#include "crypt.h"
#include <cstring>
#include <openssl/des.h>
#include <iostream>

//获取需要填充的数据大小字节数
int Crypt::getPadding(int datasize){
    const int block_size = sizeof(const_DES_cblock); 
    int padding = block_size - datasize % block_size;
    if(padding == 0) padding = block_size;
    return padding;
}

///初始化密钥, DES加密算法 密钥最多8位 多余丢弃不足补零
bool Crypt::Init(std::string password){
    const_DES_cblock key = {0}; //不足补0
    int key_size = password.size();
    if(key_size > sizeof(key)) //多余丢弃
    {
        key_size = sizeof(key);
    }
    std::memcpy(key,password.c_str(),key_size);
    DES_set_key(&key,&key_sch_);  
    return true;
}
int Crypt::Encrypt(const char* in_data,int in_size, char* out_data, bool is_end){
    if(!in_data || in_size<=0 || !out_data){
        return 0;
    }
    int write_size = 0;
    const_DES_cblock in = {0}; //输入数据
    DES_cblock out = {0};      //输出
    const int block_size = sizeof(const_DES_cblock); 
    int data_size = 0;
    int padding = block_size - in_size % block_size;
    for(int i = 0; i < in_size; i += block_size){
        if(in_size - i < block_size){
            data_size = in_size - i;
        }
        else{
            data_size = block_size;
        }
        //复制数据源
        memcpy(in,in_data+write_size,data_size); //把in_data的数据copy到in

        //填充 补充的数据大小 @@@@@@@1 @@@55555 @@@@@@@@88888888
        if(is_end && i + block_size >= in_size) //处理最后一块数据
        {
            //@@@@@@@@88888888
            if(padding == block_size){
                DES_ecb_encrypt(&in,&out,&key_sch_,DES_ENCRYPT); //把in加密到out
                memcpy(out_data+write_size,&out,block_size);
                write_size += block_size;
                memset(in, padding, sizeof(in)); //填充8
            }
            else{//@@@@@@@1 @@@55555
                memset(in + in_size % block_size, padding, padding);
            }
        }
        //加密数据
        DES_ecb_encrypt(&in,&out,&key_sch_,DES_ENCRYPT); //把in加密到out
        memcpy(out_data+write_size,&out,block_size);
        write_size += block_size;
    }
    return write_size;
}


int Crypt::Decrypt(const char* in_data,int in_size, char* out_data, bool is_end ){
    if(!in_data || in_size<=0 || !out_data){
        return 0;
    }
    int write_size = 0;
    const_DES_cblock in = {0}; //输入数据
    DES_cblock out = {0}; //输出
    const int block_size = sizeof(const_DES_cblock); 
    int data_size = 0;
    for(int i = 0; i < in_size; i+=block_size){
        std::memcpy(in,in_data+write_size,block_size);
        data_size = block_size;
        //解密
        DES_ecb_encrypt(&in, &out, &key_sch_, DES_DECRYPT);
        //处理结尾填充 @@@55555 @@@@@@@@88888888
        if(is_end && in_size - i <= block_size){
            data_size = block_size - out[7];
            if(data_size == 0){
                break;
            }
            else if(data_size < 0){
                std::cerr<<"Decrypt failed! padding size error!"<<std::endl;
                break;
            }
        }
        std::memcpy(out_data + write_size, &out, data_size);
        write_size += data_size;
    }
    return write_size;
}