/**
 * 文件名: md5.c
 * 目标: 计算文件的md5值
 */

#include <cstdio>
#include <cstring>

#include "tool.h"
#include "md5.h"
#include "file.h"
#include "tool-exception.h"
#include "__md5.h"

namespace aFuntool {
    struct MD5_CTX {
        unsigned int count[2];
        unsigned int state[4];
        unsigned char buffer[64];
    };

    static void MD5Transform(unsigned int state[4], unsigned char block[64]);

    static void MD5Encode(unsigned char *output, const unsigned int *input, unsigned int len);

    static void MD5Decode(unsigned int *output, const unsigned char *input, unsigned int len);

    unsigned char PADDING[] = {
            0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
    };

    MD5_CTX *MD5Init(){
        auto context = safeCalloc<MD5_CTX>();
        context->count[0] = 0;
        context->count[1] = 0;
        context->state[0] = 0x67452301;
        context->state[1] = 0xEFCDAB89;
        context->state[2] = 0x98BADCFE;
        context->state[3] = 0x10325476;
        return context;
    }

    void MD5Update(MD5_CTX *context, unsigned char *input, unsigned int input_len){
        unsigned int i;
        unsigned int index;
        unsigned int part_len;

        index = (context->count[0] >> (unsigned) 3) & (unsigned) 0x3F;
        part_len = 64 - index;
        context->count[0] += input_len << (unsigned) 3;

        if (context->count[0] < (input_len << (unsigned) 3))
            context->count[1]++;
        context->count[1] += input_len >> (unsigned) 29;

        if (input_len >= part_len) {
            memcpy(&context->buffer[index], input, part_len);
            MD5Transform(context->state, context->buffer);

            for (i = part_len; i + 64 <= input_len; i += 64)
                MD5Transform(context->state, &input[i]);

            index = 0;
        } else
            i = 0;
        memcpy(&context->buffer[index], &input[i], input_len - i);
    }

    void MD5Final(MD5_CTX *context, unsigned char digest[16]){
        unsigned int index;
        unsigned int pad_len;
        unsigned char bits[8];

        index = (context->count[0] >> (unsigned) 3) & (unsigned) 0x3F;
        pad_len = (index < 56) ? (56 - index) : (120 - index);
        MD5Encode(bits, context->count, 8);
        MD5Update(context, PADDING, pad_len);
        MD5Update(context, bits, 8);
        MD5Encode(digest, context->state, 16);
        safeFree(context);
    }

    static void MD5Encode(unsigned char *output, const unsigned int *input, unsigned int len){
        unsigned int i = 0;
        unsigned int j = 0;

        while (j < len) {
            output[j] = input[i] & (unsigned) 0xFF;
            output[j + 1] = (input[i] >> (unsigned) 8) & (unsigned) 0xFF;
            output[j + 2] = (input[i] >> (unsigned) 16) & (unsigned) 0xFF;
            output[j + 3] = (input[i] >> (unsigned) 24) & (unsigned) 0xFF;
            i++;
            j += 4;
        }
    }

    static void MD5Decode(unsigned int *output, const unsigned char *input, unsigned int len){
        for (unsigned int i = 0, j = 0; j < len; i++, j += 4) {
            output[i] = (input[j]) |
                        (input[j + 1] << (unsigned) 8) |
                        (input[j + 2] << (unsigned) 16) |
                        (input[j + 3] << (unsigned) 24);
        }
    }

    static void MD5Transform(unsigned int state[4], unsigned char block[64]){
        unsigned int a = state[0];
        unsigned int b = state[1];
        unsigned int c = state[2];
        unsigned int d = state[3];
        unsigned int x[64];

        MD5Decode(x, block, 64);

        FF(a, b, c, d, x[0], 7, 0xd76aa478); /* 1 */
        FF(d, a, b, c, x[1], 12, 0xe8c7b756); /* 2 */
        FF(c, d, a, b, x[2], 17, 0x242070db); /* 3 */
        FF(b, c, d, a, x[3], 22, 0xc1bdceee); /* 4 */
        FF(a, b, c, d, x[4], 7, 0xf57c0faf); /* 5 */
        FF(d, a, b, c, x[5], 12, 0x4787c62a); /* 6 */
        FF(c, d, a, b, x[6], 17, 0xa8304613); /* 7 */
        FF(b, c, d, a, x[7], 22, 0xfd469501); /* 8 */
        FF(a, b, c, d, x[8], 7, 0x698098d8); /* 9 */
        FF(d, a, b, c, x[9], 12, 0x8b44f7af); /* 10 */
        FF(c, d, a, b, x[10], 17, 0xffff5bb1); /* 11 */
        FF(b, c, d, a, x[11], 22, 0x895cd7be); /* 12 */
        FF(a, b, c, d, x[12], 7, 0x6b901122); /* 13 */
        FF(d, a, b, c, x[13], 12, 0xfd987193); /* 14 */
        FF(c, d, a, b, x[14], 17, 0xa679438e); /* 15 */
        FF(b, c, d, a, x[15], 22, 0x49b40821); /* 16 */

        /* Round 2 */
        GG(a, b, c, d, x[1], 5, 0xf61e2562); /* 17 */
        GG(d, a, b, c, x[6], 9, 0xc040b340); /* 18 */
        GG(c, d, a, b, x[11], 14, 0x265e5a51); /* 19 */
        GG(b, c, d, a, x[0], 20, 0xe9b6c7aa); /* 20 */
        GG(a, b, c, d, x[5], 5, 0xd62f105d); /* 21 */
        GG(d, a, b, c, x[10], 9, 0x2441453); /* 22 */
        GG(c, d, a, b, x[15], 14, 0xd8a1e681); /* 23 */
        GG(b, c, d, a, x[4], 20, 0xe7d3fbc8); /* 24 */
        GG(a, b, c, d, x[9], 5, 0x21e1cde6); /* 25 */
        GG(d, a, b, c, x[14], 9, 0xc33707d6); /* 26 */
        GG(c, d, a, b, x[3], 14, 0xf4d50d87); /* 27 */
        GG(b, c, d, a, x[8], 20, 0x455a14ed); /* 28 */
        GG(a, b, c, d, x[13], 5, 0xa9e3e905); /* 29 */
        GG(d, a, b, c, x[2], 9, 0xfcefa3f8); /* 30 */
        GG(c, d, a, b, x[7], 14, 0x676f02d9); /* 31 */
        GG(b, c, d, a, x[12], 20, 0x8d2a4c8a); /* 32 */

        /* Round 3 */
        HH(a, b, c, d, x[5], 4, 0xfffa3942); /* 33 */
        HH(d, a, b, c, x[8], 11, 0x8771f681); /* 34 */
        HH(c, d, a, b, x[11], 16, 0x6d9d6122); /* 35 */
        HH(b, c, d, a, x[14], 23, 0xfde5380c); /* 36 */
        HH(a, b, c, d, x[1], 4, 0xa4beea44); /* 37 */
        HH(d, a, b, c, x[4], 11, 0x4bdecfa9); /* 38 */
        HH(c, d, a, b, x[7], 16, 0xf6bb4b60); /* 39 */
        HH(b, c, d, a, x[10], 23, 0xbebfbc70); /* 40 */
        HH(a, b, c, d, x[13], 4, 0x289b7ec6); /* 41 */
        HH(d, a, b, c, x[0], 11, 0xeaa127fa); /* 42 */
        HH(c, d, a, b, x[3], 16, 0xd4ef3085); /* 43 */
        HH(b, c, d, a, x[6], 23, 0x4881d05); /* 44 */
        HH(a, b, c, d, x[9], 4, 0xd9d4d039); /* 45 */
        HH(d, a, b, c, x[12], 11, 0xe6db99e5); /* 46 */
        HH(c, d, a, b, x[15], 16, 0x1fa27cf8); /* 47 */
        HH(b, c, d, a, x[2], 23, 0xc4ac5665); /* 48 */

        /* Round 4 */
        II(a, b, c, d, x[0], 6, 0xf4292244); /* 49 */
        II(d, a, b, c, x[7], 10, 0x432aff97); /* 50 */
        II(c, d, a, b, x[14], 15, 0xab9423a7); /* 51 */
        II(b, c, d, a, x[5], 21, 0xfc93a039); /* 52 */
        II(a, b, c, d, x[12], 6, 0x655b59c3); /* 53 */
        II(d, a, b, c, x[3], 10, 0x8f0ccc92); /* 54 */
        II(c, d, a, b, x[10], 15, 0xffeff47d); /* 55 */
        II(b, c, d, a, x[1], 21, 0x85845dd1); /* 56 */
        II(a, b, c, d, x[8], 6, 0x6fa87e4f); /* 57 */
        II(d, a, b, c, x[15], 10, 0xfe2ce6e0); /* 58 */
        II(c, d, a, b, x[6], 15, 0xa3014314); /* 59 */
        II(b, c, d, a, x[13], 21, 0x4e0811a1); /* 60 */
        II(a, b, c, d, x[4], 6, 0xf7537e82); /* 61 */
        II(d, a, b, c, x[11], 10, 0xbd3af235); /* 62 */
        II(c, d, a, b, x[2], 15, 0x2ad7d2bb); /* 63 */
        II(b, c, d, a, x[9], 21, 0xeb86d391); /* 64 */
        state[0] += a;
        state[1] += b;
        state[2] += c;
        state[3] += d;
    }


    template<typename T>
    T getFileMd5(T &path) noexcept(false) {
        FILE *fd;

        unsigned long ret;
        unsigned char data[READ_DATA_SIZE];
        unsigned char md5_value[MD5_SIZE];

        if ((fd = fileOpen(path, "rb")) == nullptr)
            throw FileOpenException(path);

        char *md5str = safeCalloc<char>(MD5_STRING);
        MD5_CTX *md5 = MD5Init();
        while (true) {
            ret = fread(data, 1, READ_DATA_SIZE, fd);
            MD5Update(md5, data, ret);
            if (ret < READ_DATA_SIZE)
                break;
        }

        fileClose(fd);
        MD5Final(md5, md5_value);

        for (int i = 0; i < MD5_SIZE; i++)
            snprintf(md5str + i * 2, 2 + 1, "%02x", md5_value[i]);

        return md5str;
    }

    template AFUN_TOOL_EXPORT char *getFileMd5(char *&path);
    template AFUN_TOOL_EXPORT std::string getFileMd5(std::string &path);
}