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use fvm_shared::clock::ChainEpoch;
use fvm_shared::randomness::RANDOMNESS_LENGTH;

use crate::{sys, SyscallResult};

/// Gets 32 bytes of randomness from the ticket chain.
/// The supplied output buffer must have at least 32 bytes of capacity.
/// If this syscall succeeds, exactly 32 bytes will be written starting at the
/// supplied offset.
pub fn get_chain_randomness(
    dst: i64,
    round: ChainEpoch,
    entropy: &[u8],
) -> SyscallResult<[u8; RANDOMNESS_LENGTH]> {
    let ret = unsafe {
        sys::rand::get_chain_randomness(dst, round as i64, entropy.as_ptr(), entropy.len() as u32)?
    };
    Ok(ret)
}

/// Gets 32 bytes of randomness from the beacon system (currently Drand).
/// The supplied output buffer must have at least 32 bytes of capacity.
/// If this syscall succeeds, exactly 32 bytes will be written starting at the
/// supplied offset.
pub fn get_beacon_randomness(
    dst: i64,
    round: ChainEpoch,
    entropy: &[u8],
) -> SyscallResult<[u8; RANDOMNESS_LENGTH]> {
    let ret = unsafe {
        sys::rand::get_beacon_randomness(dst, round as i64, entropy.as_ptr(), entropy.len() as u32)?
    };
    Ok(ret)
}