from datetime import datetime
import json
import os

def readfile(filename):
    with open(module_path + filename) as f:
        return f.read()

def writefile(filename, data):
    with open(module_path + filename, 'w') as f:
        f.write(data)

# global constants
# Accusative - znahidnyj
WEEKDAYS_ACCUSATIVE = ["понеділок", "вівторок", "середу", "четвер", "п'ятницю", "суботу", "неділю"]

# Genitive - rodovyj
WEEKDAYS_GENITIVE_NEXT = ["наступного понеділка", "наступного вівторка", "наступної середи", "наступного четверга",
                          "наступної п'ятниці", "наступної суботи", "наступної неділі"]

WEEKDAYS_GENITIVE_THIS = ["цього понеділка", "цього вівторка", "цієї середи", "цього четверга", "цієї п'ятниці",
                          "цієї суботи", "цієї неділі"]

lesson_types_to_strings = {
        "lec": "лекція",
        "prac": "практика",
        "lab": "лабораторна"
}


# global variables
module_path = ""

def get_preference_by_id(user_id, name):
    if not os.path.exists(module_path + f"preference-db/{user_id}.json"):
        return None

    raw_prefs = readfile(f"preference-db/{user_id}.json")
    try:
        preferences = json.loads(raw_prefs)
    except Exception as e:
        return None

    if not name in preferences:
        return None
    
    return preferences[name]


def get_all_preferences_by_id(user_id):
    user_preferences = {"output-style": "legacy-vibrant"}

    for i in user_preferences:
        override = get_preference_by_id(user_id, i)
        if override != None:
            user_preferences[i] = override

    return user_preferences


def set_preference_by_id(user_id, name, value):
    if not os.path.exists(module_path + "preference-db/"):
        os.mkdir(module_path + "preference-db/")

    preferences = {}

    if os.path.exists(module_path + f"preference-db/{user_id}.json"):
        try:
            raw_prefs = readfile(f"preference-db/{user_id}.json")
            preferences = json.loads(raw_prefs)
        except Exception as e:
            preferences = {}
    else:
        preferences = {}

    preferences[name] = value

    final_data = json.dumps(preferences)
    writefile(f"preference-db/{user_id}.json", final_data)


def load_template(template, part):
    return readfile(f"templates/{template}/{part}.msg")


def escaped_string_markdownV2(input_string):
    result_string = input_string

    symbols_to_escape = ['_', '*', '[', ']', '(', ')', '~', '`', '>', '#', '+', '-', '=', '|', '{', '}', '.', '!']

    for symbol in symbols_to_escape:
        result_string = result_string.replace(symbol, f"\\{symbol}")

    return result_string


def escaped_string_html(input_string):
    result_string = input_string

    symbols_to_escape = ['<', '>']

    for symbol in symbols_to_escape:
        result_string = result_string.replace(symbol, f"\\{symbol}")

    return result_string


def get_human_readable_date(start_datetime, end_datetime,
                            current_day, current_week):
    human_readable_date = ""
    if ((current_day + 2) == int(start_datetime.strftime("%u"))) or \
            ((current_day == 6) and (start_datetime.strftime("%u") == "1")):
        human_readable_date += "завтра "
    elif current_week != int(start_datetime.strftime("%W")) % 2:
        human_readable_date += f"{WEEKDAYS_GENITIVE_NEXT[int(start_datetime.strftime('%u')) - 1]} "
    elif current_day != (int(start_datetime.strftime("%u")) - 1):
        human_readable_date += f"{WEEKDAYS_GENITIVE_THIS[int(start_datetime.strftime('%u')) - 1]} "
    else:
        human_readable_date += "сьогодні "

    human_readable_date += "з "
    human_readable_date += start_datetime.strftime("%H:%M")

    human_readable_date += " до "
    human_readable_date += end_datetime.strftime("%H:%M")

    return human_readable_date


def get_name_of_lesson_type(lesson_type):
    if lesson_type in lesson_types_to_strings:
        return lesson_types_to_strings[lesson_type]

'''
def generate_lesson_description(lesson, start_datetime, end_datetime, current_day, current_week, overrides={},
        custom_name_prefix="<b>Назва</b>"):
    output_settings = {"name": True, "date": True, "teacher": True, "link": True, "comment": True}
    output_settings.update(overrides)

    result = ""

    if output_settings['name']:
        result += f"{custom_name_prefix}: {escaped_string_html(lesson['name'])} ({escaped_string_html(get_name_of_lesson_type(lesson['type']))})\n"

    if output_settings['date']:
        human_readable_date = get_human_readable_date(start_datetime, end_datetime,
                                                      current_day, current_week)
        result += f"<b>Дата</b>: {escaped_string_html(human_readable_date)}\n"

    if output_settings['teacher']:
        result += f"<b>Викладач</b>: {escaped_string_html(lesson['teacher'])}\n"

    if output_settings['link']:
        result += f"<b>Посилання</b>: {escaped_string_html(lesson['link'])}\n"

    if output_settings['comment'] and 'comment' in lesson:
        result += f"<b>Примітка</b>: {escaped_string_html(lesson['comment'])}\n"

    return result
'''

def generate_lesson_description(lesson, start_datetime, end_datetime, current_day, current_week, overrides={},
        custom_name_prefix="Назва", template="legacy-vibrant"):
    # temporarily not supported
    #output_settings = {"name": True, "date": True, "teacher": True, "link": True, "comment": True}
    #output_settings.update(overrides)

    if lesson.__class__ == dict:
        active_template = load_template(template, "single")

        for i in ['name', 'teacher', 'link']:
            active_template = active_template.replace(f"%{i.upper()}%", lesson[i])


        human_readable_date = get_human_readable_date(start_datetime, end_datetime,
                                                      current_day, current_week)

        active_template = active_template.replace("%DATE%", human_readable_date)
        active_template = active_template.replace("%TYPE%", get_name_of_lesson_type(lesson['type']))
        active_template = active_template.replace("%NAME_PREFIX%", custom_name_prefix)

        return active_template

    elif lesson.__class__ == list:
        total_result = load_template(template, "date")
        human_readable_date = get_human_readable_date(start_datetime, end_datetime,
                                                      current_day, current_week)
        total_result = total_result.replace("%DATE%", human_readable_date)

        for l in lesson:
            active_template = load_template(template, "multiple")

            for i in ['name', 'teacher', 'link']:
                active_template = active_template.replace(f"%{i.upper()}%", l[i])

            active_template = active_template.replace("%DATE%", human_readable_date)
            active_template = active_template.replace("%TYPE%", get_name_of_lesson_type(l['type']))
            active_template = active_template.replace("%NAME_PREFIX%", custom_name_prefix)

            total_result += active_template + "\n"

        return total_result

def get_schedule_data_from(filename):
    raw_schedule = json.loads(readfile(filename))

    baked_schedule = {}

    for day_number, lesson_times in enumerate(raw_schedule):
        for lesson_time in lesson_times:
            timestamp = day_number * 86400 + int(lesson_time.split(":")[0]) * 3600 \
                        + int(lesson_time.split(":")[1]) * 60

            new_record = raw_schedule[day_number][lesson_time]
            item_source = filename.split(".json")[0]

            if new_record.__class__ == list:
                for item in new_record:
                    item["source"] = item_source
            else:
                new_record["source"] = item_source

            baked_schedule[timestamp] = new_record

    return baked_schedule


def process_arguments(args, base_day):
    selected_day = int(base_day)
    preferences = {}

    for arg in args:
        if arg[0] == "-":
            if arg[1:].isdigit():
                selected_day -= int(arg[1:])
            else:
                preferences[arg[1:]] = False

        elif arg[0] == "+":
            if arg[1:].isdigit():
                selected_day += int(arg[1:])
            else:
                preferences[arg[1:]] = True

    selected_day = selected_day % 14

    return preferences, selected_day


def get_lesson_description(schedule, reference_time, lesson_time, current_day, current_week, overrides={},
        custom_name_prefix="Назва", template="legacy-vibrant"):
    lesson_record = schedule[lesson_time]

    lesson_start_datetime = datetime.fromtimestamp(reference_time + lesson_time)
    lesson_end_datetime = datetime.fromtimestamp(reference_time + lesson_time + 5400)
    '''
    if lesson_record.__class__ == dict:
        if force_date_at_top:
            user_defined_overrides = dict(overrides)
            internal_overrides = dict(overrides)
            internal_overrides['date'] = False

            description = generate_lesson_description(lesson_record, lesson_start_datetime, lesson_end_datetime, current_day,
                    current_week, overrides=internal_overrides)

            if 'date' in user_defined_overrides and not user_defined_overrides['date']:
                return description
            else:
                human_readable_date = get_human_readable_date(lesson_start_datetime, lesson_end_datetime,
                        current_day, current_week)
                return f"<b><u>{human_readable_date.capitalize()}</u></b>:\n" + description
        else:
            return generate_lesson_description(lesson_record, lesson_start_datetime, lesson_end_datetime, current_day,
                    current_week, overrides=overrides)

    elif lesson_record.__class__ == list:
        user_defined_overrides = dict(overrides)
        internal_overrides = dict(overrides)
        internal_overrides['date'] = False

        descriptions = [generate_lesson_description(i, lesson_start_datetime, lesson_end_datetime, current_day,
                current_week, overrides=internal_overrides, custom_name_prefix=custom_name_prefix) for i in lesson_record]

        if 'date' in user_defined_overrides and not user_defined_overrides['date']:
            return "\n".join(descriptions)
        else:
            human_readable_date = get_human_readable_date(lesson_start_datetime, lesson_end_datetime,
                    current_day, current_week)
            return f"<b><u>{human_readable_date.capitalize()}</u></b>:\n" + "\n".join(descriptions)
    '''

    return generate_lesson_description(lesson_record, lesson_start_datetime, lesson_end_datetime, current_day,
            current_week, overrides=overrides, custom_name_prefix=custom_name_prefix, template=template)


def process(message, path):
    message_text = message["text"]
    full_command = message_text.split()

    # there is no need to check if the full_command list if empty as it
    # never will be - Telegram requires all messages to have at least
    # one printable symbol, so this is already protected
    base_command = full_command[0].lower()

    if base_command not in ["!пара", "!пари", "!schedule-ctl"]:
        return None, None

    global module_path
    module_path = path

    schedule = get_schedule_data_from("schedule-v2.json")
    schedule.update(get_schedule_data_from("additions-v2.json"))

    current_time = datetime.now()

    current_week = current_time.isocalendar()[1] % 2
    current_day = current_time.weekday()

    current_seconds = current_week * 604800 + current_day * 86400 + current_time.hour * 3600 + current_time.minute \
                      * 60 + current_time.second

    reference_time = int(current_time.strftime("%s")) - current_seconds

    output_style_preference = get_preference_by_id(message.from_user.id, "output-style")
    if output_style_preference == None:
        output_style_preference = "legacy-vibrant"

    if base_command == "!пара":
        # easter egg
        study_begin_ts = int(datetime(year=2023, month=9, day=4).strftime("%s"))
        current_ts = int(datetime.now().strftime("%s"))

        if -3600*4 < study_begin_ts - current_ts < 0:
            return "Навчання от-от розпочнеться!", None
        elif 0 <= study_begin_ts - current_ts < 1209600:
            return f"До навчання залишилося {study_begin_ts - current_ts} секунд...", None
        elif study_begin_ts - current_ts >= 1209600:
            return "Ви маєте законне право відпочити, пари почнуться не скоро", None
        
        # actual lesson finding code
        upcoming_lessons = [timestamp for timestamp in schedule if timestamp > current_seconds - 5400]

        if len(upcoming_lessons) > 0:
            closest_lesson_time = min(upcoming_lessons)
        else:
            closest_lesson_time = min(schedule)

        return get_lesson_description(schedule, reference_time, closest_lesson_time, current_day,
                current_week, custom_name_prefix="Актуальна пара", template=output_style_preference), "HTML"

    elif base_command == "!пари":
        base_day = current_week * 7 + current_day

        if len(full_command) >= 2:
            args = [i for i in full_command[1:] if len(i) > 1]
            preferences, selected_day = process_arguments(args, base_day)
        else:
            preferences = {}
            selected_day = base_day

        lesson_list = [i for i in schedule if selected_day * 86400 <= i < (selected_day + 1) * 86400]

        lesson_descriptions_list = [get_lesson_description(schedule, reference_time, lesson_time, current_day,
                current_week, overrides=preferences, custom_name_prefix="Назва", template=output_style_preference)
                                    for lesson_time in lesson_list]

        return f"<b><u>Пари у {WEEKDAYS_ACCUSATIVE[selected_day % 7]}</u></b>:\n\n\n" + "\n".join(lesson_descriptions_list), "HTML"

    elif base_command == "!schedule-ctl":
        if full_command[1] == "list":
            prefs = get_all_preferences_by_id(message.from_user.id)
            return "Ваші персональні налаштування:\n" + '\n'.join([f"- {k} = {v}" for k, v in prefs.items()]), "HTML"

        elif full_command[1] == "set":
            prefs = get_all_preferences_by_id(message.from_user.id)

            if full_command[2] in prefs:
                if full_command[2] == "output-style":
                    if full_command[3] not in os.listdir(module_path + "templates/"):
                        return f"Стилю {full_command[3]} не існує; доступні варіанти: " \
                                + ', '.join(os.listdir(module_path + "templates/")), "HTML"

                    previous_value = prefs[full_command[2]]
                    prefs[full_command[2]] = full_command[3]

                    set_preference_by_id(message.from_user.id, full_command[2], full_command[3])

                    return f"Змінено значення {full_command[2]}: {previous_value} -> {full_command[3]}", "HTML"
            else:
                return f"Такого налаштування не існує; переглянути наявні налаштування можна за допомогою команди <u>!schedule-ctl list</u>", "HTML"

        elif full_command[1] == "get":
            requested_preference = get_preference_by_id(message.from_user.id, full_command[2])
            return f"Налаштування {full_command[2]} має значення {requested_preference}", "HTML"

        else:
            return "Такої команди не існує", "HTML"