//
//  CommonUtil.m
//  WechatPayDemo
//
//  Created by Alvin on 3/22/14.
//  Copyright (c) 2014 Alvin. All rights reserved.
//

#import "CommonUtil.h"
#import <CommonCrypto/CommonDigest.h>
#include <ifaddrs.h>
#include <arpa/inet.h>
#include <net/if.h>

#define IOS_CELLULAR    @"pdp_ip0"
#define IOS_WIFI        @"en0"
#define IP_ADDR_IPv4    @"ipv4"
#define IP_ADDR_IPv6    @"ipv6"

@implementation CommonUtil

+ (NSString *)md5:(NSString *)input
{
    const char *cStr = [input UTF8String];
    unsigned char digest[16];
    CC_MD5( cStr, strlen(cStr), digest ); // This is the md5 call
    
    NSMutableString *output = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH * 2];
    
    for(int i = 0; i < CC_MD5_DIGEST_LENGTH; i++)
        [output appendFormat:@"%02x", digest[i]];
    
    return  output;
}

+ (NSString *)sha1:(NSString *)input
{
    const char *ptr = [input UTF8String];
    
    int i =0;
    int len = strlen(ptr);
    Byte byteArray[len];
    while (i!=len)
    {
        unsigned eachChar = *(ptr + i);
        unsigned low8Bits = eachChar & 0xFF;
        
        byteArray[i] = low8Bits;
        i++;
    }
    
    unsigned char digest[CC_SHA1_DIGEST_LENGTH];
    
    CC_SHA1(byteArray, len, digest);
    
    NSMutableString *hex = [NSMutableString string];
    for (int i=0; i<20; i++)
        [hex appendFormat:@"%02x", digest[i]];
    
    NSString *immutableHex = [NSString stringWithString:hex];
    
    return immutableHex;
}

+ (NSString *)getIPAddress:(BOOL)preferIPv4
{
    NSArray *searchArray = preferIPv4 ?
    @[ IOS_WIFI @"/" IP_ADDR_IPv4, IOS_WIFI @"/" IP_ADDR_IPv6, IOS_CELLULAR @"/" IP_ADDR_IPv4, IOS_CELLULAR @"/" IP_ADDR_IPv6 ] :
    @[ IOS_WIFI @"/" IP_ADDR_IPv6, IOS_WIFI @"/" IP_ADDR_IPv4, IOS_CELLULAR @"/" IP_ADDR_IPv6, IOS_CELLULAR @"/" IP_ADDR_IPv4 ] ;
    
    NSDictionary *addresses = [self getIPAddresses];
    //NSLog(@"addresses: %@", addresses);
    
    __block NSString *address;
    [searchArray enumerateObjectsUsingBlock:^(NSString *key, NSUInteger idx, BOOL *stop)
     {
         address = addresses[key];
         if(address) *stop = YES;
     } ];
    return address ? address : @"0.0.0.0";
}

+ (NSDictionary *)getIPAddresses
{
    NSMutableDictionary *addresses = [NSMutableDictionary dictionaryWithCapacity:8];
    
    // retrieve the current interfaces - returns 0 on success
    struct ifaddrs *interfaces;
    if(!getifaddrs(&interfaces)) {
        // Loop through linked list of interfaces
        struct ifaddrs *interface;
        for(interface=interfaces; interface; interface=interface->ifa_next) {
            if(!(interface->ifa_flags & IFF_UP) || (interface->ifa_flags & IFF_LOOPBACK)) {
                continue; // deeply nested code harder to read
            }
            const struct sockaddr_in *addr = (const struct sockaddr_in*)interface->ifa_addr;
            if(addr && (addr->sin_family==AF_INET || addr->sin_family==AF_INET6)) {
                NSString *name = [NSString stringWithUTF8String:interface->ifa_name];
                char addrBuf[INET6_ADDRSTRLEN];
                if(inet_ntop(addr->sin_family, &addr->sin_addr, addrBuf, sizeof(addrBuf))) {
                    NSString *key = [NSString stringWithFormat:@"%@/%@", name, addr->sin_family == AF_INET ? IP_ADDR_IPv4 : IP_ADDR_IPv6];
                    addresses[key] = [NSString stringWithUTF8String:addrBuf];
                }
            }
        }
        // Free memory
        freeifaddrs(interfaces);
    }
    
    // The dictionary keys have the form "interface" "/" "ipv4 or ipv6"
    return [addresses count] ? addresses : nil;
}

@end
