#!/bin/bash

# Turmli Bar Calendar Tool - Raspberry Pi Zero Deployment Script
# Deploys the application as a systemd service without Docker
# Optimized for low resource usage on Raspberry Pi Zero

set -e  # Exit on error

# ============================================================================
# Configuration
# ============================================================================

APP_NAME="turmli-calendar"
APP_DIR="/opt/turmli-calendar"
SERVICE_NAME="turmli-calendar.service"
SERVICE_FILE="/etc/systemd/system/${SERVICE_NAME}"
APP_USER="pi"
APP_PORT="8000"
PYTHON_VERSION="3"
REPO_DIR="$(dirname "$(readlink -f "$0")")"

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
MAGENTA='\033[0;35m'
CYAN='\033[0;36m'
NC='\033[0m' # No Color

# ============================================================================
# Helper Functions
# ============================================================================

print_header() {
    echo
    echo -e "${MAGENTA}╔════════════════════════════════════════════╗${NC}"
    echo -e "${MAGENTA}║  Turmli Calendar - Raspberry Pi Deployment ║${NC}"
    echo -e "${MAGENTA}╚════════════════════════════════════════════╝${NC}"
    echo
}

print_section() {
    echo
    echo -e "${CYAN}━━━ $1 ━━━${NC}"
    echo
}

print_success() {
    echo -e "${GREEN}✓${NC} $1"
}

print_error() {
    echo -e "${RED}✗${NC} $1"
}

print_warning() {
    echo -e "${YELLOW}⚠${NC} $1"
}

print_info() {
    echo -e "${BLUE}ℹ${NC} $1"
}

check_root() {
    if [[ $EUID -ne 0 ]]; then
        print_error "This script must be run as root (use sudo)"
        exit 1
    fi
}

check_os() {
    if ! grep -q "Raspbian\|Raspberry Pi OS" /etc/os-release 2>/dev/null; then
        print_warning "This script is optimized for Raspberry Pi OS"
        read -p "Continue anyway? (y/N): " -n 1 -r
        echo
        if [[ ! $REPLY =~ ^[Yy]$ ]]; then
            exit 1
        fi
    fi
}

# ============================================================================
# System Checks and Prerequisites
# ============================================================================

check_system() {
    print_section "System Check"

    # Check if running as root
    check_root

    # Check OS
    check_os

    # Check available memory
    local mem_total=$(grep MemTotal /proc/meminfo | awk '{print $2}')
    if [ "$mem_total" -lt 400000 ]; then
        print_warning "Low memory detected ($(($mem_total/1024))MB). This is expected for Pi Zero."
    fi

    # Check available disk space
    local disk_free=$(df /opt 2>/dev/null | tail -1 | awk '{print $4}')
    if [ "$disk_free" -lt 500000 ]; then
        print_warning "Low disk space available. Need at least 500MB free."
        print_info "Current free space: $(($disk_free/1024))MB"
    fi

    # Check /tmp space
    local tmp_free=$(df /tmp 2>/dev/null | tail -1 | awk '{print $4}')
    if [ "$tmp_free" -lt 200000 ]; then
        print_warning "/tmp has limited space. Will use alternative temp directory."
    fi

    # Check Python
    if ! command -v python${PYTHON_VERSION} &> /dev/null; then
        print_error "Python ${PYTHON_VERSION} is not installed"
        return 1
    fi
    print_success "Python $(python${PYTHON_VERSION} --version 2>&1 | cut -d' ' -f2) installed"

    # Check pip
    if ! python${PYTHON_VERSION} -m pip --version &> /dev/null; then
        print_warning "pip not found, installing..."
        apt-get update
        apt-get install -y python3-pip
    fi
    print_success "pip installed"

    # Check git (optional, for updates)
    if command -v git &> /dev/null; then
        print_success "git installed (optional)"
    else
        print_info "git not installed (optional, needed for updates)"
    fi

    return 0
}

install_dependencies() {
    print_section "Installing System Dependencies"

    # Update package list
    print_info "Updating package list..."
    apt-get update

    # Install system dependencies
    print_info "Installing system packages..."
    apt-get install -y \
        python3-dev \
        python3-venv \
        python3-pip \
        build-essential \
        libffi-dev \
        libssl-dev \
        libxml2-dev \
        libxslt1-dev \
        curl \
        systemd

    # Clean apt cache to free up space
    apt-get clean
    apt-get autoremove -y

    print_success "System dependencies installed"
}

# ============================================================================
# Application Setup
# ============================================================================

create_app_directory() {
    print_section "Creating Application Directory"

    # Create directory
    if [ -d "$APP_DIR" ]; then
        print_warning "Directory $APP_DIR already exists"
        read -p "Remove existing installation? (y/N): " -n 1 -r
        echo
        if [[ $REPLY =~ ^[Yy]$ ]]; then
            print_info "Removing existing installation..."
            systemctl stop ${SERVICE_NAME} 2>/dev/null || true
            rm -rf "$APP_DIR"
        else
            print_error "Installation cancelled"
            exit 1
        fi
    fi

    mkdir -p "$APP_DIR"
    print_success "Created $APP_DIR"
}

copy_application_files() {
    print_section "Copying Application Files"

    # Copy necessary files
    print_info "Copying application files..."
    cp -v "$REPO_DIR/main.py" "$APP_DIR/"

    # Use RPi-optimized requirements if available, otherwise fallback to standard
    if [ -f "$REPO_DIR/requirements-rpi.txt" ]; then
        print_info "Using Raspberry Pi optimized requirements"
        cp -v "$REPO_DIR/requirements-rpi.txt" "$APP_DIR/requirements.txt"
    else
        cp -v "$REPO_DIR/requirements.txt" "$APP_DIR/"
    fi

    # Copy logo if exists
    if [ -f "$REPO_DIR/Vektor-Logo.svg" ]; then
        cp -v "$REPO_DIR/Vektor-Logo.svg" "$APP_DIR/"
    fi

    # Create static directory
    mkdir -p "$APP_DIR/static"
    if [ -d "$REPO_DIR/static" ]; then
        cp -r "$REPO_DIR/static/"* "$APP_DIR/static/" 2>/dev/null || true
    fi

    # Copy logo to static directory
    if [ -f "$APP_DIR/Vektor-Logo.svg" ]; then
        cp "$APP_DIR/Vektor-Logo.svg" "$APP_DIR/static/logo.svg"
    fi

    # Create empty cache file
    touch "$APP_DIR/calendar_cache.json"

    # Set ownership
    chown -R ${APP_USER}:${APP_USER} "$APP_DIR"

    print_success "Application files copied"
}

setup_python_environment() {
    print_section "Setting Up Python Environment"

    # Create virtual environment to isolate dependencies
    print_info "Creating Python virtual environment..."
    sudo -u ${APP_USER} python${PYTHON_VERSION} -m venv "$APP_DIR/venv"

    # Upgrade pip in virtual environment
    print_info "Upgrading pip..."
    sudo -u ${APP_USER} "$APP_DIR/venv/bin/pip" install --upgrade pip wheel setuptools

    # Set temporary directory to avoid filling up /tmp (which is in RAM on Pi)
    export TMPDIR="$APP_DIR/tmp"
    mkdir -p "$TMPDIR"
    chown ${APP_USER}:${APP_USER} "$TMPDIR"

    # Install requirements
    print_info "Installing Python dependencies (this may take a while on Pi Zero)..."
    print_warning "This process might take 10-20 minutes on a Raspberry Pi Zero"

    # Install with optimizations for low memory and ARM architecture
    sudo -u ${APP_USER} TMPDIR="$TMPDIR" "$APP_DIR/venv/bin/pip" install \
        --no-cache-dir \
        --prefer-binary \
        --no-build-isolation \
        --no-deps \
        -r "$APP_DIR/requirements.txt"

    # Install dependencies separately to handle failures better
    sudo -u ${APP_USER} TMPDIR="$TMPDIR" "$APP_DIR/venv/bin/pip" install \
        --no-cache-dir \
        --prefer-binary \
        --no-build-isolation \
        -r "$APP_DIR/requirements.txt"

    # Clean up temp directory
    rm -rf "$TMPDIR"

    print_success "Python environment set up"
}

# ============================================================================
# Systemd Service Setup
# ============================================================================

create_systemd_service() {
    print_section "Creating Systemd Service"

    # Create service file
    cat > "$SERVICE_FILE" << EOF
[Unit]
Description=Turmli Bar Calendar Tool
Documentation=https://github.com/turmli/bar-calendar-tool
After=network.target network-online.target
Wants=network-online.target

[Service]
Type=simple
User=${APP_USER}
Group=${APP_USER}
WorkingDirectory=${APP_DIR}
Environment="PATH=/opt/turmli-calendar/venv/bin:/home/turmli/.local/bin:/usr/local/bin:/usr/bin:/bin"
Environment="PYTHONPATH=${APP_DIR}"
Environment="TZ=Europe/Berlin"

# Use virtual environment Python with uvicorn
ExecStart=${APP_DIR}/venv/bin/python -m uvicorn main:app --host 0.0.0.0 --port ${APP_PORT} --workers 1 --log-level info

# Restart policy
Restart=always
RestartSec=10
StartLimitInterval=200
StartLimitBurst=5

# Resource limits for Raspberry Pi Zero
MemoryMax=256M
CPUQuota=75%

# Security hardening
PrivateTmp=true
NoNewPrivileges=true
ProtectSystem=strict
ProtectHome=true
ReadWritePaths=${APP_DIR}/calendar_cache.json ${APP_DIR}/static

# Logging
StandardOutput=journal
StandardError=journal
SyslogIdentifier=${APP_NAME}

[Install]
WantedBy=multi-user.target
EOF

    print_success "Service file created at $SERVICE_FILE"

    # Reload systemd
    systemctl daemon-reload
    print_success "Systemd configuration reloaded"
}

# ============================================================================
# Service Management Functions
# ============================================================================

start_service() {
    print_section "Starting Service"

    systemctl enable ${SERVICE_NAME}
    systemctl start ${SERVICE_NAME}

    # Wait for service to start
    sleep 3

    if systemctl is-active --quiet ${SERVICE_NAME}; then
        print_success "Service started successfully"

        # Test if application is responding
        sleep 2
        if curl -s -f "http://localhost:${APP_PORT}/api/events" > /dev/null 2>&1; then
            print_success "Application is responding on port ${APP_PORT}"
        else
            print_warning "Service is running but not responding yet (may still be starting)"
        fi
    else
        print_error "Failed to start service"
        print_info "Check logs with: journalctl -u ${SERVICE_NAME} -n 50"
        return 1
    fi
}

stop_service() {
    print_section "Stopping Service"

    if systemctl is-active --quiet ${SERVICE_NAME}; then
        systemctl stop ${SERVICE_NAME}
        print_success "Service stopped"
    else
        print_info "Service is not running"
    fi
}

restart_service() {
    print_section "Restarting Service"

    systemctl restart ${SERVICE_NAME}
    sleep 2

    if systemctl is-active --quiet ${SERVICE_NAME}; then
        print_success "Service restarted successfully"
    else
        print_error "Failed to restart service"
        return 1
    fi
}

# ============================================================================
# Status and Monitoring
# ============================================================================

show_status() {
    print_section "Service Status"

    # Show service status
    systemctl status ${SERVICE_NAME} --no-pager

    echo
    print_section "Application Health"

    # Check if responding
    if curl -s -f "http://localhost:${APP_PORT}/api/events" > /dev/null 2>&1; then
        print_success "Application is healthy and responding"

        # Get event count
        local events=$(curl -s "http://localhost:${APP_PORT}/api/events" | python3 -c "import sys, json; data=json.load(sys.stdin); print(len(data.get('events', [])))" 2>/dev/null || echo "unknown")
        print_info "Calendar has $events events"
    else
        print_error "Application is not responding"
    fi

    # Show resource usage
    echo
    print_section "Resource Usage"

    local pid=$(systemctl show ${SERVICE_NAME} -p MainPID --value)
    if [ "$pid" != "0" ]; then
        if [ -f "/proc/$pid/status" ]; then
            local mem_usage=$(grep VmRSS /proc/$pid/status | awk '{print $2/1024 " MB"}')
            print_info "Memory usage: $mem_usage"
        fi
    fi

    # Show recent logs
    echo
    print_section "Recent Logs"
    journalctl -u ${SERVICE_NAME} -n 20 --no-pager
}

show_logs() {
    print_section "Application Logs"
    journalctl -u ${SERVICE_NAME} -f
}

# ============================================================================
# Update Function
# ============================================================================

update_application() {
    print_section "Updating Application"

    # Stop service
    stop_service

    # Backup current installation
    print_info "Creating backup..."
    cp -r "$APP_DIR" "${APP_DIR}.backup.$(date +%Y%m%d_%H%M%S)"

    # Copy new files
    print_info "Copying updated files..."
    cp -v "$REPO_DIR/main.py" "$APP_DIR/"

    # Use RPi-optimized requirements if available
    if [ -f "$REPO_DIR/requirements-rpi.txt" ]; then
        cp -v "$REPO_DIR/requirements-rpi.txt" "$APP_DIR/requirements.txt"
    else
        cp -v "$REPO_DIR/requirements.txt" "$APP_DIR/"
    fi

    if [ -f "$REPO_DIR/Vektor-Logo.svg" ]; then
        cp -v "$REPO_DIR/Vektor-Logo.svg" "$APP_DIR/"
        cp "$APP_DIR/Vektor-Logo.svg" "$APP_DIR/static/logo.svg"
    fi

    # Update dependencies with temp directory
    print_info "Updating Python dependencies..."
    export TMPDIR="$APP_DIR/tmp"
    mkdir -p "$TMPDIR"
    chown ${APP_USER}:${APP_USER} "$TMPDIR"

    sudo -u ${APP_USER} TMPDIR="$TMPDIR" "$APP_DIR/venv/bin/pip" install \
        --no-cache-dir \
        --prefer-binary \
        --no-build-isolation \
        -r "$APP_DIR/requirements.txt"

    # Clean up temp directory
    rm -rf "$TMPDIR"

    # Set ownership
    chown -R ${APP_USER}:${APP_USER} "$APP_DIR"

    # Restart service
    start_service

    print_success "Application updated successfully"
}

# ============================================================================
# Uninstall Function
# ============================================================================

uninstall() {
    print_section "Uninstalling Application"

    print_warning "This will remove the Turmli Calendar application"
    read -p "Are you sure? (y/N): " -n 1 -r
    echo
    if [[ ! $REPLY =~ ^[Yy]$ ]]; then
        print_info "Uninstall cancelled"
        return
    fi

    # Stop and disable service
    systemctl stop ${SERVICE_NAME} 2>/dev/null || true
    systemctl disable ${SERVICE_NAME} 2>/dev/null || true

    # Remove service file
    rm -f "$SERVICE_FILE"
    systemctl daemon-reload

    # Remove application directory
    rm -rf "$APP_DIR"

    print_success "Application uninstalled"
}

# ============================================================================
# Performance Optimization for Pi Zero
# ============================================================================

optimize_for_pi_zero() {
    print_section "Optimizing for Raspberry Pi Zero"

    # Disable unnecessary services to free up resources
    print_info "Checking for unnecessary services..."

    local services_to_check="bluetooth cups avahi-daemon triggerhappy"
    for service in $services_to_check; do
        if systemctl is-enabled --quiet "$service" 2>/dev/null; then
            print_info "Consider disabling $service to free resources"
        fi
    done

    # Configure swap if needed
    local swap_total=$(grep SwapTotal /proc/meminfo | awk '{print $2}')
    if [ "$swap_total" -lt 100000 ]; then
        print_warning "Low swap space detected. Consider increasing swap size."
        print_info "Edit /etc/dphys-swapfile and set CONF_SWAPSIZE=256"
    fi

    # Set CPU governor for better performance
    if [ -f /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor ]; then
        local governor=$(cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor)
        if [ "$governor" != "performance" ]; then
            print_info "Current CPU governor: $governor"
            print_info "Consider setting to 'performance' for better response times"
        fi
    fi

    print_success "Optimization check complete"
}

# ============================================================================
# Main Installation Function
# ============================================================================

install() {
    print_header

    # Run checks
    check_system || exit 1

    # Install dependencies
    install_dependencies

    # Setup application
    create_app_directory
    copy_application_files
    setup_python_environment

    # Setup service
    create_systemd_service

    # Optimize for Pi Zero
    optimize_for_pi_zero

    # Start service
    start_service

    # Show final status
    print_section "Installation Complete!"
    print_success "Turmli Calendar is now running"
    echo
    print_info "Access the calendar at:"
    print_info "  http://$(hostname -I | cut -d' ' -f1):${APP_PORT}"
    print_info "  http://localhost:${APP_PORT}"
    echo
    print_info "Useful commands:"
    print_info "  sudo systemctl status ${SERVICE_NAME}  - Check status"
    print_info "  sudo systemctl restart ${SERVICE_NAME} - Restart service"
    print_info "  sudo journalctl -u ${SERVICE_NAME} -f  - View logs"
    print_info "  sudo $0 status                         - Show detailed status"
    echo
}

# ============================================================================
# Command Line Interface
# ============================================================================

print_usage() {
    echo "Usage: sudo $0 {install|start|stop|restart|status|logs|update|uninstall|optimize}"
    echo
    echo "Commands:"
    echo "  install    - Full installation (first time setup)"
    echo "  start      - Start the service"
    echo "  stop       - Stop the service"
    echo "  restart    - Restart the service"
    echo "  status     - Show service status and health"
    echo "  logs       - Follow application logs"
    echo "  update     - Update application from current directory"
    echo "  uninstall  - Remove application completely"
    echo "  optimize   - Check and suggest optimizations for Pi Zero"
    echo
    echo "Examples:"
    echo "  sudo $0 install           # Initial installation"
    echo "  sudo $0 status            # Check if running properly"
    echo "  sudo $0 logs              # View real-time logs"
    echo
    echo "Configuration:"
    echo "  Port: ${APP_PORT}"
    echo "  Directory: ${APP_DIR}"
    echo "  Service: ${SERVICE_NAME}"
}

# ============================================================================
# Main Script Entry Point
# ============================================================================

case "$1" in
    install)
        check_root
        install
        ;;
    start)
        check_root
        start_service
        ;;
    stop)
        check_root
        stop_service
        ;;
    restart)
        check_root
        restart_service
        ;;
    status)
        show_status
        ;;
    logs)
        show_logs
        ;;
    update)
        check_root
        update_application
        ;;
    uninstall)
        check_root
        uninstall
        ;;
    optimize)
        check_root
        optimize_for_pi_zero
        ;;
    *)
        print_header
        print_usage
        exit 1
        ;;
esac

exit 0