/** 1 sBTC = 100_000_000 base units (8 decimals, satoshi-equivalent). */
export const SBTC_BASE = 100_000_000n;

/** Parse human sBTC/BTC amounts ("0.001", "1000 sats", raw integer) to base units. */
export function parseSbtcAmount(raw: string | number): bigint {
  if (typeof raw === 'number') {
    if (!Number.isFinite(raw)) throw new Error(`Invalid sBTC amount: ${raw}`);
    if (Number.isInteger(raw) && raw > 1_000_000) return BigInt(raw);
    return BigInt(Math.round(raw * Number(SBTC_BASE)));
  }

  const trimmed = String(raw).trim().toLowerCase();
  if (!trimmed) throw new Error('Empty sBTC amount');

  if (/^\d+$/.test(trimmed)) return BigInt(trimmed);

  const satsMatch = trimmed.match(/^([\d.]+)\s*sats?$/);
  if (satsMatch) return BigInt(Math.round(Number(satsMatch[1])));

  const btcMatch = trimmed.match(/^([\d.]+)\s*(sbtc|btc)?$/);
  if (btcMatch) {
    return BigInt(Math.round(Number(btcMatch[1]) * Number(SBTC_BASE)));
  }

  throw new Error(`Could not parse sBTC amount: ${raw}`);
}

export function formatSbtcAmount(baseUnits: bigint | string | number): string {
  const n = typeof baseUnits === 'bigint' ? baseUnits : BigInt(baseUnits);
  const whole = n / SBTC_BASE;
  const frac = n % SBTC_BASE;
  if (frac === 0n) return `${whole} sBTC`;
  const fracStr = frac.toString().padStart(8, '0').replace(/0+$/, '');
  return `${whole}.${fracStr} sBTC`;
}