#!/bin/bash

# Script configuration
SCRIPT_VERSION="1.0.0"
SCRIPT_LOG_FILE="/var/log/server_setup.log"
BACKUP_DIR="/var/backups/server_setup"
MYSQL_ROOT_PASSWORD=$(openssl rand -base64 16)
PROMETHEUS_VERSION="2.37.0"
NODE_EXPORTER_VERSION="1.3.1"

# Color codes for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m' # No Color

# Logging function
log() {
    local level=$1
    shift
    local message=$@
    local timestamp=$(date '+%Y-%m-%d %H:%M:%S')
    echo -e "${timestamp} [${level}] ${message}" | tee -a ${SCRIPT_LOG_FILE}
}

# Error handling function
handle_error() {
    local exit_code=$?
    local line_number=$1
    if [ $exit_code -ne 0 ]; then
        log "ERROR" "Failed at line ${line_number} with exit code ${exit_code}"
        exit $exit_code
    fi
}
trap 'handle_error ${LINENO}' ERR

# System health check function
check_system_health() {
    log "INFO" "Performing system health checks..."

    # Check disk space
    local disk_usage=$(df -h / | awk 'NR==2 {print $5}' | sed 's/%//')
    if [ $disk_usage -gt 85 ]; then
        log "WARNING" "Disk usage is above 85% (${disk_usage}%)"
        return 1
    fi

    # Check available memory
    local available_memory=$(free -m | awk 'NR==2 {print $7}')
    if [ $available_memory -lt 1024 ]; then
        log "WARNING" "Available memory is less than 1GB (${available_memory}MB)"
        return 1
    fi

    log "INFO" "System health checks passed"
    return 0
}

# Backup function
create_backup() {
    local backup_date=$(date +%Y%m%d_%H%M%S)
    local backup_path="${BACKUP_DIR}/${backup_date}"
    
    log "INFO" "Creating backup at ${backup_path}"
    mkdir -p "${backup_path}" || handle_error ${LINENO}
    
    # Backup existing configurations
    if [ -d "/etc/nginx" ]; then
        cp -r /etc/nginx "${backup_path}/nginx" || handle_error ${LINENO}
    fi
    if [ -d "/etc/php" ]; then
        cp -r /etc/php "${backup_path}/php" || handle_error ${LINENO}
    fi
    
    log "INFO" "Backup completed successfully"
}

# Prepare Installation Function
prepare_installation() {
    log "INFO" "Preparing for installation"
    
    # Your original prepare installing block, enhanced with logging and error handling
    rm -rf /var/lib/dpkg/lock || handle_error ${LINENO}
    rm -rf /var/lib/dpkg/lock-frontend || handle_error ${LINENO}
    rm -rf /var/cache/apt/archives/lock || handle_error ${LINENO}
    
    log "INFO" "Updating package lists"
    sudo apt-get update || handle_error ${LINENO}
    
    log "SUCCESS" "Installation preparation completed"
}

# Setup NGINX Function
setup_nginx() {
    log "INFO" "Setting up NGINX"

    # Remove Apache
    log "INFO" "Removing Apache if exists"
    sudo apt-get purge apache -y || log "WARNING" "Apache removal returned non-zero exit code"
    sudo apt-get purge apache* -y || log "WARNING" "Apache cleanup returned non-zero exit code"
    sudo kill -9 $(sudo lsof -t -i:80) 2>/dev/null || true
    sudo kill -9 $(sudo lsof -t -i:443) 2>/dev/null || true

    # Install NGINX
    log "INFO" "Installing NGINX"
    sudo apt-get update || handle_error ${LINENO}
    sudo apt install nginx -y || handle_error ${LINENO}

    # Configure firewall
    log "INFO" "Configuring firewall for NGINX"
    echo "y" | sudo ufw enable
    sudo ufw allow 'Nginx HTTP' || handle_error ${LINENO}
    sudo ufw allow 'Nginx HTTPS' || handle_error ${LINENO}
    sudo ufw allow '8443' || handle_error ${LINENO}
    sudo ufw allow OpenSSH || handle_error ${LINENO}
    
    log "SUCCESS" "NGINX setup completed"
}

# Setup PHP Function
setup_php() {
    log "INFO" "Setting up PHP"

    # Install PHP 8.2
    sudo apt-get update || handle_error ${LINENO}
    sudo apt install lsb-release ca-certificates apt-transport-https software-properties-common -y || handle_error ${LINENO}
    sudo add-apt-repository ppa:ondrej/php -y || handle_error ${LINENO}
    
    # Install PHP and extensions
    log "INFO" "Installing PHP 8.2 and extensions"
    sudo apt install php8.2 php8.2-fpm php8.2-common redis-server php8.2-redis openssl \
        php8.2-curl php8.2-mbstring php8.2-mysql php8.2-xml php8.2-zip php8.2-gd \
        php8.2-cli php8.2-imagick php8.2-intl -y || handle_error ${LINENO}

    # Install PHP 8.3
    log "INFO" "Installing PHP 8.3 and extensions"
    sudo apt install php8.3 php8.3-fpm php8.3-redis openssl php8.3-common \
        php8.3-curl php8.3-mbstring php8.3-mysql php8.3-xml php8.3-zip php8.3-gd \
        php8.3-cli php8.3-imagick php8.3-intl -y || handle_error ${LINENO}

    log "SUCCESS" "PHP setup completed"
}

# Setup Redis Function
setup_redis() {
    log "INFO" "Setting up Redis"

    sudo apt-get install redis-server -y || handle_error ${LINENO}
    
    # Configure Redis
    sudo cp /etc/redis/redis.conf /etc/redis/redis.conf.backup || handle_error ${LINENO}
    sudo sed -i 's/# maxmemory <bytes>/maxmemory 512mb/' /etc/redis/redis.conf
    sudo sed -i 's/# maxmemory-policy noeviction/maxmemory-policy allkeys-lru/' /etc/redis/redis.conf
    
    sudo systemctl restart redis-server || handle_error ${LINENO}
    
    log "SUCCESS" "Redis setup completed"
}

# Setup Domain Function
setup_domain() {
    local domain=$1
    log "INFO" "Setting up domain: ${domain}"

    # Create nginx configuration
    sudo rm -rf /etc/nginx/sites-available/default /etc/nginx/sites-enabled/default
    sudo touch /etc/nginx/sites-available/$domain || handle_error ${LINENO}

    # Your original nginx configuration block here
    sudo bash -c "cat > /etc/nginx/sites-available/$domain << 'EOF'
server {
    listen 80;
    listen [::]:80;
    root /var/www/html/$domain/public;
    index index.php index.html index.htm index.nginx-debian.html;
    server_name $domain www.$domain;
    
    # Enhanced security headers
    add_header X-Frame-Options "SAMEORIGIN";
    add_header X-XSS-Protection "1; mode=block";
    add_header X-Content-Type-Options "nosniff";
    
    location / {
        try_files \$uri \$uri/ /index.php?\$query_string;
    }

    location ~ \.php$ {
        include snippets/fastcgi-php.conf;
        fastcgi_pass unix:/var/run/php/php8.2-fpm.sock;
        fastcgi_param SCRIPT_FILENAME \$document_root\$fastcgi_script_name;
        include fastcgi_params;
    }

    location ~ /\.ht {
        deny all;
    }
    
    # Enhanced static file caching
    location ~* \.(js|css|png|jpg|jpeg|gif|ico)$ {
        expires 30d;
        add_header Cache-Control "public, no-transform";
    }
}
EOF" || handle_error ${LINENO}

    # Create symbolic link and directory structure
    ln -s /etc/nginx/sites-available/$domain /etc/nginx/sites-enabled/ || handle_error ${LINENO}
    sudo mkdir -p /var/www/html/$domain/public || handle_error ${LINENO}
    
    log "SUCCESS" "Domain setup completed"
}

# Setup SSL Function
setup_ssl() {
    local domain=$1
    log "INFO" "Setting up SSL for domain: ${domain}"

    # Install certbot if not already installed
    if ! command -v certbot &> /dev/null; then
        log "INFO" "Installing Certbot"
        sudo snap install --classic certbot || handle_error ${LINENO}
        sudo ln -s /snap/bin/certbot /usr/bin/certbot || handle_error ${LINENO}
    fi

    # Generate SSL certificate
    log "INFO" "Generating SSL certificate"
    certbot --nginx -d $domain -d www.$domain --non-interactive --agree-tos -m admin@$domain || handle_error ${LINENO}
    
    log "SUCCESS" "SSL setup completed"
}

# Setup Database Function
setup_mysql() {
    log "INFO" "Setting up MySQL"

    if ! command -v mysql &> /dev/null; then
        export DEBIAN_FRONTEND=noninteractive
        
        # Install MySQL
        echo debconf mysql-server/root_password password $MYSQL_ROOT_PASSWORD | sudo debconf-set-selections
        echo debconf mysql-server/root_password_again password $MYSQL_ROOT_PASSWORD | sudo debconf-set-selections
        sudo apt-get -y install mysql-server || handle_error ${LINENO}

        # Secure MySQL installation
        sudo mysql_secure_installation --password="$MYSQL_ROOT_PASSWORD" << EOF
y
0
n
y
y
y
y
EOF
        
        # Save MySQL password securely
        echo $MYSQL_ROOT_PASSWORD | sudo tee /root/.mysql_root_password > /dev/null
        chmod 600 /root/.mysql_root_password
        
        log "SUCCESS" "MySQL setup completed. Root password saved to /root/.mysql_root_password"
    else
        log "INFO" "MySQL is already installed"
    fi
}

# Setup Monitoring Function
setup_monitoring() {
    log "INFO" "Setting up monitoring with Prometheus and Node Exporter"
    
    # Install Node Exporter
    useradd --no-create-home --shell /bin/false node_exporter || log "WARNING" "User node_exporter already exists"
    wget "https://github.com/prometheus/node_exporter/releases/download/v${NODE_EXPORTER_VERSION}/node_exporter-${NODE_EXPORTER_VERSION}.linux-amd64.tar.gz" || handle_error ${LINENO}
    tar xvf "node_exporter-${NODE_EXPORTER_VERSION}.linux-amd64.tar.gz"
    sudo cp node_exporter-${NODE_EXPORTER_VERSION}.linux-amd64/node_exporter /usr/local/bin/ || handle_error ${LINENO}
    
    # Create Node Exporter service
    sudo bash -c 'cat > /etc/systemd/system/node_exporter.service << EOF
[Unit]
Description=Node Exporter
After=network.target

[Service]
User=node_exporter
Group=node_exporter
Type=simple
ExecStart=/usr/local/bin/node_exporter

[Install]
WantedBy=multi-user.target
EOF'

    # Start and enable services
    sudo systemctl daemon-reload
    sudo systemctl start node_exporter || handle_error ${LINENO}
    sudo systemctl enable node_exporter || handle_error ${LINENO}
    
    log "SUCCESS" "Monitoring setup completed"
}

# Main function
main() {
    local domain=""
    
    # Parse command line arguments
    while getopts "d:h" flag; do
        case "${flag}" in
            d) domain=${OPTARG};;
            h) 
                echo "Usage: $0 -d domain.com"
                exit 0
                ;;
            *)
                echo "Invalid option. Usage: $0 -d domain.com"
                exit 1
                ;;
        esac
    done

    if [ -z "$domain" ]; then
        log "ERROR" "Domain parameter is required. Usage: $0 -d domain.com"
        exit 1
    fi

    # Start installation process
    log "INFO" "Starting server setup for ${domain}"
    
    # Perform system health check
    check_system_health || {
        log "ERROR" "System health check failed. Please resolve the issues before continuing."
        exit 1
    }

    # Create initial backup
    create_backup

    # Run installation steps
    prepare_installation
    setup_nginx
    setup_php
    setup_redis
    setup_domain "$domain"
    setup_ssl "$domain"
    setup_mysql
    setup_monitoring

    # Create final backup
    create_backup

    # Print completion message
    log "INFO" "Installation completed successfully"
    echo -e "${GREEN}Installation completed successfully!${NC}"
    echo -e "${YELLOW}Important Information:${NC}"
    echo -e "MySQL Root Password: ${MYSQL_ROOT_PASSWORD}"
    echo -e "Installation Log: ${SCRIPT_LOG_FILE}"
    echo -e "Backup Directory: ${BACKUP_DIR}"
    echo -e "Monitoring URLs:"
    echo -e "  - Node Exporter: http://localhost:9100/metrics"
}

# Start script execution
main "$@"