/*
 * etcpmon_client.c - ETCP Monitor Client Network Implementation
 */

#include "etcpmon_client.h"
#include "etcpmon_graph.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ws2tcpip.h>
#include <windows.h>

//#pragma comment(lib, "ws2_32.lib")

/* Log file name */
#define LOG_FILENAME "etcpmon.log"
#define REQUEST_TIMEOUT_MS 5000

static struct etcpmon_pending_request* find_pending_request(struct etcpmon_client* client, uint8_t seq_id);

/* Get current timestamp in milliseconds (Unix epoch) */
uint64_t get_timestamp_ms(void) {
    FILETIME ft;
    GetSystemTimeAsFileTime(&ft);
    
    /* Convert FILETIME (100-nanosecond intervals since 1601) to milliseconds */
    uint64_t time = ((uint64_t)ft.dwHighDateTime << 32) | ft.dwLowDateTime;
    /* Convert from 1601 to 1970 epoch (11644473600000 milliseconds) */
    return (time / 10000) - 11644473600000ULL;
}

/* Log hex data to file */
static void log_hex_data(FILE* log, const char* prefix, const uint8_t* data, size_t len) {
    if (!log || !data || len == 0) return;
    
    fprintf(log, "%llu: [%s] ", (unsigned long long)get_timestamp_ms(), prefix);
    for (size_t i = 0; i < len && i < 256; i++) {  /* Limit to 256 bytes per line */
        fprintf(log, "%02X ", data[i]);
    }
    if (len > 256) {
        fprintf(log, "... (%llu bytes total)", (unsigned long long)len);
    }
    fprintf(log, "\n");
    fflush(log);
}

void etcpmon_client_init(struct etcpmon_client* client) {
    if (!client) return;
    memset(client, 0, sizeof(*client));
    client->sock = INVALID_SOCKET;
    client->connected = 0;
    client->fully_connected = 0;
    client->log_file = NULL;
    client->next_seq_id = 1;  /* Start from 1, 0 = broadcast */
    memset(&client->history, 0, sizeof(client->history));
    for (int i = 0; i < GRAPH_METRIC_COUNT; i++) {
        client->history.min_val[i] = 1e9f;
        client->history.max_val[i] = -1e9f;
    }
    client->history.last_minmax_update = 0;
    
    /* Новый таймер авто-запроса метрик */
    client->last_metrics_request_ms = 0;
}

void etcpmon_client_cleanup(struct etcpmon_client* client) {
    if (!client) return;
    
    etcpmon_client_disconnect(client);
    
    /* Free pending requests */
    struct etcpmon_pending_request* req = client->pending_head;
    while (req) {
        struct etcpmon_pending_request* next = req->next;
        free(req);
        req = next;
    }
    client->pending_head = NULL;
    client->pending_tail = NULL;
    
    /* Close log file */
    if (client->log_file) {
        fprintf(client->log_file, "%llu: [LOG] Log closed\n", 
               (unsigned long long)get_timestamp_ms());
        fclose(client->log_file);
        client->log_file = NULL;
    }
    
    /* Free cached data */
    if (client->conn_list) {
        free(client->conn_list);
        client->conn_list = NULL;
    }
    if (client->socket_list) {
        free(client->socket_list);
        client->socket_list = NULL;
    }
    if (client->last_metrics) {
        free(client->last_metrics);
        client->last_metrics = NULL;
    }
    if (client->last_links) {
        free(client->last_links);
        client->last_links = NULL;
    }
}

int etcpmon_client_connect(struct etcpmon_client* client, const char* addr, uint16_t port) {
    if (!client || !addr) return -1;
    
    if (client->connected) {
        etcpmon_client_disconnect(client);
    }

    /* Open log file (truncate on start) */
    if (!client->log_file) {
        client->log_file = fopen(LOG_FILENAME, "w");
        if (client->log_file) {
            fprintf(client->log_file, "%llu: [LOG] ETCP Monitor communication log started\n", 
                   (unsigned long long)get_timestamp_ms());
            fprintf(client->log_file, "%llu: [LOG] Connecting to %s:%d\n", 
                   (unsigned long long)get_timestamp_ms(), addr, port);
            fflush(client->log_file);
        }
    }
    
    /* Create socket */
    client->sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (client->sock == INVALID_SOCKET) {
        if (client->log_file) {
            fprintf(client->log_file, "%llu: [ERROR] Failed to create socket\n", 
                   (unsigned long long)get_timestamp_ms());
            fflush(client->log_file);
        }
        if (client->on_error) {
            client->on_error("Failed to create socket", client->user_data);
        }
        return -1;
    }
    
    /* Set non-blocking mode */
    u_long nonblock = 1;
    ioctlsocket(client->sock, FIONBIO, &nonblock);
    
    /* Setup address */
    struct sockaddr_in server_addr;
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(port);
    
    if (inet_pton(AF_INET, addr, &server_addr.sin_addr) != 1) {
        if (client->log_file) {
            fprintf(client->log_file, "%llu: [ERROR] Invalid address: %s\n", 
                   (unsigned long long)get_timestamp_ms(), addr);
            fflush(client->log_file);
        }
        closesocket(client->sock);
        client->sock = INVALID_SOCKET;
        if (client->on_error) {
            client->on_error("Invalid address", client->user_data);
        }
        return -1;
    }
    
    /* Connect (non-blocking) */
    int result = connect(client->sock, (struct sockaddr*)&server_addr, sizeof(server_addr));
    if (result == SOCKET_ERROR) {
        int err = WSAGetLastError();
        if (err != WSAEWOULDBLOCK && err != WSAEINPROGRESS) {
            if (client->log_file) {
                fprintf(client->log_file, "%llu: [ERROR] Connection failed: %d\n", 
                       (unsigned long long)get_timestamp_ms(), err);
                fflush(client->log_file);
            }
            closesocket(client->sock);
            client->sock = INVALID_SOCKET;
            if (client->on_error) {
                char msg[256];
                snprintf(msg, sizeof(msg), "Connection failed: %d", err);
                client->on_error(msg, client->user_data);
            }
            return -1;
        }
        /* Connection in progress, will complete asynchronously */
    }
    
    strncpy(client->server_addr, addr, sizeof(client->server_addr) - 1);
    client->server_port = port;
    client->connected = 1;
    client->fully_connected = 0;
    
    if (client->log_file) {
        fprintf(client->log_file, "%llu: [LOG] Socket created, connection in progress\n", 
               (unsigned long long)get_timestamp_ms());
        fflush(client->log_file);
    }
    
    return 0;
}

void etcpmon_client_disconnect(struct etcpmon_client* client) {
    if (!client) return;
    
    if (client->sock != INVALID_SOCKET) {
        /* Send disconnect command */
        if (client->connected) {
            struct etcpmon_msg_header hdr;
            etcpmon_build_header(&hdr, 0, ETCPMON_CMD_DISCONNECT, 0);
            
            if (client->log_file) {
                log_hex_data(client->log_file, "TX", (const uint8_t*)&hdr, sizeof(hdr));
                fprintf(client->log_file, "%llu: [LOG] Sending CMD_DISCONNECT\n", 
                       (unsigned long long)get_timestamp_ms());
            }
            
            send(client->sock, (const char*)&hdr, sizeof(hdr), 0);
        }
        
        if (client->log_file) {
            fprintf(client->log_file, "%llu: [LOG] Connection closed\n", 
                   (unsigned long long)get_timestamp_ms());
            fflush(client->log_file);
        }
        
        closesocket(client->sock);
        client->sock = INVALID_SOCKET;
    }
    
    client->connected = 0;
    client->fully_connected = 0;
    client->recv_len = 0;
    client->selected_peer_id = 0;
    client->last_metrics_request_ms = 0;
    free(client->conn_list);
    client->conn_list = NULL;
    client->conn_count = 0;
    free(client->socket_list);
    client->socket_list = NULL;
    client->socket_count = 0;
    free(client->last_metrics);
    client->last_metrics = NULL;
    free(client->last_links);
    client->last_links = NULL;
    client->last_links_count = 0;
    memset(&client->history, 0, sizeof(client->history));
    
    /* Очистить очередь pending requests и сбросить seq_id */
    struct etcpmon_pending_request* req = client->pending_head;
    while (req) {
        struct etcpmon_pending_request* next = req->next;
        free(req);
        req = next;
    }
    client->pending_head = NULL;
    client->pending_tail = NULL;
    client->next_seq_id = 1;
    client->last_response_seq_id = 0;
}

int etcpmon_client_is_connected(const struct etcpmon_client* client) {
    return client ? client->connected : 0;
}

int etcpmon_client_request_list(struct etcpmon_client* client) {
    if (!client || client->sock == INVALID_SOCKET) return -1;
    
    struct etcpmon_msg_header hdr;
    etcpmon_build_header(&hdr, 0, ETCPMON_CMD_LIST_CONN, 0);  /* seq=0 = legacy режим */
    
    if (client->log_file) {
        log_hex_data(client->log_file, "TX", (const uint8_t*)&hdr, sizeof(hdr));
        fprintf(client->log_file, "%llu: [LOG] CMD_LIST_CONN (seq=0)\n", 
               (unsigned long long)get_timestamp_ms());
        fflush(client->log_file);
    }
    
    int sent = send(client->sock, (const char*)&hdr, sizeof(hdr), 0);
    if (sent != sizeof(hdr)) {
        if (client->log_file) {
            fprintf(client->log_file, "%llu: [ERROR] Failed to send CMD_LIST_CONN: %d\n", 
                   (unsigned long long)get_timestamp_ms(), WSAGetLastError());
            fflush(client->log_file);
        }
        return -1;
    }
    
    return 0;
}

int etcpmon_client_select_connection(struct etcpmon_client* client, uint64_t peer_node_id) {
    if (!client || client->sock == INVALID_SOCKET) return -1;
    
    /* SELECT is special - it's not a request/response, it just sets state
     * So we send with seq_id=0 (broadcast) */
    uint8_t buffer[sizeof(struct etcpmon_msg_header) + sizeof(struct etcpmon_cmd_select)];
    struct etcpmon_msg_header* hdr = (struct etcpmon_msg_header*)buffer;
    struct etcpmon_cmd_select* cmd = (struct etcpmon_cmd_select*)(buffer + sizeof(*hdr));
    
    etcpmon_build_header(hdr, sizeof(*cmd), ETCPMON_CMD_SELECT_CONN, 0);  /* seq_id=0 for SELECT */
    cmd->peer_node_id = peer_node_id;
    
    if (client->log_file) {
        log_hex_data(client->log_file, "TX", buffer, sizeof(buffer));
        fprintf(client->log_file, "%llu: [LOG] CMD_SELECT_CONN peer_id=%016llX\n", 
               (unsigned long long)get_timestamp_ms(), (unsigned long long)peer_node_id);
        fflush(client->log_file);
    }
    
    int sent = send(client->sock, (const char*)buffer, sizeof(buffer), 0);
    if (sent != sizeof(buffer)) {
        if (client->log_file) {
            fprintf(client->log_file, "%llu: [ERROR] Failed to send CMD_SELECT_CONN: %d\n", 
                   (unsigned long long)get_timestamp_ms(), WSAGetLastError());
            fflush(client->log_file);
        }
        return -1;
    }
    
    client->selected_peer_id = peer_node_id;
    client->last_metrics_request_ms = 0;
    memset(&client->history, 0, sizeof(client->history));
    return 0;
}

int etcpmon_client_request_socket_list(struct etcpmon_client* client) {
    if (!client || client->sock == INVALID_SOCKET) return -1;

    struct etcpmon_msg_header hdr;
    etcpmon_build_header(&hdr, 0, ETCPMON_CMD_LIST_SOCKETS, 0);

    if (client->log_file) {
        log_hex_data(client->log_file, "TX", (const uint8_t*)&hdr, sizeof(hdr));
        fprintf(client->log_file, "%llu: [LOG] CMD_LIST_SOCKETS (seq=0)\n",
               (unsigned long long)get_timestamp_ms());
        fflush(client->log_file);
    }

    int sent = send(client->sock, (const char*)&hdr, sizeof(hdr), 0);
    if (sent != sizeof(hdr)) {
        if (client->log_file) {
            fprintf(client->log_file, "%llu: [ERROR] Failed to send CMD_LIST_SOCKETS: %d\n",
                   (unsigned long long)get_timestamp_ms(), WSAGetLastError());
            fflush(client->log_file);
        }
        return -1;
    }

    return 0;
}

int etcpmon_client_request_metrics(struct etcpmon_client* client) {
    if (!client || client->sock == INVALID_SOCKET) return -1;
    
    struct etcpmon_msg_header hdr;
    etcpmon_build_header(&hdr, 0, ETCPMON_CMD_GET_METRICS, 0);
    
    if (client->log_file) {
        log_hex_data(client->log_file, "TX", (const uint8_t*)&hdr, sizeof(hdr));
        fprintf(client->log_file, "%llu: [LOG] CMD_GET_METRICS\n", 
               (unsigned long long)get_timestamp_ms());
        fflush(client->log_file);
    }
    
    int sent = send(client->sock, (const char*)&hdr, sizeof(hdr), 0);
    if (sent != sizeof(hdr)) {
        if (client->log_file) {
            fprintf(client->log_file, "%llu: [ERROR] Failed to send CMD_GET_METRICS: %d\n", 
                   (unsigned long long)get_timestamp_ms(), WSAGetLastError());
            fflush(client->log_file);
        }
        return -1;
    }
    
    return 0;
}

static void action_auto_callback(void* arg, uint8_t msg_type, const uint8_t* payload, uint16_t payload_size) {
    (void)arg; (void)msg_type; (void)payload; (void)payload_size;
    /* legacy callback is called via on_action_result in handle_response */
}

int etcpmon_client_send_action(struct etcpmon_client* client, const char* action) {
    if (!client || client->sock == INVALID_SOCKET || !action) return -1;

    struct etcpmon_cmd_action cmd;
    memset(&cmd, 0, sizeof(cmd));
    strncpy(cmd.action, action, sizeof(cmd.action) - 1);
    cmd.action[sizeof(cmd.action) - 1] = '\0';

    return etcpmon_client_send_request(client, ETCPMON_CMD_ACTION, &cmd, sizeof(cmd),
                                        action_auto_callback, NULL);
}

/* Send request with callback - queued version */
int etcpmon_client_send_request(struct etcpmon_client* client,
                                 uint8_t type,
                                 const void* payload, uint16_t payload_size,
                                 void (*callback)(void* arg, uint8_t msg_type, const uint8_t* payload, uint16_t payload_size),
                                 void* arg) {
    if (!client || client->sock == INVALID_SOCKET || !callback) return -1;
    if (payload_size > ETCPMON_MAX_MSG_SIZE - sizeof(struct etcpmon_msg_header) || (payload_size && !payload)) {
        if (client->log_file) {
            fprintf(client->log_file, "%llu: [ERROR] Invalid request payload: type=0x%02X size=%u\n",
                    (unsigned long long)get_timestamp_ms(), type, payload_size);
            fflush(client->log_file);
        }
        return -1;
    }

    /* Не переиспользуем seq_id ещё ожидающего ответа запроса. */
    int attempts = 0;
    while (find_pending_request(client, client->next_seq_id) && attempts++ < 255) {
        if (++client->next_seq_id == 0) client->next_seq_id = 1;
    }
    if (attempts >= 255) {
        if (client->log_file) {
            fprintf(client->log_file, "%llu: [ERROR] All request sequence IDs are in use\n",
                    (unsigned long long)get_timestamp_ms());
            fflush(client->log_file);
        }
        return -1;
    }
    
    /* Allocate pending request */
    struct etcpmon_pending_request* req = (struct etcpmon_pending_request*)malloc(sizeof(*req));
    if (!req) {
        if (client->log_file) {
            fprintf(client->log_file, "%llu: [ERROR] Failed to allocate pending request\n",
                   (unsigned long long)get_timestamp_ms());
            fflush(client->log_file);
        }
        return -1;
    }
    
    /* Assign sequence ID */
    req->seq_id = client->next_seq_id++;
    if (client->next_seq_id == 0) client->next_seq_id = 1;  /* Skip 0 (broadcast) */
    req->callback = callback;
    req->arg = arg;
    req->type = type;
    req->sent_at = GetTickCount();
    req->next = NULL;
    
    /* Build message with seq_id */
    uint8_t buffer[ETCPMON_MAX_MSG_SIZE];
    
    struct etcpmon_msg_header* hdr = (struct etcpmon_msg_header*)buffer;
    etcpmon_build_header(hdr, payload_size, type, req->seq_id);
    
    if (payload && payload_size > 0) {
        memcpy(buffer + sizeof(*hdr), payload, payload_size);
    }
    
    uint16_t total_size = sizeof(*hdr) + payload_size;
    
    if (client->log_file) {
        log_hex_data(client->log_file, "TX", buffer, total_size);
        fprintf(client->log_file, "%llu: [LOG] CMD 0x%02X seq=%d queued\n",
               (unsigned long long)get_timestamp_ms(), type, req->seq_id);
        fflush(client->log_file);
    }
    
    int sent = send(client->sock, (const char*)buffer, total_size, 0);
    if (sent != total_size) {
        free(req);
        if (client->log_file) {
            fprintf(client->log_file, "%llu: [ERROR] Failed to send request: type=0x%02X sent=%d/%u error=%d\n",
                   (unsigned long long)get_timestamp_ms(), type, sent, total_size, sent == SOCKET_ERROR ? WSAGetLastError() : 0);
            fflush(client->log_file);
        }
        /* После частичной отправки следующий пакет уже нельзя писать в этот поток. */
        etcpmon_client_disconnect(client);
        if (client->on_disconnected) client->on_disconnected(client->user_data);
        return -1;
    }

    /* В очередь попадает только полностью отправленный запрос. */
    if (client->pending_tail) client->pending_tail->next = req;
    else client->pending_head = req;
    client->pending_tail = req;
    
    return 0;
}

static void handle_response(struct etcpmon_client* client, uint8_t msg_type, 
                           const uint8_t* payload, uint16_t payload_size) {
    switch (msg_type) {
        case ETCPMON_RSP_CONN_LIST: {
            if (payload_size < sizeof(struct etcpmon_rsp_conn_list)) {
                if (client->log_file) fprintf(client->log_file, "[ERROR] Empty RSP_CONN_LIST payload\n");
                break;
            }
            
            struct etcpmon_rsp_conn_list* rsp = (struct etcpmon_rsp_conn_list*)payload;
            uint8_t count = rsp->count;
            
            if (count > ETCPMON_MAX_CONNECTIONS || payload_size != sizeof(*rsp) + count * sizeof(struct etcpmon_conn_info)) {
                if (client->log_file) fprintf(client->log_file, "[ERROR] Invalid RSP_CONN_LIST: count=%u size=%u\n", count, payload_size);
                break;
            }
            
            /* Update cached list */
            struct etcpmon_conn_info* list = count ? malloc(count * sizeof(*list)) : NULL;
            if (count && !list) {
                if (client->log_file) fprintf(client->log_file, "[ERROR] Failed to allocate connection list: count=%u\n", count);
                break;
            }
            {
                if (count) memcpy(list, payload + sizeof(*rsp), count * sizeof(*list));
                for (uint8_t i = 0; i < count; i++) list[i].name[ETCPMON_MAX_CONN_NAME - 1] = '\0';
                free(client->conn_list);
                client->conn_list = list;
                client->conn_count = count;
                
                if (client->log_file) {
                    fprintf(client->log_file, "%llu: [LOG] RSP_CONN_LIST count=%d\n", 
                           (unsigned long long)get_timestamp_ms(), count);
                    for (uint8_t i = 0; i < count; i++) {
                        fprintf(client->log_file, "%llu: [LOG]   [%d] peer_id=%016llX name='%s'\n", 
                               (unsigned long long)get_timestamp_ms(), i,
                               (unsigned long long)client->conn_list[i].peer_node_id,
                               client->conn_list[i].name);
                    }
                    fflush(client->log_file);
                }
                
                if (client->on_conn_list) {
                    client->on_conn_list(client->conn_list, count, client->user_data);
                }
            }
            break;
        }
        
        case ETCPMON_RSP_SOCKET_LIST: {
            if (payload_size < sizeof(struct etcpmon_rsp_socket_list)) break;

            struct etcpmon_rsp_socket_list* rsp = (struct etcpmon_rsp_socket_list*)payload;
            uint8_t count = rsp->count;

            if (count > ETCPMON_MAX_CONNECTIONS || payload_size != sizeof(*rsp) + count * sizeof(struct etcpmon_socket_info)) {
                if (client->log_file) fprintf(client->log_file, "[ERROR] Invalid RSP_SOCKET_LIST: count=%u size=%u\n", count, payload_size);
                break;
            }

            struct etcpmon_socket_info* list = count ? malloc(count * sizeof(*list)) : NULL;
            if (count && !list) {
                if (client->log_file) fprintf(client->log_file, "[ERROR] Failed to allocate socket list: count=%u\n", count);
                break;
            }
            {
                if (count) memcpy(list, payload + sizeof(*rsp), count * sizeof(*list));
                for (uint8_t i = 0; i < count; i++) {
                    list[i].name[sizeof(list[i].name) - 1] = '\0';
                    list[i].ip[sizeof(list[i].ip) - 1] = '\0';
                    list[i].nat_ip[sizeof(list[i].nat_ip) - 1] = '\0';
                }
                free(client->socket_list);
                client->socket_list = list;
                client->socket_count = count;

                if (client->log_file) {
                    fprintf(client->log_file, "%llu: [LOG] RSP_SOCKET_LIST count=%d\n",
                           (unsigned long long)get_timestamp_ms(), count);
                    fflush(client->log_file);
                }

                if (client->on_socket_list) {
                    client->on_socket_list(client->socket_list, count, client->user_data);
                }
            }
            break;
        }

        case ETCPMON_RSP_METRICS: {
            if (payload_size < sizeof(struct etcpmon_rsp_metrics)) break;

            struct etcpmon_rsp_metrics* rsp = (struct etcpmon_rsp_metrics*)payload;
            uint8_t links_count = rsp->etcp.links_count;

            if (rsp->etcp.peer_node_id != client->selected_peer_id || client->selected_peer_id == 0) {
                if (client->log_file) {
                    fprintf(client->log_file, "[LOG] Ignoring stale metrics: peer=%016llX selected=%016llX\n",
                            (unsigned long long)rsp->etcp.peer_node_id, (unsigned long long)client->selected_peer_id);
                }
                break;
            }
            
            if (links_count > ETCPMON_MAX_LINKS || payload_size != sizeof(*rsp) + links_count * sizeof(struct etcpmon_link_metrics)) {
                if (client->log_file) fprintf(client->log_file, "[ERROR] Invalid RSP_METRICS: links=%u size=%u\n", links_count, payload_size);
                break;
            }
            
            /* Update cached metrics */
            struct etcpmon_rsp_metrics* metrics = malloc(sizeof(*metrics));
            struct etcpmon_link_metrics* links = links_count ? malloc(links_count * sizeof(*links)) : NULL;
            if (!metrics || (links_count && !links)) {
                free(metrics);
                free(links);
                if (client->log_file) fprintf(client->log_file, "[ERROR] Failed to allocate metrics: links=%u\n", links_count);
                break;
            }
            {
                free(client->last_metrics);
                free(client->last_links);
                client->last_metrics = metrics;
                client->last_links = links;
                memcpy(client->last_metrics, rsp, sizeof(*rsp));
                if (links_count) memcpy(client->last_links, payload + sizeof(*rsp),
                       links_count * sizeof(struct etcpmon_link_metrics));
                client->last_links_count = links_count;
                
                if (client->log_file) {
                    fprintf(client->log_file, "%llu: [LOG] RSP_METRICS rtt=%u bytes=%llu links=%d\n", 
                           (unsigned long long)get_timestamp_ms(),
                           rsp->etcp.rtt_last,
                           (unsigned long long)rsp->etcp.bytes_sent_total,
                           links_count);
                    fflush(client->log_file);
                }
                
                etcpmon_client_add_to_history(client, client->last_metrics);
                if (client->on_metrics) {
                    client->on_metrics(client->last_metrics, client->last_links, 
                                        links_count, client->user_data);
                }
                
            }
            break;
        }
        
        case ETCPMON_RSP_ERROR: {
            if (payload_size > sizeof(struct etcpmon_rsp_error) &&
                memchr(payload + sizeof(struct etcpmon_rsp_error), 0, payload_size - sizeof(struct etcpmon_rsp_error))) {
                struct etcpmon_rsp_error* rsp = (struct etcpmon_rsp_error*)payload;
                const char* msg = (const char*)(payload + sizeof(*rsp));

                if (client->log_file) {
                    fprintf(client->log_file, "%llu: [LOG] RSP_ERROR code=%d msg='%s'\n",
                           (unsigned long long)get_timestamp_ms(), rsp->error_code, msg);
                    fflush(client->log_file);
                }

                if (client->on_error) {
                    client->on_error(msg, client->user_data);
                }
            } else if (client->log_file) {
                fprintf(client->log_file, "[ERROR] Invalid RSP_ERROR string: size=%u\n", payload_size);
            }
            break;
        }

        case ETCPMON_RSP_ACTION_RESULT: {
            if (payload_size > sizeof(struct etcpmon_rsp_action_result) &&
                memchr(payload + sizeof(struct etcpmon_rsp_action_result), 0, payload_size - sizeof(struct etcpmon_rsp_action_result))) {
                const char* text = (const char*)(payload + sizeof(struct etcpmon_rsp_action_result));

                if (client->log_file) {
                    fprintf(client->log_file, "%llu: [LOG] RSP_ACTION_RESULT len=%u\n",
                           (unsigned long long)get_timestamp_ms(), payload_size);
                    fflush(client->log_file);
                }

                if (client->on_action_result) {
                    client->on_action_result(text, client->user_data);
                }
            } else if (client->log_file) {
                fprintf(client->log_file, "[ERROR] Invalid RSP_ACTION_RESULT string: size=%u\n", payload_size);
            }
            break;
        }

        case ETCPMON_RSP_DEBUG_CONFIG: {
            const uint8_t* names_end = payload_size > 2 ? memchr(payload + 2, 0, payload_size - 2) : NULL;
            if (!names_end || payload[1] > ETCPMON_MAX_DEBUG_CATEGORIES ||
                (size_t)(names_end - payload) + 1 + payload[1] != payload_size) {
                if (client->log_file) fprintf(client->log_file, "[ERROR] Invalid RSP_DEBUG_CONFIG: size=%u\n", payload_size);
                break;
            }
            {
                client->debug_global_level = payload[0];
                client->debug_category_count = payload[1];
                uint16_t names_len = (uint16_t)(names_end - payload - 2) + 1;
                if (2 + names_len <= payload_size) {
                    size_t copy_len = names_len < sizeof(client->debug_category_names) ? names_len : sizeof(client->debug_category_names) - 1;
                    memcpy(client->debug_category_names, payload + 2, copy_len);
                    client->debug_category_names[copy_len] = '\0';
                    uint16_t levels_off = 2 + names_len;
                    uint8_t lvl_count = client->debug_category_count;
                    if (lvl_count > ETCPMON_MAX_DEBUG_CATEGORIES) lvl_count = ETCPMON_MAX_DEBUG_CATEGORIES;
                    for (uint8_t i = 0; i < lvl_count && levels_off + i < payload_size; i++)
                        client->debug_category_levels[i] = payload[levels_off + i];
                    client->debug_config_dirty = 1;
                    if (client->log_file) {
                        fprintf(client->log_file, "%llu: [LOG] RSP_DEBUG_CONFIG global=%d categories=%d\n",
                               (unsigned long long)get_timestamp_ms(), client->debug_global_level, client->debug_category_count);
                        fflush(client->log_file);
                    }
                }
            }
            break;
        }
    }
}

/* Find pending request by seq_id */
static struct etcpmon_pending_request* find_pending_request(struct etcpmon_client* client, uint8_t seq_id) {
    struct etcpmon_pending_request* req = client->pending_head;
    while (req) {
        if (req->seq_id == seq_id) {
            return req;
        }
        req = req->next;
    }
    return NULL;
}

/* Remove pending request from queue */
static void remove_pending_request(struct etcpmon_client* client, struct etcpmon_pending_request* req) {
    struct etcpmon_pending_request** curr = &client->pending_head;
    struct etcpmon_pending_request* prev = NULL;
    while (*curr) {
        if (*curr == req) {
            *curr = req->next;
            if (client->pending_tail == req) {
                client->pending_tail = prev;
            }
            free(req);
            return;
        }
        prev = *curr;
        curr = &(*curr)->next;
    }
}

/* Handle response - find matching request and call callback */
static void handle_response_with_callback(struct etcpmon_client* client, uint8_t msg_type,
                                           const uint8_t* payload, uint16_t payload_size) {
    uint8_t seq_id = client->last_response_seq_id;
    
    /* Find pending request */
    struct etcpmon_pending_request* req = find_pending_request(client, seq_id);
    
    if (req) {
        /* Callback может отправить новый запрос или отключить клиент. */
        void (*callback)(void*, uint8_t, const uint8_t*, uint16_t) = req->callback;
        void* arg = req->arg;
        remove_pending_request(client, req);
        if (callback) callback(arg, msg_type, payload, payload_size);
        
        if (client->log_file) {
            fprintf(client->log_file, "%llu: [LOG] Response handled, seq=%d removed from queue\n",
                   (unsigned long long)get_timestamp_ms(), seq_id);
            fflush(client->log_file);
        }
    } else {
        /* No pending request - maybe broadcast/unsolicited or stale */
        if (client->log_file) {
            fprintf(client->log_file, "%llu: [LOG] Response seq=%d - no pending request (broadcast?)\n",
                   (unsigned long long)get_timestamp_ms(), seq_id);
            fflush(client->log_file);
        }
    }
    
    /* === НОВОЕ: ВСЕГДА вызываем legacy обработчики (on_conn_list / on_metrics / on_error) ===
     * Это позволяет использовать и старый код, и новый асинхронный send_request одновременно */
    if (seq_id == 0 || msg_type == ETCPMON_RSP_CONN_LIST ||
        msg_type == ETCPMON_RSP_SOCKET_LIST || msg_type == ETCPMON_RSP_DEBUG_CONFIG ||
        msg_type == ETCPMON_RSP_METRICS || msg_type == ETCPMON_RSP_ERROR ||
        msg_type == ETCPMON_RSP_ACTION_RESULT) {
        handle_response(client, msg_type, payload, payload_size);
    }
}

static void metrics_auto_callback(void* arg, uint8_t msg_type, const uint8_t* payload, uint16_t payload_size) {
    (void)arg;
    (void)msg_type;
    (void)payload;
    (void)payload_size;
    /* Ничего не делаем — legacy on_metrics вызывается автоматически ниже */
}

int etcpmon_client_process(struct etcpmon_client* client) {
    if (!client || client->sock == INVALID_SOCKET) return -1;

    /* Проверка завершения non-blocking connect */
    if (client->connected && !client->fully_connected) {
        fd_set writable, failed;
        FD_ZERO(&writable);
        FD_ZERO(&failed);
        FD_SET(client->sock, &writable);
        FD_SET(client->sock, &failed);
        struct timeval timeout = {0, 0};
        int ready = select(0, NULL, &writable, &failed, &timeout);
        if (ready == 0) return 0;
        int error = 0;
        int len = sizeof(error);
        if (ready > 0 && getsockopt(client->sock, SOL_SOCKET, SO_ERROR, (char*)&error, &len) == 0) {
            if (error == 0) {
                client->fully_connected = 1;
                if (client->log_file) {
                    fprintf(client->log_file, "%llu: [LOG] Connection established\n",
                           (unsigned long long)get_timestamp_ms());
                    fflush(client->log_file);
                }
                if (client->on_connected) {
                    client->on_connected(client->user_data);
                }
                return 0;
            } else if (error == WSAEINPROGRESS || error == WSAEALREADY) {
                return 0;
            } else {
                if (client->log_file) {
                    fprintf(client->log_file, "%llu: [ERROR] Connect failed: %d\n",
                           (unsigned long long)get_timestamp_ms(), error);
                    fflush(client->log_file);
                }
                etcpmon_client_disconnect(client);
                if (client->on_disconnected) client->on_disconnected(client->user_data);
                if (client->on_error) {
                    char msg[256];
                    snprintf(msg, sizeof(msg), "Connect failed: %d", error);
                    client->on_error(msg, client->user_data);
                }
                return -1;
            }
        }
        if (client->log_file) {
            fprintf(client->log_file, "%llu: [ERROR] Failed to check connect completion: %d\n",
                    (unsigned long long)get_timestamp_ms(), WSAGetLastError());
            fflush(client->log_file);
        }
        etcpmon_client_disconnect(client);
        if (client->on_disconnected) client->on_disconnected(client->user_data);
        return -1;
    }

    /* Один запрос метрик в полёте; зависший сервер не раздувает очередь. */
    int metrics_pending = 0;
    DWORD tick = GetTickCount();
    for (struct etcpmon_pending_request* req = client->pending_head; req; req = req->next) {
        if (tick - req->sent_at >= REQUEST_TIMEOUT_MS) {
            if (client->log_file) {
                fprintf(client->log_file, "%llu: [ERROR] Response timeout: type=0x%02X seq=%u elapsed=%lu ms\n",
                        (unsigned long long)get_timestamp_ms(), req->type, req->seq_id, (unsigned long)(tick - req->sent_at));
                fflush(client->log_file);
            }
            etcpmon_client_disconnect(client);
            if (client->on_disconnected) client->on_disconnected(client->user_data);
            return -1;
        }
        if (req->type == ETCPMON_CMD_GET_METRICS) metrics_pending = 1;
    }

    /* Авто-запрос метрик каждые 100 мс (асинхронно) */
    if (client->fully_connected && client->selected_peer_id != 0 && !metrics_pending) {
        uint64_t now = GetTickCount64();
        if (now - client->last_metrics_request_ms >= ETCPMON_UPDATE_INTERVAL_MS) {
            if (etcpmon_client_send_request(client, ETCPMON_CMD_GET_METRICS, NULL, 0, metrics_auto_callback, NULL) != 0) {
                etcpmon_client_disconnect(client);
                if (client->on_disconnected) client->on_disconnected(client->user_data);
                return -1;
            }
            client->last_metrics_request_ms = now;
        }
    }

    /* Приём данных */
    uint8_t* buf = client->recv_buffer + client->recv_len;
    int buf_space = ETCPMON_MAX_MSG_SIZE - client->recv_len;
    if (buf_space <= 0) {
        client->recv_len = 0;           /* защита от переполнения */
        buf = client->recv_buffer;
        buf_space = ETCPMON_MAX_MSG_SIZE;
    }

    int received = recv(client->sock, (char*)buf, buf_space, 0);

    if (received == SOCKET_ERROR) {
        int err = WSAGetLastError();
        if (err == WSAEWOULDBLOCK) return 0;
        if (client->log_file) {
            fprintf(client->log_file, "%llu: [ERROR] recv failed: %d\n",
                   (unsigned long long)get_timestamp_ms(), err);
            fflush(client->log_file);
        }
        etcpmon_client_disconnect(client);
        if (client->on_disconnected) client->on_disconnected(client->user_data);
        return -1;
    }

    if (received == 0) {
        if (client->log_file) {
            fprintf(client->log_file, "%llu: [LOG] Connection closed by server\n",
                   (unsigned long long)get_timestamp_ms());
            fflush(client->log_file);
        }
        etcpmon_client_disconnect(client);
        if (client->on_disconnected) client->on_disconnected(client->user_data);
        return -1;
    }

    if (client->log_file) {
        fprintf(client->log_file, "%llu: [LOG] Received %d bytes (offset=%d)\n",
               (unsigned long long)get_timestamp_ms(), received, client->recv_len);
        log_hex_data(client->log_file, "RX", buf, received);
    }

    client->recv_len += received;

    /* === ОСНОВНОЙ ПАРСЕР (ИСПРАВЛЕННЫЙ) === */
    int processed = 0;
    while (client->recv_len >= sizeof(struct etcpmon_msg_header)) {
        struct etcpmon_msg_header* hdr = (struct etcpmon_msg_header*)client->recv_buffer;

        /* Валидация */
        if (etcpmon_validate_header(hdr) != 0) {
            if (client->log_file) {
                fprintf(client->log_file, "%llu: [ERROR] Invalid header, skipping byte %02X\n",
                       (unsigned long long)get_timestamp_ms(), client->recv_buffer[0]);
                fflush(client->log_file);
            }
            memmove(client->recv_buffer, client->recv_buffer + 1, client->recv_len - 1);
            client->recv_len--;
            continue;
        }

        /* hdr->size — это ПОЛНЫЙ размер сообщения (header + payload) */
        uint16_t total_size = hdr->size;
        if (client->recv_len < total_size) {
            break; /* ждём остаток */
        }

        uint16_t payload_size = total_size - sizeof(*hdr);
        uint8_t* payload = client->recv_buffer + sizeof(*hdr);

        client->last_response_seq_id = hdr->seq_id;

        if (client->log_file) {
            fprintf(client->log_file, "%llu: [LOG] Parsed message type=0x%02X total=%d payload=%d seq=%d\n",
                   (unsigned long long)get_timestamp_ms(), hdr->type, total_size, payload_size, hdr->seq_id);
            fflush(client->log_file);
        }

        handle_response_with_callback(client, hdr->type, payload, payload_size);
        if (!client->connected) return -1;
        processed++;

        /* Удаляем обработанное сообщение */
        if (client->recv_len > total_size) {
            memmove(client->recv_buffer, client->recv_buffer + total_size,
                    client->recv_len - total_size);
        }
        client->recv_len -= total_size;
    }

    return processed;
}

void etcpmon_client_set_callbacks(struct etcpmon_client* client,
                                   void (*on_connected)(void*),
                                   void (*on_disconnected)(void*),
                                   void (*on_conn_list)(struct etcpmon_conn_info*, uint8_t, void*),
                                   void (*on_socket_list)(struct etcpmon_socket_info*, uint8_t, void*),
                                   void (*on_metrics)(struct etcpmon_rsp_metrics*,
                                                      struct etcpmon_link_metrics*,
                                                      uint8_t, void*),
                                   void (*on_error)(const char*, void*),
                                   void (*on_action_result)(const char*, void*),
                                   void* user_data) {
    if (!client) return;

    client->on_connected = on_connected;
    client->on_disconnected = on_disconnected;
    client->on_conn_list = on_conn_list;
    client->on_socket_list = on_socket_list;
    client->on_metrics = on_metrics;
    client->on_error = on_error;
    client->on_action_result = on_action_result;
    client->user_data = user_data;
}

const char* etcpmon_client_get_conn_name(struct etcpmon_client* client, uint64_t peer_id) {
    if (!client || !client->conn_list) return NULL;
    
    for (uint8_t i = 0; i < client->conn_count; i++) {
        if (client->conn_list[i].peer_node_id == peer_id) {
            return client->conn_list[i].name;
        }
    }
    return NULL;
}

struct metrics_history* etcpmon_client_get_history(struct etcpmon_client* client) {
    if (!client) return NULL;
    return &client->history;
}

static void debug_config_auto_callback(void* arg, uint8_t msg_type, const uint8_t* payload, uint16_t payload_size) {
    (void)arg; (void)msg_type; (void)payload; (void)payload_size;
}

int etcpmon_client_request_debug_config(struct etcpmon_client* client) {
    if (!client || client->sock == INVALID_SOCKET) return -1;
    return etcpmon_client_send_request(client, ETCPMON_CMD_GET_DEBUG_CONFIG, NULL, 0,
                                        debug_config_auto_callback, NULL);
}

int etcpmon_client_send_debug_config(struct etcpmon_client* client,
                                      uint8_t global_level, uint8_t count, const uint8_t* levels) {
    if (!client || client->sock == INVALID_SOCKET || !levels || count == 0 || count > ETCPMON_MAX_DEBUG_CATEGORIES) return -1;

    uint8_t payload[2 + ETCPMON_MAX_DEBUG_CATEGORIES];
    payload[0] = global_level;
    payload[1] = count;
    memcpy(payload + 2, levels, count);
    uint16_t payload_size = 2 + count;

    uint8_t buffer[sizeof(struct etcpmon_msg_header) + sizeof(payload)];
    struct etcpmon_msg_header* hdr = (struct etcpmon_msg_header*)buffer;
    etcpmon_build_header(hdr, payload_size, ETCPMON_CMD_SET_DEBUG_CONFIG, 0);
    memcpy(buffer + sizeof(*hdr), payload, payload_size);

    if (client->log_file) {
        fprintf(client->log_file, "%llu: [LOG] CMD_SET_DEBUG_CONFIG global=%d count=%d\n",
               (unsigned long long)get_timestamp_ms(), global_level, count);
        fflush(client->log_file);
    }

    int total_size = sizeof(*hdr) + payload_size;
    int sent = send(client->sock, (const char*)buffer, total_size, 0);
    if (sent != total_size) {
        if (client->log_file) {
            fprintf(client->log_file, "[ERROR] Failed to send debug config: sent=%d/%d error=%d\n",
                    sent, total_size, sent == SOCKET_ERROR ? WSAGetLastError() : 0);
            fflush(client->log_file);
        }
        etcpmon_client_disconnect(client);
        if (client->on_disconnected) client->on_disconnected(client->user_data);
        return -1;
    }
    client->debug_global_level = global_level;
    for (uint8_t i = 0; i < count; i++) client->debug_category_levels[i] = levels[i];
    return 0;
}

void etcpmon_client_add_to_history(struct etcpmon_client* client, struct etcpmon_rsp_metrics* metrics) {
    if (!client || !metrics) return;
    
    struct metrics_history* h = &client->history;
    int idx = h->head;
    
   /* BBR per-link metrics (use first link as representative) */
    if (client->last_links_count > 0 && client->last_links) {
        struct etcpmon_link_metrics* l = &client->last_links[0];
        h->values[GRAPH_METRIC_INFLIGHT_BYTES][idx] = l->inflight_bytes / 1024.f;
        h->values[GRAPH_METRIC_INFLIGHT_LIM][idx]   = l->inflight_lim_bytes / 1024.f;
        h->values[GRAPH_METRIC_MIN_RTT][idx]        = l->bbr_min_rtt_us / 1000.f;
        h->values[GRAPH_METRIC_BW_HI][idx]          = l->bbr_bw_hi / 125.f;
        h->values[GRAPH_METRIC_PACING_RATE][idx]    = l->bbr_pacing_rate / 125.f;
        h->values[GRAPH_METRIC_BW_LO][idx]          = l->bbr_bw_lo / 125.f;
        h->values[GRAPH_METRIC_INFLIGHT_HI][idx]     = l->bbr_inflight_hi / 1024.f;
        h->values[GRAPH_METRIC_BBR_MODE][idx]        = (float)l->bbr_mode;
    }
    
    h->head = (h->head + 1) % GRAPH_HISTORY_SIZE;
    if (h->count < GRAPH_HISTORY_SIZE) h->count++;

    if (client->log_file) {
        fprintf(client->log_file, "history updated: count=%d head=%d\n", h->count, h->head);
        fflush(client->log_file);
    }
}