import type { Connection, TransactionInstruction } from "@solana/web3.js";
import { ComputeBudgetProgram } from "@solana/web3.js";

export const estimatePriorityFees = async (
  connection: Connection,
  instructions: TransactionInstruction[],
  multiplier = 1,
  maxPriorityFee = 100000,
  minPriorityFee = 1,
): Promise<TransactionInstruction> => {
  const accounts = instructions.flatMap((e) => e.keys).map((e) => e.pubkey);

  const prioFees = await connection.getRecentPrioritizationFees({
    lockedWritableAccounts: accounts,
  });

  // Sort in descending order on slot so we get the latest data
  prioFees.sort((a, b) => b.slot - a.slot);

  // Estimate priority fee by taking the avg of recent fees and scale with the provider multiplier
  // to control speed/likelyhood of success
  const estimatedPrioFee = Math.floor(
    (multiplier *
      prioFees
        .slice(0, 10)
        .map((e) => e.prioritizationFee)
        .reduce((a, b) => a + b, 0)) /
      prioFees.length,
  );

  // Apply min and max cap if needed
  const prioFee = Math.max(
    minPriorityFee,
    Math.min(estimatedPrioFee, maxPriorityFee),
  );

  const addPriorityFee = ComputeBudgetProgram.setComputeUnitPrice({
    microLamports: prioFee,
  });

  return addPriorityFee;
};