solana contract

use solana_program::{
    account_info::{AccountInfo, next_account_info},
    declare_id, entrypoint, pubkey::Pubkey,
    program_error::ProgramError,
    msg, entrypoint::ProgramResult,
};
use spl_token::{ instruction::TokenInstruction, state::Account as TokenAccount};

declare_id!("YourUniqueProgramIdHere");

/// Advanced custom error definitions for detailed feedback.
#[derive(Debug, Clone, Copy)]
pub enum TokenRestrictionError {
    UnauthorizedTransfer,
    TransferCurrentlyRestricted,
    OperationNotSupported,
}

impl From<TokenRestrictionError> for ProgramError {
    fn from(e: TokenRestrictionError) -> Self {
        ProgramError::Custom(e as u32)
    }
}

/// Documents the purpose of the program and how it interfaces with SPL Token instructions.
/// Main entry point for the token sale restriction program.
entrypoint!(process_instruction);

/// Processes instructions sent to this program.
/// Instructions can be filtered to apply logic, such as blocking or allowing transfers.
fn process_instruction(
    program_id: &Pubkey,
    accounts: &[AccountInfo],
    instruction_data: &[u8]
) -> ProgramResult {
    msg!("Token Restriction Program Processing Instruction");

    let instruction = TokenInstruction::unpack(instruction_data)?;

    match instruction {
    TokenInstruction::Transfer { .. } => {
            msg!("Transfer attempted, checking for restrictions.");

            // Example restriction: Disallow all transfers
            // In practice, insert logic to determine if a transfer should be allowed or not.
            // This could include checking the current time against a preset time, ensuring the
            // sender or receiver is in a whitelist, etc.
            Err(TokenRestrictionError::UnauthorizedTransfer.into())
        },
        // This program is specifically for managing transfer restrictions.
        // Other token operations are not processed here to maintain focused functionality.
        _ => Err(TokenRestrictionError::OperationNotSupported.into()),
    }
}