#!/bin/bash

# Turmli Calendar - Raspberry Pi Monitoring Script
# Monitors the health and performance of the deployed application

set -e

# Configuration
SERVICE_NAME="turmli-calendar"
APP_PORT="8000"
LOG_FILE="/var/log/turmli-calendar/monitor.log"
ALERT_THRESHOLD_MEM=200  # MB
ALERT_THRESHOLD_CPU=80   # Percentage

# Colors
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
CYAN='\033[0;36m'
NC='\033[0m'

# Helper functions
print_header() {
    echo -e "${CYAN}════════════════════════════════════════════════${NC}"
    echo -e "${CYAN}    Turmli Calendar - System Monitor${NC}"
    echo -e "${CYAN}    $(date '+%Y-%m-%d %H:%M:%S')${NC}"
    echo -e "${CYAN}════════════════════════════════════════════════${NC}"
    echo
}

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

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

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

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

# System information
show_system_info() {
    print_section "System Information"
    
    # Hostname and OS
    echo "Hostname: $(hostname)"
    echo "OS: $(cat /etc/os-release | grep PRETTY_NAME | cut -d'"' -f2)"
    echo "Kernel: $(uname -r)"
    echo "Uptime: $(uptime -p)"
    
    # CPU info
    echo "CPU: $(cat /proc/cpuinfo | grep 'model name' | head -1 | cut -d':' -f2 | xargs)"
    echo "Cores: $(nproc)"
    
    # Temperature
    if command -v vcgencmd &> /dev/null; then
        local temp=$(vcgencmd measure_temp | cut -d'=' -f2)
        echo "Temperature: $temp"
        
        # Check throttling
        local throttled=$(vcgencmd get_throttled | cut -d'=' -f2)
        if [ "$throttled" != "0x0" ]; then
            print_warning "CPU throttling detected: $throttled"
        fi
    fi
    echo
}

# Service status
check_service_status() {
    print_section "Service Status"
    
    if systemctl is-active --quiet ${SERVICE_NAME}; then
        print_ok "Service is running"
        
        # Get PID and uptime
        local pid=$(systemctl show ${SERVICE_NAME} -p MainPID --value)
        if [ "$pid" != "0" ]; then
            echo "PID: $pid"
            
            # Process uptime
            if [ -f "/proc/$pid/stat" ]; then
                local start_time=$(stat -c %Y /proc/$pid)
                local current_time=$(date +%s)
                local uptime=$((current_time - start_time))
                echo "Process uptime: $((uptime / 3600))h $((uptime % 3600 / 60))m"
            fi
        fi
    else
        print_error "Service is not running"
        echo "Last exit status: $(systemctl show ${SERVICE_NAME} -p ExecMainStatus --value)"
    fi
    
    # Show recent restarts
    local restarts=$(systemctl show ${SERVICE_NAME} -p NRestarts --value)
    if [ "$restarts" -gt 0 ]; then
        print_warning "Service has restarted $restarts times"
    fi
    echo
}

# Application health check
check_application_health() {
    print_section "Application Health"
    
    # Test API endpoint
    if curl -s -f -m 5 "http://localhost:${APP_PORT}/api/events" > /dev/null 2>&1; then
        print_ok "API endpoint is responding"
        
        # Get event count
        local response=$(curl -s "http://localhost:${APP_PORT}/api/events" 2>/dev/null)
        if [ ! -z "$response" ]; then
            local events=$(echo "$response" | python3 -c "import sys, json; data=json.load(sys.stdin); print(len(data.get('events', [])))" 2>/dev/null || echo "unknown")
            echo "Calendar events: $events"
            
            # Check last update time
            local last_updated=$(echo "$response" | python3 -c "import sys, json; data=json.load(sys.stdin); print(data.get('last_updated', 'unknown'))" 2>/dev/null || echo "unknown")
            echo "Last updated: $last_updated"
        fi
    else
        print_error "API endpoint not responding"
    fi
    
    # Test web interface
    if curl -s -f -m 5 "http://localhost:${APP_PORT}/" > /dev/null 2>&1; then
        print_ok "Web interface is accessible"
    else
        print_error "Web interface not accessible"
    fi
    echo
}

# Resource usage
show_resource_usage() {
    print_section "Resource Usage"
    
    # Memory usage
    local mem_total=$(free -m | grep Mem | awk '{print $2}')
    local mem_used=$(free -m | grep Mem | awk '{print $3}')
    local mem_percent=$((mem_used * 100 / mem_total))
    echo "System Memory: ${mem_used}/${mem_total} MB (${mem_percent}%)"
    
    if [ "$mem_percent" -gt 90 ]; then
        print_warning "High memory usage detected"
    fi
    
    # Swap usage
    local swap_total=$(free -m | grep Swap | awk '{print $2}')
    local swap_used=$(free -m | grep Swap | awk '{print $3}')
    if [ "$swap_total" -gt 0 ]; then
        local swap_percent=$((swap_used * 100 / swap_total))
        echo "Swap: ${swap_used}/${swap_total} MB (${swap_percent}%)"
        
        if [ "$swap_percent" -gt 50 ]; then
            print_warning "High swap usage - performance may be degraded"
        fi
    fi
    
    # Process-specific memory
    local pid=$(systemctl show ${SERVICE_NAME} -p MainPID --value)
    if [ "$pid" != "0" ] && [ -f "/proc/$pid/status" ]; then
        local proc_mem=$(grep VmRSS /proc/$pid/status | awk '{print $2/1024}')
        printf "Process Memory: %.1f MB\n" "$proc_mem"
        
        if (( $(echo "$proc_mem > $ALERT_THRESHOLD_MEM" | bc -l) )); then
            print_warning "Process memory exceeds threshold (${ALERT_THRESHOLD_MEM} MB)"
        fi
    fi
    
    # CPU usage
    echo
    echo "CPU Load:"
    local load=$(uptime | awk -F'load average:' '{print $2}')
    echo "  Load average: $load"
    
    # Process CPU usage (rough estimate)
    if [ "$pid" != "0" ] && [ -f "/proc/$pid/stat" ]; then
        local cpu_usage=$(ps -p $pid -o %cpu= | tr -d ' ')
        printf "  Process CPU: %.1f%%\n" "$cpu_usage"
        
        if (( $(echo "$cpu_usage > $ALERT_THRESHOLD_CPU" | bc -l) )); then
            print_warning "High CPU usage detected"
        fi
    fi
    echo
}

# Disk usage
show_disk_usage() {
    print_section "Disk Usage"
    
    # Root filesystem
    local disk_usage=$(df -h / | tail -1)
    echo "Root filesystem:"
    echo "  $disk_usage"
    
    local disk_percent=$(df / | tail -1 | awk '{print $5}' | tr -d '%')
    if [ "$disk_percent" -gt 80 ]; then
        print_warning "Disk usage above 80%"
    fi
    
    # Application directory
    if [ -d "/opt/turmli-calendar" ]; then
        local app_size=$(du -sh /opt/turmli-calendar 2>/dev/null | cut -f1)
        echo "Application directory: $app_size"
    fi
    
    # Log directory
    if [ -d "/var/log/turmli-calendar" ]; then
        local log_size=$(du -sh /var/log/turmli-calendar 2>/dev/null | cut -f1)
        echo "Log directory: $log_size"
    fi
    echo
}

# Network statistics
show_network_stats() {
    print_section "Network Statistics"
    
    # Network interfaces
    local interfaces=$(ip -brief link show | grep UP | awk '{print $1}')
    for iface in $interfaces; do
        if [[ "$iface" != "lo" ]]; then
            echo "Interface: $iface"
            local ip=$(ip -brief addr show $iface | awk '{print $3}')
            echo "  IP: $ip"
            
            # Connection count
            local connections=$(ss -tan | grep :${APP_PORT} | grep ESTAB | wc -l)
            echo "  Active connections on port ${APP_PORT}: $connections"
        fi
    done
    echo
}

# Recent errors
show_recent_errors() {
    print_section "Recent Errors (last 10)"
    
    journalctl -u ${SERVICE_NAME} -p err -n 10 --no-pager 2>/dev/null || echo "No recent errors"
    echo
}

# Performance summary
show_performance_summary() {
    print_section "Performance Summary"
    
    local status="HEALTHY"
    local issues=0
    
    # Check service
    if ! systemctl is-active --quiet ${SERVICE_NAME}; then
        status="CRITICAL"
        ((issues++))
        print_error "Service not running"
    fi
    
    # Check API
    if ! curl -s -f -m 5 "http://localhost:${APP_PORT}/api/events" > /dev/null 2>&1; then
        status="DEGRADED"
        ((issues++))
        print_warning "API not responding"
    fi
    
    # Check memory
    local mem_percent=$(free -m | grep Mem | awk '{print ($3*100)/$2}' | cut -d'.' -f1)
    if [ "$mem_percent" -gt 90 ]; then
        status="DEGRADED"
        ((issues++))
        print_warning "High memory usage"
    fi
    
    # Check disk
    local disk_percent=$(df / | tail -1 | awk '{print $5}' | tr -d '%')
    if [ "$disk_percent" -gt 90 ]; then
        status="DEGRADED"
        ((issues++))
        print_warning "High disk usage"
    fi
    
    echo
    if [ "$issues" -eq 0 ]; then
        print_ok "System Status: $status"
    elif [ "$issues" -lt 2 ]; then
        print_warning "System Status: $status ($issues issue)"
    else
        print_error "System Status: $status ($issues issues)"
    fi
    echo
}

# Continuous monitoring mode
monitor_continuous() {
    while true; do
        clear
        print_header
        check_service_status
        check_application_health
        show_resource_usage
        show_performance_summary
        
        echo "Press Ctrl+C to exit"
        echo "Refreshing in 30 seconds..."
        sleep 30
    done
}

# Log monitoring data
log_metrics() {
    local timestamp=$(date '+%Y-%m-%d %H:%M:%S')
    local pid=$(systemctl show ${SERVICE_NAME} -p MainPID --value)
    local mem_used=$(free -m | grep Mem | awk '{print $3}')
    local cpu_load=$(uptime | awk -F'load average:' '{print $2}' | cut -d',' -f1)
    local api_status="DOWN"
    
    if curl -s -f -m 5 "http://localhost:${APP_PORT}/api/events" > /dev/null 2>&1; then
        api_status="UP"
    fi
    
    echo "$timestamp,mem=$mem_used,cpu=$cpu_load,api=$api_status" >> "$LOG_FILE"
}

# Command line interface
case "$1" in
    status)
        print_header
        check_service_status
        check_application_health
        show_performance_summary
        ;;
    full)
        print_header
        show_system_info
        check_service_status
        check_application_health
        show_resource_usage
        show_disk_usage
        show_network_stats
        show_recent_errors
        show_performance_summary
        ;;
    monitor)
        monitor_continuous
        ;;
    resources)
        print_header
        show_resource_usage
        show_disk_usage
        ;;
    health)
        print_header
        check_application_health
        ;;
    errors)
        print_header
        show_recent_errors
        ;;
    log)
        log_metrics
        echo "Metrics logged to $LOG_FILE"
        ;;
    *)
        echo "Usage: $0 {status|full|monitor|resources|health|errors|log}"
        echo
        echo "Commands:"
        echo "  status    - Quick status check"
        echo "  full      - Complete system analysis"
        echo "  monitor   - Continuous monitoring (30s refresh)"
        echo "  resources - Resource usage details"
        echo "  health    - Application health check"
        echo "  errors    - Show recent errors"
        echo "  log       - Log metrics to file"
        echo
        echo "Examples:"
        echo "  $0 status           # Quick status"
        echo "  $0 monitor          # Live monitoring"
        echo "  $0 full             # Full report"
        exit 1
        ;;
esac

exit 0