#!/usr/bin/env bash
set -euo pipefail

BASE="${BASE:-/srv/backups}"
KEEP_DAILY_DAYS="${KEEP_DAILY_DAYS:-7}"
KEEP_WEEKLY_DAYS="${KEEP_WEEKLY_DAYS:-365}"

python3 - <<'PY' "$BASE" "$KEEP_DAILY_DAYS" "$KEEP_WEEKLY_DAYS"
import datetime as dt
import os
import sys

base = sys.argv[1]
keep_daily_days = int(sys.argv[2])
keep_weekly_days = int(sys.argv[3])
now = dt.datetime.now().timestamp()

if not os.path.isdir(base):
	print(f"Backup base not found: {base}")
	sys.exit(0)

files = []
for root, _, names in os.walk(base):
	parts = set(os.path.normpath(root).split(os.sep))
	preserve_latest = "latest" in parts
	for name in names:
		path = os.path.join(root, name)
		if not os.path.isfile(path):
			continue
		try:
			mtime = os.path.getmtime(path)
		except OSError:
			continue
		age_days = (now - mtime) / 86400
		files.append((path, root, mtime, age_days, preserve_latest))

to_delete = set()

# Delete anything older than weekly window (unless it's in a latest folder)
for path, _, _, age_days, preserve_latest in files:
	if not preserve_latest and age_days > keep_weekly_days:
		to_delete.add(path)

# For weekly window, keep one file per week per directory (latest by mtime)
weekly_candidates = {}
for path, root, mtime, age_days, preserve_latest in files:
	if preserve_latest:
		continue
	if keep_daily_days < age_days <= keep_weekly_days:
		iso = dt.datetime.fromtimestamp(mtime).isocalendar()
		key = (root, iso.year, iso.week)
		best = weekly_candidates.get(key)
		if best is None or mtime > best[1]:
			weekly_candidates[key] = (path, mtime)

weekly_keep = {v[0] for v in weekly_candidates.values()}

for path, _, _, age_days, preserve_latest in files:
	if preserve_latest:
		continue
	if keep_daily_days < age_days <= keep_weekly_days and path not in weekly_keep:
		to_delete.add(path)

deleted = 0
for path in sorted(to_delete):
	try:
		os.remove(path)
		print(path)
		deleted += 1
	except OSError:
		pass

print(f"Retention complete for {base} (deleted {deleted} files)")
PY

echo "Policy: daily <= ${KEEP_DAILY_DAYS}d, weekly <= ${KEEP_WEEKLY_DAYS}d"