/* This program is based on (IIRC)
 * getdns/spec/example/example-simple-answers.c.
 *
 * Resolve DNS name argv[1] of type argv[2] using libgetdns and write
 * the resulting RRs to two files, in DNS binary wire format:
 *
 * - binout: /just_address_answers/0/address_data and
 *           /just_address_answers/1/address_data
 *
 * - treeout: output from getdns_rr_dict2wire for all RR's in the
 *            answer section
 *
 * Based on getdns/spec/example/example-simple-answers.c.
 */

#include <assert.h>
#include <inttypes.h>
#include <string.h>
#include <errno.h>
#include <stdio.h>
#include <getdns/getdns.h>
#include <getdns/getdns_ext_libevent.h>
#include <event2/event.h>

static int debug = 1;

static getdns_return_t
dump_reply(FILE *fp, getdns_dict *reply, const char *section_name)
{
	getdns_list *section = NULL;
	size_t section_len = -1;
	getdns_return_t r;
	uint8_t res_buf[4096], *res = NULL;
	size_t res_len = sizeof(res_buf);

	r = getdns_dict_get_list(reply, section_name, &section);
	if (r) {
		fprintf(stderr,
			"unable to get section \"%s\" from reply\n",
			section_name);
		return r;
	}

	r = getdns_list_get_length(section, &section_len);
	if (r) {
		fprintf(stderr, "unable to get length of section\n");
		return r;
	}

	for (size_t j = 0; j < section_len; j++) {
		getdns_dict *rr = NULL;

		r = getdns_list_get_dict(section, j , &rr);
		if (r) {
			fprintf(stderr, "unable to get rr from entry "
				"%d: %d\n", j, r);
			return r;
		}

		r = getdns_rr_dict2wire(rr, &res, &res_len);
		if (r) {
			fprintf(stderr,
				"unable to convert entry %d "
				"to wire format: %d\n", j, r);
			return r;
		}

		if (0 && debug) {
			char *s = getdns_pretty_print_dict(rr);
			puts(s);
			free(s);
		}

		if (fwrite(res, 1, res_len, fp) != res_len) {
			fprintf(stderr,
				"unable to write buffer to file: %s\n",
				strerror(errno));
			return -errno;
		}

		free(res);
	}

	return 0;
}

int
dump_tree(FILE *fp, const getdns_dict *response, const char *tree_name)
{
	getdns_return_t r;
	getdns_list *tree = NULL;
	size_t n_replies = -1;

        r = getdns_dict_get_list(response, tree_name, &tree);
	if (r) {
		fprintf(stderr, "unable to get tree %s\n", tree_name);
		return r;
	}

	r = getdns_list_get_length(tree, &n_replies);
	if (r) {
		fprintf(stderr, "unable to get number of replies\n");
		return r;
	}

	for (size_t i = 0; i < n_replies; i++) {
		getdns_dict *reply = NULL;

		r = getdns_list_get_dict(tree, i, &reply);
		if (r) {
			fprintf(stderr, "unable to get reply %d from tree\n", i);
			return r;
		}

		if (debug) {
			char *s = getdns_pretty_print_dict(reply);
			printf("Pretty-printing reply #%d:%s\n", i, s);
			free(s);
		}

		dump_reply(fp, reply, "answer");
	}

	return 0;
}


/* Set up the callback function, which will also do the processing of the results */
void callback(getdns_context        *context,
              getdns_callback_type_t callback_type,
              getdns_dict           *response,
              void                  *userarg,
              getdns_transaction_t   transaction_id)
{
	getdns_return_t r;  /* Holder for all function returns */
	uint32_t        status;
	getdns_bindata  *address_data;
	char            *first = NULL, *second = NULL;
	FILE *binoutfp = NULL, *treeoutfp = NULL;

	(void) context; /* unused parameter */

	binoutfp = fopen("binout", "w");
	assert(binoutfp != NULL);
	treeoutfp = fopen("treeout", "w");
	assert(treeoutfp != NULL);

	printf( "Callback for query \"%s\" with request ID %"PRIu64".\n"
	      , (char *)userarg, transaction_id );

	switch(callback_type) {
	case GETDNS_CALLBACK_CANCEL:
		printf("Transaction with ID %"PRIu64" was cancelled.\n", transaction_id);
		return;
	case GETDNS_CALLBACK_TIMEOUT:
		printf("Transaction with ID %"PRIu64" timed out.\n", transaction_id);
		return;
	case GETDNS_CALLBACK_ERROR:
		printf("An error occurred for transaction ID %"PRIu64".\n", transaction_id);
		return;
	default: break;
	}
	assert( callback_type == GETDNS_CALLBACK_COMPLETE );

	if ((r = getdns_dict_get_int(response, "status", &status)))
		fprintf(stderr, "Could not get \"status\" from reponse");

	else if (status != GETDNS_RESPSTATUS_GOOD)
		fprintf(stderr, "The search had no results, and a return value of %"PRIu32".\n", status);

	static char *TREES[] = {"replies_tree", "validation_chain"};
	static const int TREES_LEN = 2;
	for (int i = 0; i < TREES_LEN; i++) {
		if (dump_tree(treeoutfp, response, TREES[i]))
			fprintf(stderr, "Could not dump %s to file\n", TREES[i]);

		else if ((r = getdns_dict_get_bindata(response, "/just_address_answers/0/address_data", &address_data)))
			fprintf(stderr, "Could not get first address");

		else if (fwrite(address_data->data, 1, address_data->size, binoutfp) !=
			 address_data->size)
			fprintf(stderr, "first fwrite: %s\n", strerror(errno));

		else if (!(first = getdns_display_ip_address(address_data)))
			fprintf(stderr, "Could not convert first address to string\n");

		else if ((r = getdns_dict_get_bindata(response, "/just_address_answers/1/address_data", &address_data)))
			fprintf(stderr, "Could not get second address");

		else if (fwrite(address_data->data, 1, address_data->size, binoutfp) !=
			 address_data->size)
			fprintf(stderr, "second fwrite: %s\n", strerror(errno));

		else if (!(second = getdns_display_ip_address(address_data)))
			fprintf(stderr, "Could not convert second address to string\n");
		if (first) {
			printf("The address is %s\n", first);
			free(first);
		}
		if (second) {
			printf("The address is %s\n", second);
			free(second);
		}
		if (r) {
			assert( r != GETDNS_RETURN_GOOD );
			fprintf(stderr, ": %d\n", r);
		}
	}
	getdns_dict_destroy(response);
	if (binoutfp) fclose(binoutfp);
	if (treeoutfp) fclose(treeoutfp);
}

static getdns_return_t
send_query(getdns_context *context,
	   char *query_name,
	   const uint16_t query_type,
	   getdns_transaction_t *transaction_id)
{
	getdns_return_t r = GETDNS_RETURN_GENERIC_ERROR;
	getdns_dict *extensions = getdns_dict_create();
	char *userarg = query_name;

	assert(extensions != NULL);

	r = getdns_dict_set_int(extensions,
				"dnssec_return_validation_chain",
				GETDNS_EXTENSION_TRUE);
	if (r) return r;

#if 0
	r = getdns_dict_set_int(extensions,
				"dnssec_return_status",
				GETDNS_EXTENSION_TRUE);
	if (r) return r;
#endif

	if (query_type == 0)
		r = getdns_address(context, query_name, extensions, userarg,
				   transaction_id, callback);
	else
		r = getdns_general(context, query_name, query_type,
				   extensions, userarg,
				   transaction_id, callback);
	if (r) return r;

	return r;
}

int main(int argc, char *argv[])
{
	getdns_return_t      r;  /* Holder for all function returns */
	getdns_context      *context    = NULL;
	struct event_base   *event_base = NULL;
	char                *query_name = "www.example.com";
	uint16_t            query_type = 0;
	getdns_transaction_t transaction_id;
	getdns_list *trust_anchors;


	if (argc > 1)
		query_name = argv[1];
	if (argc > 2)
		query_type = (uint16_t) atoi(argv[2]);

	if ((r = getdns_context_create(&context, 1)))
		fprintf(stderr, "Trying to create the context failed");

	else if ((r = getdns_context_get_dnssec_trust_anchors(
			  context, &trust_anchors)) ||
		 trust_anchors == NULL)
		fprintf(stderr, "No trust anchor.\n");

	else if (!(event_base = event_base_new()))
		fprintf(stderr, "Trying to create the event base failed.\n");

	else if ((r = getdns_extension_set_libevent_base(context, event_base)))
		fprintf(stderr, "Setting the event base failed");

	else if ((r = send_query(context, query_name, query_type,
				 &transaction_id)))
		fprintf(stderr, "Queueing query failed: %d\n", r);

	else {
		printf("Request with transaction ID %"PRIu64" scheduled.\n",
		       transaction_id);
		if (event_base_dispatch(event_base) < 0)
			fprintf(stderr, "Error dispatching events\n");
	}

	/* Clean up */
	if (event_base)
		event_base_free(event_base);

	if (context)
		getdns_context_destroy(context);

	/* Assuming we get here, leave gracefully */
	exit(EXIT_SUCCESS);
}