/**
 * @file route_bgp.c
 * @brief BGP-like обмен маршрутами — исправленная версия под новую route_lib
 */

#include <stdlib.h>
#include <string.h>
#include "../lib/platform_compat.h"

#include "route_bgp.h"
#include "route_lib.h"
#include "etcp_api.h"
#include "etcp.h"
#include "etcp_connections.h"
#include "etcp_debug.h"
#include "utun_instance.h"
#include "config_parser.h"
#include "../lib/debug_config.h"
#include "../lib/mem.h"

// ============================================================================
// Вспомогательные функции
// ============================================================================

// ============================================================================
// Отправка (только preferred_conn + hop_list)
// ============================================================================

static void route_bgp_send_route(struct ROUTE_BGP* bgp, struct ETCP_CONN* conn,
                                 const struct ROUTE_ENTRY* route, uint8_t subcmd) {
    if (!bgp || !conn || !route) return;

    size_t pkt_size;
    struct BGP_ROUTE_PACKET* pkt;

    if (!route->conn_list) {
        pkt_size = sizeof(struct BGP_ROUTE_PACKET);
        pkt = u_calloc(1, pkt_size);
        if (!pkt) return;
        pkt->node_id = htobe64(bgp->instance->node_id);
        pkt->hop_count = 0;
    } else {
        uint8_t pref = route->conn_list->preferred_conn;
        if (pref >= route->conn_list->conninfo_count) pref = 0;

        struct NODE_CONN_INFO* ci = &route->conn_list->conn_info[pref];
        pkt_size = sizeof(struct BGP_ROUTE_PACKET) + ci->hop_count * sizeof(uint64_t);
        pkt = u_calloc(1, pkt_size);
        if (!pkt) return;

        pkt->node_id = htobe64(route->conn_list->node_id);
        pkt->hop_count = ci->hop_count;
        if (ci->hop_count > 0 && ci->hop_list)
            memcpy(pkt->hop_list, ci->hop_list, ci->hop_count * sizeof(uint64_t));
    }

    pkt->cmd           = ETCP_ID_ROUTE_ENTRY;
    pkt->subcmd        = subcmd;                    // ← теперь используем REROUTE
    pkt->network       = htonl(route->network);
    pkt->prefix_length = route->prefix_length;
    pkt->latency       = 0;

    struct ll_entry* send_entry = queue_entry_new(0);
    if (!send_entry) {
        u_free(pkt);
        return;
    }

    send_entry->dgram = (uint8_t*)pkt;
    send_entry->len = (uint16_t)pkt_size;

    if (etcp_send(conn, send_entry) != 0) {
        queue_entry_free(send_entry);
        u_free(pkt);
    } else {
        const char* subcmd_name = (subcmd == ROUTE_SUBCMD_ENTRY) ? "ENTRY" : 
                                  (subcmd == ROUTE_SUBCMD_WITHDRAW) ? "WITHDRAW" : "REROUTE";
        DEBUG_INFO(DEBUG_CATEGORY_BGP, "Sending route %s/%d, peer %s (%s)", 
                    ip_to_string(route->network).a, route->prefix_length, conn->log_name, subcmd_name);
    }
}

// ============================================================================
// Broadcast / Withdraw
// ============================================================================

static void route_bgp_broadcast_route(struct ROUTE_BGP* bgp, const struct ROUTE_ENTRY* route,
                                      struct ETCP_CONN* exclude, uint8_t subcmd) {
    if (!bgp) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "route_bgp_broadcast_route: bgp is NULL");
        return;
    }
    if (!route) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "route_bgp_broadcast_route: route is NULL");
        return;
    }
    DEBUG_INFO(DEBUG_CATEGORY_BGP, "route_bgp_broadcast_route: network=%s/%d exclude=%p subcmd=%d",
                ip_to_string(route->network).a, route->prefix_length, (void*)exclude, subcmd);

    struct ll_entry* entry = bgp->senders_list->head;
    int sent_count = 0;
    while (entry) {
        struct ROUTE_BGP_CONN_ITEM* item = (struct ROUTE_BGP_CONN_ITEM*)entry->data;
        if (item->conn != exclude) {
            route_bgp_send_route(bgp, item->conn, route, subcmd);
            sent_count++;
        }
        entry = entry->next;
    }
    DEBUG_TRACE(DEBUG_CATEGORY_BGP, "route_bgp_broadcast_route: sent to %d peers", sent_count);
}

static void route_bgp_broadcast_withdraw(struct ROUTE_BGP* bgp, uint64_t node_id,
                                         struct ETCP_CONN* exclude) {
    if (!bgp) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "route_bgp_broadcast_withdraw: bgp is NULL");
        return;
    }
    DEBUG_INFO(DEBUG_CATEGORY_BGP, "route_bgp_broadcast_withdraw: node_id=%016llx exclude=%p",
                (unsigned long long)node_id, (void*)exclude);

    struct BGP_WITHDRAW_PACKET* pkt = u_calloc(1, sizeof(struct BGP_WITHDRAW_PACKET));
    if (!pkt) return;

    pkt->cmd = ETCP_ID_ROUTE_ENTRY;
    pkt->subcmd = ROUTE_SUBCMD_WITHDRAW;
    pkt->node_id = htobe64(node_id);

    struct ll_entry* send_entry = queue_entry_new(0);
    if (!send_entry) { u_free(pkt); return; }
    send_entry->dgram = (uint8_t*)pkt;
    send_entry->len = sizeof(struct BGP_WITHDRAW_PACKET);

    struct ll_entry* e = bgp->senders_list->head;
    while (e) {
        struct ROUTE_BGP_CONN_ITEM* item = (struct ROUTE_BGP_CONN_ITEM*)e->data;
        if (item->conn != exclude) {
            struct ll_entry* copy = queue_entry_new(0);
            if (copy) {
                copy->dgram = u_malloc(send_entry->len);
                memcpy(copy->dgram, send_entry->dgram, send_entry->len);
                copy->len = send_entry->len;
                etcp_send(item->conn, copy);
            }
        }
        e = e->next;
    }

    queue_entry_free(send_entry);
    u_free(pkt);
}

// ============================================================================
// Callback на изменение таблицы (insert / update / delete)
// ============================================================================

static void route_bgp_on_route_change(struct ROUTE_TABLE* table,
                                      struct ROUTE_ENTRY* entry,
                                      int action, 
                                      uint64_t changed_from,
                                      void* arg) {
    struct ROUTE_BGP* bgp = (struct ROUTE_BGP*)arg;
    if (!bgp || !entry) return;

    // changed_from - это peer_node_id от кого пришёл маршрут (0 для локальных)
    // находим conn по peer_node_id для использования как exclude
    struct ETCP_CONN* exclude_conn = NULL;
    if (changed_from != 0) {
        struct ll_entry* e = bgp->senders_list->head;
        while (e) {
            struct ROUTE_BGP_CONN_ITEM* item = (struct ROUTE_BGP_CONN_ITEM*)e->data;
            if (item->conn->peer_node_id == changed_from) {
                exclude_conn = item->conn;
                break;
            }
            e = e->next;
        }
    }

    if (action == 0) {           // insert
        route_bgp_broadcast_route(bgp, entry, exclude_conn, ROUTE_SUBCMD_ENTRY);
    }
    else if (action == 1) {      // update / reroute / hop_list changed
        route_bgp_broadcast_route(bgp, entry, exclude_conn, ROUTE_SUBCMD_ENTRY_REROUTE);
    }
    else if (action == 2) {      // withdraw
        uint64_t node_id = entry->conn_list ? entry->conn_list->node_id : 0;
        route_bgp_broadcast_withdraw(bgp, node_id, exclude_conn);
    }
}

// ============================================================================
// Приём пакетов
// ============================================================================

static void route_bgp_receive_cbk(struct ETCP_CONN* from_conn, struct ll_entry* entry) {
    if (!from_conn) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "route_bgp_receive_cbk: from_conn is NULL");
        if (entry) { queue_dgram_free(entry); queue_entry_free(entry); }
        return;
    }
    if (!entry || entry->len < 2) {
        if (entry) { queue_dgram_free(entry); queue_entry_free(entry); }
        return;
    }

    DEBUG_INFO(DEBUG_CATEGORY_BGP, "route_bgp_receive_cbk: from=%016llx len=%zu", 
                (unsigned long long)from_conn->peer_node_id, entry->len);

    struct UTUN_INSTANCE* instance = from_conn->instance;
    if (!instance || !instance->rt || !instance->bgp) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "route_bgp_receive_cbk: invalid instance/rt/bgp");
        queue_dgram_free(entry); queue_entry_free(entry);
        return;
    }

    struct ROUTE_BGP* bgp = instance->bgp;
    uint8_t* data = entry->dgram;

    if (data[0] != ETCP_ID_ROUTE_ENTRY) {
        queue_dgram_free(entry); queue_entry_free(entry);
        return;
    }

    uint8_t subcmd = data[1];

    if (subcmd == ROUTE_SUBCMD_ENTRY || subcmd == ROUTE_SUBCMD_ENTRY_REROUTE) {
        if (entry->len < sizeof(struct BGP_ROUTE_PACKET)) {
            queue_dgram_free(entry); queue_entry_free(entry);
            return;
        }

        struct BGP_ROUTE_PACKET* pkt = (struct BGP_ROUTE_PACKET*)data;
        uint32_t network = ntohl(pkt->network);
        uint8_t prefix = pkt->prefix_length;
        uint64_t owner_node_id = be64toh(pkt->node_id);
        uint8_t recv_hop_count = pkt->hop_count;

        if (recv_hop_count > MAX_HOPS - 1) {
            DEBUG_WARN(DEBUG_CATEGORY_BGP, "Too many hops (%d)", recv_hop_count);
            queue_dgram_free(entry); queue_entry_free(entry);
            return;
        }

        // Строим новый hop_list: next_hop = отправитель + полученный список
        uint8_t new_hop_count = recv_hop_count + 1;
        uint64_t new_hop_list[MAX_HOPS];
        new_hop_list[0] = from_conn->peer_node_id;
        if (recv_hop_count > 0) {
            memcpy(&new_hop_list[1], pkt->hop_list, recv_hop_count * sizeof(uint64_t));
        }

        DEBUG_INFO(DEBUG_CATEGORY_BGP, "Received route %s/%d from %016llx (hops=%d)", ip_to_string(network).a, prefix, (unsigned long long)owner_node_id, new_hop_count);

        struct ROUTE_ENTRY new_route = {0};
        new_route.network = network;
        new_route.prefix_length = prefix;

        bool inserted = route_insert(instance->rt, &new_route,
                                     from_conn,
                                     owner_node_id,
                                     instance->node_id,
                                     new_hop_list,
                                     new_hop_count);

        if (!inserted) {
            DEBUG_WARN(DEBUG_CATEGORY_BGP, "Route insert rejected (loop/overlap/owner conflict)");
        } else {
            DEBUG_TRACE(DEBUG_CATEGORY_BGP, "route_bgp_receive_cbk: INSERTED");
        }

    } else if (subcmd == ROUTE_SUBCMD_WITHDRAW) {
        if (entry->len < sizeof(struct BGP_WITHDRAW_PACKET)) {
            queue_dgram_free(entry); queue_entry_free(entry);
            return;
        }
        struct BGP_WITHDRAW_PACKET* wp = (struct BGP_WITHDRAW_PACKET*)data;
        uint64_t node_id = be64toh(wp->node_id);

        DEBUG_INFO(DEBUG_CATEGORY_BGP, "Received WITHDRAW for node %016llx", (unsigned long long)node_id);

        // === ИСПРАВЛЕНИЕ: поддержка резервных путей ===
        route_remove_path(instance->rt, from_conn, node_id);
        // callback внутри route_remove_path уже сделает broadcast (withdraw или reroute)
    }

    queue_dgram_free(entry);
    queue_entry_free(entry);
}

// ============================================================================
// Init / Destroy / New / Remove conn
// ============================================================================

// Callback для готовности ETCP соединения - отправляет маршруты
static void route_bgp_on_conn_ready(struct ETCP_CONN* conn, void* arg) {
    (void)arg;
    if (conn && conn->instance && conn->instance->bgp) {
        DEBUG_TRACE(DEBUG_CATEGORY_BGP, "Connection %s ready ", conn->log_name);
        route_bgp_new_conn(conn);
    }
}

// Callback для новых ETCP соединений - устанавливает ready callback
static void route_bgp_etcp_conn_cbk(struct ETCP_CONN* conn, void* arg) {
    (void)arg;
    if (conn && conn->instance && conn->instance->bgp) {
        DEBUG_TRACE(DEBUG_CATEGORY_BGP, "Set ETCP ready callback for connection %s", conn->log_name);
        etcp_conn_set_ready_cbk(conn, route_bgp_on_conn_ready, conn->instance->bgp);
    }
}

struct ROUTE_BGP* route_bgp_init(struct UTUN_INSTANCE* instance) {
    if (!instance) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "route_bgp_init: instance is NULL");
        return NULL;
    }

    DEBUG_INFO(DEBUG_CATEGORY_BGP, "route_bgp_init: node_id=%016llx", (unsigned long long)instance->node_id);

    struct ROUTE_BGP* bgp = u_calloc(1, sizeof(struct ROUTE_BGP));
    if (!bgp) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "route_bgp_init: alloc failed");
        return NULL;
    }

    bgp->instance = instance;

    bgp->senders_list = queue_new(instance->ua, 0, "BGP_senders");
    if (!bgp->senders_list) {
        u_free(bgp);
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "route_bgp_init: queue_new failed");
        return NULL;
    }

    etcp_bind(instance, ETCP_ID_ROUTE_ENTRY, route_bgp_receive_cbk);

    if (instance->rt) {
        instance->rt->change_callback = route_bgp_on_route_change;
        instance->rt->change_callback_arg = bgp;
    }

    // Устанавливаем callback для новых ETCP соединений
    etcp_set_new_conn_cbk(instance, route_bgp_etcp_conn_cbk, NULL);

    DEBUG_INFO(DEBUG_CATEGORY_BGP, "BGP module initialized (with hop_list support)");
    return bgp;
}

void route_bgp_destroy(struct UTUN_INSTANCE* instance) {
    if (!instance) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "route_bgp_destroy: instance is NULL");
        return;
    }
    if (!instance->bgp) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "route_bgp_destroy: bgp is NULL");
        return;
    }

    DEBUG_INFO(DEBUG_CATEGORY_BGP, "route_bgp_destroy: node_id=%016llx", (unsigned long long)instance->node_id);

    etcp_unbind(instance, ETCP_ID_ROUTE_ENTRY);

    if (instance->rt && instance->rt->change_callback == route_bgp_on_route_change) {
        instance->rt->change_callback = NULL;
        instance->rt->change_callback_arg = NULL;
    }

    // очистка списка
    struct ll_entry* e;
    while ((e = queue_data_get(instance->bgp->senders_list)) != NULL) {
        queue_entry_free(e);
    }
    queue_free(instance->bgp->senders_list);

    u_free(instance->bgp);
    instance->bgp = NULL;
}

void route_bgp_new_conn(struct ETCP_CONN* conn) {
    if (!conn) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "route_bgp_new_conn: conn is NULL");
        return;
    }
    if (!conn->instance) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "route_bgp_new_conn: conn->instance is NULL");
        return;
    }
    if (!conn->instance->bgp) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "route_bgp_new_conn: conn->instance->bgp is NULL");
        return;
    }
    if (!conn->instance->rt) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "route_bgp_new_conn: conn->instance->rt is NULL");
        return;
    }

    struct ROUTE_BGP* bgp = conn->instance->bgp;
    struct ROUTE_TABLE* rt = conn->instance->rt;

    // === 1. Проверяем, уже есть ли это соединение в списке ===
    bool already_exists = false;
    struct ll_entry* e = bgp->senders_list->head;
    while (e) {
        struct ROUTE_BGP_CONN_ITEM* item = (struct ROUTE_BGP_CONN_ITEM*)e->data;
        if (item->conn == conn) {
            already_exists = true;
            break;
        }
        e = e->next;
    }

    // === 2. Если нет — добавляем (только один раз) ===
    if (!already_exists) {
        struct ll_entry* item_entry = queue_entry_new(sizeof(struct ROUTE_BGP_CONN_ITEM));
        if (!item_entry) return;

        ((struct ROUTE_BGP_CONN_ITEM*)item_entry->data)->conn = conn;
        queue_data_put(bgp->senders_list, item_entry, 0);

        DEBUG_INFO(DEBUG_CATEGORY_BGP, "New connection added to senders_list");
    }

    // === 3. В любом случае отправляем полную таблицу (это и нужно при переподключении) ===
    for (size_t i = 0; i < rt->count; i++) {
        route_bgp_send_route(bgp, conn, &rt->entries[i], ROUTE_SUBCMD_ENTRY);
    }

    DEBUG_INFO(DEBUG_CATEGORY_BGP, "Sent full routing table to %s (reconnect OK)",
               conn->log_name);
}

void route_bgp_remove_conn(struct ETCP_CONN* conn) {
    if (!conn) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "route_bgp_remove_conn: conn is NULL");
        return;
    }
    if (!conn->instance || !conn->instance->bgp) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "route_bgp_remove_conn: invalid instance/bgp");
        return;
    }

    DEBUG_INFO(DEBUG_CATEGORY_BGP, "route_bgp_remove_conn: peer=%016llx", (unsigned long long)conn->peer_node_id);

    struct ROUTE_BGP* bgp = conn->instance->bgp;
    struct ROUTE_TABLE* rt = conn->instance->rt;

    // ← КЛЮЧЕВОЕ ИЗМЕНЕНИЕ: теперь используем route_remove_conn
    if (rt) {
        route_remove_conn(rt, conn);        // автоматически вызовет reroute / withdraw через callback
    }

    // Удаляем из списка рассылки
    struct ll_entry* e = bgp->senders_list->head;
    while (e) {
        struct ROUTE_BGP_CONN_ITEM* item = (struct ROUTE_BGP_CONN_ITEM*)e->data;
        if (item->conn == conn) {
            queue_remove_data(bgp->senders_list, e);
            queue_entry_free(e);
            break;
        }
        e = e->next;
    }

    DEBUG_INFO(DEBUG_CATEGORY_BGP, "Connection removed, routes updated via route_remove_conn");
}

void route_bgp_close_conn(struct ETCP_CONN* conn) {
    route_bgp_remove_conn(conn);
}