#!/bin/bash

# entrypoint.sh
#
# This script is responsible for setting up and maintaining an XBee network interface within a Docker container.
# It checks if a device is connected to the specified port, creates a TAP network interface, and monitors the connection.
# If the device is disconnected, it cleans up and retries the connection process.
#
# Usage:
# - This script is intended to be run as the entrypoint for a Docker container.
# - Ensure that the script has executable permissions (`chmod +x entrypoint.sh`) before running it.

echo "Starting entrypoint.sh"

loop() {
    while true; do
        # Check if the XBee device is connected
        check_device_port
        if [ $? -ne 0 ]; then
            echo "No XBee device found at $XBEE_PORT. Waiting for device connection..."
            cleanup
            continue
        fi

        sleep 0.5

        # Check if the network interface is up
        check_network_state
        if [ $? -ne 0 ]; then
            echo "Network interface $XBEE_NET_IFACE_NAME not found. Creating TAP interface..."
            create_tap_interface
        fi

        sleep 0.5

        # Log messages sent and received over xbnet
        log_xbnet_messages

        sleep 0.5
    done
}


# Function to check if the XBee device is connected
check_device_port() {
    if [ -e "$XBEE_PORT" ]; then
        return 0
    else
        return 1
    fi
}

# Function to check if the network interface is up
check_network_state() {
    if ip link show $XBEE_NET_IFACE_NAME > /dev/null 2>&1; then
        return 0
    else
        return 1
    fi
}

# Function to create a TAP network interface
create_tap_interface() {
    # Start xbnet and run it in the background
    xbnet -d --serial-speed ${XBEE_BAUDRATE} ${XBEE_PORT} tap --iface-name ${XBEE_NET_IFACE_NAME} &

    # Wait until the interface is created
    while ! check_network_state; do
        sleep 1
    done

    # Create and bring up xbnet interface
    ip addr add $XBEE_NET_SRC_IP/24 dev $XBEE_NET_IFACE_NAME
    ip link set $XBEE_NET_IFACE_NAME up

    echo "-------------------------------------------"
    echo "********** Tap interface created **********"
    echo "-------------------------------------------"
    echo "Name:             ${XBEE_NET_IFACE_NAME}"
    echo "Gateway:          ${DEFAULT_GATEWAY}"
    echo "IP:               ${XBEE_NET_SRC_IP}"
    echo "Device port:      ${XBEE_PORT}"
    echo "Device baudrate:  ${XBEE_BAUDRATE}"
    echo "-------------------------------------------"
    return 0
}

# Function to log messages sent and received over xbnet using netstat
log_xbnet_messages() {
    echo "Monitoring messages on $XBEE_NET_IFACE_NAME..."

    # Continuously monitor the interface for packet statistics
    while true; do
        RX_PACKETS_BEFORE=$(cat /sys/class/net/$XBEE_NET_IFACE_NAME/statistics/rx_packets)
        TX_PACKETS_BEFORE=$(cat /sys/class/net/$XBEE_NET_IFACE_NAME/statistics/tx_packets)

        sleep 1

        RX_PACKETS_AFTER=$(cat /sys/class/net/$XBEE_NET_IFACE_NAME/statistics/rx_packets)
        TX_PACKETS_AFTER=$(cat /sys/class/net/$XBEE_NET_IFACE_NAME/statistics/tx_packets)

        RX_DIFF=$((RX_PACKETS_AFTER - RX_PACKETS_BEFORE))
        TX_DIFF=$((TX_PACKETS_AFTER - TX_PACKETS_BEFORE))

        if [[ $RX_DIFF -gt 0 ]]; then
            echo "$(date +'%Y-%m-%d %H:%M:%S') - $RX_DIFF packets received on $XBEE_NET_IFACE_NAME"
        fi

        if [[ $TX_DIFF -gt 0 ]]; then
            echo "$(date +'%Y-%m-%d %H:%M:%S') - $TX_DIFF packets sent on $XBEE_NET_IFACE_NAME"
        fi
    done
}

# Function to clean up resources and exit the script
cleanup() {
    echo "Cleaning up resources..."
    pkill -f "xbnet -d --serial-speed $XBEE_BAUDRATE $XBEE_PORT tap"

    if ip link show $XBEE_NET_IFACE_NAME > /dev/null 2>&1; then
        ip link set $XBEE_NET_IFACE_NAME down
        ip link delete $XBEE_NET_IFACE_NAME
    fi
}

# Trap signals to clean up properly
trap cleanup EXIT

# Start the loop to monitor the network and device
loop