab.xml;

}