#!/usr/bin/env python
#
# vevent keys: url, uid, summary, locations, category, description

import urllib
import vobject
import sys
import os

EVENT_KEYS = ["uid", "url", "location", "categories", "summary", "description", "dtstart" , "dtstamp"]
UNIQUE_KEY = ["dtstart", "summary"]


def get_syntax():
	return "Syntax: %s ICAL_SOURCES_FILE FINISHED_FILE AUTH_FILE" % (os.path.basename(sys.argv[0]))


def get_unique_id(event):
	unique_values = []
	for one_val in UNIQUE_KEY:
		unique_values.append(unicode(event[one_val]))
	return encode_safely(";".join(unique_values))


def encode_safely(text):
	return text.encode("iso-8859-15", "replace")


def convert_event_to_dict(event):
	result = {}
	for key in EVENT_KEYS:
		# convert lists to a string
		value = event.getChildValue(key)
		if isinstance(value, list):
			value = " ,".join(value)
		result[key] = value
	return result


def fetch_ical(url):
	result = []
	try:
		handle = urllib.urlopen(url)
		content = handle.read()
		handle.close()
	except IOError, err_msg:
		sys.stderr.write("Failed to parse iCal file (%s): %s\n" % (url, err_msg))
		return []
	events = vobject.readComponents(content)
	for top_child in events:
		for child in top_child.components():
			result.append(convert_event_to_dict(child))
	return result


def add_to_processed_list(fileout, event):
	fileout.write(get_unique_id(event) + "\n")


def submit_event_to_drupal(event):
	print "Added event: %s" % encode_safely(event["summary"])
	return True


if __name__ == "__main__":
	if len(sys.argv) != 4:
		sys.stderr.write(get_syntax() + "\n")
		sys.exit(1)

	ICAL_SOURCES_FILE = sys.argv[1]
	FINISHED_FILE = sys.argv[2]
	AUTH_FILE = sys.argv[3]

	# read the file of iCal URLs to be sourced
	try:
		ical_file = file(ICAL_SOURCES_FILE)
		ical_urls = ical_file.read().splitlines()
		ical_file.close()
	except IOError, err_msg:
		sys.write("Failed to open iCal source URL file (%s): %s\n" % (ICAL_SOURCES_FILE, err_msg))
		sys.exit(2)
	
	finished_items = []
	# read the file of processed events
	if os.path.isfile(FINISHED_FILE):
		try:
			finished_file = file(FINISHED_FILE)
			finished_items.extend(finished_file.read().splitlines())
			finished_file.close()
		except IOError, err_msg:
			sys.write("Failed to open file for finished items (%s) for reading: %s\n" % (FINISHED_FILE, err_msg))
			sys.exit(3)
	# reopen the file for appending
	try:
		finished_file = file(FINISHED_FILE, "a")
	except IOError, err_msg:
		sys.write("Failed to open file for finished items (%s) for appending: %s\n" % (FINISHED_FILE, err_msg))
		sys.exit(4)

	icals = []
	for ical_url in ical_urls:
		icals.extend(fetch_ical(ical_url))
	
	for event in icals:
		if not get_unique_id(event) in finished_items:
			# process new events
			if submit_event_to_drupal(event):
				add_to_processed_list(finished_file, event)
				finished_items.append(get_unique_id(event))
	
	finished_file.close()