#! /usr/bin/env python
import sys, os, string, whrandom, cp

generator = whrandom.whrandom()
	
def shuffle(listin):
	newlist = listin[:]
	for i in range(len(newlist)):
		n = generator.randint(0, len(newlist)-1)
		newlist[i], newlist[n] = newlist[n], newlist[i]
	return newlist

def main():
	"""
%(filename)s

Randomizes the lines of a file and writes the first n 
entries. Use to pick a random subset of items from a list.

{{out		name of outfile (stdout is default)}}
{{n			number of lines to pick; default is all}}
{{h			Prints documentation.}}
{{v			verbosity 
	1}}
{{version   print version info and exit}}

%(version)s
"""
	debug = 0
	
	docstringdict = {'filename':os.path.split(sys.argv[0])[-1],
	'version':'$Id: shuffle.py,v 1.1 2004/10/10 02:53:10 nghoffma Exp $'}
	
	optlist, formattedDocString, formattedSummary = cp.optStringParser(main.__doc__ % docstringdict,
		optWidth=15, lineWidth=60, valOffset = 4, putVals=1)	
	dict = cp.commandparser(options=optlist, usage='Options:\n' + formattedSummary, 
		debug = debug, exitWithUsage=1)
		
	if dict.status('version'):
		sys.exit( 'Version: %(version)s\n' % docstringdict )
		
	if dict.status('h'):
		print formattedDocString
		sys.exit( 0 )
	v = dict.value('v')

	file_list = dict.value('infile_list', 'in', 'file')
	
	if dict.status('out'):
		outfile = dict.value('out', 'out', 'file')
	else:
		outfile = sys.stdout
		
	numbertoprint = 0
	if dict.status('n'):
		numbertoprint = dict.value('n')
	 
	inputList = []
	for file in file_list:
		for line in file:
			if line.strip() == '': continue
			inputList.append(line)
			
		file.close()	
		
	if numbertoprint > len(inputList):
		numbertoprint = len(inputList)
	elif numbertoprint == 0:
		numbertoprint = len(inputList)
	
	shuffled = shuffle(inputList)
	
	outfile.write(string.join(shuffled[0:numbertoprint], ''))
			
main()