#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""Utils for bullish."""

# standard imports
import csv
import json
import datetime
import logging
from typing import Tuple

from io import BytesIO, TextIOWrapper
from zipfile import ZipFile

# third-party imports
import django_rq
import requests

from django_redis import get_redis_connection
from django.db import transaction

# app imports
from app.models import BhavCopyEquity


cache = get_redis_connection("default")
logger = logging.getLogger(__name__)


def fetch_bhav_copy_equity_data(date=None):
    """Fetch data from BSE India website."""
    # hack: since bseindia website doesn't respond well to python requests
    user_agent = 'Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Firefox/78.0'
    headers = {
        'User-Agent': user_agent
    }
    if date is None:
        date = datetime.datetime.now()
    datestr = date.strftime("%d%m%y")
    zipurl = f'https://www.bseindia.com/download/BhavCopy/Equity/EQ{datestr}_CSV.ZIP'
    logger.info('Fetching data from %s', zipurl)
    resp = requests.get(zipurl, headers=headers)

    if resp.ok:
        with ZipFile(BytesIO(resp.content)) as bhavcopy_zf:
            csv_file = bhavcopy_zf.namelist()[0]
            with bhavcopy_zf.open(csv_file, 'r') as infile:
                data = list(csv.reader(TextIOWrapper(infile, 'utf-8')))
        return data
    raise ValueError('Fetching data from BSE unsuccessful')


def populate_bhav_copy_data(date=None):
    """Populate DB with Bhav Copy data."""
    if date is None:
        date = datetime.datetime.now().date()
    try:
        data = fetch_bhav_copy_equity_data(date=date)
    except Exception as err:
        # Potentially add code for alerting if needed
        # Repeat job after 10 mins if job fails
        scheduler = django_rq.get_scheduler('default')
        scheduler.schedule(
            scheduled_time=datetime.datetime.now()+datetime.timedelta(minutes=10),
            func=populate_bhav_copy_data,
        )
        raise ValueError(f"Error fetching data from BSE for {date}\nDetails: {err}")
    else:
        del data[0]  # delete title row
        populate_bhav_copy_data_into_postgres(data, date=date)
        populate_bhav_copy_data_into_redis_v1(data, date=date)
        populate_bhav_copy_data_into_redis_v2(data, date=date)


def populate_bhav_copy_data_into_redis_v1(data=None, date=None):
    if date is None:
        raise ValueError("Date is required")
    if data is None:
        data = fetch_bhav_copy_equity_data(date=date)
        del data[0]
    logger.info('Populating data into redis')
    datestr = date.strftime("%d%m%y")
    pipe = cache.pipeline()
    stocks_key = f"stocks:{datestr}"
    cache.delete(stocks_key)
    data = stocks_csv_to_json(data)
    for stock in data:
        # prevent creation of duplicate entries
        stock_code = stock.get('sc_code')
        pipe.rpush(stocks_key, stock_code)
        pipe.hset(
            f"stock:{datestr}:{stock_code}",
            mapping=stock
        )
    pipe.execute()


def populate_bhav_copy_data_into_redis_v2(data=None, date=None):
    if date is None:
        raise ValueError("Date required.")
    if data is None:
        data = fetch_bhav_copy_equity_data(date=date)
        del data[0]
    logger.info('Populating data into redis v2')
    datestr = date.strftime("%d%m%y")
    data = stocks_csv_to_json(data)
    stocks_key = f"stocks:v2:{datestr}"
    cache.delete(stocks_key)
    cache.set(stocks_key, json.dumps(data))


@transaction.atomic
def populate_bhav_copy_data_into_postgres(data=None, date=None):
    logger.info('Populating data into postgres for %s', date)
    if date is None:
        raise ValueError("Date required")
    if data is None:
        data = fetch_bhav_copy_equity_data(date=date)
        del data[0]
    data = stocks_csv_to_json(data)
    for stock in data:
        stock['date'] = date
        BhavCopyEquity.objects.get_or_create(**stock)


def stocks_csv_to_json(data):
    stocks = []
    for stock in data:
        stocks.append({
            "sc_code": stock[0],
            "sc_name": stock[1],
            "sc_group": stock[2],
            "sc_type": stock[3],
            "open_price": float(stock[4]),
            "high_price": float(stock[5]),
            "low_price": float(stock[6]),
            "close_price": float(stock[7]),
            "last_price": float(stock[8]),
            "prevclose_price": float(stock[9]),
            "no_trades": int(stock[10]),
            "no_of_shrs": int(stock[11]),
            "net_turnov": float(stock[12]),
            "tdcloindi": stock[13],
        })
    return stocks


def verify_date(date: str, ret_message: str) -> Tuple[datetime.datetime, str]:
    """Verify current date.

    Check current date and time and return the appropriate date. Also take care
    of the following usecases
    - if today before publish time return yesterdays data
    - if today after publish time return todays data
    - if a future date, return current day's data with time travel message
    - if a weekend return Friday's data with custom message
    """
    # Verify Date
    logger.info('Verifying date %s', date)
    # IST
    curr_datetime = datetime.datetime.now() - datetime.timedelta(hours=5, minutes=30)
    req_datetime = datetime.datetime.strptime(date, '%Y-%m-%d')
    next_publish_time = curr_datetime.replace(hour=6, minute=0, second=0,
                                              microsecond=0)
    logger.info('Current IST Datetime: %s; Request Datetime: %s; Next Publish: %s',
                curr_datetime, req_datetime, next_publish_time)
    # Check for future date
    if req_datetime.date() > curr_datetime.date():
        ret_message += "Time travel not yet invented! Returning latest available data. "
        req_datetime = curr_datetime
    # Check for weekend
    day_num = req_datetime.weekday()
    if day_num in [5, 6]:
        ret_message += "Markets are closed on weekends. Returning data for Friday. "
        req_datetime -= datetime.timedelta(days=day_num-4)  # change req to Friday
    # Check for day
    if (req_datetime.date() == curr_datetime.date()
            and curr_datetime < next_publish_time):
        ret_message += "Today's data not yet published, returning yesterday's data. "
        req_datetime -= datetime.timedelta(days=1)
    return req_datetime, ret_message