hashname

#!/usr/bin/env python3

import itertools as it, operator as op, functools as ft
import os, sys, base64, pathlib as pl, hashlib as hl, shutil as su


it_adjacent = lambda seq, n: it.zip_longest(*([iter(seq)] * n))
_b32_abcs = dict(zip(
	# Python base32 - "Table 3: The Base 32 Alphabet" from RFC3548
	'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567',
	# Crockford's base32 - http://www.crockford.com/wrmg/base32.html
	'0123456789ABCDEFGHJKMNPQRSTVWXYZ' ))
_b32_abcs['='] = ''

def b32encode( v, chunk=4, simple=False,
		_trans=str.maketrans(_b32_abcs),
		_check=''.join(_b32_abcs.values()) + '*~$=U' ):
	chksum = 0
	for c in bytearray(v): chksum = chksum << 8 | c
	res = base64.b32encode(v).decode().strip().translate(_trans)
	if simple: return res.lower()
	res = '-'.join(''.join(filter(None, s)) for s in it_adjacent(res, chunk))
	return '{}-{}'.format(res, _check[chksum % 37].lower())


hash_person = b'hashname.1'
hash_size = 8
hash_chunk = 1 * 2**20 # 1 MiB

def get_hash(p, enc_func=ft.partial(b32encode, simple=True)):
	p_hash = hl.blake2b(digest_size=hash_size, person=hash_person)
	with p.open('rb') as src:
		for chunk in iter(ft.partial(src.read, hash_chunk), b''): p_hash.update(chunk)
	return enc_func(p_hash.digest())


def main(args=None):
	import argparse
	parser = argparse.ArgumentParser(
		description='Give file(s) distinctive names using hash of their content.'
			' Default naming scheme is "{name}.{hash}.{ext}".')
	parser.add_argument('files', nargs='+', help='File(s) to rename.')
	parser.add_argument('-p', '--dry-run',
		action='store_true', help='Print renames but not actually do it.')
	parser.add_argument('-m', '--move', metavar='dir',
		help='Move renamed files to specified dir.')
	opts = parser.parse_args(sys.argv[1:] if args is None else args)

	p_mv = pl.Path(opts.move) if opts.move else None
	if p_mv and not p_mv.is_dir():
		parser.error(f'-m/--move path is not a directory: {p_mv}')

	exit_code = 0
	def p_err(*args):
		nonlocal exit_code
		print('ERROR:', *args, file=sys.stderr)
		exit_code = 1

	for p in opts.files:
		p = pl.Path(p)
		try: p_hash = get_hash(p)
		except OSError as err:
			p_err(f'failed to process path [{p}]: {err}')
			continue
		name, ext = name if len(name := p.name.rsplit('.', 1)) == 2 else (name[0], '')
		name_new = '.'.join(filter(None, [name, p_hash, ext]))
		print(p.name, '->', name_new)
		if not opts.dry_run:
			try:
				if not opts.move: p.rename(p.parent / name_new)
				else: su.move(p, p_mv / name_new)
			except OSError as err:
				p_err(f'failed to rename/move path [{p}]: {err}')

	return exit_code

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