#!/bin/bash

# Configuration
CONNECTIONS_FILE="/etc/hysteria/hysteria_connections.json"
BLOCK_DURATION=60  # 1 minute block duration
MAX_IPS=1          # Maximum number of IPs allowed per user
BLOCK_LIST="/tmp/hysteria_blocked_ips.txt"  # File to track blocked IPs

# Ensure the connections file exists
[ ! -f "$CONNECTIONS_FILE" ] && echo "{}" > "$CONNECTIONS_FILE"
[ ! -f "$BLOCK_LIST" ] && touch "$BLOCK_LIST"

# Logging function
log_message() {
    local level="$1"
    local message="$2"
    echo "[$(date +"%Y-%m-%d %H:%M:%S")] [$level] $message"
}

# Function to update the JSON file with new connection data
update_json() {
    local username="$1"
    local ip_address="$2"
    
    if command -v jq &>/dev/null; then
        temp_file=$(mktemp)
        jq --arg user "$username" --arg ip "$ip_address" \
           '.[$user] += [$ip] | .[$user] |= unique' "$CONNECTIONS_FILE" > "$temp_file"
        mv "$temp_file" "$CONNECTIONS_FILE"
    else
        if grep -q "\"$username\"" "$CONNECTIONS_FILE"; then
            # Add IP to existing username (if it doesn't exist)
            if ! grep -q "\"$username\".*\"$ip_address\"" "$CONNECTIONS_FILE"; then
                sed -i -E "s/(\"$username\":\s*\[)([^\]]*)/\1\2,\"$ip_address\"/" "$CONNECTIONS_FILE"
            fi
        else
            # Add new username with IP
            sed -i -E "s/\{(.*)\}/{\1,\"$username\":[\"$ip_address\"]}/" "$CONNECTIONS_FILE"
        fi
    fi
    
    log_message "INFO" "Updated JSON: Added $ip_address for user $username"
}

# Function to remove an IP from the JSON when client disconnects
remove_ip() {
    local username="$1"
    local ip_address="$2"
    
    if [ ! -f "$CONNECTIONS_FILE" ]; then
        log_message "ERROR" "JSON file does not exist"
        return
    fi
    
    if grep -q "\"$username\"" "$CONNECTIONS_FILE"; then
        if command -v jq &>/dev/null; then
            temp_file=$(mktemp)
            jq --arg user "$username" --arg ip "$ip_address" \
               '.[$user] = (.[$user] | map(select(. != $ip)))' "$CONNECTIONS_FILE" > "$temp_file"
            mv "$temp_file" "$CONNECTIONS_FILE"
        else
            # Basic sed replacement (not as reliable as jq)
            sed -i -E "s/\"$ip_address\"(,|\])|\1\"$ip_address\"/\1/g" "$CONNECTIONS_FILE"
            sed -i -E "s/,\s*\]/\]/g" "$CONNECTIONS_FILE"
            sed -i -E "s/\[\s*,/\[/g" "$CONNECTIONS_FILE"
        fi
        log_message "INFO" "Updated JSON: Removed $ip_address for user $username"
    else
        log_message "WARN" "User $username not found in JSON"
    fi
}

# Block an IP using iptables and track it
block_ip() {
    local ip_address="$1"
    local username="$2"
    local unblock_time=$(( $(date +%s) + BLOCK_DURATION ))
    
    # Skip if already blocked
    if iptables -C INPUT -s "$ip_address" -j DROP 2>/dev/null; then
        log_message "INFO" "IP $ip_address is already blocked"
        return
    fi
    
    # Add to iptables
    iptables -I INPUT -s "$ip_address" -j DROP
    
    # Add to block list with expiration time
    echo "$ip_address,$username,$unblock_time" >> "$BLOCK_LIST"
    
    log_message "WARN" "Blocked IP $ip_address for user $username for $BLOCK_DURATION seconds"
}

# Explicitly unblock an IP using iptables
unblock_ip() {
    local ip_address="$1"
    
    # Remove from iptables if exists
    if iptables -C INPUT -s "$ip_address" -j DROP 2>/dev/null; then
        iptables -D INPUT -s "$ip_address" -j DROP
        log_message "INFO" "Unblocked IP $ip_address"
    fi
    
    # Remove from block list
    sed -i "/$ip_address,/d" "$BLOCK_LIST"
}

# Block all IPs for a user
block_all_user_ips() {
    local username="$1"
    local ips=()
    
    # Get all IPs for this user
    if command -v jq &>/dev/null; then
        readarray -t ips < <(jq -r --arg user "$username" '.[$user][]' "$CONNECTIONS_FILE" 2>/dev/null)
    else
        # Basic extraction without jq (less reliable)
        ip_list=$(grep -oP "\"$username\":\s*\[\K[^\]]*" "$CONNECTIONS_FILE")
        IFS=',' read -ra ip_entries <<< "$ip_list"
        for entry in "${ip_entries[@]}"; do
            # Extract IP from the JSON array entry
            ip=$(echo "$entry" | grep -oP '".*"' | tr -d '"' | tr -d '[:space:]')
            if [[ -n "$ip" ]]; then
                ips+=("$ip")
            fi
        done
    fi
    
    # Block all IPs for this user
    for ip in "${ips[@]}"; do
        ip=${ip//\"/}  # Remove quotes
        ip=$(echo "$ip" | tr -d '[:space:]')  # Remove whitespace
        if [[ -n "$ip" ]]; then
            block_ip "$ip" "$username"
        fi
    done
    
    log_message "WARN" "User $username has been completely blocked for $BLOCK_DURATION seconds"
}

# Check for and unblock expired IPs
check_expired_blocks() {
    local current_time=$(date +%s)
    local ip username expiry
    
    # Check each line in the block list
    while IFS=, read -r ip username expiry || [ -n "$ip" ]; do
        if [[ -n "$ip" && -n "$expiry" ]]; then
            if (( current_time >= expiry )); then
                unblock_ip "$ip"
                log_message "INFO" "Auto-unblocked IP $ip for user $username (block expired)"
            fi
        fi
    done < "$BLOCK_LIST"
}

# Check if a user has exceeded the IP limit
check_ip_limit() {
    local username="$1"
    local ips=()
    
    # Get all IPs for this user
    if command -v jq &>/dev/null; then
        readarray -t ips < <(jq -r --arg user "$username" '.[$user][]' "$CONNECTIONS_FILE" 2>/dev/null)
    else
        # Basic extraction without jq (less reliable)
        ip_list=$(grep -oP "\"$username\":\s*\[\K[^\]]*" "$CONNECTIONS_FILE")
        IFS=',' read -ra ip_entries <<< "$ip_list"
        for entry in "${ip_entries[@]}"; do
            # Extract IP from the JSON array entry
            ip=$(echo "$entry" | grep -oP '".*"' | tr -d '"' | tr -d '[:space:]')
            if [[ -n "$ip" ]]; then
                ips+=("$ip")
            fi
        done
    fi
    
    ip_count=${#ips[@]}
    
    # If the user has more IPs than allowed, block ALL their IPs
    if (( ip_count > MAX_IPS )); then
        log_message "WARN" "User $username has $ip_count IPs (max: $MAX_IPS) - blocking all IPs"
        block_all_user_ips "$username"
    fi
}

# Parse log lines for connections and disconnections
parse_log_line() {
    local log_line="$1"
    local ip_address=""
    local username=""
    
    # Extract IP address and username
    ip_address=$(echo "$log_line" | grep -oP '"addr": "([^:]+)' | cut -d'"' -f4)
    username=$(echo "$log_line" | grep -oP '"id": "([^">]+)' | cut -d'"' -f4)
    
    if [[ -n "$username" && -n "$ip_address" ]]; then
        if echo "$log_line" | grep -q "client connected"; then
            # Check if this IP is in the block list
            if grep -q "^$ip_address," "$BLOCK_LIST"; then
                log_message "WARN" "Rejected connection from blocked IP $ip_address for user $username"
                # Make sure the IP is still blocked in iptables
                if ! iptables -C INPUT -s "$ip_address" -j DROP 2>/dev/null; then
                    iptables -I INPUT -s "$ip_address" -j DROP
                fi
            else
                update_json "$username" "$ip_address"
                check_ip_limit "$username"
            fi
        elif echo "$log_line" | grep -q "client disconnected"; then
            remove_ip "$username" "$ip_address"
            # Note: We don't unblock on disconnect - only on block expiration
        fi
    fi
}

# Check if running as root
if [[ $EUID -ne 0 ]]; then
    log_message "ERROR" "This script must be run as root for iptables functionality"
    exit 1
fi

# Check for jq and warn if not available
if ! command -v jq &>/dev/null; then
    log_message "WARN" "'jq' is not installed. JSON handling may be less reliable."
    log_message "WARN" "Consider installing jq with: apt install jq (for Debian/Ubuntu)"
fi

# Main script
log_message "INFO" "Monitoring Hysteria server connections. Max IPs per user: $MAX_IPS"
log_message "INFO" "Block duration: $BLOCK_DURATION seconds"
log_message "INFO" "Connection data saved to: $CONNECTIONS_FILE"
log_message "INFO" "Press Ctrl+C to exit"
log_message "INFO" "--------------------------------------------------------"

# Background process to check for expired blocks every 10 seconds
(
    while true; do
        check_expired_blocks
        sleep 10
    done
) &
CHECKER_PID=$!

# Cleanup function
cleanup() {
    log_message "INFO" "Stopping IP limiter..."
    kill $CHECKER_PID 2>/dev/null
    exit 0
}

# Set trap for cleanup
trap cleanup SIGINT SIGTERM

# Monitor log for connections and disconnections
journalctl -u hysteria-server.service -f | while read -r line; do
    if echo "$line" | grep -q "client connected\|client disconnected"; then
        parse_log_line "$line"
    fi
done