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

let
  cfg = config.bagel.services.postgres;

  dataDir = "/var/db/postgresql/16";
in {
  options.bagel.services.postgres = with lib; {
    enable = mkEnableOption "PostgreSQL server";
  };

  config = lib.mkIf cfg.enable {
    systemd.tmpfiles.rules = [
      "d /var/db 0755 root root - -"
      "d /var/db/postgresql 0750 postgres postgres - -"
      "d ${dataDir} 0750 postgres postgres - -"
    ];

    services.postgresql = {
      enable = true;
      package = pkgs.postgresql_16;
      dataDir = dataDir;

      # TODO: Where to put this to properly couple things? It doesn't belong
      # here, but using it in services/hydra would require running on
      # localhost. Probably needs to be replaced with some different way of
      # ensuring the DB/user exist.
      ensureDatabases = [ "hydra" ];
      ensureUsers = [
        {
          name = "hydra";
          ensureDBOwnership = true;
        }
      ];
      identMap = ''
        hydra-users hydra hydra
        hydra-users hydra-queue-runner hydra
        hydra-users hydra-www hydra
        hydra-users root hydra
        # The postgres user is used to create the pg_trgm extension for the hydra database
        hydra-users postgres postgres
      '';
      authentication = ''
        local hydra all ident map=hydra-users
      '';

      settings = {
        max_connections = 500;
      };
    };
  };
}