#pragma once

#include <stddef.h>
#include <stdint.h>

struct BLAKE2s_param {
  uint8_t outlen; // digest length
  uint8_t keylen; // key length
  uint8_t fanout;
  uint8_t depth;
  uint32_t leaf_length;
  uint32_t node_offset;
  uint16_t node_offset_ex;
  uint8_t node_depth;
  uint8_t inner_length;
  uint64_t salt;
  uint64_t personalization;
};

struct BLAKE2s_ctx {
  uint8_t b[64]; // input buffer
  size_t c;      // pointer for b[]
  size_t outlen; // digest size TODO remove
  uint32_t h[8]; // chained state vector h
  uint32_t t[2]; // total number of bytes
  struct BLAKE2s_param param; // parameter block
};

uint32_t rotr_u32(uint32_t word, uint8_t c);

/**
 * 3.1 Mixing Function G
 */
void G(uint32_t V[16], unsigned a, unsigned b, unsigned c, unsigned d, uint32_t x, uint32_t y);

/**
 * 3.2 Compression Function F
 * @param t: 2w-bit offset counter t
 * @param f: final block indicator flag f
 */
void F(struct BLAKE2s_ctx *context, uint32_t m[16], uint32_t f);

[[nodiscard]] int BLAKE2s_init(struct BLAKE2s_ctx *ctx, size_t outlen, const void *key, size_t keylen);
void BLAKE2s_update(struct BLAKE2s_ctx *ctx, const void *d, size_t dd);
void BLAKE2s_final(struct BLAKE2s_ctx *ctx, void *out);

// All-in-one convenience function.
[[maybe_unused]] static int
BLAKE2s(void *out, size_t outlen,       // return buffer for digest
        const void *key, size_t keylen, // optional secret key
        const void *in, size_t inlen)   // data to be hashed
{
  struct BLAKE2s_ctx ctx;
  if (BLAKE2s_init(&ctx, outlen, key, keylen)) return -1;
  BLAKE2s_update(&ctx, in, inlen);
  BLAKE2s_final(&ctx, out);

  return 0;
}