import BN from "bn.js";
import { WAD } from "../constants.js";

/**
 * Conversion Utilities Module
 *
 * Safe BN ↔ number conversions and common transformations
 */

const WAD_BN = new BN(WAD.toString());

/**
 * Safely convert BN to number, throws if exceeds MAX_SAFE_INTEGER
 */
export function safeToNumber(bn: BN, context?: string): number {
  const MAX_SAFE = new BN(Number.MAX_SAFE_INTEGER.toString());
  if (bn.abs().gt(MAX_SAFE)) {
    throw new Error(
      `Value exceeds MAX_SAFE_INTEGER${context ? ` in ${context}` : ""}: ${bn.toString()}`
    );
  }
  return bn.toNumber();
}

/**
 * Convert lamports to SOL (safe conversion)
 */
export function lamportsToSol(lamports: BN): number {
  const wholeSol = lamports.div(new BN(1_000_000_000));
  const remainder = lamports.mod(new BN(1_000_000_000));

  const whole = safeToNumber(wholeSol, "lamportsToSol:whole");
  const fractional = safeToNumber(remainder, "lamportsToSol:remainder") / 1_000_000_000;

  return whole + fractional;
}

/**
 * Convert cents to dollars
 */
export function centsToDollars(cents: BN): number {
  return safeToNumber(cents, "centsToDollars") / 100;
}

/**
 * Convert timestamp BN to Date
 */
export function timestampToDate(timestamp: BN): Date {
  const seconds = safeToNumber(timestamp, "timestampToDate");
  return new Date(seconds * 1000);
}

/**
 * Check if timestamp has passed
 */
export function isTimestampPassed(timestamp: BN): boolean {
  const now = new BN(Math.floor(Date.now() / 1000));
  return now.gt(timestamp);
}

/**
 * Convert WAD to float for display
 */
export function wadToFloat(wad: BN): number {
  const wholePart = wad.div(WAD_BN);
  const remainder = wad.mod(WAD_BN);

  const whole = parseFloat(wholePart.toString());
  const fractional = parseFloat(remainder.toString()) / Number(WAD);

  return whole + fractional;
}