#!/bin/bash
# Script de diagnóstico automático para red local
# Uso: ./diagnostico_red_local.sh [interface]
# Ejemplo: ./diagnostico_red_local.sh vmbr0

set -e

# Colores para output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m' # No Color

# Variables
INTERFACE="${1:-vmbr0}"
LOG_FILE="/tmp/diagnostico_red_local_$(date +%Y%m%d_%H%M%S).log"
REPORT_FILE="/tmp/reporte_red_local_$(date +%Y%m%d_%H%M%S).md"

# Funciones de utilidad
log() {
    echo -e "${BLUE}[INFO]${NC} $1" | tee -a "$LOG_FILE"
}

success() {
    echo -e "${GREEN}[SUCCESS]${NC} $1" | tee -a "$LOG_FILE"
}

warning() {
    echo -e "${YELLOW}[WARNING]${NC} $1" | tee -a "$LOG_FILE"
}

error() {
    echo -e "${RED}[ERROR]${NC} $1" | tee -a "$LOG_FILE"
}

check_dependencies() {
    local deps=("ip" "ping" "awk" "grep" "tee")
    local missing=()

    for dep in "${deps[@]}"; do
        if ! command -v "$dep" &> /dev/null; then
            missing+=("$dep")
        fi
    done

    if [ ${#missing[@]} -gt 0 ]; then
        error "Dependencias faltantes: ${missing[*]}"
        return 1
    fi

    # Dependencias opcionales
    if command -v "nmap" &> /dev/null; then
        HAS_NMAP=true
    else
        HAS_NMAP=false
        warning "nmap no encontrado. El escaneo de red será limitado."
    fi

    if command -v "jq" &> /dev/null; then
        HAS_JQ=true
    else
        HAS_JQ=false
    fi

    return 0
}

check_interface() {
    if ! ip link show "$INTERFACE" &> /dev/null; then
        error "Interfaz $INTERFACE no encontrada"
        echo "Interfaces disponibles:"
        ip link show | awk -F': ' '/^[0-9]+:/ {print $2}' | grep -v lo
        return 1
    fi

    if [ "$(cat /sys/class/net/"$INTERFACE"/operstate 2>/dev/null)" != "up" ]; then
        warning "Interfaz $INTERFACE no está activa (operstate: $(cat /sys/class/net/"$INTERFACE"/operstate 2>/dev/null))"
    fi

    return 0
}

get_interface_info() {
    log "Obteniendo información de la interfaz $INTERFACE..."

    echo "=== INFORMACIÓN DE INTERFAZ ===" | tee -a "$REPORT_FILE"
    ip addr show "$INTERFACE" | tee -a "$REPORT_FILE"
    echo "" | tee -a "$REPORT_FILE"

    # Extraer IPs configuradas
    IPS=$(ip addr show "$INTERFACE" | awk '/inet / {print $2}')
    if [ -z "$IPS" ]; then
        warning "No hay IPs configuradas en $INTERFACE"
    else
        success "IPs configuradas:"
        echo "$IPS" | while read -r ip; do
            echo "  - $ip"
        done | tee -a "$REPORT_FILE"
    fi
}

get_routing_info() {
    log "Obteniendo información de enrutamiento..."

    echo "=== TABLA DE RUTAS ===" | tee -a "$REPORT_FILE"
    ip route show | tee -a "$REPORT_FILE"
    echo "" | tee -a "$REPORT_FILE"

    # Detectar gateway predeterminado
    DEFAULT_GW=$(ip route show default | awk '/default/ {print $3}')
    if [ -n "$DEFAULT_GW" ]; then
        success "Gateway predeterminado: $DEFAULT_GW"
        echo "Gateway: $DEFAULT_GW" | tee -a "$REPORT_FILE"

        # Probar conectividad al gateway
        log "Probando conectividad al gateway $DEFAULT_GW..."
        if ping -c 3 -W 2 "$DEFAULT_GW" &> /dev/null; then
            success "Gateway alcanzable"
            echo "Gateway alcanzable: Sí" | tee -a "$REPORT_FILE"
        else
            warning "Gateway no alcanzable"
            echo "Gateway alcanzable: No" | tee -a "$REPORT_FILE"
        fi
    else
        warning "No se encontró gateway predeterminado"
        echo "Gateway: No encontrado" | tee -a "$REPORT_FILE"
    fi

    # Detectar subred local
    LOCAL_SUBNET=$(ip route show | grep "link src" | awk '{print $1}' | head -1)
    if [ -n "$LOCAL_SUBNET" ]; then
        success "Subred local detectada: $LOCAL_SUBNET"
        echo "Subred local: $LOCAL_SUBNET" | tee -a "$REPORT_FILE"
    else
        warning "No se pudo detectar subred local"
        echo "Subred local: No detectada" | tee -a "$REPORT_FILE"
    fi
}

check_dhcp_info() {
    log "Verificando información DHCP..."

    echo "=== INFORMACIÓN DHCP ===" | tee -a "$REPORT_FILE"

    # Verificar archivos de lease DHCP
    DHCP_FILES=("/var/lib/dhcp/dhclient.leases" "/var/lib/dhclient/dhclient.leases")
    for file in "${DHCP_FILES[@]}"; do
        if [ -f "$file" ]; then
            log "Analizando $file..."
            if grep -q "interface.*$INTERFACE" "$file" 2>/dev/null; then
                success "Se encontraron leases DHCP para $INTERFACE"
                echo "Archivo DHCP: $file" | tee -a "$REPORT_FILE"

                # Extraer información relevante
                grep -A10 -B2 "interface.*$INTERFACE" "$file" | \
                    grep -E "(lease|starts|ends|option|fixed-address)" | \
                    head -20 | tee -a "$REPORT_FILE"
                break
            fi
        fi
    done

    if ! grep -q "Archivo DHCP:" "$REPORT_FILE"; then
        warning "No se encontraron leases DHCP para $INTERFACE"
        echo "DHCP: No se encontraron leases" | tee -a "$REPORT_FILE"
    fi

    echo "" | tee -a "$REPORT_FILE"
}

scan_local_network() {
    if [ -z "$LOCAL_SUBNET" ]; then
        warning "No se puede escanear red local (subred no detectada)"
        return 1
    fi

    log "Escaneando red local $LOCAL_SUBNET..."

    echo "=== ESCANEO DE RED LOCAL ===" | tee -a "$REPORT_FILE"

    if [ "$HAS_NMAP" = true ]; then
        # Escaneo rápido con nmap
        log "Ejecutando escaneo rápido con nmap..."
        nmap -sn "$LOCAL_SUBNET" 2>/dev/null | \
            grep "Nmap scan report" | \
            head -20 | \
            tee -a "$REPORT_FILE"

        # Contar dispositivos
        DEVICE_COUNT=$(nmap -sn "$LOCAL_SUBNET" 2>/dev/null | grep "Nmap scan report" | wc -l)
        success "Dispositivos detectados: $DEVICE_COUNT"
        echo "Total dispositivos: $DEVICE_COUNT" | tee -a "$REPORT_FILE"
    else
        # Método alternativo usando ping y arp
        warning "Usando método básico de detección (sin nmap)..."

        # Ping a broadcast (puede no funcionar en todas las redes)
        log "Probando detección básica..."
        ping -c 2 -b "$(echo "$LOCAL_SUBNET" | cut -d'/' -f1 | sed 's/0$/255/')" &> /dev/null || true

        # Mostrar tabla ARP
        ip neigh show | grep -v "FAILED" | \
            head -20 | \
            tee -a "$REPORT_FILE"

        DEVICE_COUNT=$(ip neigh show | grep -v "FAILED" | wc -l)
        echo "Dispositivos en tabla ARP: $DEVICE_COUNT" | tee -a "$REPORT_FILE"
    fi

    echo "" | tee -a "$REPORT_FILE"
}

check_tailscale() {
    log "Verificando estado de Tailscale..."

    echo "=== ESTADO TAILSCALE ===" | tee -a "$REPORT_FILE"

    if command -v tailscale &> /dev/null; then
        tailscale status 2>/dev/null | tee -a "$REPORT_FILE"

        # Extraer IP de Tailscale
        TAILSCALE_IP=$(tailscale status --json 2>/dev/null | \
            $([ "$HAS_JQ" = true ] && echo "jq -r '.Self.TailscaleIPs[0]'" || echo "grep -oE '100\.[0-9]+\.[0-9]+\.[0-9]+' | head -1"))

        if [ -n "$TAILSCALE_IP" ]; then
            success "Tailscale IP: $TAILSCALE_IP"
            echo "IP Tailscale: $TAILSCALE_IP" | tee -a "$REPORT_FILE"
        else
            warning "Tailscale no parece estar conectado"
            echo "Tailscale: No conectado" | tee -a "$REPORT_FILE"
        fi
    else
        warning "Tailscale no está instalado"
        echo "Tailscale: No instalado" | tee -a "$REPORT_FILE"
    fi

    echo "" | tee -a "$REPORT_FILE"
}

generate_recommendations() {
    log "Generando recomendaciones..."

    echo "=== RECOMENDACIONES ===" | tee -a "$REPORT_FILE"

    # Recomendación de IP local
    if [ -n "$LOCAL_SUBNET" ]; then
        BASE_NET=$(echo "$LOCAL_SUBNET" | cut -d'/' -f1 | cut -d'.' -f1-3)

        echo "Para configuración local entre srv-dasu y pc-dasu0:" | tee -a "$REPORT_FILE"
        echo "" | tee -a "$REPORT_FILE"
        echo "1. **IPs recomendadas (fuera de rango DHCP común):**" | tee -a "$REPORT_FILE"
        echo "   - srv-dasu: ${BASE_NET}.205/24" | tee -a "$REPORT_FILE"
        echo "   - pc-dasu0: ${BASE_NET}.100/24" | tee -a "$REPORT_FILE"
        echo "" | tee -a "$REPORT_FILE"
        echo "2. **Configuración de red:**" | tee -a "$REPORT_FILE"
        echo "   - Gateway: $(echo "$DEFAULT_GW" || echo "[gateway-del-router]")" | tee -a "$REPORT_FILE"
        echo "   - Máscara: 255.255.255.0 (/24)" | tee -a "$REPORT_FILE"
        echo "   - DNS Primario: 10.0.100.10 (dc-dasuten)" | tee -a "$REPORT_FILE"
        echo "   - DNS Secundario: 8.8.8.8" | tee -a "$REPORT_FILE"
        echo "" | tee -a "$REPORT_FILE"
        echo "3. **Verificaciones previas:**" | tee -a "$REPORT_FILE"
        echo "   - Confirmar que ${BASE_NET}.205 y ${BASE_NET}.100 no están en uso" | tee -a "$REPORT_FILE"
        echo "   - Verificar que el firewall permite ICMP y puertos necesarios" | tee -a "$REPORT_FILE"
        echo "   - Tailscale debe permanecer activo como respaldo" | tee -a "$REPORT_FILE"
    else
        echo "No se pudo generar recomendaciones específicas (subred no detectada)" | tee -a "$REPORT_FILE"
        echo "" | tee -a "$REPORT_FILE"
        echo "Recomendaciones generales:" | tee -a "$REPORT_FILE"
        echo "1. Identificar manualmente la subred del router ISP" | tee -a "$REPORT_FILE"
        echo "2. Usar IPs estáticas fuera del rango DHCP del router" | tee -a "$REPORT_FILE"
        echo "3. Mantener Tailscale como ruta de failover" | tee -a "$REPORT_FILE"
    fi

    echo "" | tee -a "$REPORT_FILE"
}

generate_summary() {
    echo "=== RESUMEN DEL DIAGNÓSTICO ===" | tee -a "$REPORT_FILE"
    echo "Fecha: $(date)" | tee -a "$REPORT_FILE"
    echo "Hostname: $(hostname)" | tee -a "$REPORT_FILE"
    echo "Interfaz analizada: $INTERFACE" | tee -a "$REPORT_FILE"
    echo "Estado interfaz: $(cat /sys/class/net/"$INTERFACE"/operstate 2>/dev/null || echo "desconocido")" | tee -a "$REPORT_FILE"
    echo "Gateway: ${DEFAULT_GW:-No detectado}" | tee -a "$REPORT_FILE"
    echo "Subred local: ${LOCAL_SUBNET:-No detectada}" | tee -a "$REPORT_FILE"
    echo "Tailscale: $(if command -v tailscale &> /dev/null; then echo "Instalado"; else echo "No instalado"; fi)" | tee -a "$REPORT_FILE"
    echo "" | tee -a "$REPORT_FILE"
    echo "Archivos generados:" | tee -a "$REPORT_FILE"
    echo "  - Log detallado: $LOG_FILE" | tee -a "$REPORT_FILE"
    echo "  - Reporte completo: $REPORT_FILE" | tee -a "$REPORT_FILE"
}

main() {
    echo "========================================="
    echo "  DIAGNÓSTICO DE RED LOCAL - srv-dasu"
    echo "========================================="
    echo ""

    # Inicializar archivos
    > "$LOG_FILE"
    > "$REPORT_FILE"

    # Verificar dependencias
    if ! check_dependencies; then
        exit 1
    fi

    # Verificar interfaz
    if ! check_interface; then
        exit 1
    fi

    # Ejecutar diagnósticos
    get_interface_info
    get_routing_info
    check_dhcp_info
    scan_local_network
    check_tailscale
    generate_recommendations
    generate_summary

    echo ""
    success "Diagnóstico completado exitosamente"
    echo ""
    echo "Para configurar IP local en $INTERFACE, edite:"
    echo "  sudo nano /etc/network/interfaces"
    echo ""
    echo "Agregue las líneas (adaptando la IP según recomendaciones):"
    echo "    post-up ip addr add 192.168.1.205/24 dev $INTERFACE"
    echo "    pre-down ip addr del 192.168.1.205/24 dev $INTERFACE"
    echo ""
    echo "Luego reinicie el servicio de red:"
    echo "  sudo systemctl restart networking"
}

# Ejecutar script principal
main "$@"