use anchor_lang::prelude::*;
use anchor_lang::system_program::{create_account, CreateAccount};
use anchor_spl::{
    token_2022::{
        initialize_account3,
        spl_token_2022::{extension::ExtensionType, pod::PodAccount},
        InitializeAccount3,
    },
    token_interface::{immutable_owner_initialize, ImmutableOwnerInitialize, Mint, Token2022},
};
 
// There is currently not an anchor constraint to automatically initialize the ImmutableOwner extension
// We can manually create and initialize the token account via CPIs in the instruction handler
pub fn initialize(ctx: Context<Initialize>) -> Result<()> {
    // Calculate space required for token and extension data
    let token_account_size = ExtensionType::try_calculate_account_len::<PodAccount>(&[
        ExtensionType::ImmutableOwner,
    ])?;
 
    // Calculate minimum lamports required for size of token account with extensions
    let lamports = (Rent::get()?).minimum_balance(token_account_size);
 
    // Invoke System Program to create new account with space for token account and extension data
    create_account(
        CpiContext::new(
            ctx.accounts.system_program.to_account_info(),
            CreateAccount {
                from: ctx.accounts.payer.to_account_info(),
                to: ctx.accounts.token_account.to_account_info(),
            },
        ),
        lamports,                          // Lamports
        token_account_size as u64,         // Space
        &ctx.accounts.token_program.key(), // Owner Program
    )?;
 
    // Initialize the token account with the immutable owner extension
    immutable_owner_initialize(CpiContext::new(
        ctx.accounts.token_program.to_account_info(),
        ImmutableOwnerInitialize {
            token_program_id: ctx.accounts.token_program.to_account_info(),
            token_account: ctx.accounts.token_account.to_account_info(),
        },
    ))?;
 
    // Initialize the standard token account data
    initialize_account3(CpiContext::new(
        ctx.accounts.token_program.to_account_info(),
        InitializeAccount3 {
            account: ctx.accounts.token_account.to_account_info(),
            mint: ctx.accounts.mint_account.to_account_info(),
            authority: ctx.accounts.payer.to_account_info(),
        },
    ))?;
    Ok(())
}
 
#[derive(Accounts)]
pub struct Initialize<'info> {
    #[account(mut)]
    pub payer: Signer<'info>,
 
    #[account(mut)]
    pub token_account: Signer<'info>,
    pub mint_account: InterfaceAccount<'info, Mint>,
    pub token_program: Program<'info, Token2022>,
    pub system_program: Program<'info, System>,
}