server.sh

#!/bin/bash

# 'core' and 'frontend' module starting script.
# This shows the accepted flags.
_help_message() {
    echo "Usage: $(basename "$0") [options]" >&2
    echo
    echo "  -h, --help              Shows this help message"
    echo "  --compile               Compiles the core server before launching"
    echo
    exit 1
}

# Creates a screen daemon if it does not exist already and does not attach to it.
_screen_daemon_no_reattach() { 
  if screen -ls | awk '{print $1}' | grep -q "followifier-$1$"; then
    echo "The $1 module is already running."
  else
    echo "Launching the $1 module..."
    screen -dmS followifier-$1 bash -c "$2; exec bash"
    echo "...$1 launched as a screen daemon."
  fi
}

# Allowing inbound and outbound TCP connections on the specified port
_allow_tcp_port() {
    PORT=$(python3 -c "import json; print(json.load(open('core/server/config.json'))['port'])")
    echo Asking password to allow TCP inbound and outbound connections on port "$PORT" on this machine...
    sudo iptables -A INPUT -p tcp --dport "$PORT" -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
    sudo iptables -A OUTPUT -p tcp --sport "$PORT" -m conntrack --ctstate ESTABLISHED -j ACCEPT   
}

# Starts the NTP server
_launch_ntp_server() {
    /etc/init.d/ntp start   
}

# Starts the local database
_start_db() {
    sudo service mongod start
}

# Launches the UI
_launch_ui() {
    _screen_daemon_no_reattach "reader" "cd frontend/reader && npm install && node index.js"
    _screen_daemon_no_reattach "gui" "cd frontend/paper && npm install && npm start"
}

# Launches the core server without compiling first
_launch_core() {
    _allow_tcp_port
    _launch_ntp_server
    _start_db
    cd core/server && ./core
}

# Compiles and launches the core server
_compile_and_launch_core() {
    _start_db
    cd core/server && ./start.sh
}

# If there are no command line arguments
if [ $# -eq 0 ]; then
    # Start UI & server without compiling the latter
    _launch_ui
    _launch_core
# If there is at least a command line argument
else
    # For every flag
    for i in "$@"
    do
        case $i in
            # Help section
            --help|-h)
                _help_message
                shift
                ;;
            # Compile section
            --compile)
                _launch_ui
                _compile_and_launch_core
                shift
                ;;
            # Anything else will just display the help message
            *)
                _help_message
                shift
                ;;
        esac
    done
fi