formatZec function

String formatZec(int zat)

Format a zatoshi amount as a ZEC decimal string WITHOUT a unit suffix (the caller appends a localized unit). Trailing fractional zeros are trimmed; a whole amount renders with no decimal point. Negative inputs (signed net amounts in history) keep their sign.

Examples: 0 → "0", 1 → "0.00000001", 100000000 → "1", 123450000 → "1.2345", -1500000 → "-0.015".

Implementation

String formatZec(int zat) {
  final negative = zat < 0;
  // `abs()` is safe: real zatoshi amounts are bounded by max supply, far
  // from int64's edge where `abs()` would overflow.
  final magnitude = zat.abs();
  final whole = magnitude ~/ zatPerZec;
  final frac = magnitude % zatPerZec;

  final String body;
  if (frac == 0) {
    body = '$whole';
  } else {
    // 8 fixed fractional digits, then trim trailing zeros (never the
    // leading ones — `00000001` must stay `0.00000001`, not `0.1`).
    final fracDigits = frac
        .toString()
        .padLeft(8, '0')
        .replaceAll(RegExp(r'0+$'), '');
    body = '$whole.$fracDigits';
  }
  return negative ? '-$body' : body;
}