import { Text, Tooltip } from '@mantine/core';
import { statusToneVars } from '@ema-platform/shared';

export interface WaitingForProps {
  /** When the clock started — normally the moment the applicant submitted. */
  since: string | null | undefined;
  /**
   * Days after which the wait reads as overdue. Amber at half of it, red past
   * it. Defaults to 14, which is the shortest SLA any configured licence type
   * currently uses; pass the real one where a queue knows it.
   */
  slaDays?: number;
  /** Set once the item is decided — a closed item is not waiting for anyone. */
  done?: boolean;
}

/**
 * Fraction of the target elapsed before the wait reads as at-risk. Matches the
 * licence queue's own `WARNING_RATIO`, so a queue using this component and one
 * using `computeSla` turn amber at the same point rather than disagreeing.
 */
const WARNING_RATIO = 0.7;

/** Whole days between `since` and now, floored. Negative clock skew reads as 0. */
function daysSince(since: string): number {
  const ms = Date.now() - new Date(since).getTime();
  return Math.max(0, Math.floor(ms / 86_400_000));
}

/**
 * How long an item has been sitting in a queue.
 *
 * No review queue showed this. An officer opening a list of thirty
 * registrations could see what each one *was*, but not which had been waiting
 * three days and which had been waiting three weeks — so the queue was worked
 * top-down by whatever the sort happened to be rather than by urgency.
 *
 * Colour comes from the platform's status tones rather than its own scale, so
 * "overdue" here is the same red as "rejected" everywhere else.
 */
export function WaitingFor({ since, slaDays = 14, done }: WaitingForProps) {
  if (!since) {
    return (
      <Text size="sm" c="dimmed">
        —
      </Text>
    );
  }

  const days = daysSince(since);

  // A decided item keeps its elapsed time visible — useful when reviewing how
  // long something took — but never coloured, because nothing is pending.
  const tone = done
    ? 'neutral'
    : days >= slaDays
      ? 'danger'
      : days >= slaDays * WARNING_RATIO
        ? 'pending'
        : 'neutral';

  const label = days === 0 ? 'today' : `${days}d`;

  return (
    <Tooltip
      label={
        done
          ? `Took ${days} day${days === 1 ? '' : 's'}`
          : `Waiting ${days} day${days === 1 ? '' : 's'} · ${slaDays}-day target`
      }
      withArrow
    >
      <Text
        size="sm"
        fw={tone === 'neutral' ? 400 : 600}
        c={tone === 'neutral' ? 'dimmed' : undefined}
        style={tone === 'neutral' ? undefined : { color: statusToneVars(tone).color }}
      >
        {label}
      </Text>
    </Tooltip>
  );
}