#include "curve25519.h"

#include <sodium.h>

#include <stddef.h>
#include <stdlib.h>

void sodium_curve25519_initialize(void) {
	if(sodium_init() == -1) {
		exit(-1);
	}
}

void sodium_curve25519_delete_keypair(struct KeyPair* p) {
	sodium_free(p->sec);
	free(p->pub);

	p->sec = NULL;
	p->pub = NULL;
}

struct KeyPair sodium_curve25519_create_keypair(void) {
	unsigned char* sec = (unsigned char*) sodium_malloc(crypto_box_SECRETKEYBYTES);
	unsigned char* pub = (unsigned char*) malloc(crypto_box_PUBLICKEYBYTES);

	randombytes_buf(sec, crypto_box_SECRETKEYBYTES);
	crypto_scalarmult_base(pub, sec);

	return (struct KeyPair){
		sec,
		pub,
	};
}

void sodium_curve25519_shared_key_deleter(struct SharedKey* s) {
	sodium_free(s->shared);

	s->shared = NULL;
}

void sodium_curve25519_key_to_array(unsigned char** buffer, size_t* len, void* key) {
	(void)buffer;
	(void)len;
	(void)key;
}

void sodium_curve25519_add_public_share(char** buffer, size_t* out_len, char const* share, size_t in_len, void* pubkey) {
	(void) buffer;
	(void) out_len;
	(void) share;
	(void) in_len;
	(void) pubkey;
}

GroupElement sodium_curve25519_derive_shared_key(struct KeyPair pair, unsigned char const* other_pub, size_t pub_len, unsigned char const* value, size_t value_len, void* priv_value, bool swap_pub_order) {
	(void) pub_len;
	(void) value_len;
	unsigned char* shared = (unsigned char*) sodium_malloc(crypto_generichash_BYTES);

	crypto_generichash_state h;

	unsigned char* scalarmult_q = (unsigned char*) sodium_malloc(crypto_scalarmult_BYTES);

	if (crypto_scalarmult(scalarmult_q, (unsigned char const*) priv_value, (unsigned char const*) value) != 0) {
		exit(-1);
	}

	crypto_generichash_init(&h, NULL, 0U, crypto_generichash_BYTES);
	crypto_generichash_update(&h, scalarmult_q, crypto_scalarmult_BYTES);
	if(swap_pub_order) {
		crypto_generichash_update(&h, (unsigned char const*) other_pub, crypto_box_PUBLICKEYBYTES);
		crypto_generichash_update(&h, (unsigned char const*) pair.pub, crypto_box_PUBLICKEYBYTES);
	} else {
		crypto_generichash_update(&h, (unsigned char const*) pair.pub, crypto_box_PUBLICKEYBYTES);
		crypto_generichash_update(&h, (unsigned char const*) other_pub, crypto_box_PUBLICKEYBYTES);
	}
	crypto_generichash_final(&h, shared, crypto_generichash_BYTES);

	sodium_free(scalarmult_q);

	return shared;
}

void sodium_curve25519_deinitialize(void) {}

Initializer curve25519_initialize = &sodium_curve25519_initialize;
KeyPairCreator curve25519_create_keypair = &sodium_curve25519_create_keypair;
KeyPairDeleter curve25519_delete_keypair = &sodium_curve25519_delete_keypair;
ElementToArray curve25519_element_to_array = NULL;//&sodium_curve25519_element_to_array;
BufferDeleter curve25519_free_buffer = NULL;//&sodium_curve25519_free_buffer;
ArrayToElement curve25519_array_to_element = NULL;//&sodium_curve25519_array_to_element;
GroupElementGetter curve25519_get_group_element = NULL;//&sodium_curve25519_get_group_element;
GroupElementDeleter curve25519_delete_group_element = NULL;//&sodium_curve25519_delete_group_element;
KeyExchangeValueGetter curve25519_get_key_exchange_value = NULL;//&sodium_curve25519_get_key_exchange_value;
GroupElementMultiplier curve25519_multiply = NULL;//&sodium_curve25519_multiply;
DecryptionShareGetter curve25519_get_decryption_share = NULL;//&sodium_curve25519_get_decryption_share;
GroupElementArraySizeGetter curve25519_get_group_element_array_size = NULL;//&sodium_curve25519_get_group_element_array_size;
PublicShareAdder curve25519_add_public_share = NULL;//&sodium_curve25519_add_public_share;
SharedKeyDeriver curve25519_derive_shared_key = &sodium_curve25519_derive_shared_key;
SharedKeyDeleter curve25519_delete_shared_key = NULL;//&sodium_curve25519_delete_shared_key;
Encrypter curve25519_encrypt = NULL;//&sodium_curve25519_encrypt;
Deinitializer curve25519_deinitialize = &sodium_curve25519_deinitialize;