#!/usr/bin/env python
# Author: Darko Poljak <darko.poljak@gmail.com>
# License: GPLv3

"""Sweeper.

Usage: sweeper.py [options] [<directory>...]

Arguments:
    <directory> directory path to scan for files

Options:
-h, --help                                show this screen
-b <blocksize>, --block-size=<blocksize>  size of block used when reading file's
                                          content [default: 4096]
-d <hashalg>, --digest-alg=<hashalg>      secure hash algorithm [default: md5]
-a <action>, --action=<action>            action on duplicate files 
                                          (print, remove, move) [default: print]
-m <directory>, --move=<directory>        move duplicate files to directory
                                          (used with move action) [default: ./dups]
"""

__author__ = 'Darko Poljak <darko.poljak@gmail.com>'
__version__ = '0.1.0'
__license__ = 'GPLv3'

__all__ = [
    'file_dups', 'rm_file_dups', 'mv_file_dups', 'iter_file_dups'
]

import sys
import hashlib
import os
from collections import defaultdict


# some differences in python versions
if sys.version_info[0] == 3:
    def _do_encode(buf):
        return buf

    def _dict_iter_items(d):
        return d.items()
else:
    def _do_encode(buf):
        return buf

    def _dict_iter_items(d):
        return d.iteritems()


def _filehash(filepath, hashalg, block_size):
    """Calculate secure hash for given file content using
       specified hash algorithm. Use block_size block size
       when reading file content.
    """
    md = hashlib.new(hashalg)
    with open(filepath, "rb") as f:
        for buf in iter(lambda: f.read(block_size), b''):
            md.update(_do_encode(buf))
    return md.hexdigest()


def file_dups(topdirs=['./'], hashalg='md5', block_size=4096):
    """Find duplicate files in directory list. Return directory
       with keys equal to file hash value and value as list of
       file paths whose content is the same.
    """
    dups = defaultdict(list)
    for topdir in topdirs:
        for dirpath, dirnames, filenames in os.walk(topdir):
            for fname in filenames:
                fpath = os.path.join(dirpath, fname)
                hexmd = _filehash(fpath, hashalg, block_size)
                dups[hexmd].append(fpath)
    result = {k: v for k, v in _dict_iter_items(dups) if len(v) > 1}
    return result


def rm_file_dups(topdirs=['./'], hashalg='md5', block_size=4096):
    """Remove duplicate files found in specified directory list.
       First file in list is kept.
    """
    for files in do_with_file_dups(topdirs, hashalg, block_size):
        for f in files:
            os.remove(f)


def mv_file_dups(topdirs=['./'], hashalg='md5', block_size=4096, dest_dir='dups'):
    """Move duplicate files found in specified directory list.
       First file in list is kept in the original directory.
    """
    if not os.path.exists(dest_dir):
        os.mkdir(dest_dir)
    if not os.path.isdir(dest_dir):
        raise OSError('%s is not a directory' % dest_dir)
    import shutil
    for files in do_with_file_dups(topdirs, hashalg, block_size):
        for i, f in enumerate(files):
            if i > 0:
                shutil.move(f, dest_dir)


def iter_file_dups(topdirs=['./'], hashalg='md5', block_size=4096):
    """Yield list of duplicate files when found in specified directory list.
    """
    dups = file_dups(topdirs, hashalg, block_size)
    for fpaths in dups.itervalues():
        yield fpaths


def main():
    """Main when used as script. See usage (--help).
    """
    import json
    from docopt import docopt

    arguments = docopt(__doc__)
 
    topdirs = args['<directory>']
    if not topdirs:
        topdirs = ['./']

    action = args['--action']
    try:
        bs = int(args['--block-size'])
        args['--block-size'] = bs
    except ValueError:
        print('Invalid block size "%s"' % args['--block-size'])
        sys.exit(1)

    if action == 'print':
        dups = file_dups(topdirs, args['--digest-alg'], args['--block-size'])
        print(json.dumps(dict(dups), indent=4))
    elif action == 'move':
        mv_file_dups(topdirs, args['--digest-alg'], args['--block-size'],
                     args['--move'])
    elif action == 'remove':
        rm_file_dups(topdirs, args['--digest-alg'], args['--block-size'])
    else:
        print('Invalid action "%s"' % action)


# if used as script call main function
if __name__ == '__main__':
   main()