#!/usr/bin/env bash
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
ROOT_DIR="$(cd "${SCRIPT_DIR}/../.." && pwd)"
ROLLBACK_DIR="${SCRIPT_DIR}/rollback"

load_database_url_from_env_file() {
  local env_file="$1"
  local line value
  while IFS= read -r line || [[ -n "${line}" ]]; do
    line="${line#"${line%%[![:space:]]*}"}"
    [[ -z "${line}" || "${line}" == \#* ]] && continue
    line="${line#export }"
    if [[ "${line}" == DATABASE_URL=* ]]; then
      value="${line#DATABASE_URL=}"
      value="${value%$'\r'}"
      value="${value%\"}"
      value="${value#\"}"
      value="${value%\'}"
      value="${value#\'}"
      printf '%s' "${value}"
      return 0
    fi
  done < "${env_file}"
  return 1
}

DATABASE_URL="${DATABASE_URL:-}"
if [[ -z "${DATABASE_URL}" && -f "${ROOT_DIR}/.env" ]]; then
  DATABASE_URL="$(load_database_url_from_env_file "${ROOT_DIR}/.env" || true)"
fi
if [[ -z "${DATABASE_URL}" ]]; then
  echo "DATABASE_URL is required (export it, or set it in ${ROOT_DIR}/.env)"
  exit 1
fi

if ! command -v psql >/dev/null 2>&1; then
  echo "psql not found in PATH"
  exit 127
fi

ROLLBACK_TO_VERSION="${ROLLBACK_TO_VERSION:-}"
DRY_RUN="${DRY_RUN:-0}"

psql "${DATABASE_URL}" -v ON_ERROR_STOP=1 -c "CREATE TABLE IF NOT EXISTS _sqlx_migrations (version BIGINT PRIMARY KEY, description TEXT NOT NULL, installed_on TIMESTAMPTZ NOT NULL DEFAULT now(), success BOOLEAN NOT NULL, checksum BYTEA NOT NULL, execution_time BIGINT NOT NULL)" >/dev/null

if [[ -z "${ROLLBACK_TO_VERSION}" ]]; then
  echo "ROLLBACK_TO_VERSION is required (e.g. 1 or 0)"
  exit 1
fi

while true; do
  current="$(psql "${DATABASE_URL}" -At -c "SELECT version FROM _sqlx_migrations WHERE success=true ORDER BY version DESC LIMIT 1" || true)"
  if [[ -z "${current}" ]]; then
    echo "No applied migrations found"
    exit 0
  fi

  if [[ "${current}" -le "${ROLLBACK_TO_VERSION}" ]]; then
    echo "Rollback completed (current=${current}, target=${ROLLBACK_TO_VERSION})"
    exit 0
  fi

  file="${ROLLBACK_DIR}/$(printf "%04d" "${current}").down.sql"
  if [[ ! -f "${file}" ]]; then
    echo "Rollback file not found for version ${current}: ${file}"
    exit 1
  fi

  echo "Rolling back version ${current} using $(basename "${file}")"
  if [[ "${DRY_RUN}" == "1" ]]; then
    psql "${DATABASE_URL}" -v ON_ERROR_STOP=1 -c "SELECT ${current}" >/dev/null
  else
    psql "${DATABASE_URL}" -v ON_ERROR_STOP=1 -f "${file}"
    psql "${DATABASE_URL}" -v ON_ERROR_STOP=1 -c "DELETE FROM _sqlx_migrations WHERE version=${current}"
  fi
done