/* AVB support */
/* SPDX-FileCopyrightText: Copyright © 2022 Wim Taymans */
/* SPDX-License-Identifier: MIT */

#include <unistd.h>

#include <spa/utils/json.h>

#include <pipewire/pipewire.h>

#include "utils.h"
#include "maap.h"

#define MAAP_ALLOCATION_POOL_SIZE	0xFE00
#define MAAP_ALLOCATION_POOL_BASE	 { 0x91, 0xe0, 0xf0, 0x00, 0x00, 0x00 }
static uint8_t maap_base[6] = MAAP_ALLOCATION_POOL_BASE;

#define MAAP_PROBE_RETRANSMITS		3

#define MAAP_PROBE_INTERVAL_MS		500
#define MAAP_PROBE_INTERVAL_VAR_MS	100

#define MAAP_ANNOUNCE_INTERVAL_MS	3000
#define MAAP_ANNOUNCE_INTERVAL_VAR_MS	2000

struct maap {
	struct server *server;
	struct spa_hook server_listener;

	struct pw_properties *props;

	struct spa_source *source;

#define STATE_IDLE	0
#define STATE_PROBE	1
#define STATE_ANNOUNCE	2
	uint32_t state;
	uint64_t timeout;
	uint32_t probe_count;

	unsigned short xsubi[3];

	uint16_t offset;
	uint16_t count;
};

static const char *message_type_as_string(uint8_t message_type)
{
	switch (message_type) {
	case AVB_MAAP_MESSAGE_TYPE_PROBE:
		return "PROBE";
	case AVB_MAAP_MESSAGE_TYPE_DEFEND:
		return "DEFEND";
	case AVB_MAAP_MESSAGE_TYPE_ANNOUNCE:
		return "ANNOUNCE";
	}
	return "INVALID";
}

static void maap_message_debug(struct maap *maap, const struct avb_packet_maap *p)
{
	uint32_t v;
	const uint8_t *addr;

	v = AVB_PACKET_MAAP_GET_MESSAGE_TYPE(p);
	pw_log_info("message-type: %d (%s)", v, message_type_as_string(v));
	pw_log_info("  maap-version: %d", AVB_PACKET_MAAP_GET_MAAP_VERSION(p));
	pw_log_info("  length: %d", AVB_PACKET_GET_LENGTH(&p->hdr));

	pw_log_info("  stream-id: 0x%"PRIx64, AVB_PACKET_MAAP_GET_STREAM_ID(p));
	addr = AVB_PACKET_MAAP_GET_REQUEST_START(p);
	pw_log_info("  request-start: %02x:%02x:%02x:%02x:%02x:%02x",
			addr[0], addr[1], addr[2], addr[3], addr[4], addr[5]);
	pw_log_info("  request-count: %d", AVB_PACKET_MAAP_GET_REQUEST_COUNT(p));
	addr = AVB_PACKET_MAAP_GET_CONFLICT_START(p);
	pw_log_info("  conflict-start: %02x:%02x:%02x:%02x:%02x:%02x",
			addr[0], addr[1], addr[2], addr[3], addr[4], addr[5]);
	pw_log_info("  conflict-count: %d", AVB_PACKET_MAAP_GET_CONFLICT_COUNT(p));
}

#define PROBE_TIMEOUT(n) (uint64_t)(((n) + (MAAP_PROBE_INTERVAL_MS + \
                        drand48() * MAAP_PROBE_INTERVAL_VAR_MS) * SPA_NSEC_PER_MSEC))
#define ANNOUNCE_TIMEOUT(n) (uint64_t)(((n) + (MAAP_ANNOUNCE_INTERVAL_MS + \
                        drand48() * MAAP_ANNOUNCE_INTERVAL_VAR_MS) * SPA_NSEC_PER_MSEC))

static int make_new_address(struct maap *maap, uint64_t now, int range)
{
	maap->offset = nrand48(maap->xsubi) % (MAAP_ALLOCATION_POOL_SIZE - range);
	maap->count = range;
	maap->state = STATE_PROBE;
	maap->probe_count = MAAP_PROBE_RETRANSMITS;
	maap->timeout = PROBE_TIMEOUT(now);
	return 0;
}

static uint16_t maap_check_conflict(struct maap *maap, const uint8_t request_start[6],
		uint16_t request_count, uint8_t conflict_start[6])
{
	uint16_t our_start, our_end;
	uint16_t req_start, req_end;
	uint16_t conf_start, conf_count = 0;

	if (memcmp(request_start, maap_base, 4) != 0)
		return 0;

	our_start = maap->offset;
	our_end = our_start + maap->count;
	req_start = request_start[4] << 8 | request_start[5];
	req_end = req_start + request_count;

	if (our_start >= req_start && our_start <= req_end) {
		conf_start = our_start;
		conf_count = SPA_MIN(our_end, req_end) - our_start;
	}
	else if (req_start >= our_start && req_start <= our_end) {
		conf_start = req_start;
		conf_count = SPA_MIN(req_end, our_end) - req_start;
	}
	if (conf_count == 0)
		return 0;

	conflict_start[4] = conf_start >> 8;
	conflict_start[5] = conf_start;
	return conf_count;
}

static int send_packet(struct maap *maap, uint64_t now,
		uint8_t type, const uint8_t conflict_start[6], uint16_t conflict_count)
{
	struct avb_ethernet_header *h;
	struct avb_packet_maap *p;
	uint8_t buf[1024];
	uint8_t bmac[6] = AVB_MAAP_MAC;
	int res = 0;
	uint8_t start[6];

	spa_memzero(buf, sizeof(buf));
	h = (void*)buf;
	p = SPA_PTROFF(h, sizeof(*h), void);

	memcpy(h->dest, bmac, 6);
	memcpy(h->src, maap->server->mac_addr, 6);
	h->type = htons(AVB_TSN_ETH);

	p->hdr.subtype = AVB_SUBTYPE_MAAP;
	AVB_PACKET_SET_LENGTH(&p->hdr, sizeof(*p));

	AVB_PACKET_MAAP_SET_MAAP_VERSION(p, 1);
	AVB_PACKET_MAAP_SET_MESSAGE_TYPE(p, type);

	memcpy(start, maap_base, 4);
	start[4] = maap->offset >> 8;
	start[5] = maap->offset;
	AVB_PACKET_MAAP_SET_REQUEST_START(p, start);
	AVB_PACKET_MAAP_SET_REQUEST_COUNT(p, maap->count);
	if (conflict_count) {
		AVB_PACKET_MAAP_SET_CONFLICT_START(p, conflict_start);
		AVB_PACKET_MAAP_SET_CONFLICT_COUNT(p, conflict_count);
	}

	if (maap->server->debug_messages) {
		pw_log_info("send: %d (%s)", type, message_type_as_string(type));
		maap_message_debug(maap, p);
	}

	if (send(maap->source->fd, p, sizeof(*h) + sizeof(*p), 0) < 0) {
		res = -errno;
		pw_log_warn("got send error: %m");
	}
	return res;
}

static int handle_probe(struct maap *maap, uint64_t now, const struct avb_packet_maap *p)
{
	uint8_t conflict_start[6];
	uint16_t conflict_count;

	conflict_count = maap_check_conflict(maap, p->request_start, ntohs(p->request_count),
				conflict_start);
	if (conflict_count == 0)
		return 0;

	switch (maap->state) {
	case STATE_PROBE:
		make_new_address(maap, now, 8);
		break;
	case STATE_ANNOUNCE:
		send_packet(maap, now, AVB_MAAP_MESSAGE_TYPE_DEFEND, conflict_start, conflict_count);
		break;
	}
	return 0;
}

static int handle_defend(struct maap *maap, uint64_t now, const struct avb_packet_maap *p)
{
	uint8_t conflict_start[6];
	uint16_t conflict_count;

	conflict_count = maap_check_conflict(maap, p->conflict_start, ntohs(p->conflict_count),
				conflict_start);
	if (conflict_count != 0)
		make_new_address(maap, now, 8);
	return 0;
}

static int maap_message(struct maap *maap, uint64_t now, const void *message, int len)
{
	const struct avb_packet_maap *p = message;

	if (AVB_PACKET_GET_SUBTYPE(&p->hdr) != AVB_SUBTYPE_MAAP)
		return 0;

	if (maap->server->debug_messages)
		maap_message_debug(maap, p);

	switch (AVB_PACKET_MAAP_GET_MESSAGE_TYPE(p)) {
	case AVB_MAAP_MESSAGE_TYPE_PROBE:
		handle_probe(maap, now, p);
		break;
	case AVB_MAAP_MESSAGE_TYPE_DEFEND:
	case AVB_MAAP_MESSAGE_TYPE_ANNOUNCE:
		handle_defend(maap, now, p);
		break;
	}
	return 0;
}

static void on_socket_data(void *data, int fd, uint32_t mask)
{
	struct maap *maap = data;
	struct timespec now;

	if (mask & SPA_IO_IN) {
		int len;
		uint8_t buffer[2048];

		len = recv(fd, buffer, sizeof(buffer), 0);

		if (len < 0) {
			pw_log_warn("got recv error: %m");
		}
		else if (len < (int)sizeof(struct avb_packet_header)) {
			pw_log_warn("short packet received (%d < %d)", len,
					(int)sizeof(struct avb_packet_header));
		} else {
			clock_gettime(CLOCK_REALTIME, &now);
			maap_message(maap, SPA_TIMESPEC_TO_NSEC(&now), buffer, len);
		}
	}
}

static int load_state(struct maap *maap)
{
	const char *str;
	char key[512];
	struct spa_json it[2];
	bool have_offset = false;
	int count = 0, offset = 0, len;
	const char *val;

	snprintf(key, sizeof(key), "maap.%s", maap->server->ifname);
	pw_conf_load_state("module-avb", key, maap->props);

	if ((str = pw_properties_get(maap->props, "maap.addresses")) == NULL)
		return 0;

	if (spa_json_begin_array(&it[0], str, strlen(str)) <= 0)
		return 0;

	if (spa_json_enter_object(&it[0], &it[1]) <= 0)
		return 0;

	while ((len = spa_json_object_next(&it[1], key, sizeof(key), &val)) > 0) {
		if (spa_streq(key, "start")) {
			uint8_t addr[6];
			if (avb_utils_parse_addr(val, len, addr) >= 0 &&
			    memcmp(addr, maap_base, 4) == 0) {
				offset = addr[4] << 8 | addr[5];
				have_offset = true;
			}
		}
		else if (spa_streq(key, "count")) {
			spa_json_parse_int(val, len, &count);
		}
	}
	if (count > 0 && have_offset) {
		maap->count = count;
		maap->offset = offset;
		maap->state = STATE_PROBE;
		maap->probe_count = MAAP_PROBE_RETRANSMITS;
		maap->timeout = PROBE_TIMEOUT(0);
	}
	return 0;
}

static int save_state(struct maap *maap)
{
	char *ptr;
	size_t size;
	FILE *f;
	char key[512];
	uint32_t count;

	if ((f = open_memstream(&ptr, &size)) == NULL)
		return -errno;

	fprintf(f, "[ ");
	fprintf(f, "{ \"start\": \"%02x:%02x:%02x:%02x:%02x:%02x\", ",
			maap_base[0], maap_base[1], maap_base[2],
			maap_base[3], (maap->offset >> 8) & 0xff,
			maap->offset & 0xff);
	fprintf(f, " \"count\": %u } ", maap->count);
	fprintf(f, "]");
	fclose(f);

	count = pw_properties_set(maap->props, "maap.addresses", ptr);
	free(ptr);

	if (count > 0) {
		snprintf(key, sizeof(key), "maap.%s", maap->server->ifname);
		pw_conf_save_state("module-avb", key, maap->props);
	}
	return 0;
}

static void maap_periodic(void *data, uint64_t now)
{
	struct maap *maap = data;

	if (now < maap->timeout)
		return;

	switch(maap->state) {
	case STATE_IDLE:
		break;
	case STATE_PROBE:
		send_packet(maap, now, AVB_MAAP_MESSAGE_TYPE_PROBE, NULL, 0);
		if (--maap->probe_count == 0) {
			maap->state = STATE_ANNOUNCE;
			save_state(maap);
		}
		maap->timeout = PROBE_TIMEOUT(now);
		break;
	case STATE_ANNOUNCE:
		send_packet(maap, now, AVB_MAAP_MESSAGE_TYPE_ANNOUNCE, NULL, 0);
		maap->timeout = ANNOUNCE_TIMEOUT(now);
		break;
	}
}

static void maap_free(struct maap *maap)
{
	pw_loop_destroy_source(maap->server->impl->loop, maap->source);
	spa_hook_remove(&maap->server_listener);
	pw_properties_free(maap->props);
	free(maap);
}

static void maap_destroy(void *data)
{
	struct maap *maap = data;
	maap_free(maap);
}

static const struct server_events server_events = {
	AVB_VERSION_SERVER_EVENTS,
	.destroy = maap_destroy,
	.periodic = maap_periodic,
};

struct avb_maap *avb_maap_register(struct server *server)
{
	struct maap *maap;
	uint8_t bmac[6] = AVB_MAAP_MAC;
	int fd, res;

	fd = avb_server_make_socket(server, AVB_TSN_ETH, bmac);
	if (fd < 0) {
		res = fd;
		goto error;
	}

	maap = calloc(1, sizeof(*maap));
	if (maap == NULL) {
		res = -errno;
		goto error_close;
	}
	maap->props = pw_properties_new(NULL, NULL);
	if (maap->props == NULL) {
		res = -errno;
		goto error_free;
	}

	maap->server = server;
	pw_log_info("0x%"PRIx64" %d", server->entity_id, server->ifindex);

	pw_random(maap->xsubi, sizeof(maap->xsubi));

	load_state(maap);

	maap->source = pw_loop_add_io(server->impl->loop, fd, SPA_IO_IN, true, on_socket_data, maap);
	if (maap->source == NULL) {
		res = -errno;
		pw_log_error("maap %p: can't create maap source: %m", maap);
		goto error_free;
	}
	avdecc_server_add_listener(server, &maap->server_listener, &server_events, maap);

	return (struct avb_maap *)maap;

error_free:
	free(maap);
error_close:
	close(fd);
error:
	errno = -res;
	return NULL;
}

int avb_maap_reserve(struct avb_maap *m, uint32_t count)
{
	struct maap *maap = (struct maap*)m;
	if (count > maap->count)
		make_new_address(maap, 0, count);
	return 0;
}

int avb_maap_get_address(struct avb_maap *m, uint8_t addr[6], uint32_t index)
{
	struct maap *maap = (struct maap*)m;
	uint16_t offset;

	if (maap->state != STATE_ANNOUNCE)
		return -EAGAIN;

	memcpy(addr, maap_base, 6);
	offset = maap->offset + index;
	addr[4] = offset >> 8;
	addr[5] = offset;
	return 0;
}