tfhe 1.6.0

use super::backward_compatibility::key_switching_key::{
    CompressedKeySwitchingKeyMaterialVersions, CompressedKeySwitchingKeyVersions,
    KeySwitchingKeyMaterialVersions, KeySwitchingKeyVersions,
};
use super::{ClientKey, CompressedServerKey, ServerKey};
use crate::conformance::ParameterSetConformant;
use crate::integer::client_key::secret_encryption_key::SecretEncryptionKeyView;
use crate::integer::IntegerCiphertext;
use crate::shortint::key_switching_key::KeySwitchingKeyConformanceParams;
use crate::shortint::parameters::ShortintKeySwitchingParameters;
use rayon::prelude::*;
use serde::{Deserialize, Serialize};
use tfhe_versionable::Versionize;

#[cfg(test)]
mod test;

// This is used to have the ability to build a keyswitching key without owning the ServerKey
// It is a bit of a hack, but at this point it seems ok
pub(crate) struct KeySwitchingKeyBuildHelper<'keys> {
    pub(crate) build_helper: crate::shortint::key_switching_key::KeySwitchingKeyBuildHelper<'keys>,
}

impl<'keys> KeySwitchingKeyBuildHelper<'keys> {
    pub fn new<'input_key, InputEncryptionKey>(
        input_key_pair: (InputEncryptionKey, Option<&'keys ServerKey>),
        output_key_pair: (&'keys ClientKey, &'keys ServerKey),
        params: ShortintKeySwitchingParameters,
    ) -> Self
    where
        InputEncryptionKey: Into<SecretEncryptionKeyView<'input_key>>,
    {
        let (secret_key, src_sks) = input_key_pair;
        let secret_key: SecretEncryptionKeyView<'_> = secret_key.into();

        Self {
            build_helper: crate::shortint::key_switching_key::KeySwitchingKeyBuildHelper::new(
                (&secret_key.key, src_sks.map(AsRef::as_ref)),
                (output_key_pair.0.as_ref(), output_key_pair.1.as_ref()),
                params,
            ),
        }
    }
}

#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Versionize)]
#[versionize(KeySwitchingKeyMaterialVersions)]
pub struct KeySwitchingKeyMaterial {
    pub(crate) material: crate::shortint::key_switching_key::KeySwitchingKeyMaterial,
}

impl KeySwitchingKeyMaterial {
    pub fn into_raw_parts(self) -> crate::shortint::key_switching_key::KeySwitchingKeyMaterial {
        let Self { material } = self;
        material
    }

    pub fn from_raw_parts(
        material: crate::shortint::key_switching_key::KeySwitchingKeyMaterial,
    ) -> Self {
        Self { material }
    }

    pub fn as_view(&self) -> KeySwitchingKeyMaterialView<'_> {
        KeySwitchingKeyMaterialView {
            material: self.material.as_view(),
        }
    }
}

#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Versionize)]
#[versionize(KeySwitchingKeyVersions)]
pub struct KeySwitchingKey {
    pub(crate) key: crate::shortint::KeySwitchingKey,
}

impl From<KeySwitchingKeyBuildHelper<'_>> for KeySwitchingKey {
    fn from(value: KeySwitchingKeyBuildHelper) -> Self {
        Self {
            key: value.build_helper.into(),
        }
    }
}

impl From<KeySwitchingKeyBuildHelper<'_>> for KeySwitchingKeyMaterial {
    fn from(value: KeySwitchingKeyBuildHelper) -> Self {
        Self {
            material: value.build_helper.key_switching_key_material,
        }
    }
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct KeySwitchingKeyMaterialView<'key> {
    pub(crate) material: crate::shortint::key_switching_key::KeySwitchingKeyMaterialView<'key>,
}

#[derive(Clone, Copy, Debug, PartialEq)]
pub struct KeySwitchingKeyView<'keys> {
    pub(crate) key: crate::shortint::KeySwitchingKeyView<'keys>,
}

impl KeySwitchingKey {
    pub fn new<'input_key, InputEncryptionKey, ClientKeyType>(
        input_key_pair: (InputEncryptionKey, Option<&ServerKey>),
        output_key_pair: (&ClientKeyType, &ServerKey),
        params: ShortintKeySwitchingParameters,
    ) -> Self
    where
        InputEncryptionKey: Into<SecretEncryptionKeyView<'input_key>>,
        ClientKeyType: AsRef<ClientKey>,
    {
        let input_secret_encryption_key: SecretEncryptionKeyView<'_> = input_key_pair.0.into();
        let ret = Self {
            key: crate::shortint::KeySwitchingKey::new(
                (
                    input_secret_encryption_key.key,
                    input_key_pair.1.map(|k| &k.key),
                ),
                (&output_key_pair.0.as_ref().key, &output_key_pair.1.key),
                params,
            ),
        };

        assert!(
            ret.key.key_switching_key_material.cast_rshift == 0,
            "Attempt to build a KeySwitchingKey \
            between integer key pairs with different message modulus and carry"
        );

        ret
    }

    /// Deconstruct a [`KeySwitchingKey`] into its constituents.
    pub fn into_raw_parts(self) -> crate::shortint::KeySwitchingKey {
        self.key
    }

    /// Construct a [`KeySwitchingKey`] from its constituents.
    pub fn from_raw_parts(key: crate::shortint::KeySwitchingKey) -> Self {
        Self { key }
    }

    pub fn cast<Int: IntegerCiphertext>(&self, ct: &Int) -> Int {
        Int::from_blocks(
            ct.blocks()
                .par_iter()
                .map(|b| {
                    let mut ret = self.key.cast(b);

                    // These next 2 lines are to handle Crt ciphertexts
                    ret.message_modulus = b.message_modulus;
                    ret.carry_modulus = b.carry_modulus;

                    ret
                })
                .collect::<Vec<_>>(),
        )
    }

    pub fn as_view(&self) -> KeySwitchingKeyView<'_> {
        KeySwitchingKeyView {
            key: self.key.as_view(),
        }
    }
}

impl<'keys> KeySwitchingKeyView<'keys> {
    pub fn from_keyswitching_key_material(
        key_switching_key_material: KeySwitchingKeyMaterialView<'keys>,
        dest_server_key: &'keys ServerKey,
        src_server_key: Option<&'keys ServerKey>,
    ) -> Self {
        Self {
            key: crate::shortint::KeySwitchingKeyView::from_raw_parts(
                key_switching_key_material.material,
                dest_server_key.as_ref(),
                src_server_key.map(AsRef::as_ref),
            ),
        }
    }
}

// This is used to have the ability to build a keyswitching key without owning the ServerKey
// It is a bit of a hack, but at this point it seems ok
pub(crate) struct CompressedKeySwitchingKeyBuildHelper<'keys> {
    pub(crate) build_helper:
        crate::shortint::key_switching_key::CompressedKeySwitchingKeyBuildHelper<'keys>,
}

impl<'keys> CompressedKeySwitchingKeyBuildHelper<'keys> {
    pub fn new<'input_key, InputEncryptionKey>(
        input_key_pair: (InputEncryptionKey, Option<&'keys CompressedServerKey>),
        output_key_pair: (&'keys ClientKey, &'keys CompressedServerKey),
        params: ShortintKeySwitchingParameters,
    ) -> Self
    where
        InputEncryptionKey: Into<SecretEncryptionKeyView<'input_key>>,
    {
        let (secret_key, src_sks) = input_key_pair;
        let secret_key: SecretEncryptionKeyView<'_> = secret_key.into();

        Self {
            build_helper:
                crate::shortint::key_switching_key::CompressedKeySwitchingKeyBuildHelper::new(
                    (&secret_key.key, src_sks.map(|k| &k.key)),
                    (output_key_pair.0.as_ref(), &output_key_pair.1.key),
                    params,
                ),
        }
    }
}

#[derive(Clone, Debug, Serialize, Deserialize, Versionize)]
#[versionize(CompressedKeySwitchingKeyMaterialVersions)]
pub struct CompressedKeySwitchingKeyMaterial {
    pub(crate) material: crate::shortint::key_switching_key::CompressedKeySwitchingKeyMaterial,
}

impl CompressedKeySwitchingKeyMaterial {
    pub fn decompress(&self) -> KeySwitchingKeyMaterial {
        KeySwitchingKeyMaterial {
            material: self.material.decompress(),
        }
    }

    pub fn from_raw_parts(
        material: crate::shortint::key_switching_key::CompressedKeySwitchingKeyMaterial,
    ) -> Self {
        Self { material }
    }

    pub fn into_raw_parts(
        self,
    ) -> crate::shortint::key_switching_key::CompressedKeySwitchingKeyMaterial {
        let Self { material } = self;
        material
    }
}

#[derive(Clone, Debug, Serialize, Deserialize, Versionize)]
#[versionize(CompressedKeySwitchingKeyVersions)]
pub struct CompressedKeySwitchingKey {
    pub(crate) key: crate::shortint::CompressedKeySwitchingKey,
}

impl From<CompressedKeySwitchingKeyBuildHelper<'_>> for CompressedKeySwitchingKey {
    fn from(value: CompressedKeySwitchingKeyBuildHelper) -> Self {
        Self {
            key: value.build_helper.into(),
        }
    }
}

impl From<CompressedKeySwitchingKeyBuildHelper<'_>> for CompressedKeySwitchingKeyMaterial {
    fn from(value: CompressedKeySwitchingKeyBuildHelper) -> Self {
        Self {
            material: value.build_helper.key_switching_key_material,
        }
    }
}

impl CompressedKeySwitchingKey {
    pub fn new<'input_key, InputEncryptionKey, ClientKeyType>(
        input_key_pair: (InputEncryptionKey, Option<&CompressedServerKey>),
        output_key_pair: (&ClientKeyType, &CompressedServerKey),
        params: ShortintKeySwitchingParameters,
    ) -> Self
    where
        InputEncryptionKey: Into<SecretEncryptionKeyView<'input_key>>,
        ClientKeyType: AsRef<ClientKey>,
    {
        let input_secret_encryption_key: SecretEncryptionKeyView<'_> = input_key_pair.0.into();
        let ret = Self {
            key: crate::shortint::CompressedKeySwitchingKey::new(
                (
                    input_secret_encryption_key.key,
                    input_key_pair.1.map(|k| &k.key),
                ),
                (&output_key_pair.0.as_ref().key, &output_key_pair.1.key),
                params,
            ),
        };

        assert!(
            ret.key.key_switching_key_material.cast_rshift == 0,
            "Attempt to build a CompressedKeySwitchingKey \
            between integer key pairs with different message modulus and carry"
        );

        ret
    }

    pub fn decompress(&self) -> KeySwitchingKey {
        KeySwitchingKey {
            key: self.key.decompress(),
        }
    }
}

impl ParameterSetConformant for KeySwitchingKeyMaterial {
    type ParameterSet = KeySwitchingKeyConformanceParams;

    fn is_conformant(&self, parameter_set: &Self::ParameterSet) -> bool {
        let Self { material } = self;
        material.is_conformant(parameter_set)
    }
}

impl ParameterSetConformant for CompressedKeySwitchingKeyMaterial {
    type ParameterSet = KeySwitchingKeyConformanceParams;

    fn is_conformant(&self, parameter_set: &Self::ParameterSet) -> bool {
        let Self { material } = self;
        material.is_conformant(parameter_set)
    }
}