#!/usr/bin/env bash
# 008-create-db-iwanhae - Create the personal database `iwanhae` owned by
# the admin role from 007, so plain `psql` works without -d.
# up:   CREATE DATABASE iwanhae OWNER iwanhae (skip if it already exists)
# down: DROP DATABASE - refuses while it contains user objects (data safety)
set -euo pipefail

DB=iwanhae
ROLE=iwanhae

db_exists() {
  runuser -u postgres -- psql -v ON_ERROR_STOP=1 -tAc \
    "SELECT 1 FROM pg_database WHERE datname='$DB'" | grep -q 1
}

user_object_count() {
  runuser -u postgres -- psql -v ON_ERROR_STOP=1 -d "$DB" -tAc \
    "SELECT count(*) FROM pg_class c JOIN pg_namespace n ON n.oid = c.relnamespace
      WHERE n.nspname NOT IN ('pg_catalog', 'information_schema')
        AND c.relkind IN ('r', 'p', 'v', 'm', 'S', 'f')" | tr -d ' '
}

case "${1:-}" in
  up)
    if db_exists; then
      echo "    database $DB already exists - skipping"
    else
      runuser -u postgres -- psql -v ON_ERROR_STOP=1 -qc \
        "CREATE DATABASE $DB OWNER $ROLE"
      echo "    database $DB created, owner $ROLE"
    fi
    ;;
  down)
    if ! db_exists; then
      echo "    database $DB does not exist - nothing to do"
      exit 0
    fi
    if [[ $(user_object_count) -gt 0 ]]; then
      echo "refusing to drop $DB - it contains user objects (data would be lost)" >&2
      echo "drop it manually if you really want: runuser -u postgres -- psql -c 'DROP DATABASE $DB WITH (FORCE)'" >&2
      exit 1
    fi
    runuser -u postgres -- psql -v ON_ERROR_STOP=1 -qc \
      "DROP DATABASE $DB WITH (FORCE)"   # FORCE: kick lingering psql sessions
    echo "    database $DB dropped (was empty)"
    ;;
esac