'''
Batch rename files by providing a string to be `eval`ed, using variable `x` as
the current filename.
Yes I know this is weird, but for certain tasks it's just too quick and easy to pass up.

For example:

Prefix all the files:
brename.py "'Test_' + x"

Keep the first word and extension:
brename.py "(x.split(' ')[0] + '.' + x.split('.')[-1]) if ' ' in x else x"
'''
import argparse
import os
import random
import re
import sys
import unicodedata

from voussoirkit import betterhelp
from voussoirkit import interactive
from voussoirkit import pathclass
from voussoirkit import safeprint
from voussoirkit import spinal
from voussoirkit import stringtools

# These constants are provided for use in your eval string
cwd = pathclass.cwd()

# These variables are provided so that if you have any difficulty typing
# literal quotes etc into your command line, you can just use these variable
# names in your eval string.
apostrophe = "'"
dot = '.'
hyphen = '-'
quote = '"'
space = ' '
underscore = '_'

# For backwards compatibility, these names which were once locally defined
# functions are now just references to stringtools.
excise = stringtools.excise
title = stringtools.title_capitalize

def natural_sorter(x):
    '''
    Thank you Mark Byers
    http://stackoverflow.com/a/11150413
    '''
    convert = lambda text: int(text) if text.isdigit() else text.lower()
    alphanum_key = lambda key: [convert(c) for c in re.split(r'([0-9]+)', key)]
    return alphanum_key(x)

def unicode_normalize(s):
    return unicodedata.normalize('NFC', s)

def brename(transformation, autoyes=False, do_naturalsort=False, recurse=False):
    if recurse:
        walker = spinal.walk_generator('.', yield_files=True, yield_directories=True)
        olds = list(walker)
    else:
        olds = cwd.listdir()

    if do_naturalsort:
        olds.sort(key=lambda x: natural_sorter(x.absolute_path))
    else:
        olds.sort()

    pairs = []
    for (index, old) in enumerate(olds):
        # These variables are assigned so that you can use them in your
        # transformation string.
        x = old.basename
        parent = old.parent
        noext = old.replace_extension('').basename
        ext = old.extension.ext
        index1 = index + 1

        new = eval(transformation)
        new = parent.with_child(new)
        if new.basename == old.basename:
            continue
        pairs.append((old, new))

    if not pairs:
        print('Nothing to replace')
        return

    loop(pairs, dry=True)

    if not (autoyes or interactive.getpermission('Is this correct?')):
        return

    # Sort in reverse so that renaming a file inside a directory always
    # occurs before renaming the directory itself. If you rename the
    # directory first, then the path to the file is invalid by the time
    # you want to rename it.
    pairs = sorted(pairs, reverse=True)
    loop(pairs, dry=False)

def longest_length(li):
    longest = 0
    for item in li:
        longest = max(longest, len(item))
    return longest

def loop(pairs, dry=False):
    for (old, new) in pairs:
        if dry:
            line = f'{old.absolute_path}\n{new.absolute_path}\n'
            safeprint.safeprint(line)
        else:
            os.rename(old.absolute_path, new.absolute_path)

def brename_argparse(args):
    return brename(
        args.transformation,
        autoyes=args.autoyes,
        do_naturalsort=args.naturalsort,
        recurse=args.recurse,
    )

DOCSTRING = '''
brename - batch file renaming
=============================

> brename.py eval_string <flags>

eval_string:
    A string which will be evaluated by Python's eval. The name of the file or
    folder will be in the variable `x`. In addition, many other variables are
    provided for your convenience:
    `quote` ("), `apostrophe` (') so you don't have to escape command quotes.
    `hyphen` (-) because leading hyphens often cause problems with argparse.
    `stringtools` entire stringtools module. See voussoirkit/stringtools.py.
    `space` ( ), `dot` (.), `underscore` (_) so you don't have to add quotes to
    your command while using these common characters.
    `index` the file's index within the loop.
    `index1` the file's index+1, in case you want your names to start from 1.
    `parent` a pathclass.Path object for the directory containing the file.
    `cwd` a pathclass.Path object for the cwd of this program session.
    `noext` the name of the file, but without its extension.
    `ext` the file's extension, with no dot.

-y | --yes:
    Accept the results without confirming.

--recurse:
    Recurse into subfolders and rename those files too.

--naturalsort:
    Before renaming, the files will be sorted using natural sort instead of the
    default lexicographic sort. Natural sort means that "My file 20" will come
    before "My file 100" because 20<100. Lexicographic sort means 100 will come
    first because 1 is before 2.
    The purpose of this flag is so your index and index1 variables are applied
    in the order you desire.
'''

def main(argv):
    parser = argparse.ArgumentParser(description=__doc__)

    parser.add_argument('transformation', help='python command using x as variable name')
    parser.add_argument('-y', '--yes', dest='autoyes', action='store_true')
    parser.add_argument('--recurse', action='store_true')
    parser.add_argument('--naturalsort', action='store_true')
    parser.set_defaults(func=brename_argparse)

    return betterhelp.single_main(argv, parser, DOCSTRING)

if __name__ == '__main__':
    raise SystemExit(main(sys.argv[1:]))