//
//  BulldogTool.cpp
//  UUTUtils
//
//  Created by zhuge on 2018/1/23.
//  Copyright © 2018年 zhuge. All rights reserved.
//

#include "BulldogTool.h"
#include <zlib.h>
#include "base64.h"
#include "ZipUtils.h"

#include <stdlib.h>

static BulldogTool* mBulldogTool = nullptr;
BulldogTool* BulldogTool::getInstance(){
    if (!mBulldogTool) {
        srand((int)time(0));
        mBulldogTool = new(std::nothrow) BulldogTool();
    }
    return mBulldogTool;
}

string BulldogTool::encrypt(string content){
    string ret = "";
    uLong tlen = strlen(content.c_str()); /* 需要把字符串的结束符'\0'也一并处理 */
    
    char* buf = NULL;
    uLong blen;
    
    
    z_stream c_stream;
    int err = 0;
    
    c_stream.zalloc = NULL;
    c_stream.zfree = NULL;
    c_stream.opaque = NULL;
    //只有设置为MAX_WBITS + 16才能在在压缩文本中带header和trailer
    auto initRs = deflateInit2(&c_stream, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
                               MAX_WBITS + 16, 8, Z_DEFAULT_STRATEGY);
    if (initRs != Z_OK) {
        return "";
    }
    /* 计算缓冲区大小，并为其分配内存 */
    blen = deflateBound(&c_stream,tlen); /* 压缩后的长度是不会超过blen的 */
    if((buf = (char*)malloc(sizeof(char) * blen)) == NULL){
        printf("no enough memory!\n");
    }
    memset(buf, 0, blen);
    
    c_stream.next_in  = (Bytef*)content.c_str();
    c_stream.avail_in  = tlen;
    c_stream.next_out = (Bytef*)buf;
    c_stream.avail_out  = blen;
    while(c_stream.avail_in != 0 && c_stream.total_out < blen) {
        auto defateRs = deflate(&c_stream, Z_NO_FLUSH);
        if (!(defateRs == Z_OK)) {
            return "";
        }
    }
    if (!(c_stream.avail_in == 0)) {
        return "";
    }
    for(;;) {
        if((err = deflate(&c_stream, Z_FINISH)) == Z_STREAM_END) break;
        if (!(err == Z_OK)) {
            return "";
        }
    }
    auto deflatEndRs = deflateEnd(&c_stream);
    if (!(deflatEndRs == Z_OK)) {
        return "";
    }
    blen = c_stream.total_out;
    
    char *buffer = nullptr;
    int len = base64Encode((unsigned char*)buf, blen, &buffer);
    if (buffer != nullptr) {
        for (int i = 0 ; i < len; i++) {
            //base64的结果再1、2位置互换
            if (i % 2 == 0 && (i + 1) < len  ) {
                char tmp = buffer[i];
                buffer[i] = buffer[i+1];
                buffer[i+1] = tmp;
            }
        }
        
        for (int i = 0 ; i < len; i++) {
            //加上干扰字符
            if (i % 10 == 0) {
                ret = ret + randomString(1);
            }
            //对base64Encode结果  '+'转'-'  '/'转'_'  (为了网络传输成功)
            if (buffer[i] == '+') {
                buffer[i] = '-';
            }
            if (buffer[i] == '/') {
                buffer[i] = '_';
            }
            ret = ret + string(buffer+i, buffer + i+1);
        }
        //        ret = string(buffer, buffer + len);
    }
    free(buf);
    free(buffer);
    
    return ret;
}

string BulldogTool::decrypt(string content){
    if(content == ""){
        return "";
    }
    
    string clearContent = "";
    for (int i = 0; i < content.length(); i++) {
        //对base64Decode结果  '-'转'+'  '_'转'/'
        if (content[i] == '-') {
            content[i] = '+';
        }
        if (content[i] == '_') {
            content[i] = '/';
        }
        //去掉干扰字符
        if (i % 11 != 0) {
            clearContent += content[i];
        }
    }
    for (int i = 0; i < clearContent.length(); i++) {
        //base64的结果再1、2位置互换
        if (i % 2 == 0 && (i + 1) < clearContent.length()  ) {
            char tmp = clearContent[i];
            clearContent[i] = clearContent[i+1];
            clearContent[i+1] = tmp;
        }
        
    }
    
    string ret = "";
    unsigned char *buffer = nullptr;
    unsigned char *deflated = nullptr;
    int dataLen = strlen(clearContent.c_str());
    int decodeLen = base64Decode((unsigned char*)clearContent.c_str(), (unsigned int)dataLen, &buffer);
    if (buffer != nullptr) {
        ssize_t deflatedLen = ZipUtils::inflateMemory(buffer, decodeLen, &deflated);
        if (deflated != nullptr) {
            ret = string((char*)deflated, (char*)deflated + deflatedLen);
        }
    }
    free(buffer);
    free(deflated);
    return ret;
}



int BulldogTool::randomInt(int start, int end){
    if (end < start) {
        // ----------ERROR:随机值范围不对
        return 0;
    }
    int len = end - start + 1;
    int value = rand() % len;
    return value + start;
}

string BulldogTool::randomString(int len){
    char charPool[] = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r',
        's','t','u','v','w','x','y','z','A','B','C','D','E','F','G','H','I','J','K','L','M','N',
        'O','P','Q','R','S','T','U','V','W','X','Y','Z','0','1','2','3','4','5','6','7','8','9'};
    char retTmp[len+1];
    memset(&retTmp[0], 0, sizeof(retTmp)  / sizeof(char));
    for (int i = 0 ; i < len; i++) {
        int randIndex = randomInt(0, (sizeof(charPool) / sizeof(char)) - 1);
        retTmp[i] = charPool[randIndex];
    }
    string ret = string(retTmp);
    return ret;
}