/*
 *  This code is taken from duckdb/common/crypto/md5.hpp with following changes:
 *  1. removed other duckdb dependencies.
 *  2. Add the DigestToBase10 method which produce the md5 in decimal
 */
/*
** This code taken from the SQLite test library.  Originally found on
** the internet.  The original header comment follows this comment.
** The code is largerly unchanged, but there have been some modifications.
*/
/*
 * This code implements the MD5 message-digest algorithm.
 * The algorithm is due to Ron Rivest.  This code was
 * written by Colin Plumb in 1993, no copyright is claimed.
 * This code is in the public domain; do with it what you wish.
 *
 * Equivalent code is available from RSA Data Security, Inc.
 * This code has been tested against that, and is equivalent,
 * except that you don't need to include two pages of legalese
 * with every copy.
 *
 * To compute the message digest of a chunk of bytes, declare an
 * MD5Context structure, pass it to MD5Init, call MD5Update as
 * needed on buffers full of bytes, and then call MD5Final, which
 * will fill a supplied 16-byte array with the digest.
 */
#include "md5.h"
#include <folly/Conv.h>
#include <folly/Format.h>

namespace facebook::velox::crypto {

/*
 * Note: this code is harmless on little-endian machines.
*/
    static void ByteReverse(unsigned char *buf, unsigned longs) {
        unsigned int t;
        do {
            t = (unsigned int)((unsigned)buf[3] << 8 | buf[2]) << 16 | ((unsigned)buf[1] << 8 | buf[0]);
            *(unsigned int *)buf = t;
            buf += 4;
        } while (--longs);
    }
/* The four core functions - F1 is optimized somewhat */

/* #define F1(x, y, z) (x & y | ~x & z) */
#define F1(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) ((x) ^ (y) ^ (z))
#define F4(x, y, z) ((y) ^ ((x) | ~(z)))

/* This is the central step in the MD5 algorithm. */
#define MD5STEP(f, w, x, y, z, data, s) ((w) += f(x, y, z) + (data), (w) = (w) << (s) | (w) >> (32 - (s)), (w) += (x))

/*
 * The core of the MD5 algorithm, this alters an existing MD5 hash to
 * reflect the addition of 16 longwords of new data.  MD5Update blocks
 * the data and converts bytes into longwords for this routine.
 */
    static void MD5Transform(unsigned int buf[4], const unsigned int in[16]) {
        unsigned int a, b, c, d;

        a = buf[0];
        b = buf[1];
        c = buf[2];
        d = buf[3];

        MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
        MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
        MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
        MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
        MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
        MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
        MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
        MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
        MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
        MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
        MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
        MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
        MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
        MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
        MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
        MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);

        MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
        MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
        MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
        MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
        MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
        MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
        MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
        MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
        MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
        MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
        MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
        MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
        MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
        MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
        MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
        MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

        MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
        MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
        MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
        MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
        MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
        MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
        MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
        MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
        MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
        MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
        MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
        MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
        MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
        MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
        MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
        MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);

        MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
        MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
        MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
        MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
        MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
        MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
        MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
        MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
        MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
        MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
        MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
        MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
        MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
        MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
        MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
        MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);

        buf[0] += a;
        buf[1] += b;
        buf[2] += c;
        buf[3] += d;
    }

/*
 * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
 * initialization constants.
 */
    MD5Context::MD5Context() {
        buf[0] = 0x67452301;
        buf[1] = 0xefcdab89;
        buf[2] = 0x98badcfe;
        buf[3] = 0x10325476;
        bits[0] = 0;
        bits[1] = 0;
    }

/*
 * Update context to reflect the concatenation of another buffer full
 * of bytes.
 */
    void MD5Context::MD5Update(const unsigned char* input, unsigned long long len) {
        unsigned int t;

        /* Update bitcount */

        t = bits[0];
        if ((bits[0] = t + ((unsigned int)len << 3)) < t) {
            bits[1]++; /* Carry from low to high */
        }
        bits[1] += len >> 29;

        t = (t >> 3) & 0x3f; /* Bytes already in shsInfo->data */

        /* Handle any leading odd-sized chunks */

        if (t) {
            unsigned char *p = (unsigned char *)in + t;

            t = 64 - t;
            if (len < t) {
                std::memcpy(p, input, len);
                return;
            }
            std::memcpy(p, input, t);
            ByteReverse(in, 16);
            MD5Transform(buf, (unsigned int *)in);
            input += t;
            len -= t;
        }

        /* Process data in 64-byte chunks */

        while (len >= 64) {
            std::memcpy(in, input, 64);
            ByteReverse(in, 16);
            MD5Transform(buf, (unsigned int *)in);
            input += 64;
            len -= 64;
        }

        /* Handle any remaining bytes of data. */
        std::memcpy(in, input, len);
    }

/*
 * Final wrapup - pad to 64-byte boundary with the bit pattern
 * 1 0* (64-bit count of bits processed, MSB-first)
 */
    void MD5Context::Finish(unsigned char* out_digest) {
        unsigned count;
        unsigned char *p;

        /* Compute number of bytes mod 64 */
        count = (bits[0] >> 3) & 0x3F;

        /* Set the first char of padding to 0x80.  This is safe since there is
           always at least one byte free */
        p = in + count;
        *p++ = 0x80;

        /* Bytes of padding needed to make 64 bytes */
        count = 64 - 1 - count;

        /* Pad out to 56 mod 64 */
        if (count < 8) {
            /* Two lots of padding:  Pad the first block to 64 bytes */
            std::memset(p, 0, count);
            ByteReverse(in, 16);
            MD5Transform(buf, (unsigned int *)in);

            /* Now fill the next block with 56 bytes */
            std::memset(in, 0, 56);
        } else {
            /* Pad block to 56 bytes */
            std::memset(p, 0, count - 8);
        }
        ByteReverse(in, 14);

        /* Append length in bits and transform */
        ((unsigned int *)in)[14] = bits[0];
        ((unsigned int *)in)[15] = bits[1];

        MD5Transform(buf, (unsigned int *)in);
        ByteReverse((unsigned char *)buf, 4);
        std::memcpy(out_digest, buf, 16);
    }

    void MD5Context::DigestToBase16(const unsigned char* digest, char *zbuf) {
        static char const HEX_CODES[] = "0123456789abcdef";
        int i, j;

        for (j = i = 0; i < MD5_HASH_LENGTH_BINARY; i++) {
            int a = digest[i];
            zbuf[j++] = HEX_CODES[(a >> 4) & 0xf];
            zbuf[j++] = HEX_CODES[a & 0xf];
        }
    }

    std::string MD5Context::DigestToBase10(const unsigned char* digest) {
      __uint128_t val = 0;
      for (int i = 0; i < MD5_HASH_LENGTH_BINARY; i++) {
        val = static_cast<__uint128_t>(val << 4) | ((digest[i] >> 4) & 0xf);
        val = static_cast<__uint128_t>(val << 4) | (digest[i] & 0xf);
      }
      auto dec = folly::to<std::string>(static_cast<__uint128_t>(val));
      return dec;
    }

    int MD5Context::FinishHex(char *out_digest) {
      unsigned char digest[MD5_HASH_LENGTH_BINARY];
      Finish(digest);
      DigestToBase16(digest, out_digest);
      return 32;
    }

    int MD5Context::FinishDec(char *out_digest, bool needPadding) {
      unsigned char digest[MD5_HASH_LENGTH_BINARY];
      Finish(digest);
      // padding the string with 0 at beginning if the length is less than 32 and the needPadding == true
      auto dec = needPadding ? folly::sformat("{:0>*}", 32, DigestToBase10(digest)) : DigestToBase10(digest);
      int size = dec.size();
      std::memcpy(out_digest, dec.data(), size);
      return size;
    }

    std::string MD5Context::FinishHex() {
      char digest[MD5_HASH_LENGTH_TEXT];
      FinishHex(digest);
      return std::string(digest, MD5_HASH_LENGTH_TEXT);
    }

} // namespace facebook::velox::crypto
