#pragma once

// Derived from the "RSA Data Security, Inc. MD5 Message-Digest Algorithm":
// src: https://github.com/freebsd/freebsd-src/blob/release/14.2.0/sys/kern/md5c.c

#include <cstdint>

#define MD5_BLOCK_LENGTH 64
#define MD5_DIGEST_LENGTH 16
#define MD5_DIGEST_STRING_LENGTH (MD5_DIGEST_LENGTH * 2 + 1)

/* MD5 context. */
struct MD5_CTX {
    uint64_t count;           /* number of bits, modulo 2^64 (lsb first) */
    uint32_t state[4];        /* state (ABCD) */
    unsigned char buffer[64]; /* input buffer */
};

/* MD5 initialization. Begins an MD5 operation, writing a new context. */
inline void md5_init(MD5_CTX* context) {
    context->count = 0;

    /* Load magic initialization constants.  */
    context->state[0] = 0x67452301;
    context->state[1] = 0xefcdab89;
    context->state[2] = 0x98badcfe;
    context->state[3] = 0x10325476;
}

void md5_update(MD5_CTX* ctx, const uint8_t* in, size_t len);
void md5_final(MD5_CTX* ctx, uint8_t* digest);

inline void md5(uint8_t* digest, const uint8_t* in, const size_t len) {
    MD5_CTX ctx;
    md5_init(&ctx);
    md5_update(&ctx, in, len);
    md5_final(&ctx, digest);
}

inline void md5(uint8_t* digest, const uint8_t* in, const size_t len, const uint8_t* in2, size_t len2) {
    MD5_CTX ctx;
    md5_init(&ctx);
    md5_update(&ctx, in, len);
    md5_update(&ctx, in2, len2);
    md5_final(&ctx, digest);
}