#!/usr/bin/env python3

import sys

file = sys.argv[1]
line = int(sys.argv[2]) - 1
indent_expected = int(sys.argv[3])
indent_found = int(sys.argv[4])

with open(file) as f:
    lines = f.readlines()

    before = lines[:line]

    is_a_list = lines[line].strip()[0] == '-'

    i = line
    while (i < len(lines) and
           (lines[i].strip() == '' or
            (not is_a_list and lines[i].startswith(indent_found * ' ')) or
            (is_a_list and (lines[i].startswith(indent_found * ' ' + '-') or
                            lines[i].startswith(indent_found * ' ' + ' '))))):
        i += 1

    contents = lines[line:i]
    after = lines[i:]

    new_contents = []
    for line in contents:
        if line.strip() != '':
            line = (indent_expected * ' ') + line[indent_found:]
        new_contents.append(line)

with open(file, 'w') as f:
    f.write(''.join(before))
    f.write(''.join(new_contents))
    f.write(''.join(after))