use cipher::{BlockDecryptMut, BlockEncryptMut, KeyIvInit};
use des::Des;

type DesEncryptor = cbc::Encryptor<Des>;
type DesDecryptor = cbc::Decryptor<Des>;

/// 利用Sha512生成8字节的密钥
///
/// - `key` 原始密钥
fn generate_key<T: AsRef<[u8]>>(key: T) -> [u8; 8] {
    let mut hasher = hmac_sha256::Hash::new();
    hasher.update(key);
    let result = hasher.finalize();
    let mut compressed_key = [0u8; 8];
    for i in 0..8 {
        compressed_key[i] = result[i];
        for j in 1..4 {
            compressed_key[i] ^= result[i + j * 8];
        }
    }
    compressed_key
}

/// 使用指定的密钥和填充方式对数据进行加密。
/// 如果需要字符串形式的密文，可以配合使用`hex`或者`base64`等函数。
///
/// - `key` 密钥
/// - `padding` 填充方式
/// - `plain_data` 明文数据
fn encrypt<T: AsRef<[u8]>, D: AsRef<[u8]>>(
    key: T,
    padding: super::Padding,
    plain_data: D,
) -> Vec<u8> {
    let key = generate_key(key);
    let encryptor = DesEncryptor::new(key.as_slice().into(), &key.into());
    let result = match padding {
        super::Padding::NoPadding => encryptor
            .encrypt_padded_vec_mut::<cipher::block_padding::NoPadding>(plain_data.as_ref()),
        super::Padding::ZeroPadding => encryptor
            .encrypt_padded_vec_mut::<cipher::block_padding::ZeroPadding>(plain_data.as_ref()),
        super::Padding::Pkcs7Padding => {
            encryptor.encrypt_padded_vec_mut::<cipher::block_padding::Pkcs7>(plain_data.as_ref())
        }
    };
    result
}

/// 使用指定的密钥和填充方式对数据进行解密。
///
/// - `key` 密钥
/// - `padding` 填充方式
/// - `cipher_data` 密文数据
fn decrypt<T: AsRef<[u8]>, D: AsRef<[u8]>>(
    key: T,
    padding: super::Padding,
    cipher_data: D,
) -> Result<Vec<u8>, super::DecryptFailedError> {
    let key = generate_key(key);
    let decryptor = DesDecryptor::new(key.as_slice().into(), &key.into());
    let result = match padding {
        super::Padding::NoPadding => decryptor
            .decrypt_padded_vec_mut::<cipher::block_padding::NoPadding>(cipher_data.as_ref()),
        super::Padding::ZeroPadding => decryptor
            .decrypt_padded_vec_mut::<cipher::block_padding::ZeroPadding>(cipher_data.as_ref()),
        super::Padding::Pkcs7Padding => {
            decryptor.decrypt_padded_vec_mut::<cipher::block_padding::Pkcs7>(cipher_data.as_ref())
        }
    };
    result.map_err(|_| super::DecryptFailedError {})
}

/// 快捷无填充加密函数
///
/// - `key` 密钥
/// - `plain_data` 明文数据
pub fn encrypt_no_padding<T: AsRef<[u8]>, D: AsRef<[u8]>>(key: T, plain_data: D) -> Vec<u8> {
    encrypt(key, super::Padding::NoPadding, plain_data)
}

/// 快捷无填充解密函数
///
/// - `key` 密钥
/// - `cipher_data` 密文数据
pub fn decrypt_no_padding<T: AsRef<[u8]>, D: AsRef<[u8]>>(
    key: T,
    cipher_data: D,
) -> Result<Vec<u8>, super::DecryptFailedError> {
    decrypt(key, super::Padding::NoPadding, cipher_data)
}

/// 快捷零填充加密函数
///
/// - `key` 密钥
/// - `plain_data` 明文数据
pub fn encrypt_zero_padding<T: AsRef<[u8]>, D: AsRef<[u8]>>(key: T, plain_data: D) -> Vec<u8> {
    encrypt(key, super::Padding::ZeroPadding, plain_data)
}

/// 快捷零填充解密函数
///
/// - `key` 密钥
/// - `cipher_data` 密文数据
pub fn decrypt_zero_padding<T: AsRef<[u8]>, D: AsRef<[u8]>>(
    key: T,
    cipher_data: D,
) -> Result<Vec<u8>, super::DecryptFailedError> {
    decrypt(key, super::Padding::ZeroPadding, cipher_data)
}

/// 快捷Pkcs7填充加密函数
///
/// - `key` 密钥
/// - `plain_data` 明文数据
pub fn encrypt_pkcs7_padding<T: AsRef<[u8]>, D: AsRef<[u8]>>(key: T, plain_data: D) -> Vec<u8> {
    encrypt(key, super::Padding::Pkcs7Padding, plain_data)
}

/// 快捷Pkcs7填充解密函数
///
/// - `key` 密钥
/// - `cipher_data` 密文数据
pub fn decrypt_pkcs7_padding<T: AsRef<[u8]>, D: AsRef<[u8]>>(
    key: T,
    cipher_data: D,
) -> Result<Vec<u8>, super::DecryptFailedError> {
    decrypt(key, super::Padding::Pkcs7Padding, cipher_data)
}