/**
 * Timestamp normalisation for values coming out of the smartbotic-database.
 *
 * The daemon stamps documents with `_created_at` and `_updated_at` in
 * NANOSECONDS - around 1.78e18. Everything else in the platform works in
 * milliseconds: Date.now() in nodes, TimeUtils::nowMs() in C++, and the
 * startedAt / finishedAt the engine writes onto an execution.
 *
 * Two traps live here, and the workflow list fell into both at once:
 *
 *  - The metadata keys are snake_case (`_created_at`). Reading `_createdAt`
 *    returns undefined and every date renders as "unknown".
 *  - A nanosecond value is far larger than the largest date JavaScript accepts
 *    (8.64e15 ms). Passing one to new Date() or date-fns yields Invalid Date,
 *    so fixing only the key name still renders "unknown" - which makes the
 *    first fix look like it did nothing.
 */

// The largest instant the ECMAScript Date type can represent, in milliseconds.
const MAX_JS_DATE_MS = 8640000000000000

// Well past any plausible millisecond timestamp (1e15 ms is the year 33658) and
// well below any plausible nanosecond one, so it separates the two units
// without having to be told which was meant.
const NANOSECOND_THRESHOLD = 1e15

/**
 * Convert a database timestamp to milliseconds, tolerating either unit.
 * Returns null when the value is missing or cannot be a real instant, so
 * callers can render their own placeholder rather than an Invalid Date.
 */
export function toMillis(value: unknown): number | null {
  const raw = typeof value === 'string' ? Number(value) : value

  if (typeof raw !== 'number' || !isFinite(raw) || raw <= 0) {
    return null
  }

  const millis = raw > NANOSECOND_THRESHOLD ? Math.floor(raw / 1000000) : raw

  if (millis > MAX_JS_DATE_MS) {
    return null
  }

  return millis
}

/**
 * Read a document's timestamp regardless of which spelling it carries.
 *
 * The database writes snake_case, but parts of this codebase were written
 * against camelCase and some responses are reshaped before they arrive. Trying
 * both costs nothing and removes a whole class of silent "unknown".
 */
export function readTimestamp(
  data: Record<string, any> | null | undefined,
  ...keys: string[]
): number | null {
  if (!data) {
    return null
  }
  for (const key of keys) {
    const millis = toMillis(data[key])
    if (millis !== null) {
      return millis
    }
  }
  return null
}