import BN from "bn.js";

/**
 * WAD precision (10^18)
 */
export const WAD = BigInt("1000000000000000000");

/**
 * Trading fee percentage (3% in WAD format)
 */
export const TRADE_FEE_PERCENTAGE = BigInt("30000000000000000");

/**
 * ln(2) in WAD format - used in lnWad calculation for range reduction
 */
export const LN_2_WAD = BigInt("693147180559945309");

/**
 * ln(4) in WAD format - used for liquidity parameter calculation
 */
export const LN_4_WAD = BigInt("1386294361119890612");

/**
 * Maximum q_vector difference multiplier (matches on-chain constant)
 * From programs/pit/src/constants.rs::MAX_Q_VECTOR_DIFF_MULTIPLIER
 *
 * Used to calculate dynamic trade limits: max_allowed_diff = 40 × b
 */
export const MAX_Q_VECTOR_DIFF_MULTIPLIER = 40;

/**
 * Conservative simulation limit (40 SOL) used for frontend trade previews.
 *
 * The actual on-chain limit is market-specific: `MAX_Q_VECTOR_DIFF_MULTIPLIER × b`.
 * Use {@link getMaxTradeAmountForMarket} for accurate per-market limits.
 *
 * @deprecated Use getMaxTradeAmountForMarket(bLamports) instead
 */
export const MAX_SIMULATION_SOL_AMOUNT = new BN(40).mul(new BN(1_000_000_000));

/**
 * Calculate maximum trade amount for a given market
 * Based on on-chain constraint: max(q_i) - min(q_i) < 40 × b
 *
 * @param bLamports - Market's liquidity parameter b (in lamports)
 * @returns Maximum trade amount in lamports
 */
export function getMaxTradeAmountForMarket(bLamports: BN): BN {
  return bLamports.muln(MAX_Q_VECTOR_DIFF_MULTIPLIER);
}