#!/usr/bin/env python
# Copyright 2011-2025 Gentoo Authors; Distributed under the GPL v2

import os
import sys

if len(sys.argv) != 4:
    print(
        "need 3 args, first being directory to scan, second being latest, third being it's size"
    )
    sys.exit(1)

path = sys.argv[1]
maxsize = int(sys.argv[3])
if len(sys.argv[2]) != 8:
    print("date arg must be YYYYMMDD")
    sys.exit(1)
root = sys.argv[2]

if not hasattr(__builtins__, "set"):
    from sets import Set as set
file_list = [x for x in os.listdir(path) if os.path.isfile(os.path.join(path, x))]
pref_name = "snapshot-"
post_name = ".patch.bz2"
deltas = [x for x in file_list if x.startswith(pref_name) and x.endswith(post_name)]
chains = {}
for x in deltas:
    try:
        start, end = x[len(pref_name) : -len(post_name)].split("-")
    except ValueError:
        continue
    if end in chains:
        print("warning, end %s already exists; this is a bit weird" % end)
        continue
    chains[end] = start

save_files = set()
node = root
count = 0
while node in chains:
    s = f"{pref_name}{chains[node]}-{node}{post_name}"
    count += os.stat(os.path.join(path, s)).st_size
    if count > maxsize:
        break
    save_files.update([s, s + ".md5sum", s + ".gpgsig"])
    node = chains[node]

for x in file_list:
    if x not in save_files:
        print("nuking %s" % x)
        try:
            os.unlink(os.path.join(path, x))
        except OSError as oe:
            print("failed removing {} cause of {}".format(os.path.join(path, x), str(oe)))