solana-program-examples/basics/close-account/native/program/src/processor.rs

use borsh::{BorshDeserialize, BorshSerialize};
use solana_program::{account_info::AccountInfo, entrypoint::ProgramResult, pubkey::Pubkey};

use crate::instructions::{close_user::close_user, create_user::create_user};
use crate::state::user::User;

#[derive(BorshSerialize, BorshDeserialize)]
pub enum MyInstruction {
    CreateUser(User),
    CloseUser,
}

pub fn process_instruction(
    program_id: &Pubkey,
    accounts: &[AccountInfo],
    input: &[u8],
) -> ProgramResult {
    let instruction = MyInstruction::try_from_slice(input)?;
    match instruction {
        MyInstruction::CreateUser(data) => create_user(program_id, accounts, data),
        MyInstruction::CloseUser => close_user(accounts),
    }
}