#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <sodium.h>

/* Local encryption key */
#include "recipient_pk.h"

/* Exim4 dlfunc API header */
#include <local_scan.h>

int kitencrypt(uschar **yield, int argc, uschar *argv[]) {
	int sinit;
	size_t messagelen;
	unsigned char * message;

	sinit = sodium_init();
	if (sinit == -1 ) {
		*yield = string_copy(US"Unable to initialize libsodium");
		return ERROR;
	}
	if (argc != 1) {
		*yield = string_sprintf("Wrong number of arguments (got %i, expected 1)", argc);
		return ERROR;
	}

	// get cleartext message
	message = argv[0];
	messagelen = strlen(message);

	// prepare buffer for ciphertext
	unsigned int cipherlen = messagelen + crypto_box_SEALBYTES;
	unsigned char * ciphertext = malloc(cipherlen);
	explicit_bzero(ciphertext, cipherlen);

	// encrypt message
	crypto_box_seal(ciphertext, message, messagelen, recipient_pk);

	// base64-encode the ciphertext
	unsigned int outputsize = sodium_base64_ENCODED_LEN(cipherlen, sodium_base64_VARIANT_URLSAFE);
	unsigned char * outstring = malloc(outputsize);
	explicit_bzero(outstring, outputsize);

	sodium_bin2base64(outstring, outputsize,
			ciphertext, cipherlen,
			sodium_base64_VARIANT_URLSAFE);

	free(ciphertext);

	*yield = string_copy(outstring);

	free(outstring);

	return OK;
}