#!/usr/bin/env python
# -*- coding: utf-8 -*-
from __future__ import print_function

import os
import shutil
import sys
from codecs import open
from collections import namedtuple
from tempfile import NamedTemporaryFile
from time import time

from autojump_utils import create_dir
from autojump_utils import is_osx
from autojump_utils import is_python3
from autojump_utils import move_file
from autojump_utils import unico


if sys.version_info[0] == 3:
    ifilter = filter
    imap = map
else:
    from itertools import ifilter  # noqa
    from itertools import imap  # noqa


BACKUP_THRESHOLD = 24 * 60 * 60
Entry = namedtuple('Entry', ['path', 'weight'])


def dictify(entries):
    """
    Converts a list of entries into a dictionary where
        key = path
        value = weight
    """
    result = {}
    for entry in entries:
        result[entry.path] = entry.weight
    return result


def entriefy(data):
    """Converts a dictionary into an iterator of entries."""
    convert = lambda tup: Entry(*tup)
    if is_python3():
        return map(convert, data.items())
    return imap(convert, data.iteritems())


def load(config):
    """Returns a dictonary (key=path, value=weight) loaded from data file."""
    if not os.path.exists(config['data_path']):
        return {}

    # example: u'10.0\t/home/user\n' -> ['10.0', u'/home/user']
    parse = lambda line: line.strip().split('\t')

    correct_length = lambda x: len(x) == 2

    # example: ['10.0', u'/home/user'] -> (u'/home/user', 10.0)
    tupleize = lambda x: (x[1], float(x[0]))

    try:
        with open(
                config['data_path'],
                'r', encoding='utf-8',
                errors='replace',
        ) as f:
            return dict(
                imap(
                    tupleize,
                    ifilter(correct_length, imap(parse, f)),
                ),
            )
    except (IOError, EOFError):
        return load_backup(config)


def load_backup(config):
    if os.path.exists(config['backup_path']):
        move_file(config['backup_path'], config['data_path'])
        return load(config)
    return {}


def save(config, data):
    """Save data and create backup, creating a new data file if necessary."""
    data_dir = os.path.dirname(config['data_path'])
    create_dir(data_dir)

    # atomically save by writing to temporary file and moving to destination
    try:
        temp = NamedTemporaryFile(delete=False, dir=data_dir)
        # Windows cannot reuse the same open file name
        temp.close()

        with open(temp.name, 'w', encoding='utf-8', errors='replace') as f:
            for path, weight in data.items():
                f.write(unico('%s\t%s\n' % (weight, path)))

            f.flush()
            os.fsync(f)
    except IOError as ex:
        print('Error saving autojump data (disk full?)' % ex, file=sys.stderr)
        sys.exit(1)

    # move temp_file -> autojump.txt
    move_file(temp.name, config['data_path'])

    # create backup file if it doesn't exist or is older than BACKUP_THRESHOLD
    if not os.path.exists(config['backup_path']) or \
            (time() - os.path.getmtime(config['backup_path']) > BACKUP_THRESHOLD):  # noqa
        shutil.copy(config['data_path'], config['backup_path'])