#!/bin/zsh
#
# Disk Space Monitor
# Warns when disk usage exceeds 90% threshold
# Sends alerts via Telegram when critical
#

STATE_DIR="/Users/mattbruce/.openclaw/workspace/scripts/security-monitors/state"
LOG_FILE="/Users/mattbruce/.openclaw/workspace/scripts/security-monitors/logs/disk-monitor.log"
ALERT_STATE_FILE="$STATE_DIR/disk-alert-state"

# Thresholds
WARN_THRESHOLD=80
CRITICAL_THRESHOLD=90

# Create directories
mkdir -p "$(dirname $LOG_FILE)" "$STATE_DIR"

# Timestamp helper
timestamp() {
  date '+%Y-%m-%d %H:%M:%S %Z'
}

# Log to file
log() {
  echo "[$(timestamp)] $1" >> "$LOG_FILE"
}

# Send alert to queue
send_alert() {
  local level="$1"
  local message="$2"
  echo "$(timestamp) | $level | DISK | $message" >> "$STATE_DIR/alerts.queue"
}

# Check disk usage
check_disk_usage() {
  local filesystem="$1"
  local usage
  usage=$(df -h "$filesystem" 2>/dev/null | tail -1 | awk '{print $5}' | tr -d '%')
  echo "$usage"
}

# Get all mounted filesystems and their usage (exclude system/special volumes)
get_all_filesystems() {
  df -h 2>/dev/null | tail -n +2 | grep -v "devfs\|map \|CoreSimulator\|Cryptex" | awk '{print $6","$5}'
}

# Main monitoring logic
main() {
  local alert_needed=false
  local alert_level=""
  local alert_details=""
  local max_usage=0
  local critical_fs=""
  
  # Check main filesystem (/) first
  local root_usage
  root_usage=$(check_disk_usage "/")
  if [[ -n "$root_usage" ]]; then
    max_usage=$root_usage
    critical_fs="/"
  fi
  
  # Check all filesystems
  local fs_list
  fs_list=$(get_all_filesystems)
  
  local details="Disk Usage Report:\n"
  while IFS=',' read -r mount usage; do
    [[ -z "$mount" ]] && continue
    local usage_num=$(echo "$usage" | tr -d '%')
    details="${details}  $mount: $usage\n"
    
    if [[ "$usage_num" -gt "$max_usage" ]]; then
      max_usage=$usage_num
      critical_fs="$mount"
    fi
    
    if [[ "$usage_num" -ge "$CRITICAL_THRESHOLD" ]]; then
      alert_needed=true
      alert_level="CRITICAL"
    elif [[ "$usage_num" -ge "$WARN_THRESHOLD" ]] && [[ "$alert_level" != "CRITICAL" ]]; then
      alert_needed=true
      alert_level="WARNING"
    fi
  done <<< "$fs_list"
  
  # Check if we already alerted for this state (prevent spam)
  local last_state=""
  local last_usage=0
  if [[ -f "$ALERT_STATE_FILE" ]]; then
    last_state=$(cat "$ALERT_STATE_FILE" | cut -d'|' -f1)
    last_usage=$(cat "$ALERT_STATE_FILE" | cut -d'|' -f2)
  fi
  
  # Alert logic with hysteresis (alert on rising, clear on falling below threshold-5%)
  local should_alert=false
  
  if [[ "$alert_needed" == "true" ]]; then
    if [[ "$alert_level" == "CRITICAL" ]]; then
      # Always alert for critical, but not more than once per hour
      if [[ "$last_state" != "CRITICAL" ]] || [[ $((max_usage - last_usage)) -ge 5 ]]; then
        should_alert=true
      fi
    elif [[ "$alert_level" == "WARNING" ]]; then
      # Alert for warning if we haven't already, or if it's getting worse
      if [[ "$last_state" != "WARNING" ]] && [[ "$last_state" != "CRITICAL" ]]; then
        should_alert=true
      fi
    fi
  elif [[ "$last_state" == "CRITICAL" ]] || [[ "$last_state" == "WARNING" ]]; then
    # Disk has recovered below threshold - send all-clear
    if [[ $max_usage -lt $((WARN_THRESHOLD - 5)) ]]; then
      alert_level="RECOVERED"
      should_alert=true
    fi
  fi
  
  if [[ "$should_alert" == "true" ]]; then
    local hostname=$(hostname -s)
    local emoji=""
    local title=""
    
    case "$alert_level" in
      CRITICAL)
        emoji="🚨"
        title="CRITICAL: Disk Space Exhaustion Imminent"
        ;;
      WARNING)
        emoji="⚠️"
        title="WARNING: Disk Space Running Low"
        ;;
      RECOVERED)
        emoji="✅"
        title="RESOLVED: Disk Space Recovered"
        ;;
    esac
    
    local alert_msg="$emoji **$title** $emoji

**Host:** $hostname
**Time:** $(timestamp)
**Most Critical Mount:** $critical_fs (${max_usage}% used)

**All Filesystems:**
$details
$(if [[ "$alert_level" == "CRITICAL" ]]; then echo "🛑 **ACTION REQUIRED:** Free up disk space immediately!"; fi)
$(if [[ "$alert_level" == "WARNING" ]]; then echo "💡 **Recommendation:** Review and clean up unnecessary files."; fi)

_Detected by OpenClaw Disk Monitor_"
    
    send_alert "$alert_level" "$alert_msg"
    log "$alert_level alert sent for $critical_fs (${max_usage}% usage)"
    
    # Update state
    echo "$alert_level|$max_usage|$(timestamp)" > "$ALERT_STATE_FILE"
    
    # Log to daily security log
    local daily_log="/Users/mattbruce/.openclaw/workspace/memory/$(date '+%Y-%m-%d')-security.log"
    echo "DISK_${alert_level}|$(timestamp)|$critical_fs|${max_usage}%" >> "$daily_log"
  else
    # Normal operation - log periodically (every 6 runs ~ 30 min)
    local counter_file="$STATE_DIR/disk-check-counter"
    local counter=0
    [[ -f "$counter_file" ]] && counter=$(cat "$counter_file")
    counter=$((counter + 1))
    
    if [[ $counter -ge 6 ]]; then
      log "Disk check normal. Max usage: $max_usage% on $critical_fs"
      counter=0
    fi
    echo "$counter" > "$counter_file"
  fi
}

# Run main function
main "$@"