from icalendar import Calendar, Event
import toml, argparse, os, sys, hashlib, json, pytz, glob, os, time
from dateutil.relativedelta import relativedelta
from dateutil.rrule import rrulestr
import datetime as dt
from datetime import time, timedelta, datetime
from watchdog.observers import Observer
from watchdog.events import FileSystemEventHandler
import xmpp_alert, email_alert

# Parse args
parser = argparse.ArgumentParser(description="A simple calendar alerting daemon written in Python")
parser.add_argument('--config', type=str, help='Path to config file. Must be .toml')
args = parser.parse_args()

if not args.config:
    print("Error: No config file provided.")
    sys.exit(1)  # Exit with error code
elif not os.path.isfile(args.config):
    print("Error: The specified config file does not exist.")
    sys.exit(1)  # Exit with error code
else:
    print("Config file path: ", args.config)

# Get config
try:
    with open(args.config, 'r') as f:
        config = toml.load(f)
except Exception as e:
    print("Error: Failed to parse TOML file.")
    print(e)
    sys.exit(1)   # Exit with error code

cal_dir = config["app"]["calendar_dir"]

# Get all .ics files from your directory
files = glob.glob(os.path.join(cal_dir, '*.ics'))

class DateTimeEncoder(json.JSONEncoder):
    def default(self, o):
        if isinstance(o, (datetime, timedelta)):
            return str(o)  # Convert the datetime or timedelta object to a string
        return super().default(o)

class FileChangeHandler(FileSystemEventHandler):
    def on_modified(self, event):
        print(f"File modified: {event.src_path}")
        if not event.is_directory:   # If it's a file and not a directory
            print(str(datetime.now()), "Sync detected, updating events")
            with open(event.src_path, 'r') as f:
                cal_str = f.read()
            
            # Parse the calendar
            try:
                event_dict = calendar_parser(cal_str)
                new_hash = self.calculate_event_hash(event_dict)
            except Exception as i:
                print("Failed to parse calendar event at: {}.\n Error:\n{}".format(event.src_path,i))
                return 

            for i, old_event in enumerate(event_list):
                if old_event["uid"] == event_dict["uid"]:
                    old_hash = old_event["hash"]
                    
                    if new_hash != old_hash:  # If the hashes don't match, it means that the event has been modified or deleted
                        print("Event with UID {} has been modified or deleted".format(old_event["uid"]))
                        
                        # Update the event in the list
                        event_list[i] = event_dict
                    else:  # If the hashes match, it means that the event hasn't been modified
                        print("Event with UID {} hasn't been modified".format(old_event["uid"]))
                    
                    break
            else:  # If no matching event is found in the list, add the new event to the list
                event_list.append(event_dict)

    def on_deleted(self, event):
        print(f"File deleted: {event.src_path}")
        if not event.is_directory:   # If it's a file and not a directory
            print(str(dt.datetime.now()), "Sync detected, updating events")
            
            for i, old_event in enumerate(event_list):
                uid = os.path.splitext(os.path.basename(event.src_path))[0]   # Get the UID from the file path without extension
                
                if old_event["uid"] == uid:   # If the same event is found
                    print("Event with UID {} has been deleted".format(old_event["uid"]))
                    
                    # Remove the event from the list
                    del event_list[i]
                    break

    def on_created(self, event):
        print(f"File created: {event.src_path}")
        if not event.is_directory:   # If it's a file and not a directory
            print(str(dt.datetime.now()), "Sync detected, updating events")
            
            with open(event.src_path, 'r') as f:
                cal_str = f.read()
                
            try:
                event_dict = calendar_parser(cal_str)
                new_hash = self.calculate_event_hash(event_dict)
            except Exception as i:
                print("Failed to parse calendar event at: {}.\n Error:\n{}".format(event.src_path,i))
                return 
            
            for old_event in event_list:
                if old_event["uid"] == event_dict["uid"]:   # If the same event is found
                    print("Event with UID {} already exists".format(old_event["uid"]))
                    break
            else:    # If no matching event is found in the list, add the new event to the list
                event_list.append(event_dict)

    def calculate_event_hash(self, event):
        return hashlib.md5(json.dumps(event, sort_keys=True, cls=DateTimeEncoder).encode()).hexdigest()

def calculate_recur_dates(dtstart, vrecur):
    rule_str = "RRULE:{}".format(vrecur.to_ical().decode('utf-8'))
    start_date = dtstart
    if vrecur.get("COUNT") is None:
        # If no COUNT, calculate an end date based on FREQ and INTERVAL to prevent generating too many dates
        freq = vrecur.get('FREQ')[0]
        interval = vrecur.get('INTERVAL')[0]
        
        delta = None
    
        if freq == "DAILY":
            delta = relativedelta(days=interval)
        elif freq == "MONTHLY":
            delta = relativedelta(months=interval)
        elif freq == "YEARLY":
            delta = relativedelta(years=interval)
        
        count = 0
        current_date = datetime.now().replace(tzinfo=pytz.UTC)
        origin_date = start_date
        while origin_date < current_date:
            count += interval
            origin_date += delta*interval
            
        rule_str += ";COUNT={}".format(count+10)
        
    ruleset = rrulestr(rule_str, dtstart=start_date)
    
    # Generate future dates according to the rules
    dates = list(ruleset)
    return [d for d in dates if d > start_date]
    
def calendar_parser(cal_str):
    # Parse the calendar
    cal = Calendar.from_ical(cal_str)

    for component in cal.walk():
        if component.name == "VEVENT":  # If it's a VEVENT, create a new event dictionary
            uid = component.get("UID")
            dtstart = component.get("DTSTART").dt
            dtstart = dtstart if isinstance(dtstart, dt.datetime) else datetime.combine(dtstart, dt.time.min) # Ensure dates are always as datetime
            dtstart = dtstart.replace(tzinfo=pytz.UTC)
            summary = component.get("SUMMARY")
            vrecur = component.get("RRULE")
            recur_dates = [None]
            if vrecur is not None:
                recur_dates = calculate_recur_dates(dtstart, vrecur)

            valarm_list = []  # List to hold all VALARM for this event
            for subcomponent in component.walk():  # Find all VALARMs for this VEVENT
                if subcomponent.name == "VALARM":
                    valarm = Event.from_ical(subcomponent.to_ical())
                    timedelta = valarm.get("TRIGGER").dt
                    valarm_list.append(timedelta)    # Add this VALARM to the list
            event_dict = {"uid": str(uid), "dtstart": dtstart, "summary": summary, "recur_dates": recur_dates, "valarm": valarm_list, "alert_history": []}
            handler = FileChangeHandler()  # Create an instance of the FileChangeHandler class
            new_hash = handler.calculate_event_hash(event_dict)  # Calculate the hash of the event dictionary
            event_dict["hash"] = new_hash  # Store the hash in the event dictionary
            return event_dict 

def get_next_alert(event, current_time):
    recur_dates = event["recur_dates"]
    valarm_deltas = event["valarm"]
    dtstart = event["dtstart"]
    next_event = None
    if recur_dates[0] is None:
        next_event = dtstart
    elif current_time <= dtstart:
        next_event = dtstart
    else:
        next_event = recur_dates[0]
    if current_time > next_event:
        return None, next_event
    next_alert_list = [next_event + i for i in valarm_deltas if next_event + i >= current_time]
    if next_alert_list == []:
        next_alert = next_event
    else:
        next_alert = min(next_alert_list)
    return next_alert - timedelta(seconds=5), next_event

# Create initial event_list using calendar_parser
event_list = []  # List to hold dictionaries for each event
for file in files:
    with open(file, 'r') as f:
        cal_str = f.read()
    event_dict = calendar_parser(cal_str)
    event_list.append(event_dict)

observer = Observer()
handler = FileChangeHandler()
observer.schedule(handler, cal_dir, recursive=True)
observer.start()
try:
    while True:
        with open("status", 'w') as f:
            #Refresh the status file
            f.write("")
        current_time = dt.datetime.now().replace(tzinfo=pytz.UTC)
        for event in event_list:
            next_alert, next_event = get_next_alert(event, current_time)
            if next_alert == None:
                continue
            monitor_status = "Current time: {}\nMonitoring: {}\nEvent date: {}\nNext alert on: {}\nAlert history: {}\n".format(current_time, event["summary"], next_event, next_alert, event["alert_history"])
            with open("status", 'a') as f:
                # Write the output to the file
                f.write(monitor_status)
                f.write("\n")
            if current_time >= next_alert and next_alert < next_alert + timedelta(seconds=15):
                if len(event["alert_history"]) == 0:
                    print("First alert for '{}' detected".format(event["summary"]))
                    event["alert_history"] = [{"timestamp_alert_triggered": current_time, "alert_defintition_time": next_alert}]
                elif next_alert in [i["alert_defintition_time"] for i in event["alert_history"]]:
                    continue
                else:
                    print("Posting alert for {}!".format(event["summary"]))
                    event["alert_history"].append({"timestamp_alert_triggered": current_time, "alert_defintition_time": next_alert})
                xmpp_alert.send_xmpp(event["summary"], next_alert, next_event, args.config)
                email_alert.send_email(event["summary"], next_alert, next_event, args.config)
                with open("alert_history", 'a') as f:
                    f.write(event)
        time.sleep(1)
except KeyboardInterrupt:
    observer.stop()
observer.join()