#!/usr/bin/env python3

import os
import sys
import csv
import json
import logging
import datetime
import ofxtools

from typing import List
from dataclasses import dataclass
from ofxtools import OFXClient
from ofxtools.Client import StmtRq, CcStmtEndRq, CcStmtRq
from ofxtools.Parser import OFXTree


@dataclass
class ClientConfig:
    url: str
    userid: str
    org: str
    clientuid: str
    fid: str
    bankid: str
    version: int


@dataclass
class AccountConfig:
    name: str
    accttype: str
    acctid: str
    csv_file: str
    fields: List[str]


@dataclass
class Config:
    """
    Basic class for abstracting the configuration.
    """
    secret: str
    client: ClientConfig
    accounts: List[AccountConfig]


@dataclass
class Transaction:
    date: str
    description: str
    amount: str


def get_transactions(client: OFXClient, secret: str, account: AccountConfig):
    """ The idea is that I run this often enough so that the last 30 days of
    data are enough to never lose a transaction. This would be the syntax to
    create a datetime object with an arbitrary date:
        datetime.datetime(2020, 1, 1, tzinfo=ofxtools.utils.UTC)"""
    dtend = datetime.datetime.utcnow().replace(tzinfo=ofxtools.utils.UTC)
    dtstart = dtend - datetime.timedelta(days=30)

    if account.accttype.upper() in ("CHECKING", "SAVINGS"):
        rq = StmtRq(acctid=account.acctid, accttype=account.accttype.upper(),
                    dtstart=dtstart, dtend=dtend)
    else:
        rq = CcStmtRq(acctid=account.acctid, dtstart=dtstart, dtend=dtend)
    response = client.request_statements(secret, rq)
    parser = OFXTree()
    parser.parse(response)
    ofx = parser.convert()

    # Sort by date because my credit transactions come in random order.
    translist = sorted(ofx.statements[0].banktranlist, reverse=True,
                       key=lambda t: t.dtposted)

    ts = [Transaction(t.dtposted.strftime("%m/%d/%Y"),
                      t.name + " " + t.memo  if t.memo else t.name,
                      str(t.trnamt)) for t in translist]
    return ts


def write_csv(account: AccountConfig, transactions: List[Transaction]):

    def transaction_to_csv_row(t: Transaction) -> List[str]:
        """ This allows to user to specify how to order the fields in the CSV
        file.  I have implemented this feature because the columns in my
        checking account and in my credit card accounts are different.  If the
        field is one of 'date', 'description', or 'amount' we get that
        attribute from the transaction. Otherwise, we use the field itself
        (usually an empty string in my case).  """
        return [getattr(t, f) if hasattr(t, f) else f
                for f in account.fields]

    def merge_rows(csv_rows: List, ofx_rows: List) -> (List, int):
        """ Prepend new transactions to the one from the CSV file. We assume
        that both the new transactions from OFX and the transactions in the CSV
        file are sorted in descending order, meaning the newest transaction
        comes first.  The idea is then to see if one of the new transactions
        matches the latest one in the CSV file. If yes, we include all newer
        transactions from the CSV file. If no, we include all transactions. """
        csv_rows.reverse()
        ofx_rows.reverse()
        newest_csv_row = csv_rows[-1]
        new_rows = 0
        row_found = False
        for row in ofx_rows:
            if row_found is False and row == newest_csv_row:
                row_found = True
            elif row_found is True:
                csv_rows.append(row)
                new_rows += 1
        if not row_found:
            csv_rows += ofx_rows
            new_rows = len(ofx_rows)
        csv_rows.reverse()
        return (csv_rows, new_rows)

    status = "no change"
    csv_file = account.csv_file
    ofx_rows = [transaction_to_csv_row(t) for t in transactions]
    if not os.path.isfile(csv_file):
        new_rows = len(ofx_rows)
        status = f"new ({new_rows})"
        rows = ofx_rows
        header = ["date", "description", "amount"]
    else:
        with open(csv_file, 'r') as f:
            reader = csv.reader(f)
            header = next(reader) # skip header
            csv_rows = list(reader)
        rows, new_rows = merge_rows(csv_rows, ofx_rows)
        if new_rows > 0:
            status = f"update ({new_rows})"

    logging.warning(f"{account.name:30} -> {account.csv_file:30} | {status}")
    if new_rows == 0:
        return

    with open(account.csv_file, "w") as f:
        csv_writer = csv.writer(f)
        csv_writer.writerow(header)
        for r in rows:
            csv_writer.writerow(r)


def get_client(c: ClientConfig) -> OFXClient:
    return OFXClient(c.url, userid=c.userid, org=c.org, fid=c.fid,
                     clientuid=c.clientuid, bankid=c.bankid,
                     version=c.version, prettyprint=True)


def parse_config(config_file: str) -> Config:
    with open(config_file, 'r') as f:
        # We could use the dacite package to parse the configuration
        # recursively with full type checking. Probably not worth it at this
        # point.
        config = Config(**json.load(f))
        config.client = ClientConfig(**config.client)
        config.accounts = [AccountConfig(**a) for a in config.accounts]
    return config


def main(config: Config):
    client = get_client(config.client)
    for account in config.accounts:
        transactions = get_transactions(client, config.secret, account)
        write_csv(account, transactions)


if __name__ == "__main__":
    logging.basicConfig(level=logging.WARNING, format='%(message)s')
    try:
        config_file = sys.argv[1]
    except IndexError:
        config_file = "getofx.json"
    config = parse_config(config_file)
    main(config)