"""Download subscriber info from PayPal.

Run it like this:

$ export PAYPAL_CLIENT_ID=XXX
$ export PAYPAL_CLIENT_SECRET=YYY
$ python3 paypal_report.py 2021-11-01T00:00:00-0700 2021-11-30T23:59:59-0700 > out.csv

"""
import argparse
import csv
import sys
import os

import requests


def get_access_token(client_id, client_secret):
    url = 'https://api-m.paypal.com/v1/oauth2/token?grant_type=client_credentials'
    response = requests.post(
        url,
        auth=(client_id, client_secret),
        headers={
            'Accept': 'application/json',
            'Accept-Language': 'en_US',
        },
    )
    data = response.json()
    return data['access_token']


def get_transactions(access_token, start_date, end_date, page=1):
    print(f'Fetching transactions page {page}.', file=sys.stderr)
    url = f'https://api-m.paypal.com/v1/reporting/transactions?start_date={start_date}&end_date={end_date}&fields=all&page_size=500&page={page}'
    response = requests.get(
        url,
        headers={
            'Content-Type': 'application/json',
            'Authorization': f'Bearer {access_token}',
        },
    )
    data = response.json()
    if page < data['total_pages']:
        return data['transaction_details'] + get_transactions(access_token, start_date, end_date, page + 1)
    else:
        return data['transaction_details']


if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='Download PayPal subscriber info.')
    parser.add_argument('start_date', help='start date inclusive (eg. 2021-11-01T00:00:00-0700)')
    parser.add_argument('end_date', help='end date inclusive (eg. 2021-11-30T23:59:59-0700)')
    args = parser.parse_args()
    try:
        client_id = os.environ['PAYPAL_CLIENT_ID']
        client_secret = os.environ['PAYPAL_CLIENT_SECRET']
    except KeyError:
        sys.exit('Please set PAYPAL_CLIENT_ID and PAYPAL_CLIENT_SECRET environment variables.')
    access_token = get_access_token(client_id, client_secret)
    transactions = get_transactions(access_token, args.start_date, args.end_date)
    writer = csv.writer(sys.stdout)
    for t in transactions:
        transaction_info = t['transaction_info']
        if 'paypal_reference_id' in transaction_info:
            writer.writerow(
                (
                    transaction_info['paypal_reference_id'],
                    transaction_info['transaction_subject'],
                ),
            )
        else:
            print(f'Skipping transaction {transaction_info["transaction_id"]} with no PayPal Reference ID.', file=sys.stderr)