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

from codecs import open
from collections import namedtuple
import os
import shutil
import sys
import fcntl
from time import time

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

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


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."""
    xdg_aj_home = os.path.join(
        os.path.expanduser('~'),
        '.local',
        'share',
        'autojump')

    if is_osx() and os.path.exists(xdg_aj_home):
        migrate_osx_xdg_data(config)

    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:
            fcntl.flock(f.fileno(), fcntl.LOCK_SH)
            d = dict(
                imap(
                    tupleize,
                    ifilter(correct_length, imap(parse, f))))
            fcntl.flock(f.fileno(), fcntl.LOCK_UN)
            return d
    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 migrate_osx_xdg_data(config):
    """
    Older versions incorrectly used Linux XDG_DATA_HOME paths on OS X. This
    migrates autojump files from ~/.local/share/autojump to ~/Library/autojump
    """
    assert is_osx(), "This function should only be run on OS X."

    xdg_data_home = os.path.join(os.path.expanduser('~'), '.local', 'share')
    xdg_aj_home = os.path.join(xdg_data_home, 'autojump')
    data_path = os.path.join(xdg_aj_home, 'autojump.txt')
    backup_path = os.path.join(xdg_aj_home, 'autojump.txt.bak')

    if os.path.exists(data_path):
        move_file(data_path, config['data_path'])
    if os.path.exists(backup_path):
        move_file(backup_path, config['backup_path'])

    # cleanup
    shutil.rmtree(xdg_aj_home)
    if len(os.listdir(xdg_data_home)) == 0:
        shutil.rmtree(xdg_data_home)


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

    with open(config['data_path'], 'w', encoding='utf-8') as f:
        fcntl.flock(f.fileno(), fcntl.LOCK_EX)
        for path, weight in data.items():
            f.write(unico("%s\t%s\n" % (weight, path)))
        fcntl.flock(f.fileno(), fcntl.LOCK_UN)

    # 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'])