#!/usr/bin/env python

# Script by Ben Limmer
# https://github.com/l1m5
#
# This simple Python script will combine all the host files you provide
# as sources into one, unique host file to keep you internet browsing happy.

import os
import platform
import re
import string
import subprocess
import sys
import tempfile
import urllib2
import zipfile
import StringIO

# Project Settings
BASEDIR_PATH = os.path.dirname(os.path.realpath(__file__))
DATA_PATH = BASEDIR_PATH + '/data'
DATA_FILENAMES = 'hosts'
UPDATE_URL_FILENAME = 'update.info'
SOURCES = os.listdir(DATA_PATH)
README_TEMPLATE = BASEDIR_PATH + '/readme_template.md'
README_FILE = BASEDIR_PATH + '/readme.md'
TARGET_HOST = '0.0.0.0'

# Exclusions
EXCLUSION_PATTERN = '([a-zA-Z\d-]+\.){0,}' #append domain the end

# Common domains to exclude
COMMON_EXCLUSIONS = ['hulu.com']

# Global vars
exclusionRegexs = []
numberOfRules = 0

def main():
	promptForUpdate()
	promptForExclusions()
	mergeFile = createInitialFile()
	finalFile = removeDups(mergeFile)
	finalizeFile(finalFile)
	updateReadme(numberOfRules)
	printSuccess('Success! Your shiny new hosts file has been prepared.\nIt contains ' + str(numberOfRules) + ' unique entries.')
	promptForMove(finalFile)

# Prompt the User
def promptForUpdate():
	response = query_yes_no("Do you want to update all data sources?")
	if (response == "yes"):
		updateAllSources()
	else:
		print 'OK, we\'ll stick with what we\'ve  got locally.'

def promptForExclusions():
	response = query_yes_no("Do you want to exclude any domains?\n" +
							"For example, hulu.com video streaming must be able to access " +
							"its tracking and ad servers in order to play video.")
	if (response == "yes"):
		displayExclusionOptions()
	else:
		print 'OK, we won\'t exclude any domains.'

def promptForMoreCustomExclusions():
	response = query_yes_no("Do you have more domains you want to enter?")
	if (response == "yes"):
		return True
	else:
		return False

def promptForMove(finalFile):
  response = query_yes_no("Do you want to replace your existing hosts file with the newly generated file?")
  if (response == "yes"):
    moveHostsFileIntoPlace(finalFile)
  else:
    return False
# End Prompt the User

# Exclusion logic
def displayExclusionOptions():
	for exclusionOption in COMMON_EXCLUSIONS:
		response = query_yes_no("Do you want to exclude the domain " + exclusionOption + " ?")
		if (response == "yes"):
			excludeDomain(exclusionOption)
		else:
			continue
	response = query_yes_no("Do you want to exclude any other domains?")
	if (response == "yes"):
		gatherCustomExclusions()

def gatherCustomExclusions():
	while True:
		domainFromUser = raw_input("Enter the domain you want to exclude (e.g. facebook.com): ")
		if (isValidDomainFormat(domainFromUser)):
			excludeDomain(domainFromUser)
		if (promptForMoreCustomExclusions() == False):
			return

def excludeDomain(domain):
	exclusionRegexs.append(re.compile(EXCLUSION_PATTERN + domain))

def matchesExclusions(strippedRule):
	strippedDomain = strippedRule.split()[1]
	for exclusionRegex in exclusionRegexs:
		if exclusionRegex.search(strippedDomain):
			return True
	return False
# End Exclusion Logic

# Update Logic
def updateAllSources():
	for source in SOURCES:
		updateURL = getUpdateURLFromFile(source)
		if (updateURL == None):
			continue;
		print 'Updating source ' + source + ' from ' + updateURL
		updatedFile = urllib2.urlopen(updateURL)

		updatedFile = updatedFile.read()

		if '.zip' in updateURL:
			updatedZippedFile = zipfile.ZipFile(StringIO.StringIO(updatedFile))
			for name in updatedZippedFile.namelist():
				if name in ('hosts', 'hosts.txt'):
					updatedFile = updatedZippedFile.open(name).read()
					break

		updatedFile = string.replace( updatedFile, '\r', '' ) #get rid of carriage-return symbols

		dataFile   = open(DATA_PATH + '/' + source + '/' + DATA_FILENAMES, 'w')
		dataFile.write(updatedFile)
		dataFile.close()

def getUpdateURLFromFile(source):
	pathToUpdateFile = DATA_PATH + '/' + source + '/' + UPDATE_URL_FILENAME
	if os.path.exists(pathToUpdateFile):
		updateFile = open(pathToUpdateFile, 'r')
		retURL = updateFile.readline().strip()
		updateFile.close()
	else:
		retURL = None
		printFailure('Warning: Can\'t find the update file for source ' + source + '\n' +
					 'Make sure that there\'s a file at ' + pathToUpdateFile)
	return retURL
# End Update Logic

# File Logic
def createInitialFile():
	mergeFile = tempfile.NamedTemporaryFile()
	for source in SOURCES:
		curFile = open(DATA_PATH + '/' + source +'/' + DATA_FILENAMES, 'r')
		mergeFile.write('\n# Begin ' + source + '\n')
		mergeFile.write(curFile.read())
		mergeFile.write('\n# End ' + source + '\n')
	return mergeFile

def removeDups(mergeFile):
	global numberOfRules

	finalFile = open(BASEDIR_PATH + '/hosts', 'w+b')
	mergeFile.seek(0) # reset file pointer

	hostnames = set()
	hostnames.add("localhost")
	for line in mergeFile.readlines():
		if line[0].startswith("#") or re.match(r'^\s*$', line[0]):
			finalFile.write(line) #maintain the comments for readability
			continue
		strippedRule = stripRule(line) #strip comments
		if matchesExclusions(strippedRule):
			continue
		hostname, normalizedRule = normalizeRule(strippedRule) # normalize rule

		if normalizedRule and (hostname not in hostnames):
			finalFile.write(normalizedRule)
			hostnames.add(hostname)
			numberOfRules += 1

	mergeFile.close()

	return finalFile

def normalizeRule(rule):
	result = re.search(r'^[ \t]*(\d+\.\d+\.\d+\.\d+)\s+([\w\.-]+)(.*)',rule)
	if result:
		target, hostname, suffix = result.groups()
		return hostname, "%s %s %s\n" % (TARGET_HOST, hostname, suffix)
	print '==>%s<==' % rule
	return None, None

def finalizeFile(finalFile):
	writeOpeningHeader(finalFile)
	finalFile.close()

# Some sources put comments around their rules, for accuracy we need to strip them
# the comments are preserved in the output hosts file
def stripRule(line):
	splitLine = line.split()
	if (len(splitLine) < 2) :
		printFailure('A line in the hostfile is going to cause problems because it is nonstandard\n' +
					 'The line reads ' + line + ' please check your data files. Maybe you have a comment without a #?')
		sys.exit()
	return splitLine[0] + ' ' + splitLine[1]

def writeOpeningHeader(finalFile):
	global numberOfRules
	finalFile.seek(0) #reset file pointer
	fileContents = finalFile.read(); #save content
	finalFile.seek(0) #write at the top
	finalFile.write('# This file is a merged collection of hosts from reputable sources,\n')
	finalFile.write('# with a dash of crowd sourcing via Github\n#\n')
	finalFile.write('# Project home page: https://github.com/StevenBlack/hosts\n#\n')
	finalFile.write('# Current sources:\n')
	for source in SOURCES:
		finalFile.write('#    ' + source + '\n')
	finalFile.write('#\n')
	finalFile.write('# Merging these sources produced ' + str(numberOfRules) + ' unique entries\n')
	finalFile.write('# ===============================================================\n')
	finalFile.write('\n')
	finalFile.write('127.0.0.1 localhost\n')
	finalFile.write('\n')
	finalFile.write(fileContents)

def updateReadme(numberOfRules):
	with open(README_FILE, "wt") as out:
		for line in open(README_TEMPLATE):
			out.write(line.replace('@NUM_ENTRIES@', str(numberOfRules)))

def moveHostsFileIntoPlace(finalFile):
	if (os.name == 'posix'):
		print 'Moving the file requires administrative privileges. You might need to enter your password.'
		if(subprocess.call(["/usr/bin/sudo", "cp", os.path.abspath(finalFile.name), "/etc/hosts"])):
			printFailure("Moving the file failed.")
		print 'Flushing the DNS Cache to utilize new hosts file...'
		if (platform.system() == 'Darwin'):
			if(subprocess.call(["/usr/bin/sudo", "killall", "-HUP", "mDNSResponder"])):
				printFailure("Flushing the DNS Cache failed.")
		else:
			if(subprocess.call(["/usr/bin/sudo", "/etc/rc.d/init.d/nscd", "restart"])):
				printFailure("Flushing the DNS Cache failed.")
	elif (os.name == 'nt'):
		print 'Automatically moving the hosts file in place is not yet supported.'
		print 'Please move the generated file to %SystemRoot%\system32\drivers\etc\hosts'

# End File Logic

# Helper Functions
## {{{ http://code.activestate.com/recipes/577058/ (r2)
def query_yes_no(question, default="yes"):
    """Ask a yes/no question via raw_input() and return their answer.

    "question" is a string that is presented to the user.
    "default" is the presumed answer if the user just hits <Enter>.
        It must be "yes" (the default), "no" or None (meaning
        an answer is required of the user).

    The "answer" return value is one of "yes" or "no".
    """
    valid = {"yes":"yes",   "y":"yes",  "ye":"yes",
             "no":"no",     "n":"no"}
    if default == None:
        prompt = " [y/n] "
    elif default == "yes":
        prompt = " [Y/n] "
    elif default == "no":
        prompt = " [y/N] "
    else:
        raise ValueError("invalid default answer: '%s'" % default)

    while 1:
        sys.stdout.write(colorize(question, colors.PROMPT) + prompt)
        choice = raw_input().lower()
        if default is not None and choice == '':
            return default
        elif choice in valid.keys():
            return valid[choice]
        else:
            printFailure("Please respond with 'yes' or 'no' "\
                             "(or 'y' or 'n').\n")
## end of http://code.activestate.com/recipes/577058/ }}}

def isValidDomainFormat(domain):
	if (domain == ''):
		print "You didn\'t enter a domain. Try again."
		return False
	domainRegex = re.compile("www\d{0,3}[.]|https?")
	if (domainRegex.match(domain)):
		print "The domain " + domain + " is not valid. Do not include www.domain.com or http(s)://domain.com. Try again."
		return False
	else:
		return True

# Colors
class colors:
    PROMPT 	= '\033[94m'
    SUCCESS = '\033[92m'
    FAIL 	= '\033[91m'
    ENDC 	= '\033[0m'

def colorize(text, color):
	return color + text + colors.ENDC

def printSuccess(text):
	print colorize(text, colors.SUCCESS)

def printFailure(text):
	print colorize(text, colors.FAIL)
# End Helper Functions

if __name__ == "__main__":
	main()