import {
  PublicKey,
  SystemProgram,
  SYSVAR_RENT_PUBKEY,
  TransactionInstruction,
} from '@solana/web3.js'
import { TOKEN_PROGRAM_ID } from '@solana/spl-token'

const SPL_ASSOCIATED_TOKEN_ACCOUNT_PROGRAM_ID: PublicKey = new PublicKey(
  'ATokenGPvbdGVxr1b2hvZbsiqW5xWH25efTNsLJA8knL'
)

export async function findAssociatedTokenAddress(
  walletAddress: PublicKey,
  tokenMintAddress: PublicKey
): Promise<PublicKey> {
  return (
    await PublicKey.findProgramAddress(
      [
        walletAddress.toBuffer(),
        TOKEN_PROGRAM_ID.toBuffer(),
        tokenMintAddress.toBuffer(),
      ],
      SPL_ASSOCIATED_TOKEN_ACCOUNT_PROGRAM_ID
    )
  )[0]
}

export async function createAssociatedTokenAccount(
  fundingAddress: PublicKey,
  walletAddress: PublicKey,
  splTokenMintAddress: PublicKey
): Promise<TransactionInstruction> {
  const associatedTokenAddress = await findAssociatedTokenAddress(
    walletAddress,
    splTokenMintAddress
  )
  const keys = [
    {
      pubkey: fundingAddress,
      isSigner: true,
      isWritable: true,
    },
    {
      pubkey: associatedTokenAddress,
      isSigner: false,
      isWritable: true,
    },
    {
      pubkey: walletAddress,
      isSigner: false,
      isWritable: false,
    },
    {
      pubkey: splTokenMintAddress,
      isSigner: false,
      isWritable: false,
    },
    {
      pubkey: SystemProgram.programId,
      isSigner: false,
      isWritable: false,
    },
    {
      pubkey: TOKEN_PROGRAM_ID,
      isSigner: false,
      isWritable: false,
    },
    {
      pubkey: SYSVAR_RENT_PUBKEY,
      isSigner: false,
      isWritable: false,
    },
  ]
  return new TransactionInstruction({
    keys,
    programId: SPL_ASSOCIATED_TOKEN_ACCOUNT_PROGRAM_ID,
    data: Buffer.from([]),
  })
}