#!/usr/bin/env bash

SERVER="$1"
USERNAME="$2"
PASSWORD="$3"

PORT="443"
VPN_DNS="10.10.10.10"
PPP_INTERFACE="ppp0"

if [ -z "$SERVER" ] || [ -z "$USERNAME" ] || [ -z "$PASSWORD" ]; then
    echo "Usage: sudo $0 SERVER USERNAME PASSWORD"
    echo
    echo "Example:"
    echo "sudo $0 pl2v.secwhapi.net sec1925733 YOUR_PASSWORD"
    exit 1
fi

# Resolve VPN server hostname to IPv4 address
SERVER_IP=$(getent ahostsv4 "$SERVER" | awk 'NR==1 {print $1}')

if [ -z "$SERVER_IP" ]; then
    echo "Error: Could not resolve VPN server: $SERVER"
    exit 1
fi

# Detect current default route
DEFAULT_ROUTE=$(ip route show default | head -n1)

GATEWAY=$(echo "$DEFAULT_ROUTE" | awk '
{
    for (i=1; i<=NF; i++) {
        if ($i == "via") {
            print $(i+1)
        }
    }
}')

INTERFACE=$(echo "$DEFAULT_ROUTE" | awk '
{
    for (i=1; i<=NF; i++) {
        if ($i == "dev") {
            print $(i+1)
        }
    }
}')

if [ -z "$GATEWAY" ] || [ -z "$INTERFACE" ]; then
    echo "Error: Could not determine current gateway or network interface."
    exit 1
fi

echo
echo "WhoVPN SSTP connection"
echo "----------------------"
echo "Server:             $SERVER"
echo "Server IP:          $SERVER_IP"
echo "Port:               $PORT"
echo "Physical interface: $INTERFACE"
echo "Gateway:            $GATEWAY"
echo "VPN DNS:            $VPN_DNS"
echo

# Keep VPN server reachable through the original connection.
# This prevents the SSTP tunnel from trying to route itself through ppp0.
ip route replace "$SERVER_IP" via "$GATEWAY" dev "$INTERFACE"

SSTP_PID=""

cleanup() {
    echo
    echo "Disconnecting WhoVPN..."

    # Stop SSTP if it is still running
    if [ -n "$SSTP_PID" ]; then
        kill "$SSTP_PID" 2>/dev/null || true
        wait "$SSTP_PID" 2>/dev/null || true
    fi

    # Restore original default route
    ip route replace default via "$GATEWAY" dev "$INTERFACE"

    # Remove temporary route to VPN server
    ip route del "$SERVER_IP" via "$GATEWAY" dev "$INTERFACE" 2>/dev/null || true

    # Remove DNS configuration from ppp0 if it still exists
    if ip link show "$PPP_INTERFACE" >/dev/null 2>&1; then
        resolvectl revert "$PPP_INTERFACE" 2>/dev/null || true
    fi

    echo "Network settings restored."
}

trap cleanup EXIT INT TERM

# Start SSTP connection
sstpc \
    "$SERVER:$PORT" \
    --user "$USERNAME" \
    --password "$PASSWORD" \
    require-mschap-v2 \
    noauth \
    noipdefault &

SSTP_PID=$!

echo "Connecting to WhoVPN..."
echo "Waiting for PPP interface..."

# Wait up to 30 seconds for ppp0
for i in $(seq 1 30); do
    if ip link show "$PPP_INTERFACE" >/dev/null 2>&1; then
        break
    fi

    # Check if sstpc exited unexpectedly
    if ! kill -0 "$SSTP_PID" 2>/dev/null; then
        echo "Error: SSTP connection terminated before PPP interface was created."
        exit 1
    fi

    sleep 1
done

if ! ip link show "$PPP_INTERFACE" >/dev/null 2>&1; then
    echo "Error: PPP interface was not created."
    exit 1
fi

echo "PPP interface detected: $PPP_INTERFACE"

# Route all normal traffic through SSTP
ip route replace default dev "$PPP_INTERFACE"

# Configure WhoVPN DNS
resolvectl dns "$PPP_INTERFACE" "$VPN_DNS"

# Make ppp0 the preferred interface for all DNS queries
resolvectl domain "$PPP_INTERFACE" '~.'

echo
echo "WhoVPN connected successfully."
echo
echo "VPN interface: $PPP_INTERFACE"
echo "DNS server:    $VPN_DNS"
echo
echo "Check your IP with:"
echo "curl -4 https://api.ipify.org"
echo
echo "Check DNS configuration with:"
echo "resolvectl status $PPP_INTERFACE"
echo
echo "Press Ctrl+C to disconnect."

# Keep script running while SSTP is connected
wait "$SSTP_PID"