"""
BSD 2-Clause License
restic subprocess wrapper
Copyright (c) 2018, Max Resnick <max@ofmax.li>
All rights reserved.

restic-py is simple wrapper to restic binary for backups and monitoring
"""
import os
import tempfile
import configparser
import glob
import argparse
import logging
import sys
import time
import io

import sh

# logging
LOGLEVELS = {'DEBUG': logging.DEBUG,
             'INFO': logging.INFO,
             'WARNING': logging.WARNING,
             'ERROR': logging.ERROR}

HOME_DIR = os.path.expanduser('~')
DEFAULT_CONFIG = '{}/.local/etc/restic-wrapper/restic.ini'.format(HOME_DIR)
CONFIG = os.environ.get('RESTIC_CONFIG', DEFAULT_CONFIG)

# TODO should be a configurable location
logging.basicConfig(filename='{}/.local/logs/restic.log'.format(HOME_DIR),
                    level=LOGLEVELS[os.getenv('RESTIC_LOGLEVEL', 'INFO')])
log = logging.getLogger(__name__)

# cmd line parser
parser = argparse.ArgumentParser(description='wrapper to restic')
parser.add_argument('cmd',
                    type=str,
                    choices=('backup', 'prune', 'check', 'watch'),
                    help='run backup')

# config
cfg = configparser.ConfigParser()
cfg.read(CONFIG)

PASSWORD_FILE = '{}/.ssh/resticpass'.format(HOME_DIR)
exclude_file = os.path.expanduser(cfg['restic']['exclude'])
restic_uri = cfg['restic']['repo_uri']
BACKUP_CMD = sh.restic.bake('backup',
                            '--password-file', PASSWORD_FILE,
                            '--exclude-file', exclude_file,
                            '--exclude-caches',
                            '--repo', restic_uri)
PRUNE_CMD = sh.restic.bake('forget',
                           '--password-file', PASSWORD_FILE,
                           '--repo', restic_uri,
                           '--keep-daily', 7,
                           '--keep-weekly', 5,
                           '--keep-monthly', 12,
                           '--keep-yearly', 75)
CHECK_CMD = sh.restic.bake('check',
                           '--password-file', PASSWORD_FILE,
                           '--repo', restic_uri)


def _check_auth():
    try:
        os.environ['SSH_AUTH_SOCK']
    except KeyError:
        log.error('ssh agent not running')


def run_backup():
    directories = []
    for chunk in glob.iglob('{}/*'.format(HOME_DIR)):
        if os.path.isdir(chunk):
            try:
                out = BACKUP_CMD(chunk)
                directories.append(chunk)
                log.info('{} {}'.format('restic-run', chunk))
            except sh.ErrorReturnCode_1 as e:
                log.error('{} {} {}'.format('restic-run', chunk, e))
    # backs up non chunked files
    with tempfile.NamedTemporaryFile(delete=True) as tmp:
        tmp.write('\n'.join(directories).encode())
        out = BACKUP_CMD('--exclude-file', tmp.name, HOME_DIR)
        log.info('{} {}'.format('restic-run', HOME_DIR))


def run_prune():
    try:
        out = PRUNE_CMD()
    except sh.ErrorReturnCode_1 as e:
        log.error('{} {}'.format('restic-prune', e))


def run_check():
    try:
        out = CHECK_CMD()
    except sh.ErrorReturnCode_1 as e:
        log.error('{} {}'.format('restic-check', e))


def follow(logfile, pattern):
    # catch up
    for line in logfile.readlines():
        if pattern in line:
            yield line
    logfile.seek(0, 2)
    while True:
        line = logfile.readline()
        if not line:
            time.sleep(0.1)
            continue
        if pattern in line:
            yield line


def run_watch():
    logfile = open("restic.log","r")
    loglines = follow(logfile, 'ERROR')
    # TODO notification
    for line in loglines:
        print(line)


def main():
    _check_auth()
    cmd_arg = parser.parse_args()
    cmd = 'run_{}'.format(cmd_arg.cmd)
    try:
        run = globals()[cmd]
    except KeyError:
        log.error('command {} not found'.format(cmd))
        sys.exit(1)
    run()