import csv
import re

from datetime import datetime, date
from itertools import islice
from typing import Any, Optional

from beancount.core import data  # type: ignore
from beancount.core.amount import Amount  # type: ignore
from beancount.core.number import Decimal  # type: ignore
from beancount.ingest import cache, importer  # type: ignore


COL_DATE = "Date de comptabilisation"
COL_LABEL = "Libelle simplifie"
COL_DEBIT = "Debit"
COL_CREDIT = "Credit"
COL_DETAIL = "Informations complementaires"
COL_DATE_OP = "Date operation"

END_DATE_REGEX = "Date de fin de téléchargement : ([0-3][0-9]/[0-1][0-9]/[0-9]{4})"
START_DATE_REGEX = "Date de début de téléchargement : ([0-3][0-9]/[0-1][0-9]/[0-9]{4})"

EXPECTED_HEADER = "Date de comptabilisation;Libelle simplifie;Libelle operation;Reference;Informations complementaires;Type operation;Categorie;Sous categorie;Debit;Credit;Date operation;Date de valeur;Pointage operation"


def is_valid_header(header: str) -> bool:
    return header == EXPECTED_HEADER


class CDEImporter(importer.ImporterProtocol):
    def __init__(self, account: str):
        self.account = account

    def identify(self, file: cache._FileMemo) -> bool:
        try:
            # NOTE: beancount.ingest.cache._FileMemo handles automatic encoding
            # detection
            lines: list[str] = file.head().splitlines()
            header: str = lines[0]
            return is_valid_header(header)

        except:
            return False

    def file_account(self, file: cache._FileMemo) -> Optional[str]:
        return self.account

    def file_name(self, file: cache._FileMemo) -> Optional[str]:
        return "CaisseEpargne_Statement.csv"

    def file_date(self, file: cache._FileMemo) -> Optional[date]:
        lines: list[str] = file.contents().splitlines()
        csv_reader: csv.DictReader = csv.DictReader(
            lines, delimiter=";", strict=True, quoting=csv.QUOTE_NONE
        )

        row: Optional[dict[str, str]] = next(csv_reader)
        if row is None:
            return None

        return datetime.strptime(row[COL_DATE], "%d/%m/%Y").date()

    def extract(self, file: cache._FileMemo, existing_entries=None) -> list[Any]:
        directives: list[Any] = []

        lines: list[str] = file.contents().splitlines()
        csv_reader = csv.DictReader(
            lines, delimiter=";", strict=True, quoting=csv.QUOTE_NONE
        )

        for index, row in enumerate(csv_reader):
            lineno: int = index + 2  # entries start at line 2
            meta = data.new_metadata(file.name, lineno)

            transaction_date: date = datetime.strptime(row[COL_DATE], "%d/%m/%Y").date()
            op_date: date = datetime.strptime(row[COL_DATE_OP], "%d/%m/%Y")
            label: str = row[COL_LABEL]
            debit: str = row[COL_DEBIT]
            credit: str = row[COL_CREDIT]
            detail: str = row[COL_DETAIL] if row[COL_DETAIL] else ""

            postings: list[data.Posting] = []

            if debit:
                amount = Decimal(debit.replace(",", "."))
                postings.append(
                    data.Posting(
                        self.account,
                        Amount(amount, "EUR"),
                        None,
                        None,
                        None,
                        {"op-date": op_date},
                    )
                )

            if credit:
                amount = Decimal(credit.replace(",", "."))
                postings.append(
                    data.Posting(
                        self.account,
                        Amount(amount, "EUR"),
                        None,
                        None,
                        None,
                        {"op-date": op_date},
                    )
                )

            directives.append(
                data.Transaction(
                    meta,
                    transaction_date,
                    self.FLAG,
                    label,
                    detail,
                    data.EMPTY_SET,
                    data.EMPTY_SET,
                    postings,
                )
            )

        return directives