#include "menu.h"
#include "fuctions.h"
#include <iostream>
#include <fstream>
#include <cstring>
#include <cstdlib>
#include <ctime>
#include "conio.h"
#include "io.h"

using namespace std;

void tean(long *k, long *v, long N) {
  long y=v[0], z=v[1];
  long limit,sum=0;
  if(N>0) { /* ENCRYPT */
    limit=DELTA*N;
    while(sum!=limit) {
      y+=((z<<4)^(z>>5)) + (z^sum) + k[sum&3];
      sum+=DELTA;
      z+=((y<<4)^(y>>5)) + (y^sum) + k[(sum>>11)&3];
    }
  } else { /* DECRYPT */
    sum=DELTA*(-N);
    while(sum) {
      z-=((y<<4)^(y>>5)) + (y^sum) + k[(sum>>11)&3];
      sum-=DELTA;
      y-=((z<<4)^(z>>5)) + (z^sum) + k[sum&3];
    }
  }
  v[0]=y; v[1]=z;
}

void cl_enc_block(long *k, long *v) {
 tean(k,v,ROUNDS);
}

void cl_dec_block(long *k, long *v) {
 tean(k,v,-ROUNDS);
}

void keychange(long *k, const char* code)
{
    for (int i = 0; i < 4; i++) {
        k[i] = (long)code[i] * (long)code[i] * (long)code[i+1] * (long)code[i+1]; 
    }
}        
        

bool EnCode(const char* file, const char* code)
{
    if (isEncrypted(file)) {
        cout<<"[此文件已經加密!]"<<endl;
        return false;
    }   
    long k[4]; 
    long v[2];
    long t[2];
    long* lt;
    char newfile[FILE_NAME_MAX_LEN];
    char fix[LEN];
    streampos freallen, fpos;
    long filelen;
    int flag;
    char ch;
    char remnant[LEN];
    char outPath[_MAX_PATH];
    
    keychange(k, code);

    char *fp = strrchr(file, '\\') + 1;
    int i = 0;
    while (*fp) {
        newfile[i++] = *fp++;
    }
    outPath[i] = '\0';  
    
    changeName(newfile, czOutFix);
    getFix(file, fix);
    
    fstream finout(file, ios::in|ios::out|ios::binary);    
    if (!finout.is_open()) {
        cout<<"[無法打開文件!]"<<endl;
        finout.close();
        return false;
    }     
    
    //cout<<"[成功打開文件!]"<<endl;
    cout<<"[按任意鍵選擇加密文件存放目錄!]";
    getch();

    outputPath(outPath);
    _chdir(outPath);

    system("CLS"); 
    cout<<"[文件加密中...]"<<endl; 
    
    freallen = finout.seekg(0, ios_base::end).tellg();
    filelen = long(freallen);

    if (filelen % 8 == 0) flag = 0;
    else {
        flag = filelen%8;
        filelen = (filelen/8)*8;
    }    
       
    finout.seekg(0, ios_base::beg);
    
    ofstream fout(newfile, ios::out | ios::binary);
    
    if (fout.is_open()) {
        while (finout.read((char*)v, 8)) {
                cl_enc_block(k, v);    
                fout.write((char*)v, 8);
                fpos = finout.tellg();
        }
    }  
    finout.clear();  
    if (flag) {
        int s = 0;
        finout.seekg(fpos, ios_base::beg);
        while (finout.read((char*)&ch, 1)) {
            remnant[s++] = ch;
        }
        remnant[s++] = 1;
        while (s < 8) remnant[s++] = 0;    
        memcpy(t, remnant, 8);
        lt = (long*)t;
        cl_enc_block(k, lt);
        fout.write((char*)lt, 8);
    }    
    
    memcpy(t, code, 8);
    lt = (long*)t;
    cl_enc_block(k, lt);
    fout.write((char*)lt, 8); 
    
    memcpy(t, fix, 8);
    lt = (long*)t;
    cl_enc_block(k, lt);
    fout.write((char*)lt, 8);
             
    v[0] = 0x0L; v[1] = (long)flag;
    cl_enc_block(k, v);
    fout.write((char*)v, 8);
                 
        
        
    finout.clear();

    cout<<"[加密成功!]"<<endl;  
    finout.close();
    fout.close();
    return true;
}        
             
    
    
bool DeCode(const char* file, const char* code)
{
    long k[4];
    long v[2];
    streampos fpos, pos = 0;
    char newfile[FILE_NAME_MAX_LEN];
    char fix[LEN];
    char key[LEN];
    char remnant[LEN];
    char* pkey;
    char* pfix;
    char* prem;
    char ch;
    int flag;
    char outPath[_MAX_PATH];
    
    keychange(k, code);
    char *fp = strrchr(file, '\\') + 1;
    int i = 0;
    while (*fp) {
        newfile[i++] = *fp++;
    }
    outPath[i] = '\0';
    
    ifstream fin(file, ios::in | ios::binary);
    if (!fin.is_open()) {
        cout <<"[無法打開文件!]"<<endl;
        fin.close();
        return false;
    }
           
    fin.seekg(-24, ios_base::end);
    fin.read((char*)v, 8);
    cl_dec_block(k, v);
    memcpy(key, v, 8);
    pkey = (char*)key;
    pkey[8] = '\0';
    
    
    if (strcmp(code, pkey)) {
        cout<<"[密碼不正確!]"<<endl;
        fin.close();
        return false;
    }

    fin.read((char*)v, 8);
    cl_dec_block(k, v);
    memcpy(fix, v, 8);
    pfix = (char*)fix;
    pfix[8] = '\0';
    
    fin.read((char*)v, 8);
    cl_dec_block(k, v);
    flag = (int)v[1];

    changeName(newfile, pfix);
    
    cout<<"[密碼正確!]"; 
    cout<<"[按任意鍵選擇解密文件存放目錄!]";
    getch();
    outputPath(outPath);
    _chdir(outPath);

    system("CLS");
      
    cout<<"[文件解密中...]"<<endl; 
    fpos = fin.seekg(0, ios_base::end).tellg();     
    ofstream fout(newfile, ios::out | ios::binary);
    fin.seekg(0, ios_base::beg);

    while (fin.tellg() < fpos-streampos(24+(flag?8:0))) {
       if (fin.read((char*)v, 8)) {
                cl_dec_block(k, v);    
                fout.write((char*)v, 8);
        }
    }
    fin.read((char*)v, 8);
    cl_dec_block(k, v);
    memcpy(remnant, v, 8);
    prem = (char*)remnant;

    for (int s = 0; s < flag; s++) {
        fout.write((char*)&prem[s], 1);
    }    
    
    fin.clear();
    cout<<"[解密成功!]"<<endl;    
    fin.close();
    fout.close();
    return true;
}