/**
 * Stacked stat column: label / value / delta. The delta slot is always rendered
 * (a muted "—" placeholder when there is no change) so that every row reserves the
 * same vertical space and the columns line up across the standings table.
 */
export function StatColumn({
  label,
  value,
  delta,
  reserveDelta = false,
}: {
  label: string;
  value: React.ReactNode;
  /** Optional change indicator rendered on its own line below the value. */
  delta?: React.ReactNode;
  /**
   * When true, the delta line is always rendered (a muted placeholder when there is
   * no delta) so columns stay vertically aligned across rows. When false and no delta
   * is provided, the line is omitted entirely.
   */
  reserveDelta?: boolean;
}) {
  const showDeltaLine = delta !== undefined || reserveDelta;
  return (
    <div className="text-right shrink-0 flex-1 sm:flex-none">
      <p className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">
        {label}
      </p>
      <div className="flex items-baseline justify-end">{value}</div>
      {showDeltaLine && (
        <div className="flex items-baseline justify-end leading-none mt-0.5">
          {delta ?? <span className="text-xs text-muted-foreground/60">—</span>}
        </div>
      )}
    </div>
  );
}

export function StatDivider({ className = "h-12" }: { className?: string } = {}) {
  return <div className={`${className} w-px bg-border shrink-0 self-center`} />;
}

/**
 * 7-day change indicator. `rank` deltas are unitless places; `points` deltas are
 * rounded point totals. Positive = up (green ▲), negative = down (coral ▼).
 */
export function DeltaBadge({
  delta,
  kind,
}: {
  delta: number;
  kind: "rank" | "points";
}) {
  const magnitude = kind === "rank" ? Math.abs(delta) : Math.abs(Math.round(delta));
  const up = delta > 0;
  const label =
    kind === "rank"
      ? up
        ? `up ${magnitude}`
        : `down ${magnitude}`
      : up
        ? `+${magnitude} points`
        : `-${magnitude} points`;

  if (up) {
    return (
      <span className="text-xs font-semibold text-primary" aria-label={label}>
        ▲{magnitude}
      </span>
    );
  }
  return (
    <span
      className="text-xs font-semibold"
      style={{ color: "var(--coral-accent, #ef4444)" }}
      aria-label={label}
    >
      ▼{magnitude}
    </span>
  );
}

export function RankingDisplay({
  displayRank,
  rankChange,
  reserveDelta = false,
}: {
  displayRank: string | number;
  rankChange?: number;
  reserveDelta?: boolean;
}) {
  return (
    <StatColumn
      label="Ranking"
      reserveDelta={reserveDelta}
      value={<span className="text-2xl font-bold leading-none">{displayRank}</span>}
      delta={
        rankChange !== undefined && rankChange !== 0 ? (
          <DeltaBadge delta={rankChange} kind="rank" />
        ) : undefined
      }
    />
  );
}