import csv
import os
import re
from dataclasses import dataclass
from datetime import datetime

import pytz
from beancount.core.number import D
from beanprices import source

FOLDER = "~/net/downloads"
PATTERN = re.compile(r"Depot_\d{2}\.\d{2}\.\d{4}\.csv")
TZ = pytz.timezone("Europe/Berlin")


@dataclass
class WatchlistEntry:
    date: datetime
    price_map: dict


def parse_header(line):
    datestr = line.strip().removeprefix("Depotbewertung vom ")

    return datetime.strptime(datestr, "%d.%m.%Y %H:%M:%S")


def parse_file(handle):
    date = parse_header(handle.readline()).replace(tzinfo=TZ)
    handle.readline()
    handle.readline()

    handle.readline()
    handle.readline()
    handle.readline()

    reader = csv.DictReader(handle, delimiter=";")

    prices = dict()

    for row in reader:
        if isin := row["ISIN"]:
            price = D(row["Aktueller Preis"].replace(",", "."))
            prices[isin] = source.SourcePrice(price, date, row["Währung"])

    return WatchlistEntry(date, prices)


def get_entries():
    for entry in os.scandir(os.path.expanduser(FOLDER)):
        if entry.is_file():
            if not PATTERN.match(entry.name):
                continue

            with open(entry, encoding="cp1252") as handle:
                yield parse_file(handle)


class Source(source.Source):
    def get_latest_price(self, isin):
        entries = sorted(get_entries(), key=lambda e: e.date, reverse=True)
        if not entries:
            return None

        return entries[0].price_map.get(isin, None)

    def get_historical_price(self, isin, time):
        for entry in get_entries():
            if entry.date.date() == time.date():
                return entry.price_map.get(isin, None)

        return None