/* Управляемая сеть: настоящий BGP receiver/sender, подписи и очереди, без UDP.
 * Доставка по каждому ребру сохраняет FIFO, порядок между рёбрами меняется. */
#include <assert.h>
#include <stdio.h>
#include <string.h>
#include "utun_instance.h"
#include "config_updater.h"
#include "topo_group.h"
#include "etcp.h"
#include "etcp_api.h"
#include "node_conn_direct.h"
#include "../lib/debug_config.h"
#include "test_utils.h"

#define N 4
#define GROUP 42
static struct UASYNC* ua;
static struct UTUN_INSTANCE* nodes[N];
static struct TOPO_GROUP* groups[N];
static struct ETCP_CONN* conns[N][N];
static struct NODE_CONN_DIRECT* owners[N][N];
static unsigned graph, delivered;
static uint32_t random_state = 1;

static unsigned next_random(void) {
    random_state = random_state * 1664525U + 1013904223U;
    return random_state;
}

static unsigned edge(int a, int b) {
    if (a > b) { int t = a; a = b; b = t; }
    unsigned bit = 1;
    for (int i = 0; i < N; i++) for (int j = i + 1; j < N; j++, bit <<= 1)
        if (i == a && j == b) return bit;
    return 0;
}

static void release(struct ll_entry* e) { queue_dgram_free(e); queue_entry_free(e); }

/* Единственный ручной потребитель send_input_q; штатный normalizer отключён. */
static int step(void) {
    uasync_poll(ua, 0);
    int work = 0, offset = next_random() % (N * N);
    for (int k = 0; k < N * N; k++) {
        int a = ((k + offset) % (N * N)) / N, b = (k + offset) % N;
        if (a == b) continue;
        struct ll_queue* q = conns[a][b]->send_input_q;
        assert(queue_entry_count(q) <= 1);
        struct ll_entry* e = queue_data_get(q);
        if (!e) continue;
        work++;
        if ((graph & edge(a, b)) && e->len && e->dgram[0] == ETCP_ID_TOPO_ENTRY) {
            delivered++;
            nodes[b]->api_bindings.callbacks[ETCP_ID_TOPO_ENTRY](conns[b][a], e);
        } else release(e);
        queue_resume_callback(q);
    }
    return work;
}

static void settle(void) {
    unsigned before = delivered;
    int idle = 0;
    for (int i = 0; i < 4000 && idle < 16; i++) idle = step() ? 0 : idle + 1;
    assert(idle == 16);
    DEBUG_INFO(DEBUG_CATEGORY_BGP, "model settled graph=%02x packets=%u", graph, delivered - before);
}

/* Смена графа без обработки очередей между событиями разрыва и восстановления. */
static void change(unsigned mask) {
    unsigned old = graph; graph = mask;
    for (int a = 0; a < N; a++) for (int b = a + 1; b < N; b++) {
        if (!(old & edge(a, b)) || (mask & edge(a, b))) continue;
        conns[a][b]->links_up = conns[b][a]->links_up = 0;
        topo_group_remove_conn(groups[a], conns[a][b], TOPO_REMOVE_REMOTE_LEAVE);
        topo_group_remove_conn(groups[b], conns[b][a], TOPO_REMOVE_REMOTE_LEAVE);
        struct ll_entry* e;
        while ((e = queue_data_get(conns[a][b]->send_input_q))) release(e);
        while ((e = queue_data_get(conns[b][a]->send_input_q))) release(e);
    }
    for (int a = 0; a < N; a++) for (int b = a + 1; b < N; b++) {
        if ((old & edge(a, b)) || !(mask & edge(a, b))) continue;
        conns[a][b]->links_up = conns[b][a]->links_up = 1;
        assert(topo_group_new_conn(groups[a], conns[a][b]) == 0);
        assert(topo_group_new_conn(groups[b], conns[b][a]) == 0);
    }
}

/* Независимый эталон — кратчайшие расстояния в графе реальных соединений. */
static void verify(void) {
    int distance[N][N];
    for (int a = 0; a < N; a++) for (int b = 0; b < N; b++)
        distance[a][b] = a == b ? 0 : (graph & edge(a, b)) ? 1 : 100;
    for (int k = 0; k < N; k++) for (int a = 0; a < N; a++) for (int b = 0; b < N; b++)
        if (distance[a][k] + distance[k][b] < distance[a][b]) distance[a][b] = distance[a][k] + distance[k][b];
    for (int a = 0; a < N; a++) for (int b = 0; b < N; b++) {
        if (a == b) continue;
        struct ETCP_CONN* conn = topo_group_find_conn_for_node(groups[a], nodes[b]->node_id);
        DEBUG_DEBUG(DEBUG_CATEGORY_BGP, "verify graph=%02x src=%d dst=%d expected=%d conn=%p", graph, a, b, distance[a][b], conn);
        assert((conn != NULL) == (distance[a][b] < 100));
        if (!conn) continue;
        struct TOPO_GROUP_NODE* node = topo_node_find_by_id(groups[a], nodes[b]->node_id);
        uint8_t count; uint64_t* hops = topo_node_best_hop_list(node, &count, NULL);
        assert(count == distance[a][b]);
        int previous = a;
        for (int h = count - 1; h >= 0; h--) {
            int current = 0;
            while (current < N && nodes[current]->node_id != hops[h]) current++;
            assert(current < N && (graph & edge(previous, current)));
            previous = current;
        }
        assert(previous == b);
        for (int h = 0; h < count; h++) for (int j = h + 1; j < count; j++) assert(hops[h] != hops[j]);
        if (graph & edge(a, b)) assert(topo_group_peer_ready(groups[a], nodes[b]->node_id));
    }
}

static void create(void) {
    ua = uasync_create(); assert(ua);
    for (int i = 0; i < N; i++) {
        struct SC_MYKEYS keys; assert(sc_generate_keypair(&keys) == SC_OK);
        char pub[65], priv[65], config[512];
        bytes_to_hex(keys.public_key, 32, pub, sizeof(pub)); bytes_to_hex(keys.private_key, 32, priv, sizeof(priv));
        snprintf(config, sizeof(config), "[global]\nmy_public_key=%s\nmy_private_key=%s\n", pub, priv);
        nodes[i] = utun_instance_create_from_str(ua, config); assert(nodes[i]);
        assert(utun_core_start(nodes[i]) == 0);
        groups[i] = topo_groups_create_group(nodes[i]->topo_groups, GROUP, TOPO_GROUP_TYPE_UTUN, NULL); assert(groups[i]);
    }
    for (int a = 0; a < N; a++) for (int b = 0; b < N; b++) {
        if (a == b) continue;
        struct ETCP_CONN* c = conns[a][b] = etcp_connection_create(nodes[a], "virtual_bgp"); assert(c);
        c->peer_node_id = nodes[b]->node_id;
        assert(sc_init_ctx(&c->crypto_ctx, &nodes[a]->my_keys) == SC_OK);
        assert(sc_set_peer_public_key(&c->crypto_ctx, nodes[b]->my_keys.public_key, SC_PEER_PUBKEY_BIN) == SC_OK);
        queue_set_callback(c->send_input_q, NULL, NULL);
        etcp_conn_ready(c);
        assert(node_conn_direct_open(nodes[a], c->peer_node_id, NULL, NULL, &owners[a][b], NULL) >= 0);
    }
}

int main(void) {
    debug_config_init(); debug_set_level(DEBUG_LEVEL_WARN); debug_set_category_level(DEBUG_CATEGORY_BGP, DEBUG_LEVEL_DEBUG);
    utun_instance_set_tun_init_enabled(0);
    create();
    unsigned triangle = edge(0, 1) | edge(1, 2) | edge(0, 2) | edge(2, 3);
    change(triangle); settle(); verify();
    /* One-sided REINIT with routes retained, then simultaneous REINIT at all peers. */
    etcp_fire_conn_status(conns[0][1], ETCP_CONN_STATUS_REINIT); settle(); verify();
    for (int a = 0; a < N; a++) for (int b = 0; b < N; b++)
        if (graph & edge(a, b)) etcp_fire_conn_status(conns[a][b], ETCP_CONN_STATUS_REINIT);
    settle(); verify();
    change(triangle & ~edge(0, 2)); settle(); verify();
    change(triangle); settle(); verify();
    change(triangle & ~edge(1, 2) & ~edge(0, 2)); settle(); verify();
    change(triangle); settle(); verify();
    /* Все графы, включая изолированные компоненты; затем churn без ожидания сходимости. */
    for (unsigned mask = 0; mask < 64; mask++) { change(mask); settle(); verify(); }
    for (int i = 0; i < 100; i++) {
        change(next_random() >> 26);
        for (unsigned n = next_random() % 5; n; n--) step();
    }
    settle(); verify();
    change(0); settle(); verify();
    for (int a = 0; a < N; a++) for (int b = 0; b < N; b++) if (a != b) node_conn_direct_close(owners[a][b]);
    for (int a = 0; a < N; a++) utun_instance_destroy(nodes[a]);
    uasync_poll(ua, 0); uasync_destroy(ua, 0);
    DEBUG_INFO(DEBUG_CATEGORY_BGP, "BGP paths: triangle, partitions, all four-node graphs and churn passed packets=%u", delivered);
    return 0;
}