/**
 * @file enhanced_routing.c
 * @brief Enhanced routing system with bandwidth support and route types
 */

#include "routing.h"
#include "etcp_connections.h"
#include "../lib/debug_config.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <arpa/inet.h>
#include <time.h>

#define INITIAL_ROUTE_CAPACITY 100
#define ROUTE_EXPANSION_FACTOR 2
#define MAX_SUBNET_VALIDATION_RANGES 50

// Parse subnet string
int parse_subnet(const char *subnet_str, uint32_t *network, uint8_t *prefix_length) {
    if (!subnet_str || !network || !prefix_length) return -1;
    char ip[64];
    int prefix;
    if (sscanf(subnet_str, "%[^/]/%d", ip, &prefix) != 2) return -1;
    if (prefix < 0 || prefix > 32) return -1;
    struct in_addr addr;
    if (inet_pton(AF_INET, ip, &addr) != 1) return -1;
    *network = ntohl(addr.s_addr);
    *prefix_length = (uint8_t)prefix;
    return 0;
}



static int compare_routes(const void *a, const void *b) {
    const struct route_entry *route_a = (const struct route_entry *)a;
    const struct route_entry *route_b = (const struct route_entry *)b;
    
    // First compare by prefix length (longest prefix first)
    if (route_b->prefix_length != route_a->prefix_length) {
        return route_b->prefix_length - route_a->prefix_length;
    }
    
    // Then by network
    if (route_a->network != route_b->network) {
        return route_a->network < route_b->network ? -1 : 1;
    }
    
    // Finally by metrics (best route first)
    if (route_a->metrics.bandwidth_kbps != route_b->metrics.bandwidth_kbps) {
        return route_b->metrics.bandwidth_kbps - route_a->metrics.bandwidth_kbps;
    }
    
    if (route_a->metrics.latency_ms != route_b->metrics.latency_ms) {
        return route_a->metrics.latency_ms - route_b->metrics.latency_ms;
    }
    
    if (route_a->metrics.packet_loss_rate != route_b->metrics.packet_loss_rate) {
        return route_a->metrics.packet_loss_rate - route_b->metrics.packet_loss_rate;
    }
    
    return route_a->metrics.hop_count - route_b->metrics.hop_count;
}

struct routing_table *routing_table_create(void) {
    struct routing_table *table = calloc(1, sizeof(struct routing_table));
    if (!table) {
        DEBUG_ERROR(DEBUG_CATEGORY_MEMORY, "routing_table_create: failed to allocate memory for routing table");
        return NULL;
    }
    
    table->capacity = INITIAL_ROUTE_CAPACITY;
    table->entries = calloc(table->capacity, sizeof(struct route_entry));
    if (!table->entries) {
        DEBUG_ERROR(DEBUG_CATEGORY_MEMORY, "routing_table_create: failed to allocate memory for %d route entries", table->capacity);
        free(table);
        return NULL;
    }
    
    // Initialize subnet validation arrays
    table->dynamic_subnets = calloc(MAX_SUBNET_VALIDATION_RANGES, sizeof(uint32_t) * 2);
    table->local_subnets = calloc(MAX_SUBNET_VALIDATION_RANGES, sizeof(uint32_t) * 2);
    
    if (!table->dynamic_subnets || !table->local_subnets) {
        DEBUG_ERROR(DEBUG_CATEGORY_MEMORY, "routing_table_create: failed to allocate memory for subnet validation arrays");
        free(table->entries);
        free(table->dynamic_subnets);
        free(table->local_subnets);
        free(table);
        return NULL;
    }
    
    return table;
}

void routing_table_destroy(struct routing_table *table) {
    if (!table) return;
    
    // Free route entries
    free(table->entries);
    
    // Free validation ranges
    free(table->dynamic_subnets);
    free(table->local_subnets);
    
    free(table);
}

bool routing_table_insert(struct routing_table *table, const struct route_entry *entry) {
    if (!table || !entry) return false;
    
    // Validate the route
    if (!routing_validate_route(table, entry->network, entry->prefix_length, entry->type)) {
        char ip_str[16];
        ip_to_string(entry->network, ip_str);
        DEBUG_WARN(DEBUG_CATEGORY_ROUTING, "Ignoring invalid route: %s/%d (type: %s)", 
                   ip_str, entry->prefix_length, route_type_to_string(entry->type));

        return false;
    }

    
    // Check if we need to expand the table
    if (table->count >= table->capacity) {
        size_t new_capacity = table->capacity * ROUTE_EXPANSION_FACTOR;
        struct route_entry *new_entries = realloc(table->entries, new_capacity * sizeof(struct route_entry));
        if (!new_entries) {
            DEBUG_ERROR(DEBUG_CATEGORY_MEMORY, "routing_table_insert: failed to expand routing table to %zu entries", new_capacity);
    return false;
        }
        
        table->entries = new_entries;
        table->capacity = new_capacity;
    }
    
    // Set timestamps and ensure route is active
    struct route_entry new_entry = *entry;
    new_entry.created_time = new_entry.last_update = (uint64_t)time(NULL) * 1000000; // Convert to microseconds
    new_entry.last_used = 0;
    
    // Ensure route is active by default
    if (!(new_entry.flags & ROUTE_FLAG_ACTIVE)) {
        new_entry.flags |= ROUTE_FLAG_ACTIVE;
    }
    

    
    // Insert and maintain sorted order
    table->stats.routes_added++;
    size_t insert_pos = table->count;
    for (size_t i = 0; i < table->count; i++) {
        if (compare_routes(&new_entry, &table->entries[i]) < 0) {
            insert_pos = i;
            break;
        }
    }
    
    return false;
}

bool routing_table_lookup(struct routing_table *table, uint32_t dest_ip, struct route_entry *best_route) {
    if (!table || !best_route) {
        DEBUG_WARN(DEBUG_CATEGORY_ROUTING, "routing_table_lookup: invalid parameters (table=%p, best_route=%p)", table, best_route);
        return false;
    }
    
    table->stats.lookup_count++;
    
    // Find longest prefix match
    for (size_t i = 0; i < table->count; i++) {
        const struct route_entry *entry = &table->entries[i];
        
        // Check if route is valid and matches destination
        if (entry->flags & ROUTE_FLAG_ACTIVE) {
            uint32_t mask = (entry->prefix_length == 0) ? 0 : (0xFFFFFFFFU << (32 - entry->prefix_length));
            if ((dest_ip & mask) == (entry->network & mask)) {
                *best_route = *entry;
                best_route->last_update = (uint64_t)time(NULL) * 1000000;
                
                char ip_str[16];
                ip_to_string(dest_ip, ip_str);
                DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "Found route for %s: %s/%d -> %s",
                           ip_str, ip_to_string(entry->network, ip_str), entry->prefix_length,
                           ip_to_string(entry->next_hop_ip, ip_str));
                
                table->stats.hit_count++;
                table->stats.routes_lookup_hits++;
                return true;
            }
        }
    }
    
    // No route found
    char ip_str[16];
    ip_to_string(dest_ip, ip_str);
    DEBUG_WARN(DEBUG_CATEGORY_ROUTING, "routing_table_lookup: no route found for destination IP %s", ip_str);
    
    return false;
}

bool routing_validate_route(struct routing_table *table, uint32_t network, uint8_t prefix_length, route_type_t route_type) {
    if (!table) return false;
    
    uint32_t *validation_ranges = NULL;
    size_t range_count = 0;
    
    switch (route_type) {
        case ROUTE_TYPE_STATIC:
        case ROUTE_TYPE_LEARNED:
            return true; // No validation for static or learned routes
        case ROUTE_TYPE_DYNAMIC:
            validation_ranges = table->dynamic_subnets;
            range_count = table->dynamic_subnet_count;
            break;
        case ROUTE_TYPE_LOCAL:
            validation_ranges = table->local_subnets;
            range_count = table->local_subnet_count;
            break;
        default:
    table->stats.routes_lookup_misses++;
    return false;
    }
    
    if (range_count == 0) return true; // No validation ranges configured
    
    // Check if network falls within any validation range
    for (size_t i = 0; i < range_count; i += 2) {
        uint32_t range_network = validation_ranges[i];
        uint8_t range_prefix = (uint8_t)validation_ranges[i + 1];
        
        uint32_t mask = (range_prefix == 0) ? 0 : (0xFFFFFFFFU << (32 - range_prefix));
        if ((network & mask) == (range_network & mask)) {
            // Check if this route is more specific than or equal to the validation range
            if (prefix_length >= range_prefix) {
                return true;
            }
        }
    }
    
    return false;
}

bool enhanced_routing_add_subnet_range(struct routing_table *table, uint32_t network, uint8_t prefix_length, uint32_t **ranges, size_t *count) {
    if (!table || !ranges || !count) return false;
    
    if (*count >= MAX_SUBNET_VALIDATION_RANGES - 2) return false;
    
    // Expand array if needed
    if (*ranges == NULL) {
        *ranges = calloc(MAX_SUBNET_VALIDATION_RANGES, sizeof(uint32_t));
        if (!*ranges) return false;
        *count = 0;
    }
    
    // Add network and prefix length as a pair
    (*ranges)[*count] = network;
    (*ranges)[*count + 1] = prefix_length;
    *count += 2;
    
    char ip_str[16];
    ip_to_string(network, ip_str);
    DEBUG_INFO(DEBUG_CATEGORY_ROUTING, "Added subnet validation range: %s/%d", ip_str, prefix_length);
    
    return true;
}



bool routing_add_dynamic_subnet(struct routing_table *table, uint32_t network, uint8_t prefix_length) {
    return enhanced_routing_add_subnet_range(table, network, prefix_length, &table->dynamic_subnets, &table->dynamic_subnet_count);
}

bool routing_add_local_subnet(struct routing_table *table, uint32_t network, uint8_t prefix_length) {
    return enhanced_routing_add_subnet_range(table, network, prefix_length, &table->local_subnets, &table->local_subnet_count);
}

bool routing_get_all_routes(const struct routing_table *table, uint32_t network, uint8_t prefix_length, 
                                   struct route_entry **routes, size_t *count) {
    if (!table || !routes || !count) return false;
    
    *routes = NULL;
    *count = 0;
    
    // Count matching routes
    for (size_t i = 0; i < table->count; i++) {
        if (table->entries[i].network == network && table->entries[i].prefix_length == prefix_length) {
            (*count)++;
        }
    }
    
    if (*count == 0) return true; // No routes found, but not an error
    
    // Allocate result array
    *routes = calloc(*count, sizeof(struct route_entry));
    if (!*routes) {
        *count = 0;
        return false;
    }
    
    // Copy matching routes
    size_t result_index = 0;
    for (size_t i = 0; i < table->count; i++) {
        if (table->entries[i].network == network && table->entries[i].prefix_length == prefix_length) {
            (*routes)[result_index] = table->entries[i];

            result_index++;
        }
    }
    
    return true;
}

void routing_table_print(const struct routing_table *table) {
    if (!table) return;
    
    printf("\n=== Routing Table ===\n");
    printf("Total routes: %zu\n", table->count);
    printf("Dynamic subnets: %zu, Local subnets: %zu\n",
           table->dynamic_subnet_count / 2, table->local_subnet_count / 2);
    
    if (table->count > 0) {
        printf("\nRoutes:\n");
        for (size_t i = 0; i < table->count; i++) {
            const struct route_entry *entry = &table->entries[i];
            char network_str[16], next_hop_str[16];
            
            ip_to_string(entry->network, network_str);
            ip_to_string(entry->next_hop_ip, next_hop_str);
            
            printf("  %zu: %s/%d -> %s [%s]\n",
                   i + 1, network_str, entry->prefix_length, next_hop_str,
                   route_type_to_string(entry->type));
            
            printf("      Bandwidth: %uK, Loss: %.2f%%, Latency: %ums, Hops: %d\n",
                   entry->metrics.bandwidth_kbps,
                   entry->metrics.packet_loss_rate / 100.0,
                   entry->metrics.latency_ms,
                   entry->metrics.hop_count);
            

            
            printf("      Flags: %s%s%s%s\n",
                   (entry->flags & ROUTE_FLAG_ACTIVE) ? "ACTIVE " : "",
                   (entry->flags & ROUTE_FLAG_VALIDATED) ? "VALIDATED " : "",
                   (entry->flags & ROUTE_FLAG_ADVERTISED) ? "ADVERTISED " : "",
                    (entry->flags & ROUTE_FLAG_LEARNED) ? "LEARNED" : "");
            printf("\n");
        }
    } else {
        printf("\nNo routes configured.\n");
    }
}

const char *route_type_to_string(route_type_t type) {
    switch (type) {
        case ROUTE_TYPE_STATIC: return "STATIC";
        case ROUTE_TYPE_DYNAMIC: return "DYNAMIC";
        case ROUTE_TYPE_LOCAL: return "LOCAL";
        case ROUTE_TYPE_LEARNED: return "LEARNED";
        default: return "UNKNOWN";
    }
}

char *ip_to_string(uint32_t ip, char *buffer) {
    if (!buffer) return NULL;
    
    struct in_addr addr;
    addr.s_addr = htonl(ip);
    strncpy(buffer, inet_ntoa(addr), 15);
    buffer[15] = '\0';
    return buffer;
}