#!/usr/bin/env python3

import argparse
import datetime
import hashlib
import json
import pathlib
import os
import sqlite3
import subprocess
import sys
import tempfile

DATETIME_FMT = '%Y-%m-%d %H:%M:%S'
try:
    _data_home = os.environ['XDG_DATA_HOME']
except KeyError:
    _data_home = pathlib.Path(os.path.expanduser('~'), '.local', 'share')
SHARE_DIR = pathlib.Path(_data_home, 'rt-auto-remind')
SHARE_DIR.mkdir(parents=True, exist_ok=True)

class LastRunStorage:
    DB_FILENAME = 'RunData.db'
    V1_CREATE_SQL = '''
CREATE TABLE IF NOT EXISTS LastRunV1(
    key text PRIMARY KEY,
    max_date text
);
'''
    V1_SELECT = 'SELECT max_date FROM LastRunV1 WHERE key = ?'
    V1_INSERT = 'INSERT OR REPLACE INTO LastRunV1 VALUES(?, ?);'

    def __init__(self, args):
        self.db = sqlite3.connect(str(SHARE_DIR / self.DB_FILENAME))
        self.db.executescript(self.V1_CREATE_SQL)
        if args.key is None:
            self.key = ';'.join(
                '{}={!r}'.format(key, str(getattr(args, key)))
                for key in ['body_file', 'date_field', 'max_days_diff', 'search']
            )
        else:
            self.key = args.key

    def load(self):
        cursor = self.db.execute(self.V1_SELECT, (self.key,))
        result = cursor.fetchone()
        if result is None:
            return None
        else:
            return datetime.datetime.strptime(result[0], DATETIME_FMT)

    def save(self, end_date):
        end_date_s = end_date.strftime(DATETIME_FMT)
        with self.db:
            self.db.execute(self.V1_INSERT, (self.key, end_date_s))

    def close(self):
        self.db.close()


def parse_arguments(arglist):
    parser = argparse.ArgumentParser()

    action = parser.add_mutually_exclusive_group()
    action.add_argument(
        '--correspond',
        dest='action', action='store_const', const='correspond',
        default='correspond',
        help="Send correspondence on found tickets (default)",
    )
    action.add_argument(
        '--comment',
        dest='action', action='store_const', const='comment',
        help="Comment on found tickets",
    )

    parser.add_argument(
        '--key', '-k',
        help="Use this string to load and save run times in the database"
        " (default is auto-generated)",
    )
    parser.add_argument(
        '--dry-run', '-n',
        action='store_true',
        help="Show the rt-bulk-send command that would be run; don't run it",
    )

    parser.add_argument(
        'date_field',
        help="RT date field to constrain in the search",
    )
    parser.add_argument(
        'min_days_diff',
        type=int,
        help="The earliest end of the date constraint, in days from today",
    )
    parser.add_argument(
        'max_days_diff',
        type=int,
        help="The latest end of the date constraint, in days from today",
    )
    parser.add_argument(
        'search',
        help="TicketSQL search, like you would pass to `rt search`",
    )
    parser.add_argument(
        'body_file',
        type=pathlib.Path,
        help="Path to file that has the content of your correspondence/comment",
    )
    parser.add_argument(
        'rt_args', metavar='rt arguments',
        nargs=argparse.REMAINDER,
        help="Additional arguments to pass to `rt correspond/comment`",
    )
    args = parser.parse_args(arglist)
    args.min_delta = datetime.timedelta(days=args.min_days_diff)
    args.max_delta = datetime.timedelta(days=args.max_days_diff)
    return args

def main(arglist=None, stdout=sys.stdout, stderr=sys.stderr):
    args = parse_arguments(arglist)
    last_run_db = LastRunStorage(args)
    last_run_range_end = last_run_db.load()
    start_datetime = datetime.datetime.utcnow()
    date_range_start = start_datetime + args.min_delta
    if (last_run_range_end is not None) and (last_run_range_end > date_range_start):
        date_range_start = last_run_range_end
    date_range_end = start_datetime + args.max_delta
    search = '({search}) AND {field} > "{start}" AND {field} <= "{end}"'.format(
        search=args.search,
        field=args.date_field,
        start=date_range_start.strftime(DATETIME_FMT),
        end=date_range_end.strftime(DATETIME_FMT),
    )
    send_cmd = [
        'rt-bulk-send', '--{}'.format(args.action),
        search, str(args.body_file), *args.rt_args,
    ]
    if args.dry_run:
        import pprint
        pprint.pprint(send_cmd)
        returncode = 0
    else:
        try:
            subprocess.run(send_cmd, check=True)
        except subprocess.CalledProcessError as error:
            returncode = error.returncode
        else:
            last_run_db.save(date_range_end)
            returncode = 0
    last_run_db.close()
    return returncode

if __name__ == '__main__':
    exit(main())