"""
XTerm creation and cleanup.
Utility functions to run an xterm (connected via screen(1)) on each host.

Requires xterm(1) and GNU screen(1).
"""

import re
from subprocess import Popen
from mininet.util import quietRun

def makeXterm( node, title ):
    """Run screen on a node, and hook up an xterm.
       node: Node object
       title: base title
       returns: process created"""
    title += ': ' + node.name
    if not node.inNamespace:
        title += ' (root)'
    cmd = [ 'xterm', '-title', title, '-e' ]
    if not node.execed:
        node.cmd( 'screen -dmS ' + node.name )
        cmd += [ 'screen', '-D', '-RR', '-S', node.name ]
    else:
        cmd += [ 'sh', '-c', 'exec tail -f /tmp/' + node.name + '*.log' ]
    return Popen( cmd )

def cleanUpScreens():
    "Remove moldy old screen sessions."
    r = r'(\d+.[hsc]\d+)'
    output = quietRun( 'screen -ls' ).split( '\n' )
    for line in output:
        m = re.search( r, line )
        if m:
            quietRun( 'screen -S ' + m.group( 1 ) + ' -X kill' )

def makeXterms( nodes, title ):
    """Create XTerms.
       nodes: list of Node objects
       title: base title for each
       returns: list of created xterm processes"""
    return [ makeXterm( node, title ) for node in nodes ]