#ifndef _NOSTR_AES_H_
#define _NOSTR_AES_H_

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

// Configure for NIP-04 requirements: AES-256-CBC only
#define CBC 1
#define ECB 0
#define CTR 0

// Configure for AES-256 (required by NIP-04)
#define AES128 0
#define AES192 0
#define AES256 1

#define AES_BLOCKLEN 16 // Block length in bytes - AES is 128b block only

#if defined(AES256) && (AES256 == 1)
    #define AES_KEYLEN 32
    #define AES_keyExpSize 240
#elif defined(AES192) && (AES192 == 1)
    #define AES_KEYLEN 24
    #define AES_keyExpSize 208
#else
    #define AES_KEYLEN 16   // Key length in bytes
    #define AES_keyExpSize 176
#endif

struct AES_ctx
{
  uint8_t RoundKey[AES_keyExpSize];
#if (defined(CBC) && (CBC == 1)) || (defined(CTR) && (CTR == 1))
  uint8_t Iv[AES_BLOCKLEN];
#endif
};

void AES_init_ctx(struct AES_ctx* ctx, const uint8_t* key);
#if (defined(CBC) && (CBC == 1)) || (defined(CTR) && (CTR == 1))
void AES_init_ctx_iv(struct AES_ctx* ctx, const uint8_t* key, const uint8_t* iv);
void AES_ctx_set_iv(struct AES_ctx* ctx, const uint8_t* iv);
#endif

#if defined(CBC) && (CBC == 1)
// buffer size MUST be multiple of AES_BLOCKLEN;
// Suggest https://en.wikipedia.org/wiki/Padding_(cryptography)#PKCS7 for padding scheme
// NOTES: you need to set IV in ctx via AES_init_ctx_iv() or AES_ctx_set_iv()
//        no IV should ever be reused with the same key 
void AES_CBC_encrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, size_t length);
void AES_CBC_decrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, size_t length);
#endif // #if defined(CBC) && (CBC == 1)

#endif // _NOSTR_AES_H_
