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use std::ops::RangeInclusive;

use crate::Envelope;
#[cfg(feature = "known_value")]
use crate::extension::known_values;

use anyhow::Result;
use bc_components::Salt;
use bc_rand::{RandomNumberGenerator, SecureRandomNumberGenerator};
use dcbor::prelude::*;

/// Support for decorrelation of envelopes using salt.
impl Envelope {
    /// Add a number of bytes of salt generally proportionate to the size of the object being salted.
    pub fn add_salt(&self) -> Self {
        let mut rng = SecureRandomNumberGenerator;
        self.add_salt_using(&mut rng)
    }

    /// Add the given Salt as an assertion
    pub fn add_salt_instance(&self, salt: Salt) -> Self {
        self.add_assertion(known_values::SALT, salt)
    }

    /// Add a specified number of bytes of salt.
    ///
    /// Returns an error if the number of bytes is less than 8.
    pub fn add_salt_with_len(&self, count: usize) -> Result<Self> {
        let mut rng = SecureRandomNumberGenerator;
        self.add_salt_with_len_using(count, &mut rng)
    }

    #[doc(hidden)]
    /// Add a specified number of bytes of salt.
    ///
    /// Returns an error if the number of bytes is less than 8.
    pub fn add_salt_with_len_using(&self, count: usize, rng: &mut impl RandomNumberGenerator) -> Result<Self> {
        let salt = Salt::new_with_len_using(count, rng)?;
        Ok(self.add_salt_instance(salt))
    }

    /// Add a number of bytes of salt chosen randomly from the given range.
    ///
    /// Returns an error if the minimum number of bytes is less than 8.
    pub fn add_salt_in_range(&self, range: RangeInclusive<usize>) -> Result<Self> {
        let mut rng = SecureRandomNumberGenerator;
        self.add_salt_in_range_using(&range, &mut rng)
    }

    #[doc(hidden)]
    /// Add a number of bytes of salt chosen randomly from the given range.
    ///
    /// Returns an error if the minimum number of bytes is less than 8.
    pub fn add_salt_in_range_using(&self, range: &RangeInclusive<usize>, rng: &mut impl RandomNumberGenerator) -> Result<Self> {
        Ok(self.add_salt_instance(Salt::new_in_range_using(range, rng)?))
    }

    #[doc(hidden)]
    /// Add a deterministic amount of salt.
    ///
    /// Only used for testing.
    pub fn add_salt_using(&self, rng: &mut impl RandomNumberGenerator) -> Self {
        let salt = Salt::new_for_size_using(self.tagged_cbor().to_cbor_data().len(), rng);
        self.add_salt_instance(salt)
    }
}