#!/usr/bin/python
# coding=utf-8
###
### Google Calendar MultiMerge
### (C) 2016 Matti 'ccr' Hamalainen <ccr@tnsp.org>
###
### Python 2.7 <= x < 3 required! Please refer to
### README.txt for information on other depencies.
###
import os
import sys
import signal
import re
import codecs
import math
import time
#import datetime

import smtplib
from email.mime.text import MIMEText

import httplib2
import ConfigParser

import oauth2client
from oauth2client import client
from oauth2client import tools
from oauth2client import file
from googleapiclient import discovery


###
### Misc. helper functions
###
gcm_no_compare_fields = [
    "id", "iCalUID", "etag", "sequence", "gcm_cal_id",
    "created", "updated", "htmlLink", "organizer", "creator",
]


## Wrapper for print() that does not break when redirecting stdin/out
## because of piped output not having a defined encoding. We default
## to UTF-8 encoding in output here.
def gcm_print(smsg):
    gcm_msgbuf.append(smsg)
    if sys.stdout.encoding != None:
        print(smsg.encode(sys.stdout.encoding))
    else:
        print(smsg.encode("UTF-8"))


## Fatal errors
def gcm_fatal(smsg):
    gcm_print(u"ERROR: "+ smsg)
    if cfg.email_ok and cfg.email:
        ## If e-mail is set, send e-mail
        msg = MIMEText(("\n".join(gcm_msgbuf)).encode("UTF-8"), "plain")
        msg.set_charset("UTF-8")
        msg["Subject"] = cfg.email_subject
        msg["From"] = cfg.email_sender
        msg["To"] = ",".join(cfg.email_to)
        try:
            smtpH = smtplib.SMTP(cfg.email_server)
            smtpH.sendmail(cfg.email_sender, cfg.email_to, msg.as_string())
            smtpH.quit()
        except Exception as e:
            gcm_print(u"FATAL: Oh crap, e-mail sending failed: {0}".format(str(e)))
    sys.exit(1)


## Debug messages
def gcm_debug(smsg):
    if cfg.debug:
        gcm_print(u"DBG: "+ smsg)
    else:
        gcm_msgbuf.append(u"DBG: {0}".format(smsg))


## Handler for SIGINT signals
def gcm_signal_handler(signal, frame):
    gcm_print(u"\nQuitting due to SIGINT / Ctrl+C!")
    sys.exit(0)


## Function for handling Google API credentials
def gcm_get_credentials(mcfg):
    try:
        store = oauth2client.file.Storage(mcfg.credential_file)
    except Exception as e:
            gcm_fatal(u"Failed to read credential file:\n{0}\n\nERROR: {1}\n".format(mcfg.credential_file, str(e)))

    credentials = store.get()
    if not credentials or credentials.invalid:
        try:
            flow = client.flow_from_clientsecrets(mcfg.secret_file, mcfg.scope)
        except Exception as e:
            gcm_fatal(u"Failed to fetch client secret:\n{0}\n\nERROR: {1}\n".format(mcfg.secret_file, str(e)))

        flow.user_agent = mcfg.app_name
        credentials = tools.run_flow(flow, store, mcfg)
    if not credentials or credentials.invalid:
        gcm_fatal(u"Failed to authenticate / invalid credentials.")
    return credentials


def gcm_dump_events(events):
    for event in events:
        ev_start = event["start"].get("dateTime", event["start"].get("date"))
        ev_end = event["end"].get("dateTime", event["end"].get("date"))
        gcm_print(u"{0:25} - {1:25} : {2}".format(ev_start, ev_end, event["summary"]))


## Generate gcm IDs for given list of events
def gcm_generate_ids(events, calendar_id, sep):
    if not events:
        return events

    for ev in events:
        ev["gcm_cal_id"] = calendar_id
        ev["gcm_id"] = calendar_id + sep + ev["iCalUID"]

    return events


## Find event by its gcm_id from given list or return None if not found
def gcm_get_event_by_gcm_id(list, id):
    for event in list:
        if event["gcm_id"] == id:
            return event
    return None



def gcm_compare_events(ev1, ev2):
    for field in ev1:
        if not field in gcm_no_compare_fields and ev1[field] != ev2[field]:
            return False
    return True


###
### Class for parsing and manipulating RGB colors
###
class GCMColor():
    def __init__(self, src = None):
        if src == None:
            self.r = self.g = self.b = 0
        elif isinstance(src, basestring):
            if len(src) == 6:
                self.r = int(src[0:2], 16)
                self.g = int(src[2:4], 16)
                self.b = int(src[4:6], 16)
            elif len(src) == 7 and src[0] == "#":
                self.r = int(src[1:3], 16)
                self.g = int(src[3:5], 16)
                self.b = int(src[6:7], 16)
            else:
                gcm_fatal(u"Expected hex-triplet string for GCMColor() initializer: {0}".format(src))
        elif isinstance(src, GCMColor):
            self.r = src.r
            self.g = src.g
            self.b = src.b
        else:
            gcm_fatal(u"Invalid initializer for GCMColor() object.")

    def delta(self, other):
        ctmp = GCMColor()
        ctmp.r = other.r - self.r
        ctmp.g = other.g - self.g
        ctmp.b = other.b - self.b
        return ctmp

    def dist(self, other):
        ctmp = self.delta(other)
        return math.sqrt(ctmp.r * ctmp.r + ctmp.g * ctmp.g + ctmp.b * ctmp.b)


def gcm_find_nearest_color(colors, cfind, maxdist):
    c_fg = GCMColor(cfind["foreground"])
    c_bg = GCMColor(cfind["background"])

    bdist_fg = 99999999999
    bdist_bg = 99999999999
    best_fit = None
    for id, col in colors.iteritems():
        dist_fg = GCMColor(col["foreground"]).dist(c_fg)
        dist_bg = GCMColor(col["background"]).dist(c_bg)
        if dist_fg <= bdist_fg and dist_bg <= bdist_bg:
            best_fit = id
            bdist_fg = dist_fg
            bdist_bg = dist_bg

    if bdist_fg <= maxdist and bdist_bg <= maxdist:
        return best_fit
    else:
        return None


##
## Class for handling configuration / settings
##
class GCMSettings(dict):
    def __init__(self):
        self.m_data = {}
        self.m_saveable = {}
        self.m_validate = {}
        self.m_translate = {}

    def __getattr__(self, name):
        if name in self.m_data:
            return self.m_data[name]
        else:
            gcm_fatal(u"GCMSettings.__getattr__(): No such attribute '"+ name +"'.")

    def mvalidate(self, name, value):
        if name in self.m_validate and self.m_validate[name]:
            if not self.m_validate[name](value):
                gcm_fatal(u"GCMSettings.mvalidate(): Invalid value for attribute '{0}': {1}".format(name, value))

    def mtranslate(self, name, value):
        if name in self.m_translate and self.m_translate[name]:
            return self.m_translate[name](value)
        else:
            return value

    def mdef(self, name, saveable, validate, translate, value):
        self.mvalidate(name, value)
        self.m_saveable[name] = saveable
        self.m_validate[name] = validate
        self.m_translate[name] = translate
        self.m_data[name] = self.mtranslate(name, value)

    def mset(self, name, value):
        self.mvalidate(name, value)
        if name in self.m_data:
            self.m_data[name] = self.mtranslate(name, value)
        else:
            gcm_fatal(u"GCMSettings.mset(): No such attribute '"+ name +"'.")

    def mget(self, name):
        if name in self.m_data:
            return self.m_data[name]
        else:
            return None

    def mread(self, cfgparser, sect):
        for name in self.m_saveable:
            if cfgparser.has_option(sect, name):
                value = cfgparser.get(sect, name)
                self.mset(name, value)
                gcm_debug(u"{0} -> '{1}' == {2}".format(name, value, self.mget(name)))

    def is_str(self, mvalue):
        return isinstance(mvalue, basestring)

    def is_string(self, mvalue):
        return mvalue == None or self.is_str(mvalue)

    def is_log_level(self, mvalue):
        if not self.is_str(mvalue):
            return False
        else:
            return mvalue.upper() in ["CRITICAL", "ERROR", "WARNING", "INFO", "DEBUG"]

    def trans_log_level(self, mvalue):
        return mvalue.upper()

    def is_filename(self, mvalue):
        if not self.is_str(mvalue):
            return False
        else:
            return re.match("^[a-z0-9][a-z0-9\.\_\-]+$", mvalue, flags=re.IGNORECASE)

    def trans_bool(self, mvalue):
        if self.is_str(mvalue):
            if re.match("^\s*(true|1|on|yes)\s*$", mvalue, re.IGNORECASE):
                mvalue = True
            elif re.match("^\s*(false|0|off|no)\s*$", mvalue, re.IGNORECASE):
                mvalue = False
            else:
                return None
        return mvalue

    def is_bool(self, mvalue):
        mval = self.trans_bool(mvalue)
        if not isinstance(mval, bool):
            gcm_fatal(u"GCMSettings.is_bool(): Invalid boolean value '{0}', should be true|false|1|0|on|off|yes|no.".format(mvalue))
        else:
            return True

    def trans_list(self, mvalue):
        morig = mvalue
        if self.is_str(mvalue):
            mvalue = re.split("\s*,\s*", mvalue, flags=re.IGNORECASE)
            if not isinstance(mvalue, list):
                gcm_fatal(u"GCMSettings.trans_list(): Could not parse list '{0}'.".format(mvalue))
        elif not isinstance(mvalue, list):
            gcm_fatal(u"GCMSettings.trans_list(): Invalid value '{0}'.".format(mvalue))
        return mvalue

    def is_list(self, mvalue):
        return self.trans_list(mvalue)

    def is_email(self, mvalue):
        if not self.is_string(mvalue):
            return False
        else:
            return re.match("^.*?\s+<[a-z0-9]+[a-z0-9\.\+\-]*\@[a-z0-9]+[a-z0-9\.\-]+>\s*$|[a-z0-9]+[a-z0-9\.\+\-]*\@[a-z0-9]+[a-z0-9\.\-]+", mvalue, flags=re.IGNORECASE)

    def trans_email_list(self, mvalue):
        if mvalue == None:
            return mvalue
        else:
            return self.trans_list(mvalue.strip())

    def is_email_list(self, mvalue):
        mvalue = self.trans_email_list(mvalue)
        if mvalue != None:
            for email in mvalue:
                if not self.is_email(email):
                    gcm_fatal(u"Invalid e-mail address '{0}' in list {1}.".format(email, ", ".join(mvalue)))
        return True


###
### Main program starts
###
gcm_msgbuf = []
signal.signal(signal.SIGINT, gcm_signal_handler)


## Settings
cfg = GCMSettings()

cfg.mdef("debug", True, cfg.is_bool, cfg.trans_bool, False)

cfg.mdef("email_ok", False, None, None, False)
cfg.mdef("email", True, cfg.is_bool, cfg.trans_bool, False)
cfg.mdef("email_to", True, cfg.is_email_list, cfg.trans_email_list, None)
cfg.mdef("email_sender", True, cfg.is_email, None, None)
cfg.mdef("email_subject", True, cfg.is_string, None, u"Google Calendar MultiMerge status")
cfg.mdef("email_server", True, cfg.is_string, None, None)

cfg.mdef("source_regex", True, cfg.is_string, None, u"^R:\s*(.*?)\s*\(\s*(.+?)\s*\)\s*$")
cfg.mdef("source_regmap", False, cfg.is_list, cfg.trans_list, [1, 2])
cfg.mdef("source_regmap_len", False, None, None, len(cfg.source_regmap))

cfg.mdef("dest_name", True, cfg.is_string, None, u"Raahen kansainvälisyystoiminta [{0}]")
cfg.mdef("dest_regex", True, cfg.is_string, None, u"^Raahen kansainvälisyystoiminta")
cfg.mdef("dest_id", True, cfg.is_string, None, None)

cfg.mdef("noauth_local_webserver", False, None, None, True)
#cfg.mdef("auth_host_name", False, None, None, "localhost")
#cfg.mdef("auth_host_port", False, None, None, [8080, 8090])
cfg.mdef("logging_level", True, cfg.is_log_level, cfg.trans_log_level, "ERROR")

# No need to touch these
cfg.mdef("app_name", False, None, None, "Google Calendar MultiMerge")
cfg.mdef("scope", False, None, None, "https://www.googleapis.com/auth/calendar")
#cfg.mdef("scope", False, None, None, "https://www.googleapis.com/auth/calendar.readonly")
cfg.mdef("secret_file", True, cfg.is_filename, None, "client_secret.json")
cfg.mdef("credential_file", True, cfg.is_filename, None, "client_credentials.json")


## Read, parse and validate configuration file
if len(sys.argv) > 1:
    gcm_debug(u"Reading configuration from '{0}'.".format(sys.argv[1]))
    try:
        cfgparser = ConfigParser.RawConfigParser()
        cfgparser.readfp(codecs.open(sys.argv[1], "r", "UTF-8"))
    except Exception as e:
        gcm_fatal(u"Failed to read configuration file '{0}': {1}".format(sys.argv[1], str(e)))

    # Check that the required section exists
    section = "gcm"
    if not cfgparser.has_section(section):
        gcm_fatal(u"Invalid configuration, missing '{0}' section.".format(section))

    # Debug setting is a special case, we need to get it
    # set before everything else, so do it here ..
    if cfgparser.has_option(section, "debug"):
        cfg.mset("debug", cfgparser.get(section, "debug"))

    # Parse the settings and validate
    cfg.mread(cfgparser, section)


## Validate settings
if cfg.email:
    if cfg.email_subject == None or len(cfg.email_subject) == 0:
        gcm_fatal(u"E-mail enabled but email_subject not set.")
    elif cfg.email_sender == None:
        gcm_fatal(u"E-mail enabled but email_sender not set.")
    elif cfg.email_to == None:
        gcm_fatal(u"E-mail enabled but email_to not set.")
    else:
        cfg.mset("email_ok", True)


if len(cfg.source_regmap) != cfg.source_regmap_len:
    gcm_fatal(u"Setting source_regmap list must be {0} items.".format(cfg.source_regmap_len))
else:
    # Force to integers
    try:
        cfg.source_regmap = map(lambda x: int(x), cfg.source_regmap)
    except Exception as e:
        gcm_fatal(u"Invalid source_regmap: {0}".format(str(e)))


if not cfg.dest_regex and not cfg.dest_id:
    gcm_fatal(u"Target calendar ID or name required, but not set.")



## Initialize and authorize API connection
credentials = gcm_get_credentials(cfg)
http = credentials.authorize(httplib2.Http())
service = discovery.build("calendar", "v3", http=http)


## Fetch complete calendar list
gcm_debug(u"Fetching available calendars ..")
calendars = []
cal_token = None
while True:
    # We want everything except deleted and hidden calendars
    result = service.calendarList().list(
        showHidden=False,
        showDeleted=False,
        pageToken=cal_token
        ).execute()

    calendars.extend(result.get("items", []))
    cal_token = result.get("nextPageToken")
    if not cal_token:
        break

if len(calendars) == 0:
    gcm_fatal(u"No calendars found?")

gcm_debug(u"{0} calendars total found.".format(len(calendars)))


## Filter desired SOURCE calendars based on specified regexp
src_re = re.compile(cfg.source_regex, re.UNICODE)
dst_re = re.compile(cfg.dest_regex, re.UNICODE)
src_calendars = []
dst_calendar = None
for calendar in calendars:
    if u"summary" in calendar:
        # Find destination calendar ID if not set
        if not cfg.dest_id and dst_re.match(calendar["summary"]):
            cfg.mset("dest_id", calendar["id"])
            dst_calendar = calendar

        # If summary or summaryOverride match the regexp, add calendar
        mre = src_re.match(calendar["summary"])
        if not mre and u"summaryOverride" in calendar:
            mre = src_re.match(calendar[u"summaryOverride"])

        if mre:
            calendar["gcm_title"] = mre.group(cfg.source_regmap[0])
            calendar["gcm_id"] = mre.group(cfg.source_regmap[1])
            src_calendars.append(calendar)

gcm_debug(u"{0} source calendars found.".format(len(src_calendars)))


## Check if we have destination calendar ID
if not dst_calendar:
    gcm_fatal(u"Could not find target/destination calendar ID for '"+ cfg.dest_name +"'.")
else:
    gcm_debug(u"Target calendar '{0}' id {1}.".format(dst_calendar["summary"], dst_calendar["id"]))


## Fetch colors
try:
    colors = service.colors().get().execute()
except Exception as e:
    gcm_fatal(u"Failed to fetch calendar color settings:\n\n{0}".format(str(e)))


## Now, we fetch and collect events
gcm_debug(u"Fetching calendar events .. ")
src_events = []
for calendar in src_calendars:
    gcm_debug(u"- "+calendar["id"])
    try:
        result = service.events().list(
            timeZone="EEST",
            calendarId=calendar["id"],
            singleEvents=True,
            showDeleted=False,
#            orderBy="startTime",
            ).execute()
    except Exception as e:
        gcm_fatal(u"Failed to fetch calendar events for {0}:\n\n{1}\n\nERROR: {2}\n".format(calendar["id"], calendar, str(e)))

    c_found = None
    if "colorId" in calendar and calendar["colorId"] in colors["calendar"]:
        gcm_debug(u"Calendar color: {0}".format(colors["calendar"][calendar["colorId"]]))
        c_found = gcm_find_nearest_color(colors["event"], colors["calendar"][calendar["colorId"]], 100)
        if c_found:
            gcm_debug(u"Found nearest event color ID: {0}, {1}".format(c_found, colors["event"][c_found]))
        else:
            gcm_debug(u"No matching event color found!")

    # Add events, if any, to main list
    events = gcm_generate_ids(result.get("items", []), calendar["id"], "___")
    if events:
        for event in events:
            if c_found != None:
                event["colorId"] = c_found
            event["summary"] = u"[{1}] {0}".format(event["summary"], calendar["gcm_id"])
        src_events.extend(events)
        if cfg.debug:
            gcm_dump_events(events)


## Get current events
gcm_debug(u"Fetching current target calendar events {0}".format(cfg.dest_id))
result = service.events().list(
    calendarId=cfg.dest_id,
    singleEvents=True,
    showDeleted=True,
    ).execute()

dst_events = gcm_generate_ids(result.get("items", []), "", "")
gcm_debug(u"Found {0} event(s).".format(len(dst_events)))


## Start merging events ..
gcm_debug(u"Re-merging events to target calendar ..")
dst_ids = frozenset(map(lambda x: x["gcm_id"], dst_events))
src_ids = frozenset(map(lambda x: x["gcm_id"], src_events))

for event in src_events:
    # Does the event exist already in the target?
    if event["gcm_id"] in dst_ids:
        # Check if event NEEDS updating .. aka compare data
        gcm_debug(u"Event {0} : {1} exists, checking ..".format(event["id"], event["gcm_id"]))
        d_event = gcm_get_event_by_gcm_id(dst_events, event["gcm_id"])
        if not gcm_compare_events(event, d_event):
            # Seems we need to update
            gcm_debug(u"Updating event {0} : {1}..".format(event["id"], event["gcm_id"]))
            try:
                event.pop("sequence", None)
                event.pop("id", None)
                event["iCalUID"] = event["gcm_id"]
                new_event = service.events().update(calendarId=cfg.dest_id, eventId=d_event["id"], body=event).execute()
            except Exception as e:
                gcm_fatal(u"Failed to update event {0}:\n\n{1}\n\nERROR: {2}\n".format(event["gcm_id"], event, str(e)))
        else:
            gcm_debug(u"No need to update event {0} : {1}.".format(event["id"], event["gcm_id"]))
    else:
        ## Event does not seem to exist. Insert new event.
        gcm_debug(u"Inserting new event {0}".format(event["gcm_id"]))
        event.pop("id", None)
        event["iCalUID"] = event["gcm_id"]     # Replace Google generated ID with our own
        try:
            new_event = service.events().insert(calendarId=cfg.dest_id, body=event).execute()
        except Exception as e:
            gcm_fatal(u"Failed to insert new event:\n\n{0}\n\nERROR: {1}\n".format(event, str(e)))


## Remove "stale" events
gcm_debug(u"Purging stale events ..")
for event in dst_events:
    gcm_debug(u"Checking event {0}".format(event["gcm_id"]))
    if not event["gcm_id"] in src_ids and event["status"] != u"cancelled":
        gcm_debug(u"Deleting event {0}".format(event["gcm_id"]))
        try:
            service.events().delete(calendarId=cfg.dest_id, eventId=event["id"]).execute()
        except Exception as e:
            gcm_fatal(u"Failed to delete stale event:\n{0}\n\nERROR: {1}\n".format(event, str(e)))

##
## Finally, update the calendar name with timestamp
##
t_time = time.localtime()
t_str = time.strftime("%d.%m.%Y %H:%M", t_time)
gcm_debug(u"Updating target calendar name timestamp {0}".format(t_str))

try:
    dst_calendar["summary"] = cfg.dest_name.format(t_str)
    new_calendar = service.calendars().update(calendarId=cfg.dest_id, body=dst_calendar).execute()
except Exception as e:
    gcm_fatal(u"Failed to update target calendar:\n{0}\n\nERROR: {1}\n".format(dst_calendar, str(e)))


gcm_debug(u"Finished.")