# Anchor CPI related

## SPL token transfer CPI

### Method #1

#[program]
pub mod locker_manager {
    ...

    pub fn create_locker(
        ctx: Context<CreateLocker>,
        beneficiary: Pubkey,
        deposit_amount: u64,
        nonce: u8,
        start_ts: i64,
        end_ts: i64,
        period_count: u64,
        // reward_kepper: Option<RewardKeeper>,
    ) -> Result<()> {
        ...

        transfer(ctx.accounts.transfer_ctx(), deposit_amount)?;
        ...
        Ok(())
    }
}

#[derive(Accounts)]
pub struct CreateLocker<'info> {
    #[account(zero)] 
    pub locker: Box<Account<'info, Locker>>,
    #[account(mut)]
    pub vault: Account<'info, TokenAccount>,
    /// CHECK: This is not dangerous because we don't read or write from this account
    #[account(mut)]
    pub depositor: AccountInfo<'info>,
    pub depositor_authority: Signer<'info>,
    // Misc.
    pub token_program: Program<'info, Token>,
    pub rent: Sysvar<'info, Rent>,
    pub clock: Sysvar<'info, Clock>,
}

impl<'info> CreateLocker<'info> {
    pub fn transfer_ctx(&self) -> CpiContext<'_, '_, '_, 'info, Transfer<'info>> {
        CpiContext::new(
            self.token_program.to_account_info(), 
            Transfer {
                from: self.depositor.clone(),
                to: self.vault.to_account_info(),
                authority: self.depositor_authority.to_account_info()
            }
        )
    }
}

## Method #2

#[program]
pub mod locker_manager {
    ...

    pub fn create_locker(
        ctx: Context<CreateLocker>,
        beneficiary: Pubkey,
        deposit_amount: u64,
        nonce: u8,
        start_ts: i64,
        end_ts: i64,
        period_count: u64,
        // reward_kepper: Option<RewardKeeper>,
    ) -> Result<()> {
        ...

        transfer(ctx.accounts.into(), deposit_amount)?;
        ...
        Ok(())
    }
}

#[derive(Accounts)]
pub struct CreateLocker<'info> {
    #[account(zero)] // TOCHECK: why not mut?
    pub locker: Box<Account<'info, Locker>>,
    #[account(mut)]
    pub vault: Account<'info, TokenAccount>,
    /// CHECK: This is not dangerous because we don't read or write from this account
    #[account(mut)]
    pub depositor: AccountInfo<'info>,
    pub depositor_authority: Signer<'info>,
    // Misc.
    pub token_program: Program<'info, Token>,
    pub rent: Sysvar<'info, Rent>,
    pub clock: Sysvar<'info, Clock>,
}
impl<'a, 'b, 'c, 'info> From<&mut CreateLocker<'info>>
    for CpiContext<'a, 'b, 'c, 'info, Transfer<'info>>
{
    fn from(accounts: &mut CreateLocker<'info>) -> CpiContext<'a, 'b, 'c, 'info, Transfer<'info>> {
        let cpi_accounts = Transfer {
            from: accounts.depositor.clone(),
            to: accounts.vault.to_account_info(),
            authority: accounts.depositor_authority.to_account_info().clone(),
        };
        let cpi_program = accounts.token_program.to_account_info().clone();
        CpiContext::new(cpi_program, cpi_accounts)
    }
}