#!/bin/bash

# 配置參數
LOG_FILE="/var/log/system_monitor.log"
CPU_THRESHOLD=80
MEMORY_THRESHOLD=80
DISK_THRESHOLD=80
EMAIL="your_email@example.com"

# 檢查并創建日志文件
if [ ! -f "$LOG_FILE" ]; then
  touch "$LOG_FILE"
fi

# 記錄日志函數
log() {
  echo "$(date +"%Y-%m-%d %H:%M:%S") - $1" >> "$LOG_FILE"
}

# 檢查CPU使用率
check_cpu() {
  CPU_USAGE=$(top -bn1 | grep "Cpu(s)" | sed "s/.*, *\([0-9.]*\)%* id.*/\1/" | awk '{print 100 - $1}')
  if (( $(echo "$CPU_USAGE > $CPU_THRESHOLD" | bc -l) )); then
    log "CPU usage is high: $CPU_USAGE%"
    echo "CPU usage is high: $CPU_USAGE%" | mail -s "CPU Usage Alert" "$EMAIL"
  fi
}

# 檢查內存使用率
check_memory() {
  MEMORY_USAGE=$(free | grep Mem | awk '{print $3/$2 * 100.0}')
  if (( $(echo "$MEMORY_USAGE > $MEMORY_THRESHOLD" | bc -l) )); then
    log "Memory usage is high: $MEMORY_USAGE%"
    echo "Memory usage is high: $MEMORY_USAGE%" | mail -s "Memory Usage Alert" "$EMAIL"
  fi
}

# 檢查磁盤使用率
check_disk() {
  DISK_USAGE=$(df / | tail -1 | awk '{print $5}' | sed 's/%//')
  if (( $DISK_USAGE > $DISK_THRESHOLD )); then
    log "Disk usage is high: $DISK_USAGE%"
    echo "Disk usage is high: $DISK_USAGE%" | mail -s "Disk Usage Alert" "$EMAIL"
  fi
}

# 主循環
while true; do
  check_cpu
  check_memory
  check_disk
  sleep 60
done