{
  pkgs,
}:
let
  inherit (pkgs) lib;
in
{
  name,
  default_config ? true,
  config ? { },
  extra_config ? '''',
  package ? pkgs.postgresql,
  port ? 5432,
  bind ? "localhost",
  initialDatabases ? [ ],
  ...
}:
let
  merged_config =
    (
      if default_config then
        {
          listen_addresses = "localhost";
          port = 5432;
          shared_buffers = "128MB";
          work_mem = "4MB";
          logging_collector = false;

        }
      else
        { }
    )
    // config
    // {
      unix_socket_directories = ".";
      listen_addresses = bind;
      inherit port;
    };
  toStr =
    value:
    if true == value then
      "yes"
    else if false == value then
      "no"
    else if lib.isString value then
      "'${lib.replaceStrings [ "'" ] [ "''" ] value}'"
    else
      builtins.toString value;
  configFile = pkgs.writeTextFile {
    name = "postgresql.conf";
    text =
      lib.concatStringsSep "\n" (
        lib.mapAttrsToList (n: v: "${n} = ${toStr v}") (
          lib.filterAttrs (lib.const (x: x != null)) merged_config
        )
      )
      + extra_config;
  };
  setupInitialDatabases =
    if initialDatabases != [ ] then
      (lib.concatMapStrings (db: ''
        echo "Checking presence of database ${db.name}"
        dbAlreadyExists="$(echo "SELECT 1 AS result FROM pg_database WHERE datname='${db.name}';" | psql --dbname postgres | ${pkgs.gnugrep}/bin/grep -c 'exists = "1"' || true)"
        echo "$dbAlreadyExists"
        if [ 1 -ne "$dbAlreadyExists" ]; then
          echo "Creating database ${db.name}"
          echo 'CREATE DATABASE "${db.name}";' | psql --dbname postgres
          ${lib.optionalString (db.user != null && db.password != null) ''
            echo "Creating user ${db.user}"
            psql --dbname postgres <<'EOF'
            DO $$
              BEGIN
                CREATE ROLE "${db.user}" WITH LOGIN PASSWORD '${db.password}';
                EXCEPTION WHEN duplicate_object THEN RAISE NOTICE '%, skipping', SQLERRM USING ERRCODE = SQLSTATE;
              END
            $$;
            GRANT ALL PRIVILEGES ON DATABASE "${db.name}" TO "${db.user}";
            \c ${db.name}
            GRANT ALL PRIVILEGES ON SCHEMA public TO "${db.user}";
            EOF
          ''}
        else
          echo "Database ${db.name} already exists"
        fi
      '') initialDatabases)
    else
      "";
  setupScript = pkgs.writeShellApplication {
    name = "setup-postgres";
    runtimeInputs = [
      package
      pkgs.coreutils
    ];
    text = ''
      POSTGRES_RUN_INITIAL_SCRIPT="false"
      if [[ ! -d "$PGDATA" ]]; then
        initdb --no-instructions
        POSTGRES_RUN_INITIAL_SCRIPT="true"
        echo
        echo "PostgreSQL initdb process completed"
        echo
      fi
      cp ${configFile} "$PGDATA"/postgresql.conf
      if [[ "$POSTGRES_RUN_INITIAL_SCRIPT" == "true" ]]; then
        echo
        echo "PostgreSQL is setting up the initial database"
        echo
        pg_ctl -w start -o "-c listen_addresses= -p ${builtins.toString port}"
        ${setupInitialDatabases}
        pg_ctl -m fast -w stop
      else 
        echo
        echo "Database directory exists. Skipping initialization"
        echo
      fi
      unset POSTGRES_RUN_INITIAL_SCRIPT
    '';
  };

  script = pkgs.writeShellApplication {
    name = "run-postgres";
    text = ''
      set -euo pipefail
      PGDATA=$RUNTIME_PATH/${name}
      PGHOST=$RUNTIME_PATH/${name}
      PGPORT=${builtins.toString port}
      echo "Starting postgres with PGDATA=''${PGDATA} PGHOST=''${PGHOST} PGPORT=''${PGPORT}"
      export PGDATA PGHOST PGPORT
      ${setupScript}/bin/setup-postgres
      ${package}/bin/postgres
    '';
  };
in
# configFileCheck = pkgs.runCommand {} ''
#     ${package}/bin/postgres -D${configFile} -C config_file
#     touch $out
#   '';
{
  processes."${name}" = {
    command = "${script}/bin/run-postgres";
    shutdown.signal = 2;
    readiness_probe = {
      exec.command = "${package}/bin/pg_isready -h $RUNTIME_PATH/${name} -p ${builtins.toString port} -d postgres";
      initial_delay_seconds = 2;
      period_seconds = 2;
      timeout_seconds = 2;
      success_threshold = 1;
      failure_threshold = 5;
    };
    availability.restart = "on_failure";
  };
}