#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#
# Send emails according to a CSV input with fields and templating support.
#
# Copyright (C) 2022 Silvio Rhatto <rhatto@riseup.net>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published
# by the Free Software Foundation, either version 3 of the License,
# or any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# Dependencies
import argparse
import csv
import sys, os, subprocess

class MinimailerCSV:
    """Send emails according to a CSV input with fields and templating support"""

    def __init__(self, args):
        self.args = args
        self.data = []

        if os.path.exists(args.template_file[0]):
            with open(args.template_file[0], 'r') as template_file:
                self.template = template_file.read()
        else:
            raise FileNotFoundError('No such file ' + template_file)

        if os.path.exists(args.csv_file[0]):
            with open(args.csv_file[0], newline='') as csv_file:
                self.csv = csv.DictReader(csv_file,
                        delimiter=args.delimiter,
                        quotechar=args.quotechar,
                        )

                for row in self.csv:
                    self.data.append(row)

        else:
            raise FileNotFoundError('No such file ' + csv_file)

    def send(self):
        for item in self.data:
            print('sending message to {}'.format(item[self.args.recipient_field_address]))

            message = self.template.format(**item)

            with subprocess.Popen('{sendmail} {recipient}'.format(
                message=message,
                sendmail=self.args.sendmail_command,
                recipient=item[self.args.recipient_field_address],
                ), text=True, stdin=subprocess.PIPE, stdout=subprocess.PIPE, shell=True) as proc:

                proc.stdin.write(message)
                proc.stdin.close()

if __name__ == "__main__":
    """Process from CLI"""

    epilog = """Examples:

      minimailer-csv message.tmpl data.csv --sendmail-command 'msmtp -a default'
      minimailer-csv message.tmpl data.csv --recipient-field-address 'contact'
    """

    description = 'Send emails according to a CSV input with fields and templating support'
    parser      = argparse.ArgumentParser(
                    description=description,
                    epilog=epilog,
                    formatter_class=argparse.RawDescriptionHelpFormatter,
                  )

    parser.add_argument('template_file',       nargs=1,   help='Message template filename')
    parser.add_argument('csv_file',            nargs=1,   help='CSV filename. It\'s required that the first line in the CSV contain the field names.')
    #parser.add_argument('mstmp_account_name', nargs='?', help='MSTMP account name')

    # Defaults
    sendmail_command_default        = '/usr/bin/msmtp -a default'
    recipiend_field_address_default = 'email'
    delimiter_default               = ','
    quotechar_default               = '"'

    parser.add_argument(
            '--sendmail-command',
            help='Sendmail command invocation. Defaults to ' + sendmail_command_default
            )

    parser.add_argument(
            '--recipient-field-address',
            help='Email address field in the CSV file. Defaults to ' + recipiend_field_address_default
            )

    parser.add_argument(
            '--delimiter',
            help='CSV field delimiter. Defaults to' + delimiter_default,
            )

    parser.add_argument(
            '--quotechar',
            help='CSV quotechar. Defaults to' + quotechar_default,
            )

    # Set defaults
    #parser.set_defaults(msmtp_account_name='default')
    parser.set_defaults(sendmail_command=sendmail_command_default)
    parser.set_defaults(recipiend_field_address=recipiend_field_address_default)
    parser.set_defaults(delimiter=delimiter_default)
    parser.set_defaults(quotechar=quotechar_default)

    args = parser.parse_args()

    # Dispatch
    try:
        mailer = MinimailerCSV(args)

        mailer.send()

    except (FileNotFoundError, KeyboardInterrupt, subprocess.SubprocessError) as e:
        print(e)
        exit(1)