import type { PublicKey } from '@solana/web3.js';
import { SystemProgram, SYSVAR_RENT_PUBKEY, TransactionInstruction } from '@solana/web3.js';
import { ASSOCIATED_TOKEN_PROGRAM_ID, TOKEN_PROGRAM_ID } from '../constants.js';

/**
 * Construct an AssociatedTokenAccount instruction
 *
 * @param payer                    Payer of the initialization fees
 * @param associatedToken          New associated token account
 * @param owner                    Owner of the new account
 * @param mint                     Token mint account
 * @param programId                SPL Token program account
 * @param associatedTokenProgramId SPL Associated Token program account
 *
 * @return Instruction to add to a transaction
 */
export function createAssociatedTokenAccountInstruction(
    payer: PublicKey,
    associatedToken: PublicKey,
    owner: PublicKey,
    mint: PublicKey,
    programId = TOKEN_PROGRAM_ID,
    associatedTokenProgramId = ASSOCIATED_TOKEN_PROGRAM_ID
): TransactionInstruction {
    const keys = [
        { pubkey: payer, isSigner: true, isWritable: true },
        { pubkey: associatedToken, isSigner: false, isWritable: true },
        { pubkey: owner, isSigner: false, isWritable: false },
        { pubkey: mint, isSigner: false, isWritable: false },
        { pubkey: SystemProgram.programId, isSigner: false, isWritable: false },
        { pubkey: programId, isSigner: false, isWritable: false },
        { pubkey: SYSVAR_RENT_PUBKEY, isSigner: false, isWritable: false },
    ];

    return new TransactionInstruction({
        keys,
        programId: associatedTokenProgramId,
        data: Buffer.alloc(0),
    });
}