// utun_instance.c - Root instance implementation
#include "utun_instance.h"
#include "config_parser.h"
#include "config_updater.h"
#include "tun_if.h"
#include "tun_route.h"
#include "route_lib.h"
#include "routing.h"
#include "route_bgp.h"
#include "etcp_connections.h"
#include "etcp.h"
#include "../lib/u_async.h"
#include "../lib/debug_config.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include "../lib/platform_compat.h"



// Forward declarations
static uint32_t get_dest_ip(const uint8_t *packet, size_t len);

// Global instance for signal handlers
static struct UTUN_INSTANCE *g_instance = NULL;

// Global flag to control TUN initialization (disabled by default)
static int g_tun_init_enabled = 0;

// Function to control TUN initialization
void utun_instance_set_tun_init_enabled(int enabled) {
    g_tun_init_enabled = enabled ? 1 : 0;
    DEBUG_INFO(DEBUG_CATEGORY_TUN, "TUN initialization %s", enabled ? "enabled" : "disabled");
}

// Common initialization function (called by both create functions)
// Returns 0 on success, -1 on error (instance is NOT freed on error - caller must handle)
static int instance_init_common(struct UTUN_INSTANCE* instance, struct UASYNC* ua, struct utun_config* config) {
    // Initialize basic fields
    instance->running = 0;
    instance->ua = ua;
    instance->config = config;
    
    // Set node_id from config
    instance->node_id = config->global.my_node_id;
    
    // Set my keys
    if (sc_init_local_keys(&instance->my_keys, config->global.my_public_key_hex, config->global.my_private_key_hex) != SC_OK) {
        DEBUG_ERROR(DEBUG_CATEGORY_MEMORY, "Failed to initialize local keys");
        return -1;
    }
    
    // Create memory pools
    instance->ack_pool = memory_pool_init(sizeof(struct ACK_PACKET));
    instance->data_pool = memory_pool_init(PACKET_DATA_SIZE);
    instance->pkt_pool = memory_pool_init(sizeof(struct ETCP_DGRAM) + PACKET_DATA_SIZE);
    
    // Create routing module
    if (routing_create(instance) != 0) {
        DEBUG_ERROR(DEBUG_CATEGORY_MEMORY, "Failed to create routing module");
        return -1;
    }
    DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "Routing module created");
    
    // Add local subnets from config as static routes
    struct CFG_ROUTE_ENTRY* subnet = config->my_subnets;
    while (subnet) {
        struct ROUTE_ENTRY entry = {0};
        entry.network = ntohl(subnet->ip.addr.v4.s_addr);  // Convert network byte order to host
        entry.prefix_length = subnet->netmask;
        entry.next_hop = NULL;  // Local route
        entry.type = ROUTE_TYPE_LOCAL;
        entry.flags = ROUTE_FLAG_ACTIVE | ROUTE_FLAG_VALIDATED;
        entry.metrics.bandwidth_kbps = UINT32_MAX;  // Unlimited
        entry.metrics.latency_ms = 0;
        entry.metrics.packet_loss_rate = 0;
        entry.metrics.hop_count = 0;
        
        if (route_table_insert(instance->rt, &entry)) {
            char ip_str[INET_ADDRSTRLEN];
            struct in_addr addr;
            addr.s_addr = htonl(entry.network);  // Convert back to network byte order for printing
            inet_ntop(AF_INET, &addr, ip_str, sizeof(ip_str));
            DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "Added local route: %s/%d", 
                      ip_str, entry.prefix_length);
        } else {
            char ip_str[INET_ADDRSTRLEN];
            struct in_addr addr;
            addr.s_addr = htonl(entry.network);  // Convert back to network byte order for printing
            inet_ntop(AF_INET, &addr, ip_str, sizeof(ip_str));
            DEBUG_WARN(DEBUG_CATEGORY_ROUTING, "Failed to add local route: %s/%d (skipping)", 
                      ip_str, entry.prefix_length);
        }
        
        subnet = subnet->next;
    }
    
    // Initialize TUN device if enabled
    if (g_tun_init_enabled) {
        instance->tun = tun_init(ua, config);
        if (!instance->tun) {
            DEBUG_ERROR(DEBUG_CATEGORY_TUN, "Failed to initialize TUN device");
            return -1;
        }
        DEBUG_INFO(DEBUG_CATEGORY_TUN, "TUN interface initialized: %s", instance->tun->ifname);
        
        // Add system routes for route_subnets
        if (config->route_subnets) {
            int added = tun_route_add_all(instance->tun->ifname, config->route_subnets);
            DEBUG_INFO(DEBUG_CATEGORY_TUN, "Added %d system routes for TUN interface", added);
        }
    } else {
        DEBUG_INFO(DEBUG_CATEGORY_TUN, "TUN initialization disabled - skipping TUN device setup");
        instance->tun = NULL;
    }
    
    // Initialize BGP module for route exchange
    instance->bgp = route_bgp_init(instance);
    if (!instance->bgp) {
        DEBUG_ERROR(DEBUG_CATEGORY_BGP, "Failed to initialize BGP module");
        // Non-fatal: BGP is optional for basic operation
    } else {
        DEBUG_INFO(DEBUG_CATEGORY_BGP, "BGP module initialized");
    }
    
    return 0;
}

// Create and initialize root instance from config file
struct UTUN_INSTANCE* utun_instance_create(struct UASYNC* ua, const char *config_file) {
    // Ensure keys and node_id exist in config (generates them if missing)
    if (config_ensure_keys_and_node_id(config_file) < 0) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONFIG, "Failed to ensure keys and node_id in config: %s", config_file);
        return NULL;
    }
    
    // Load configuration
    struct utun_config* config = parse_config(config_file);
    if (!config) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONFIG, "Failed to load config from %s", config_file);
        return NULL;
    }
    
    // Open log file only if not using global debug system output
    if (config->global.log_file) {
        debug_set_output_file(config->global.log_file);
    }
    
    // Allocate instance
    struct UTUN_INSTANCE *instance = calloc(1, sizeof(struct UTUN_INSTANCE));
    if (!instance) {
        free_config(config);
        return NULL;
    }
    
    // Initialize using common function
    if (instance_init_common(instance, ua, config) != 0) {
        // Cleanup on error
        if (instance->config) free_config(instance->config);
        free(instance);
        return NULL;
    }
    
    return instance;
}

// Create instance from existing config structure (config ownership transfers to instance)
struct UTUN_INSTANCE* utun_instance_create_from_config(struct UASYNC* ua, struct utun_config* config) {
    if (!config) {
        DEBUG_ERROR(DEBUG_CATEGORY_CONFIG, "utun_instance_create_from_config: NULL config");
        return NULL;
    }
    
    // Allocate instance
    struct UTUN_INSTANCE *instance = calloc(1, sizeof(struct UTUN_INSTANCE));
    if (!instance) {
        DEBUG_ERROR(DEBUG_CATEGORY_MEMORY, "Failed to allocate UTUN_INSTANCE");
        return NULL;
    }
    
    // Initialize using common function (config ownership transferred to instance)
    if (instance_init_common(instance, ua, config) != 0) {
        // Cleanup on error - caller still owns config since we failed
        free(instance);
        return NULL;
    }
    
    return instance;
}

// Destroy instance and cleanup resources
void utun_instance_destroy(struct UTUN_INSTANCE *instance) {
    if (!instance) return;
    
    DEBUG_INFO(DEBUG_CATEGORY_MEMORY, "[INSTANCE_DESTROY] Starting cleanup for instance %p", instance);
    
    // Диагностика ресурсов ДО cleanup
    utun_instance_diagnose_leaks(instance, "BEFORE_CLEANUP");
    
    // Stop running if not already
    instance->running = 0;
    
    // Cleanup ETCP sockets and connections FIRST (before destroying uasync)
    DEBUG_INFO(DEBUG_CATEGORY_MEMORY, "[INSTANCE_DESTROY] Cleaning up ETCP sockets and connections");
    struct ETCP_SOCKET* sock = instance->etcp_sockets;
    while (sock) {
        struct ETCP_SOCKET* next = sock->next;
        DEBUG_INFO(DEBUG_CATEGORY_MEMORY, "[INSTANCE_DESTROY] Removing socket %p, fd=%d", sock, sock->fd);
        etcp_socket_remove(sock);  // Полный cleanup сокета
        sock = next;
    }
    instance->etcp_sockets = NULL;
    DEBUG_INFO(DEBUG_CATEGORY_MEMORY, "[INSTANCE_DESTROY] ETCP sockets cleanup complete");
    
    // Safe cleanup of ETCP connections with NULL pointer checks
    struct ETCP_CONN* conn = instance->connections;
    while (conn) {
        struct ETCP_CONN* next = conn->next;
        DEBUG_INFO(DEBUG_CATEGORY_MEMORY, "[INSTANCE_DESTROY] Closing connection %p", conn);
        if (conn) {  // Дополнительная проверка на случай поврежденного списка
            etcp_connection_close(conn);  // Закрыть соединение (с проверкой NULL внутри)
        }
        conn = next;
    }
    instance->connections = NULL;
    DEBUG_INFO(DEBUG_CATEGORY_MEMORY, "[INSTANCE_DESTROY] ETCP connections cleanup complete");
    
    // Cleanup TUN
    if (instance->tun) {
        DEBUG_INFO(DEBUG_CATEGORY_TUN, "Closing TUN interface: %s", instance->tun->ifname);
        
        // Flush all system routes for this interface
        tun_route_flush(instance->tun->ifname);
        DEBUG_INFO(DEBUG_CATEGORY_TUN, "Flushed system routes for %s", instance->tun->ifname);
        
        tun_close(instance->tun);
        instance->tun = NULL;
    }
    
    // Cleanup routing module
    routing_destroy(instance);
    
    // Cleanup BGP module
    if (instance->bgp) {
        DEBUG_INFO(DEBUG_CATEGORY_BGP, "Destroying BGP module");
        route_bgp_destroy(instance);
        instance->bgp = NULL;
    }
    
    // Cleanup config
    if (instance->config) {
        DEBUG_INFO(DEBUG_CATEGORY_MEMORY, "[INSTANCE_DESTROY] Freeing configuration");
        free_config(instance->config);
        instance->config = NULL;
    }
    
    // Cleanup packet pool (ensure no leak if stop wasn't called)
    if (instance->pkt_pool) {
        DEBUG_INFO(DEBUG_CATEGORY_MEMORY, "[INSTANCE_DESTROY] Destroying packet pool");
        memory_pool_destroy(instance->pkt_pool);
        instance->pkt_pool = NULL;
    }
    
    // Cleanup packet pool (ensure no leak if stop wasn't called)
    if (instance->ack_pool) {
        DEBUG_INFO(DEBUG_CATEGORY_MEMORY, "[INSTANCE_DESTROY] Destroying ack pool");
        memory_pool_destroy(instance->ack_pool);
        instance->ack_pool = NULL;
    }
    
    // Cleanup data pool
    if (instance->data_pool) {
        DEBUG_INFO(DEBUG_CATEGORY_MEMORY, "[INSTANCE_DESTROY] Destroying data pool");
        memory_pool_destroy(instance->data_pool);
        instance->data_pool = NULL;
    }
    
    // Note: uasync is NOT destroyed here - caller must destroy it separately
    // This allows sharing uasync between multiple instances
    instance->ua = NULL;
    
    // Clear global instance
    if (g_instance == instance) {
        g_instance = NULL;
    }
    
    // Free the instance memory
    DEBUG_INFO(DEBUG_CATEGORY_MEMORY, "[INSTANCE_DESTROY] Freeing instance memory");
    free(instance);
    DEBUG_INFO(DEBUG_CATEGORY_MEMORY, "[INSTANCE_DESTROY] Instance destroyed completely");
}

// Stop instance
void utun_instance_stop(struct UTUN_INSTANCE *instance) {
    if (!instance) return;
    instance->running = 0;
    // Wakeup main loop using built-in uasync wakeup
    if (instance->ua) {
        memory_pool_destroy(instance->pkt_pool);
        uasync_wakeup(instance->ua);
    }


}

int utun_instance_init(struct UTUN_INSTANCE *instance) {
    if (!instance) return -1;
    
    // Set TUN interface in routing module
    if (instance->tun) {
        routing_set_tun(instance);
        DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "TUN interface registered in routing module");
    }
    
    // Note: TUN socket is already registered in tun_init()
    
    // Initialize connections
    // Добавляем прямой вывод для отладки проблемы double free
    fprintf(stderr, "DEBUG: utun_instance_init() calling init_connections() for instance %p\n", instance);
    fflush(stderr);
    
    int conn_result = init_connections(instance);
    
    fprintf(stderr, "DEBUG: init_connections() returned: %d\n", conn_result);
    fflush(stderr);
    
    if (conn_result < 0) {
        fprintf(stderr, "DEBUG: Failed to initialize connections, returning error\n");
        fflush(stderr);
        return -1;
    }
    
    fprintf(stderr, "DEBUG: Connections initialized successfully, count=%d\n", instance->connections_count);
    fflush(stderr);
    
    // Start the main loop
    instance->running = 1;
    
    return 0;
}

// Диагностическая функция для анализа утечек
void utun_instance_diagnose_leaks(struct UTUN_INSTANCE *instance, const char *phase) {
    if (!instance) {
        DEBUG_ERROR(DEBUG_CATEGORY_MEMORY, "[DIAGNOSE] NULL instance for phase: %s", phase);
        return;
    }
    
    struct {
        int etcp_sockets_count;
        int etcp_connections_count;
        int etcp_links_count;
    } report = {0};
    
    // Подсчёт ETCP сокетов
    struct ETCP_SOCKET *sock = instance->etcp_sockets;
    while (sock) {
        report.etcp_sockets_count++;
        // Подсчёт линков в каждом сокете
        for (size_t i = 0; i < sock->num_channels; i++) {
            if (sock->links[i]) {
                report.etcp_links_count++;
            }
        }
        sock = sock->next;
    }
    
    // Подсчёт ETCP соединений
    struct ETCP_CONN *conn = instance->connections;
    while (conn) {
        report.etcp_connections_count++;
        // Подсчёт линков в соединениях
        struct ETCP_LINK *link = conn->links;
        while (link) {
            report.etcp_links_count++;
            link = link->next;
        }
        conn = conn->next;
    }
    
    printf("\n🔍 [UTUN_INSTANCE LEAK DIAGNOSIS] Phase: %s\n", phase);
    printf("   Instance: %p\n", instance);
    printf("   Node ID: %llu\n", (unsigned long long)instance->node_id);
    printf("   UA instance: %p\n", instance->ua);
    printf("   Running: %d\n", instance->running);
    
    printf("\n📊 STRUCTURE COUNTS:\n");
    printf("   ETCP Sockets: %d active\n", report.etcp_sockets_count);
    printf("   ETCP Connections: %d active\n", report.etcp_connections_count);
    printf("   ETCP Links: %d total\n", report.etcp_links_count);
    
    printf("\n🔧 RESOURCE STATUS:\n");
    printf("   Memory Pool: %s\n", instance->pkt_pool ? "ALLOCATED" : "NULL");
    printf("   TUN Interface: %s\n", instance->tun ? instance->tun->ifname : "NULL");
    printf("   TUN FD: %d\n", instance->tun ? instance->tun->fd : -1);
    printf("   Connections list: %p\n", instance->connections);
    printf("   ETCP Sockets list: %p\n", instance->etcp_sockets);
    
    printf("\n⚠️  POTENTIAL LEAKS:\n");
    if (instance->pkt_pool) {
        printf("   ❌ Memory Pool not freed\n");
    }
    if (instance->tun) {
        printf("   ❌ TUN interface not closed\n");
    }
    if (report.etcp_sockets_count > 0) {
        printf("   ❌ %d ETCP sockets still allocated\n", report.etcp_sockets_count);
    }
    if (report.etcp_connections_count > 0) {
        printf("   ❌ %d ETCP connections still allocated\n", report.etcp_connections_count);
    }
    if (report.etcp_links_count > 0) {
        printf("   ❌ %d ETCP links still allocated\n", report.etcp_links_count);
    }
    
    printf("\n📋 RECOMMENDATIONS:\n");
    if (instance->pkt_pool) {
        printf("   → Call memory_pool_destroy() before freeing instance\n");
    }
    if (instance->tun) {
        printf("   → Call tun_close() to close TUN interface\n");
    }
    if (report.etcp_sockets_count > 0) {
        printf("   → Iterate and call etcp_socket_remove() for each socket\n");
    }
    if (report.etcp_connections_count > 0) {
        printf("   → Iterate and call etcp_connection_close() for each connection\n");
    }
    
    printf("\n");
}