page

#! /usr/bin/env python3

import sys, getopt, os, pickle

# TODO add option for --next and --previous, storing the current page in an environment variable.

def printUsage():
	usage = """
	Paging tool by Rohitt Vashishtha
		
	Usage: pipeinput | page --size=<pagesize> --num=<pagenum>

	Description: Use this tool to print a long file a few lines at a time
	and run mre commands manually after each cycle. Makes dealing with large
	amount of data easier for mere humans. Have fun. :)

	License: "THE BEER-WARE LICENSE" (Revision 42): Rohitt Vashishtha wrote
	this file. As long as you retain this notice you can do whatever you
	want with this stuff. If we meet some day, and you think this stuff is
	worth it, you can buy me a beer in return.
	- Rohitt Vashishtha
"""
	print(usage)

def getDefaultParams():
	params = {}
	params['size']=10
	params['num']=1
	try:
		file = open('~/Documents/scripts/params.page', 'r')
		params['num'] = int(file.readline())
	except FileNotFoundError:
		pass
	except ValueError:
		pass
	return params

def setParams(argv):
	params = getDefaultParams()
	try:
		opts, args = getopt.getopt(argv,"hs:n:",["size=","num=","next","prev"])
	except getopt.GetoptError:
		print ('Incorrect usage. Use page -h to print usage.')
		sys.exit(2)
	for opt, arg in opts:
		if opt == '-h':
			printUsage()
			sys.exit(0)
		elif opt in ("-n", "--num"):
			params['num'] = int(arg)
		elif opt in ("-s", "--size"):
			params['size'] = int(arg)
		elif opt in ("--next"):
			params['num'] += 1
		elif opt in ("--prev"):
			params['num'] -= 1
	try:
		file = open('~/Documents/scripts/params.page', 'w+')
		file.write(str(params['num']))
		file.close()
	except FileNotFoundError:
		pass
	print(params)
	return params

def printPage(params):
	linestoskip = params['size']*(params['num']-1)
	linestoprint = params['size']
	for line in sys.stdin:
		if linestoskip > 0:
			linestoskip -= 1
			# print("> ",line)
		if linestoskip == 0 and linestoprint > 0:
			sys.stdout.write(line)
			# print(line)
			linestoprint -= 1
		if linestoprint == 0:
			sys.exit(0)

if __name__ == "__main__":
	printPage(setParams(sys.argv[1:]))