#!/usr/bin/env python3

import argparse
import json
import os
import sys
from datetime import datetime

__version__ = "20251110.02"


def filter_entries(entries, years=6, months=6, weeks=6, days=6, head=5):
    def date2day(d):
        return d.strftime("%Y-%m-%d")

    def date2week(d):
        return f"{d.strftime('%Y')}w{d.date().isocalendar()[1]}"

    def date2month(d):
        return d.strftime("%Y-%m")

    def date2year(d):
        return d.strftime("%Y")

    def date2list(d):
        return [date2day(d), date2week(d), date2month(d), date2year(d)]

    def reduce(entries, date2id, start_date, name, max_age):
        ids = []
        reduced = []
        for entry in entries:
            id = date2id(entry[1])
            age = (start_date - entry[1].date()).days
            if age > 0 and age < max_age:
                if id in ids:
                    continue
                ids.append(id)
                reduced.append(entry + [name, id, age])

        reduced.sort(key=lambda x: x[1], reverse=True)
        return reduced

    entries = sorted(entries, key=lambda x: x[1])
    original_entries = entries.copy()
    result = []
    for i in range(min(head, len(entries))):
        last_entry = entries.pop()
        result.append(last_entry + ["head", str(i + 1), None])

    start_date = result[-1][1].date()
    result.extend([entry for i, entry in enumerate(reduce(entries, date2day, start_date, "day", days * 1)) if i < days])
    start_date = result[-1][1].date()
    result.extend(
        [entry for i, entry in enumerate(reduce(entries, date2week, start_date, "week", weeks * 7)) if i < weeks]
    )
    start_date = result[-1][1].date()
    result.extend(
        [entry for i, entry in enumerate(reduce(entries, date2month, start_date, "month", months * 31)) if i < months]
    )
    start_date = result[-1][1].date()
    result.extend(
        [entry for i, entry in enumerate(reduce(entries, date2year, start_date, "year", years * 366)) if i < years]
    )

    result.sort(key=lambda x: x[1], reverse=True)

    filtered = [f + ["removed", "", None] for f in original_entries if f[0] not in [r[0] for r in result]]

    return result, filtered


def get_opts():
    parser = argparse.ArgumentParser(
        description="Filter entries based on file timestamps, or parsed dates for keeping backups for example. Filenames read from stdin. Note: you must use any of --keep, --drop, --stderr, --json. ",
        epilog="Example usage (watch out for actual deletion): # ls | grep ^backup- | daterake -n 5 --drop -s | xargs echo rm -f ",
    )
    parser.add_argument("--version", action="version", version=__version__)

    parser.add_argument(
        "--head", "-n", type=int, default=1, help="Number of latest entries to keep. Default: %(default)s"
    )
    parser.add_argument(
        "--days", "-d", type=int, default=7, help="Number of daily entries to keep. Default: %(default)s"
    )
    parser.add_argument(
        "--weeks", "-w", type=int, default=6, help="Number of weekly entries to keep. Default: %(default)s"
    )
    parser.add_argument(
        "--months", "-m", type=int, default=6, help="Number of monthly entries to keep. Default: %(default)s"
    )
    parser.add_argument(
        "--years", "-y", type=int, default=4, help="Number of annual entries to keep. Default: %(default)s"
    )
    parser.add_argument(
        "--parse", default=None, help="Parse names, instead of using file timestamps (ex: 'service-%%Y-%%m-%%d.log')"
    )
    parser.add_argument("--json", default=False, action="store_true", help="Print output as JSON")
    parser.add_argument("--verbose", "-v", default=False, action="store_true", help="Print output as verbose table")
    parser.add_argument("--stderr", "-s", default=False, action="store_true", help="Print full output in stderr")
    parser.add_argument("--drop", "--invert", default=False, action="store_true", help="Print the names to drop")
    parser.add_argument("--keep", default=False, action="store_true", help="Print the names to keep")

    args = parser.parse_args()

    if args.head < 1:
        parser.error("HEAD must be at least 1")
    if not any((args.keep, args.drop, args.stderr, args.json)):
        parser.error("Not using any of keep, drop, json or stderr will not print out anything.")

    if sys.stdin.isatty():
        parser.print_help()
        sys.exit(0)
    return args


def printable_date(d):
    return d.strftime("%Y-%m-%d %a %H:%M:%S")


def print_table(printable, verbose, file=sys.stdout):
    for entry in printable:
        if verbose:
            print(f"{entry[0]:20s}  {printable_date(entry[1])}  {entry[2]:5s}  {entry[3]}", file=file)
        else:
            print(entry[0], file=file)


def main():

    args = get_opts()
    entries = []

    for entry_file in [f.rstrip("\n") for f in sys.stdin.readlines()]:
        if args.parse is not None:
            entries.append([entry_file, datetime.strptime(entry_file, args.parse)])
        else:
            entries.append([entry_file, datetime.fromtimestamp(os.path.getmtime(entry_file))])

    keep, remove = filter_entries(entries, args.years, args.months, args.weeks, args.days, args.head)

    if args.json:
        print(
            json.dumps(
                [
                    {"name": f[0], "date": printable_date(f[1]), "match": f[2], "match-id": f[3], "age": f[4]}
                    for f in keep + remove
                ],
                indent=2,
            )
        )
    else:
        if args.keep:
            print_table(keep, args.verbose)
        if args.drop:
            print_table(remove, args.verbose)
        if args.stderr:
            print_table(keep, True, file=sys.stderr)
            print_table(remove, True, file=sys.stderr)


if __name__ == "__main__":
    main()