//
//  EncryptionTools.m
//

#import "EncryptionTools.h"

@interface EncryptionTools()
@property (nonatomic, assign) int keySize;
@property (nonatomic, assign) int blockSize;
@end

@implementation EncryptionTools

+ (instancetype)sharedEncryptionTools
{
    static EncryptionTools *instance;
    
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        instance = [[self alloc] init];
        instance.algorithm = kCCAlgorithmAES;
    });
    
    return instance;
}

- (void)setAlgorithm:(uint32_t)algorithm
{
    _algorithm = algorithm;
    switch (algorithm) {
        case kCCAlgorithmAES:
            self.keySize = kCCKeySizeAES128;
            self.blockSize = kCCBlockSizeAES128;
            break;
        case kCCAlgorithmDES:
            self.keySize = kCCKeySizeDES;
            self.blockSize = kCCBlockSizeDES;
            break;
        default:
            break;
    }
}

- (NSString *)encryptString:(NSString *)string keyString:(NSString *)keyString iv:(NSData *)iv
{
    if (string == nil) {
        return nil;
    }
    // 设置秘钥
    NSData *keyData = [keyString dataUsingEncoding:NSUTF8StringEncoding];
    uint8_t cKey[self.keySize];
    bzero(cKey, sizeof(cKey));
    [keyData getBytes:cKey length:self.keySize];
    
    // 设置iv
    uint8_t cIv[self.blockSize];
    bzero(cIv, self.blockSize);
    int option = 0;
    /**
     kCCOptionPKCS7Padding                      CBC 的加密
     kCCOptionPKCS7Padding | kCCOptionECBMode   ECB 的加密
     */
    if (iv) {
        [iv getBytes:cIv length:self.blockSize];
        option = kCCOptionPKCS7Padding;
    } else {
        option = kCCOptionPKCS7Padding | kCCOptionECBMode;
    }
    
    // 设置输出缓冲区
    NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];
    size_t bufferSize = [data length] + self.blockSize;
    void *buffer = malloc(bufferSize);
    
    // 开始加密
    size_t encryptedSize = 0;

    /*
     CCCrypt 对称加密算法的核心函数(加密/解密)
     第一个参数：kCCEncrypt 加密/ kCCDecrypt 解密
     第二个参数：加密算法，默认使用的是 AES/DES
     第三个参数：加密选项 ECB/CBC
                kCCOptionPKCS7Padding                      CBC 的加密
                kCCOptionPKCS7Padding | kCCOptionECBMode   ECB 的加密
     第四个参数：加密密钥
     第五个参数：密钥的长度
     第六个参数：初始向量
     第七个参数：加密的数据
     第八个参数：加密的数据长度
     第九个参数：密文的内存地址
     第十个参数：密文缓冲区的大小
     第十一个参数：加密结果的大小
     */
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt,
                                          self.algorithm,
                                          option,
                                          cKey,
                                          self.keySize,
                                          cIv,
                                          [data bytes],
                                          [data length],
                                          buffer,
                                          bufferSize,
                                          &encryptedSize);
    
    NSData *result = nil;
    if (cryptStatus == kCCSuccess) {
        result = [NSData dataWithBytesNoCopy:buffer length:encryptedSize];
    } else {    
        free(buffer);
        NSLog(@"[错误] 加密失败|状态编码: %d", cryptStatus);
    }
    
    return [result base64EncodedStringWithOptions:0];
}

- (NSString *)decryptString:(NSString *)string keyString:(NSString *)keyString iv:(NSData *)iv
{
    if (string == nil) {
        return nil;
    }
    // 设置秘钥
    NSData *keyData = [keyString dataUsingEncoding:NSUTF8StringEncoding];
    uint8_t cKey[self.keySize];
    bzero(cKey, sizeof(cKey));
    [keyData getBytes:cKey length:self.keySize];
    
    // 设置iv
    uint8_t cIv[self.blockSize];
    bzero(cIv, self.blockSize);
    int option = 0;
    if (iv) {
        [iv getBytes:cIv length:self.blockSize];
        option = kCCOptionPKCS7Padding;
    } else {
        option = kCCOptionPKCS7Padding | kCCOptionECBMode;
    }
    
    // 设置输出缓冲区
    NSData *data = [[NSData alloc] initWithBase64EncodedString:string options:0];
    size_t bufferSize = [data length] + self.blockSize;
    void *buffer = malloc(bufferSize);
    
    // 开始解密
    size_t decryptedSize = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt,
                                          self.algorithm,
                                          option,
                                          cKey,
                                          self.keySize,
                                          cIv,
                                          [data bytes],
                                          [data length],
                                          buffer,
                                          bufferSize,
                                          &decryptedSize);
    
    NSData *result = nil;
    if (cryptStatus == kCCSuccess) {
        result = [NSData dataWithBytesNoCopy:buffer length:decryptedSize];
    } else {
        free(buffer);
        NSLog(@"[错误] 解密失败|状态编码: %d", cryptStatus);
    }
    
    return [[NSString alloc] initWithData:result encoding:NSUTF8StringEncoding];
}


+ (NSString *)getStringFromGBKStr:(NSString *)gbkStr
{
    gbkStr = [gbkStr stringByReplacingOccurrencesOfString:@"0000"withString:@""];
    
    Byte byte[gbkStr.length/2];
    NSScanner *hexScanner;
    NSString *tmp;
    
    for(NSUInteger i=0;i<gbkStr.length/2;i++){
        
        tmp = [gbkStr substringWithRange:NSMakeRange(i*2,2)];
        unsigned int iStr = 0;
        hexScanner = [NSScanner scannerWithString:tmp];
        [hexScanner scanHexInt:&iStr];
        byte[i]=iStr;
    }
    
    NSData *data = [NSData dataWithBytes:byte length:gbkStr.length/2];
    NSStringEncoding enc = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);
    NSString *retStr = [[NSString alloc] initWithData:data encoding:enc];
    
    return retStr;
}

@end