#!/bin/bash
# Home Stack Monitor & Self-Healing
# Monitors services, alerts on issues, attempts auto-recovery
# Runs every 15 minutes

set -e

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
DATA_FILE="$SCRIPT_DIR/monitor-state.json"
source "$SCRIPT_DIR/../../.env" 2>/dev/null || true

TELEGRAM_CHAT="${TELEGRAM_CHAT:-1793951355}"
NTFY_URL="${NTFY_URL:-}"
NTFY_TOPIC="${NTFY_TOPIC:-}"
NTFY_MIN_PRIORITY="${NTFY_MIN_PRIORITY:-4}"

# Services to monitor
# Format: name|url|type|restart_command(optional)
# type: http, ping, port
SERVICES=(
    "Gitea|http://gitea.kangaroo-eel.ts.net:3000|http"
    "n8n|http://n8n.kangaroo-eel.ts.net:5678|http"
    "Home Assistant|http://homeassistant.kangaroo-eel.ts.net:8123|http"
    "FreshRSS|http://freshrss.kangaroo-eel.ts.net|http"
    "Tailscale|100.100.100.100|ping"
)

# Thresholds
HTTP_TIMEOUT=10
PING_COUNT=3
DISK_WARNING=80  # Alert at 80% disk usage
DISK_CRITICAL=90 # Critical at 90%

log() {
    echo "[$(date '+%Y-%m-%d %H:%M:%S')] $1"
}

init_state() {
    if [[ ! -f "$DATA_FILE" ]]; then
        echo '{"services": {}, "alerts_sent": {}, "stats": {"checks": 0, "failures": 0, "recoveries": 0}}' > "$DATA_FILE"
    fi
}

# Check HTTP endpoint
check_http() {
    local url="$1"
    local status
    
    status=$(curl -s -o /dev/null -w "%{http_code}" --max-time "$HTTP_TIMEOUT" "$url" 2>/dev/null || echo "000")
    
    if [[ "$status" == "200" || "$status" == "302" || "$status" == "401" ]]; then
        echo "up"
    else
        echo "down:$status"
    fi
}

# Check ping
check_ping() {
    local host="$1"
    
    if ping -c "$PING_COUNT" -W 2 "$host" > /dev/null 2>&1; then
        echo "up"
    else
        echo "down:timeout"
    fi
}

# Check disk space on Proxmox (if accessible)
check_disk() {
    # This would need SSH access to Proxmox host
    # For now, placeholder - can be extended with SSH key setup
    echo "unknown"
}

# Update service state in JSON
update_state() {
    local name="$1"
    local status="$2"
    local timestamp=$(date -Iseconds)
    
    local temp_file=$(mktemp)
    jq --arg name "$name" \
       --arg status "$status" \
       --arg time "$timestamp" \
       '.services[$name] = {"status": $status, "last_check": $time}' \
       "$DATA_FILE" > "$temp_file"
    mv "$temp_file" "$DATA_FILE"
}

# Get previous state
get_previous_state() {
    local name="$1"
    jq -r ".services[\"$name\"].status // \"unknown\"" "$DATA_FILE"
}

# Check if alert already sent (cooldown 1 hour)
alert_cooldown_active() {
    local name="$1"
    local alert_type="$2"
    local cooldown_seconds=3600  # 1 hour
    
    local last_alert=$(jq -r ".alerts_sent[\"$name-$alert_type\"] // 0" "$DATA_FILE")
    local now=$(date +%s)
    
    if ((last_alert > 0)); then
        local diff=$((now - last_alert))
        if ((diff < cooldown_seconds)); then
            return 0  # Cooldown active
        fi
    fi
    return 1  # No cooldown
}

# Log alert sent
log_alert() {
    local name="$1"
    local alert_type="$2"
    local now=$(date +%s)
    
    local temp_file=$(mktemp)
    jq --arg key "$name-$alert_type" \
       --arg time "$now" \
       '.alerts_sent[$key] = $time' \
       "$DATA_FILE" > "$temp_file"
    mv "$temp_file" "$DATA_FILE"
}

# Send Telegram alert
send_telegram() {
    local message="$1"
    local priority="${2:-normal}"
    
    curl -s -X POST "https://api.telegram.org/bot${TELEGRAM_BOT_TOKEN}/sendMessage" \
        -H "Content-Type: application/json" \
        -d "{
            \"chat_id\": \"$TELEGRAM_CHAT\",
            \"text\": \"$message\",
            \"parse_mode\": \"Markdown\"
        }" > /dev/null || log "Failed to send Telegram"
}

# Send ntfy alert
send_ntfy() {
    local title="$1"
    local message="$2"
    local priority="${3:-4}"
    local sound="${4:-default}"

    [[ -z "$NTFY_URL" ]] && return 0
    [[ -z "$NTFY_TOPIC" ]] && return 0

    # Enforce minimum priority (default 4)
    if [[ "$priority" =~ ^[0-9]+$ ]] && [[ "$NTFY_MIN_PRIORITY" =~ ^[0-9]+$ ]]; then
        if (( priority < NTFY_MIN_PRIORITY )); then
            priority="$NTFY_MIN_PRIORITY"
        fi
    fi

    curl -s -X POST "${NTFY_URL%/}/${NTFY_TOPIC}" \
        -H "Title: $title" \
        -H "Priority: $priority" \
        -H "Sound: $sound" \
        -d "$message" > /dev/null 2>&1 || log "Failed to send ntfy"
}

# Attempt self-healing
attempt_heal() {
    local name="$1"
    local url="$2"
    
    log "Attempting to heal $name..."
    
    case "$name" in
        "Home Assistant")
            # Try to restart via SSH or API if configured
            log "Home Assistant heal: Check if SSH available"
            # Placeholder - would need HA SSH config
            ;;
        "Gitea"|"n8n"|"FreshRSS")
            # These are Docker/LXC - could restart container if SSH configured
            log "$name heal: Would attempt container restart if SSH configured"
            ;;
    esac
    
    # Wait and recheck
    sleep 10
    local recheck
    recheck=$(check_http "$url")
    
    if [[ "$recheck" == "up" ]]; then
        log "✅ $name recovered after heal attempt"
        return 0
    else
        log "❌ $name still down after heal attempt"
        return 1
    fi
}

# Check all services
check_services() {
    log "Checking services..."
    
    local down_services=()
    local recovered_services=()
    local stats_changed=false
    
    for service_def in "${SERVICES[@]}"; do
        IFS='|' read -r name url check_type <<< "$service_def"
        
        log "Checking $name ($url)..."
        
        local current_status
        case "$check_type" in
            http) current_status=$(check_http "$url") ;;
            ping) current_status=$(check_ping "$url") ;;
            *) current_status="unknown" ;;
        esac
        
        local previous_status=$(get_previous_state "$name")
        
        # Update state
        update_state "$name" "$current_status"
        
        # Track stats
        local temp_file=$(mktemp)
        jq '.stats.checks += 1' "$DATA_FILE" > "$temp_file"
        mv "$temp_file" "$DATA_FILE"
        
        # Analyze state change
        if [[ "$current_status" == "up" ]]; then
            if [[ "$previous_status" != "up" && "$previous_status" != "unknown" ]]; then
                # Service recovered
                recovered_services+=("$name")
                send_telegram "✅ *$name* is back online! 🎉"
                log_alert "$name" "recovery"
            fi
        else
            # Service down
            local status_code="${current_status#down:}"
            
            if [[ "$previous_status" == "up" ]]; then
                # Just went down
                down_services+=("$name|$status_code")
                
                # Try to heal
                if attempt_heal "$name" "$url"; then
                    recovered_services+=("$name (auto-healed)")
                    update_state "$name" "up"
                else
                    # Send alert
                    if ! alert_cooldown_active "$name" "down"; then
                        send_telegram "🚨 *Service Down: $name*\n\nStatus: $status_code\nURL: $url\n\nAuto-heal failed. Manual intervention may be needed."
                        send_ntfy "🚨 Service Down: $name" "$name is down (status: $status_code)\nURL: $url" 4 default
                        log_alert "$name" "down"
                        
                        # Update failure stats
                        temp_file=$(mktemp)
                        jq '.stats.failures += 1' "$DATA_FILE" > "$temp_file"
                        mv "$temp_file" "$DATA_FILE"
                    fi
                fi
            elif [[ "$previous_status" != "up" ]]; then
                # Still down
                if ! alert_cooldown_active "$name" "still_down"; then
                    send_telegram "⚠️ *Still Down: $name*\n\nHas been down for a while. Might need attention."
                    log_alert "$name" "still_down"
                fi
            fi
        fi
    done
    
    log "Check complete. ${#down_services[@]} down, ${#recovered_services[@]} recovered"
}

# Generate daily health report
daily_report() {
    local stats=$(jq '.stats' "$DATA_FILE")
    local checks=$(echo "$stats" | jq -r '.checks')
    local failures=$(echo "$stats" | jq -r '.failures')
    local uptime_pct=100
    
    if ((checks > 0)); then
        uptime_pct=$((100 - (failures * 100 / checks)))
    fi
    
    local report="🏠 *Home Stack Daily Report*\n\n"
    report+="📊 *Uptime: ${uptime_pct}%*\n"
    report+="🔍 Checks: $checks\n"
    report+="❌ Failures: $failures\n\n"
    
    report+="*Current Status:*\n"
    
    for service_def in "${SERVICES[@]}"; do
        IFS='|' read -r name url _ <<< "$service_def"
        local status=$(jq -r ".services[\"$name\"].status // \"unknown\"" "$DATA_FILE")
        local last_check=$(jq -r ".services[\"$name\"].last_check // \"never\"" "$DATA_FILE")
        
        if [[ "$status" == "up" ]]; then
            report+="✅ $name\n"
        else
            report+="❌ $name ($status)\n"
        fi
    done
    
    send_telegram "$report"
}

# Cleanup old alerts (older than 24 hours)
cleanup_alerts() {
    local cutoff=$(($(date +%s) - 86400))
    local temp_file=$(mktemp)
    
    jq --argjson cutoff "$cutoff" '.alerts_sent |= with_entries(select(.value > $cutoff))' "$DATA_FILE" > "$temp_file"
    mv "$temp_file" "$DATA_FILE"
}

# Main
main() {
    init_state
    
    case "${1:-check}" in
        check)
            check_services
            cleanup_alerts
            ;;
        report)
            daily_report
            ;;
        status)
            jq '.' "$DATA_FILE"
            ;;
        reset-stats)
            local temp_file=$(mktemp)
            jq '.stats = {"checks": 0, "failures": 0, "recoveries": 0}' "$DATA_FILE" > "$temp_file"
            mv "$temp_file" "$DATA_FILE"
            log "Stats reset"
            ;;
        *)
            echo "Usage: $0 [check|report|status|reset-stats]"
            echo "  check - Run health check on all services"
            echo "  report - Generate daily status report"
            echo "  status - Show full state"
            echo "  reset-stats - Reset statistics counters"
            ;;
    esac
}

main "$@"