server

#!/usr/bin/env ruby

require 'colorize'
require 'json'

OPTIONS_FILEPATH = '.python-server-config'
DEFAULT_OPTS = {
    :port => 8000
}
options = {}

def abort
    puts "Aborting...".red
    exit 1
end


legal_commands = [ "up", "down" ]


command = ARGV[0]


unless legal_commands.include? command
    puts "Unrecognized 'server' command: #{command}".red
    abort
end

# Parse options
if File.exists? OPTIONS_FILEPATH
    options = JSON.parse(File.read(OPTIONS_FILEPATH))
else
    options = DEFAULT_OPTS
    puts "Can't find '#{OPTIONS_FILEPATH}'. Assuming defaults:".green
    puts JSON.pretty_generate(options).green + "\n"
end


# 'screen' management functions

# Create new screen
def create_new_screen( screen_name )
    %x( screen -dmS #{screen_name} )
end

# Kill specified screen
def kill_screen( screen_name )
    %x( screen -S #{screen_name} -X quit )
end

# Start a python server
def start_server_at( screen_name, port = "" )
    %x( screen -S #{screen_name} -X python -m SimpleHTTPServer #{port} )
end

# Kills python server at specified screen
def kill_server( screen_name )
    %x( screen -S #{screen_name} -X stuff $'\003' )
end


# Specify task handlers
tasks = {}

# Start up a python server in a screen session
# then save the session name in options
tasks['up'] = Proc.new {
    unless options['session'].nil?
        # Check if there's actually a screen still running
        out = %x( screen -d | grep #{options['session']})
        active_sessions = out.chomp.split("\t").reject! { |c| c.empty? or c =~ /Detached/ }

        if active_sessions.size > 1
            puts "Found multiple active sessions.".red
            puts "Please clean this shit up before calling on me again.".red
            abort
        elsif active_sessions.size == 1
            screen_name = active_sessions[0]
            puts "Killed existing screen session: #{screen_name}".yellow
            kill_screen( screen_name )
        end

        # Looks like there isn't any active screen sessions
        # Best to clean up the options
        options['session'] = nil
    end

    screen_name = 'python_server'

    puts "Creating screen session '#{screen_name}'".green
    create_new_screen screen_name
    puts "Starting up python server at port:#{options[:port]}".green
    start_server_at( screen_name, options[:port] )

    options['session'] = screen_name
}

# Find a session name in the options file,
# Open the screen session and shut down
# the python server
tasks['down'] = Proc.new {
    session = options['session']

    if session.nil?
        puts "Can't find a screen session here".red
        abort
    end

    puts "Shutting down server...".green
    kill_server( session )
    puts "Killing associated screen session...".green
    kill_screen( session )
    options['session'] = nil

    puts "All done.".green
}

# Execute specific task
tasks[command].call


# Write options to file
File.open(OPTIONS_FILEPATH, 'w') do |f|
    f.write JSON.pretty_generate(options)
end