/* This implementation was sourced from
 * 	https://github.com/galenguyer/md5
 * and is in the public domain. */
#include "hash.h"

#include <blue/core/hash.h>
#include <memory.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

#define F(x, y, z)        (z ^ (x & (y ^ z)))
#define G(x, y, z)        (y ^ (z & (x ^ y)))
#define H(x, y, z)        (x ^ y ^ z)
#define I(x, y, z)        (y ^ (x | ~z))

#define ROTATE_LEFT(x, s) (x << s | x >> (32 - s))

#define STEP(f, a, b, c, d, x, t, s)                                           \
	(a += f(b, c, d) + x + t, a = ROTATE_LEFT(a, s), a += b)

void md5_init(struct b_hash_ctx *ctx)
{
	ctx->ctx_state.md5.a = 0x67452301;
	ctx->ctx_state.md5.b = 0xefcdab89;
	ctx->ctx_state.md5.c = 0x98badcfe;
	ctx->ctx_state.md5.d = 0x10325476;

	ctx->ctx_state.md5.count[0] = 0;
	ctx->ctx_state.md5.count[1] = 0;
}

uint8_t *md5_transform(struct b_hash_ctx *ctx, const void *data, uintmax_t size)
{
	uint8_t *ptr = (uint8_t *)data;
	uint32_t a, b, c, d, aa, bb, cc, dd;

#define GET(n) (ctx->ctx_state.md5.block[(n)])
#define SET(n)                                                                 \
	(ctx->ctx_state.md5.block[(n)] = ((uint32_t)ptr[(n) * 4 + 0] << 0)     \
	                               | ((uint32_t)ptr[(n) * 4 + 1] << 8)     \
	                               | ((uint32_t)ptr[(n) * 4 + 2] << 16)    \
	                               | ((uint32_t)ptr[(n) * 4 + 3] << 24))

	a = ctx->ctx_state.md5.a;
	b = ctx->ctx_state.md5.b;
	c = ctx->ctx_state.md5.c;
	d = ctx->ctx_state.md5.d;

	do {
		aa = a;
		bb = b;
		cc = c;
		dd = d;

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

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

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

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

		a += aa;
		b += bb;
		c += cc;
		d += dd;

		ptr += 64;
	} while (size -= 64);

	ctx->ctx_state.md5.a = a;
	ctx->ctx_state.md5.b = b;
	ctx->ctx_state.md5.c = c;
	ctx->ctx_state.md5.d = d;

#undef GET
#undef SET

	return ptr;
}

void md5_update(struct b_hash_ctx *ctx, const void *buffer, size_t buffer_size)
{
	uint32_t saved_low = ctx->ctx_state.md5.count[0];
	uint32_t used;
	uint32_t free;

	if ((ctx->ctx_state.md5.count[0] = ((saved_low + buffer_size) & 0x1fffffff))
	    < saved_low) {
		ctx->ctx_state.md5.count[1]++;
	}
	ctx->ctx_state.md5.count[1] += (uint32_t)(buffer_size >> 29);

	used = saved_low & 0x3f;

	if (used) {
		free = 64 - used;

		if (buffer_size < free) {
			memcpy(&ctx->ctx_state.md5.input[used], buffer,
			       buffer_size);
			return;
		}

		memcpy(&ctx->ctx_state.md5.input[used], buffer, free);
		buffer = (uint8_t *)buffer + free;
		buffer_size -= free;
		md5_transform(ctx, ctx->ctx_state.md5.input, 64);
	}

	if (buffer_size >= 64) {
		buffer = md5_transform(
			ctx, buffer, buffer_size & ~(unsigned long)0x3f);
		buffer_size = buffer_size % 64;
	}

	memcpy(ctx->ctx_state.md5.input, buffer, buffer_size);
}

void md5_finish(struct b_hash_ctx *ctx, void *out, size_t max)
{
	uint32_t used = ctx->ctx_state.md5.count[0] & 0x3f;
	ctx->ctx_state.md5.input[used++] = 0x80;
	uint32_t free = 64 - used;

	if (free < 8) {
		memset(&ctx->ctx_state.md5.input[used], 0, free);
		md5_transform(ctx, ctx->ctx_state.md5.input, 64);
		used = 0;
		free = 64;
	}

	memset(&ctx->ctx_state.md5.input[used], 0, free - 8);

	unsigned char digest[B_DIGEST_LENGTH_MD5];

	ctx->ctx_state.md5.count[0] <<= 3;
	ctx->ctx_state.md5.input[56] = (uint8_t)(ctx->ctx_state.md5.count[0]);
	ctx->ctx_state.md5.input[57] = (uint8_t)(ctx->ctx_state.md5.count[0] >> 8);
	ctx->ctx_state.md5.input[58]
		= (uint8_t)(ctx->ctx_state.md5.count[0] >> 16);
	ctx->ctx_state.md5.input[59]
		= (uint8_t)(ctx->ctx_state.md5.count[0] >> 24);
	ctx->ctx_state.md5.input[60] = (uint8_t)(ctx->ctx_state.md5.count[1]);
	ctx->ctx_state.md5.input[61] = (uint8_t)(ctx->ctx_state.md5.count[1] >> 8);
	ctx->ctx_state.md5.input[62]
		= (uint8_t)(ctx->ctx_state.md5.count[1] >> 16);
	ctx->ctx_state.md5.input[63]
		= (uint8_t)(ctx->ctx_state.md5.count[1] >> 24);

	md5_transform(ctx, ctx->ctx_state.md5.input, 64);

	digest[0] = (uint8_t)(ctx->ctx_state.md5.a);
	digest[1] = (uint8_t)(ctx->ctx_state.md5.a >> 8);
	digest[2] = (uint8_t)(ctx->ctx_state.md5.a >> 16);
	digest[3] = (uint8_t)(ctx->ctx_state.md5.a >> 24);
	digest[4] = (uint8_t)(ctx->ctx_state.md5.b);
	digest[5] = (uint8_t)(ctx->ctx_state.md5.b >> 8);
	digest[6] = (uint8_t)(ctx->ctx_state.md5.b >> 16);
	digest[7] = (uint8_t)(ctx->ctx_state.md5.b >> 24);
	digest[8] = (uint8_t)(ctx->ctx_state.md5.c);
	digest[9] = (uint8_t)(ctx->ctx_state.md5.c >> 8);
	digest[10] = (uint8_t)(ctx->ctx_state.md5.c >> 16);
	digest[11] = (uint8_t)(ctx->ctx_state.md5.c >> 24);
	digest[12] = (uint8_t)(ctx->ctx_state.md5.d);
	digest[13] = (uint8_t)(ctx->ctx_state.md5.d >> 8);
	digest[14] = (uint8_t)(ctx->ctx_state.md5.d >> 16);
	digest[15] = (uint8_t)(ctx->ctx_state.md5.d >> 24);

	memcpy(out, digest, b_min(size_t, sizeof digest, max));
}

struct b_hash_function_ops z__b_md5_ops = {
	.hash_init = md5_init,
	.hash_update = md5_update,
	.hash_finish = md5_finish,
};