// SPDX-License-Identifier: BSD-3-Clause OR Apache-2.0
#include "agents/echo_agent.h"

#include "platform/hal_io.h"
#include "platform/hal_time.h"

#include "ud3tn/agent_manager.h"
#include "ud3tn/agent_util.h"
#include "ud3tn/bundle_processor.h"
#include "ud3tn/common.h"
#include "ud3tn/eid.h"

#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>

struct echo_agent_params {
	bool is_ipn;
	const char *local_eid;
	uint64_t lifetime_ms;

	uint64_t last_bundle_timestamp_s;
	uint64_t last_bundle_sequence_number;
};

static uint64_t allocate_sequence_number(
	struct echo_agent_params *const config,
	const uint64_t time_s)
{
	if (config->last_bundle_timestamp_s == time_s)
		return ++config->last_bundle_sequence_number;

	config->last_bundle_timestamp_s = time_s;
	config->last_bundle_sequence_number = 1;

	return 1;
}

static void callback(struct bundle_adu data, void *p, const void *bp_context)
{
	struct echo_agent_params *const params = p;

	const uint64_t time_ms = hal_time_get_timestamp_ms();
	const uint64_t seqnum = allocate_sequence_number(
		params,
		time_ms
	);

	LOGF_DEBUG(
		"Echo Agent: Responding to echo request from %s.",
		data.source
	);

	agent_create_forward_bundle_direct(
		bp_context,
		params->local_eid,
		data.protocol_version,
		params->is_ipn ? AGENT_ID_ECHO_IPN : AGENT_ID_ECHO_DTN,
		data.source,
		time_ms,
		seqnum,
		params->lifetime_ms,
		data.payload,
		data.length,
		0
	);

	// Pointer responsibility was taken by agent_create_forward_bundle
	data.payload = NULL;
	bundle_adu_free_members(data);
}

int echo_agent_setup(struct bundle_agent_interface *const bai,
		     const uint64_t lifetime_ms)
{
	struct echo_agent_params *params = malloc(
		sizeof(struct echo_agent_params)
	);

	params->is_ipn = get_eid_scheme(bai->local_eid) == EID_SCHEME_IPN;
	params->local_eid = bai->local_eid;
	params->lifetime_ms = lifetime_ms;
	params->last_bundle_timestamp_s = 0;
	params->last_bundle_sequence_number = 0;

	const struct agent agent = {
		.auth_trx = true,
		.is_subscriber = true,
		.sink_identifier = (
			params->is_ipn
			? AGENT_ID_ECHO_IPN
			: AGENT_ID_ECHO_DTN
		),
		.trx_callback = callback,
		.param = params,
	};
	const agent_no_t rv = bundle_processor_perform_agent_action(
		bai->bundle_signaling_queue,
		BP_SIGNAL_AGENT_REGISTER,
		agent
	);

	if (rv == AGENT_NO_INVALID) {
		free(params);
		return -1;
	}

	return 0;
}