harb/kraiken-lib/src/position.ts

/**
 * Position profit calculations for Harberger staking.
 *
 * Positions earn profit through their proportional share of new token issuance.
 * This aligns with the Harberger tax economic model where stakers earn from protocol growth.
 */

/**
 * Calculate profit for an active position.
 *
 * Active positions earn their proportional share of all new tokens minted
 * since the position was created.
 *
 * @param totalSupplyInit - Total token supply when position was created
 * @param currentTotalSupply - Current total token supply
 * @param positionShare - Position's proportional share (0-1)
 * @returns Profit in token units (not wei)
 */
export function calculateActivePositionProfit(totalSupplyInit: bigint, currentTotalSupply: bigint, positionShare: number): number {
  if (totalSupplyInit < 0n || currentTotalSupply < 0n) {
    throw new Error('Supply values must be non-negative');
  }

  if (positionShare < 0 || positionShare > 1) {
    throw new Error('Position share must be between 0 and 1');
  }

  if (currentTotalSupply < totalSupplyInit) {
    // If supply decreased (shouldn't happen in normal operation), return 0
    return 0;
  }

  // Convert to token units (assuming 18 decimals)
  const initSupply = Number(totalSupplyInit) / 1e18;
  const currentSupply = Number(currentTotalSupply) / 1e18;

  // Calculate new issuance since position creation
  const newIssuance = currentSupply - initSupply;

  // Position earns its share of new issuance
  return newIssuance * positionShare;
}

/**
 * Calculate profit for a closed position.
 *
 * Closed positions earned their proportional share of all new tokens minted
 * during the position's lifetime (from creation to closure).
 *
 * @param totalSupplyInit - Total token supply when position was created
 * @param totalSupplyEnd - Total token supply when position was closed
 * @param positionShare - Position's proportional share (0-1)
 * @returns Profit in token units (not wei)
 */
export function calculateClosedPositionProfit(totalSupplyInit: bigint, totalSupplyEnd: bigint, positionShare: number): number {
  if (totalSupplyInit < 0n || totalSupplyEnd < 0n) {
    throw new Error('Supply values must be non-negative');
  }

  if (positionShare < 0 || positionShare > 1) {
    throw new Error('Position share must be between 0 and 1');
  }

  if (totalSupplyEnd < totalSupplyInit) {
    // If supply decreased during position lifetime, return 0
    return 0;
  }

  // Convert to token units (assuming 18 decimals)
  const initSupply = Number(totalSupplyInit) / 1e18;
  const endSupply = Number(totalSupplyEnd) / 1e18;

  // Calculate new issuance during position lifetime
  const newIssuance = endSupply - initSupply;

  // Position earned its share of new issuance
  return newIssuance * positionShare;
}